gecko-dev/dom/bindings/Codegen.py

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# You can obtain one at http://mozilla.org/MPL/2.0/.

# Common codegen classes.

import os
import string
import operator

from WebIDL import *
from Configuration import NoSuchDescriptorError

AUTOGENERATED_WARNING_COMMENT = \
    "/* THIS FILE IS AUTOGENERATED - DO NOT EDIT */\n\n"
ADDPROPERTY_HOOK_NAME = '_addProperty'
FINALIZE_HOOK_NAME = '_finalize'
TRACE_HOOK_NAME = '_trace'
CONSTRUCT_HOOK_NAME = '_constructor'
HASINSTANCE_HOOK_NAME = '_hasInstance'

def replaceFileIfChanged(filename, newContents):
    """
    Read a copy of the old file, so that we don't touch it if it hasn't changed.
    Returns True if the file was updated, false otherwise.
    """
    oldFileContents = ""
    try:
        oldFile = open(filename, 'rb')
        oldFileContents = ''.join(oldFile.readlines())
        oldFile.close()
    except:
        pass

    if newContents == oldFileContents:
        return False

    f = open(filename, 'wb')
    f.write(newContents)
    f.close()

def toStringBool(arg):
    return str(not not arg).lower()

def toBindingNamespace(arg):
    return re.sub("((_workers)?$)", "Binding\\1", arg);

class CGThing():
    """
    Abstract base class for things that spit out code.
    """
    def __init__(self):
        pass # Nothing for now
    def declare(self):
        """Produce code for a header file."""
        assert(False)  # Override me!
    def define(self):
        """Produce code for a cpp file."""
        assert(False) # Override me!

class CGNativePropertyHooks(CGThing):
    """
    Generate a NativePropertyHooks for a given descriptor
    """
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        if self.descriptor.workers:
            return ""
        return "  extern const NativePropertyHooks NativeHooks;\n"
    def define(self):
        if self.descriptor.workers:
            return ""
        parent = self.descriptor.interface.parent
        parentHooks = ("&" + toBindingNamespace(parent.identifier.name) + "::NativeHooks"
                       if parent else 'NULL')
        return """
const NativePropertyHooks NativeHooks = { ResolveProperty, EnumerateProperties, %s };
""" % parentHooks

class CGDOMJSClass(CGThing):
    """
    Generate a DOMJSClass for a given descriptor
    """
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        return "  extern DOMJSClass Class;\n"
    def define(self):
        traceHook = TRACE_HOOK_NAME if self.descriptor.customTrace else 'NULL'
        protoList = ['prototypes::id::' + proto for proto in self.descriptor.prototypeChain]
        # Pad out the list to the right length with _ID_Count so we
        # guarantee that all the lists are the same length.  _ID_Count
        # is never the ID of any prototype, so it's safe to use as
        # padding.
        while len(protoList) < self.descriptor.config.maxProtoChainLength:
            protoList.append('prototypes::id::_ID_Count')
        prototypeChainString = ', '.join(protoList)
        nativeHooks = "NULL" if self.descriptor.workers else "&NativeHooks"
        return """
DOMJSClass Class = {
  { "%s",
    JSCLASS_IS_DOMJSCLASS | JSCLASS_HAS_RESERVED_SLOTS(1),
    %s, /* addProperty */
    JS_PropertyStub,       /* delProperty */
    JS_PropertyStub,       /* getProperty */
    JS_StrictPropertyStub, /* setProperty */
    JS_EnumerateStub,
    JS_ResolveStub,
    JS_ConvertStub,
    %s, /* finalize */
    NULL,                  /* checkAccess */
    NULL,                  /* call */
    NULL,                  /* hasInstance */
    NULL,                  /* construct */
    %s, /* trace */
    JSCLASS_NO_INTERNAL_MEMBERS
  },
  { %s },
  -1, %s,
  %s
};
""" % (self.descriptor.interface.identifier.name,
       ADDPROPERTY_HOOK_NAME if self.descriptor.concrete and not self.descriptor.workers and self.descriptor.wrapperCache else 'JS_PropertyStub',
       FINALIZE_HOOK_NAME, traceHook, prototypeChainString,
       str(self.descriptor.nativeIsISupports).lower(),
       nativeHooks)

class CGPrototypeJSClass(CGThing):
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        # We're purely for internal consumption
        return ""
    def define(self):
        return """
static JSClass PrototypeClass = {
  "%sPrototype", 0,
  JS_PropertyStub,       /* addProperty */
  JS_PropertyStub,       /* delProperty */
  JS_PropertyStub,       /* getProperty */
  JS_StrictPropertyStub, /* setProperty */
  JS_EnumerateStub,
  JS_ResolveStub,
  JS_ConvertStub,
  NULL,                  /* finalize */
  NULL,                  /* checkAccess */
  NULL,                  /* call */
  NULL,                  /* hasInstance */
  NULL,                  /* construct */
  NULL,                  /* trace */
  JSCLASS_NO_INTERNAL_MEMBERS
};
""" % (self.descriptor.interface.identifier.name)

class CGInterfaceObjectJSClass(CGThing):
    def __init__(self, descriptor):
        CGThing.__init__(self)
        self.descriptor = descriptor
    def declare(self):
        # We're purely for internal consumption
        return ""
    def define(self):
        if not self.descriptor.hasInstanceInterface:
            return ""
        ctorname = "NULL" if not self.descriptor.interface.ctor() else CONSTRUCT_HOOK_NAME
        hasinstance = HASINSTANCE_HOOK_NAME
        return """
static JSClass InterfaceObjectClass = {
  "Function", 0,
  JS_PropertyStub,       /* addProperty */
  JS_PropertyStub,       /* delProperty */
  JS_PropertyStub,       /* getProperty */
  JS_StrictPropertyStub, /* setProperty */
  JS_EnumerateStub,
  JS_ResolveStub,
  JS_ConvertStub,
  NULL,                  /* finalize */
  NULL,                  /* checkAccess */
  %s, /* call */
  %s, /* hasInstance */
  %s, /* construct */
  NULL,                  /* trace */
  JSCLASS_NO_INTERNAL_MEMBERS
};
""" % (ctorname, hasinstance, ctorname)

class CGList(CGThing):
    """
    Generate code for a list of GCThings.  Just concatenates them together, with
    an optional joiner string.  "\n" is a common joiner.
    """
    def __init__(self, children, joiner=""):
        CGThing.__init__(self)
        self.children = children
        self.joiner = joiner
    def append(self, child):
        self.children.append(child)
    def prepend(self, child):
        self.children.insert(0, child)
    def declare(self):
        return self.joiner.join([child.declare() for child in self.children
                                 if child is not None])
    def define(self):
        return self.joiner.join([child.define() for child in self.children
                                 if child is not None])

class CGGeneric(CGThing):
    """
    A class that spits out a fixed string into the codegen.  Can spit out a
    separate string for the declaration too.
    """
    def __init__(self, define="", declare=""):
        self.declareText = declare
        self.defineText = define
    def declare(self):
        return self.declareText
    def define(self):
        return self.defineText

# We'll want to insert the indent at the beginnings of lines, but we
# don't want to indent empty lines.  So only indent lines that have a
# non-newline character on them.
lineStartDetector = re.compile("^(?=[^\n#])", re.MULTILINE)
class CGIndenter(CGThing):
    """
    A class that takes another CGThing and generates code that indents that
    CGThing by some number of spaces.  The default indent is two spaces.
    """
    def __init__(self, child, indentLevel=2):
        CGThing.__init__(self)
        self.child = child
        self.indent = " " * indentLevel
    def declare(self):
        decl = self.child.declare()
        if decl is not "":
            return re.sub(lineStartDetector, self.indent, decl)
        else:
            return ""
    def define(self):
        defn = self.child.define()
        if defn is not "":
            return re.sub(lineStartDetector, self.indent, defn)
        else:
            return ""

class CGWrapper(CGThing):
    """
    Generic CGThing that wraps other CGThings with pre and post text.
    """
    def __init__(self, child, pre="", post="", declarePre=None,
                 declarePost=None, definePre=None, definePost=None,
                 declareOnly=False, defineOnly=False, reindent=False):
        CGThing.__init__(self)
        self.child = child
        self.declarePre = declarePre or pre
        self.declarePost = declarePost or post
        self.definePre = definePre or pre
        self.definePost = definePost or post
        self.declareOnly = declareOnly
        self.defineOnly = defineOnly
        self.reindent = reindent
    def declare(self):
        if self.defineOnly:
            return ''
        decl = self.child.declare()
        if self.reindent:
            # We don't use lineStartDetector because we don't want to
            # insert whitespace at the beginning of our _first_ line.
            decl = stripTrailingWhitespace(
                decl.replace("\n", "\n" + (" " * len(self.declarePre))))
        return self.declarePre + decl + self.declarePost
    def define(self):
        if self.declareOnly:
            return ''
        defn = self.child.define()
        if self.reindent:
            # We don't use lineStartDetector because we don't want to
            # insert whitespace at the beginning of our _first_ line.
            defn = stripTrailingWhitespace(
                defn.replace("\n", "\n" + (" " * len(self.definePre))))
        return self.definePre + defn + self.definePost

class CGNamespace(CGWrapper):
    def __init__(self, namespace, child, declareOnly=False):
        pre = "namespace %s {\n" % namespace
        post = "} // namespace %s\n" % namespace
        CGWrapper.__init__(self, child, pre=pre, post=post,
                           declareOnly=declareOnly)
    @staticmethod
    def build(namespaces, child, declareOnly=False):
        """
        Static helper method to build multiple wrapped namespaces.
        """
        if not namespaces:
            return CGWrapper(child, declareOnly=declareOnly)
        inner = CGNamespace.build(namespaces[1:], child, declareOnly=declareOnly)
        return CGNamespace(namespaces[0], inner, declareOnly=declareOnly)

class CGIncludeGuard(CGWrapper):
    """
    Generates include guards for a header.
    """
    def __init__(self, prefix, child):
        """|prefix| is the filename without the extension."""
        define = 'mozilla_dom_%s_h__' % prefix
        CGWrapper.__init__(self, child,
                           declarePre='#ifndef %s\n#define %s\n\n' % (define, define),
                           declarePost='\n#endif // %s\n' % define)

def getTypes(descriptor):
    """
    Get all argument and return types for all members of the descriptor
    """
    members = [m for m in descriptor.interface.members]
    signatures = [s for m in members if m.isMethod() for s in m.signatures()]
    types = []
    for s in signatures:
        assert len(s) == 2
        (returnType, arguments) = s
        types.append(returnType)
        types.extend([a.type for a in arguments])

    types.extend(a.type for a in members if a.isAttr())
    return types

class CGHeaders(CGWrapper):
    """
    Generates the appropriate include statements.
    """
    def __init__(self, descriptors, dictionaries, declareIncludes,
                 defineIncludes, child):
        """
        Builds a set of includes to cover |descriptors|.

        Also includes the files in |declareIncludes| in the header
        file and the files in |defineIncludes| in the .cpp.
        """

        # Determine the filenames for which we need headers.
        interfaceDeps = [d.interface for d in descriptors]
        ancestors = []
        for iface in interfaceDeps:
            while iface.parent:
                ancestors.append(iface.parent)
                iface = iface.parent
        interfaceDeps.extend(ancestors)
        bindingIncludes = set(self.getDeclarationFilename(d) for d in interfaceDeps)

        # Grab all the implementation declaration files we need.
        implementationIncludes = set(d.headerFile for d in descriptors)

        # Now find all the things we'll need as arguments because we
        # need to wrap or unwrap them.
        bindingHeaders = set()
        for d in descriptors:
            types = getTypes(d)
            for dictionary in dictionaries:
                curDict = dictionary
                while curDict:
                    types.extend([m.type for m in curDict.members])
                    curDict = curDict.parent

            for t in types:
                if t.unroll().isUnion():
                    # UnionConversions.h includes UnionTypes.h
                    bindingHeaders.add("mozilla/dom/UnionConversions.h")
                elif t.unroll().isInterface():
                    if t.unroll().isSpiderMonkeyInterface():
                        bindingHeaders.add("jsfriendapi.h")
                        bindingHeaders.add("mozilla/dom/TypedArray.h")
                    else:
                        typeDesc = d.getDescriptor(t.unroll().inner.identifier.name)
                        if typeDesc is not None:
                            implementationIncludes.add(typeDesc.headerFile)
                            bindingHeaders.add(self.getDeclarationFilename(typeDesc.interface))
                elif t.unroll().isDictionary():
                    bindingHeaders.add(self.getDeclarationFilename(t.unroll().inner))

        declareIncludes = set(declareIncludes)
        for d in dictionaries:
            if d.parent:
                declareIncludes.add(self.getDeclarationFilename(d.parent))
            bindingHeaders.add(self.getDeclarationFilename(d))

        # Let the machinery do its thing.
        def _includeString(includes):
            return ''.join(['#include "%s"\n' % i for i in includes]) + '\n'
        CGWrapper.__init__(self, child,
                           declarePre=_includeString(sorted(declareIncludes)),
                           definePre=_includeString(sorted(set(defineIncludes) |
                                                           bindingIncludes |
                                                           bindingHeaders |
                                                           implementationIncludes)))
    @staticmethod
    def getDeclarationFilename(decl):
        # Use our local version of the header, not the exported one, so that
        # test bindings, which don't export, will work correctly.
        basename = os.path.basename(decl.filename())
        return basename.replace('.webidl', 'Binding.h')

def SortedTuples(l):
    """
    Sort a list of tuples based on the first item in the tuple
    """
    return sorted(l, key=operator.itemgetter(0))

def SortedDictValues(d):
    """
    Returns a list of values from the dict sorted by key.
    """
    # Create a list of tuples containing key and value, sorted on key.
    d = SortedTuples(d.items())
    # We're only interested in the values.
    return (i[1] for i in d)

def UnionTypes(descriptors):
    """
    Returns a tuple containing a set of header filenames to include, a set of
    tuples containing a type declaration and a boolean if the type is a struct
    for member types of the unions and a CGList containing CGUnionStructs for
    every union.
    """

    # Now find all the things we'll need as arguments and return values because
    # we need to wrap or unwrap them.
    headers = set()
    declarations = set()
    unionStructs = dict()
    for d in descriptors:
        if d.interface.isExternal():
            continue

        for t in getTypes(d):
            t = t.unroll()
            if t.isUnion():
                name = str(t)
                if not name in unionStructs:
                    unionStructs[name] = CGUnionStruct(t, d)
                    for f in t.flatMemberTypes:
                        f = f.unroll()
                        if f.isInterface():
                            if f.isSpiderMonkeyInterface():
                                headers.add("jsfriendapi.h")
                                headers.add("mozilla/dom/TypedArray.h")
                            else:
                                typeDesc = d.getDescriptor(f.inner.identifier.name)
                                if typeDesc is not None:
                                    declarations.add((typeDesc.nativeType, False))
                        elif f.isDictionary():
                            declarations.add((f.inner.identifier.name, True))

    return (headers, declarations, CGList(SortedDictValues(unionStructs), "\n"))

def UnionConversions(descriptors):
    """
    Returns a CGThing to declare all union argument conversion helper structs.
    """
    # Now find all the things we'll need as arguments because we
    # need to unwrap them.
    unionConversions = dict()
    for d in descriptors:
        if d.interface.isExternal():
            continue

        def addUnionTypes(type):
            if type.isUnion():
                type = type.unroll()
                name = str(type)
                if not name in unionConversions:
                    unionConversions[name] = CGUnionConversionStruct(type, d)

        members = [m for m in d.interface.members]
        signatures = [s for m in members if m.isMethod() for s in m.signatures()]
        for s in signatures:
            assert len(s) == 2
            (_, arguments) = s
            for a in arguments:
                addUnionTypes(a.type)

        for m in members:
            if m.isAttr() and not m.readonly:
                addUnionTypes(m.type)

    return CGWrapper(CGList(SortedDictValues(unionConversions), "\n"),
                     post="\n\n")

class Argument():
    """
    A class for outputting the type and name of an argument
    """
    def __init__(self, argType, name):
        self.argType = argType
        self.name = name
    def __str__(self):
        return self.argType + ' ' + self.name

class CGAbstractMethod(CGThing):
    """
    An abstract class for generating code for a method.  Subclasses
    should override definition_body to create the actual code.

    descriptor is the descriptor for the interface the method is associated with

    name is the name of the method as a string

    returnType is the IDLType of the return value

    args is a list of Argument objects

    inline should be True to generate an inline method, whose body is
    part of the declaration.

    static should be True to generate a static method, which only has
    a definition.
    """
    def __init__(self, descriptor, name, returnType, args, inline=False, static=False):
        CGThing.__init__(self)
        self.descriptor = descriptor
        self.name = name
        self.returnType = returnType
        self.args = args
        self.inline = inline
        self.static = static
    def _argstring(self):
        return ', '.join([str(a) for a in self.args])
    def _decorators(self):
        decorators = []
        if self.inline:
            decorators.append('inline')
        if self.static:
            decorators.append('static')
        decorators.append(self.returnType)
        return ' '.join(decorators)
    def declare(self):
        if self.inline:
            return self._define()
        return "\n  %s %s(%s);\n" % (self._decorators(), self.name, self._argstring())
    def _define(self):
        return self.definition_prologue() + "\n" + self.definition_body() + self.definition_epilogue()
    def define(self):
        return "" if self.inline else self._define()
    def definition_prologue(self):
        maybeNewline = " " if self.inline else "\n"
        return "\n%s%s%s(%s)\n{" % (self._decorators(), maybeNewline,
                                    self.name, self._argstring())
    def definition_epilogue(self):
        return "\n}\n"
    def definition_body(self):
        assert(False) # Override me!

class CGAbstractStaticMethod(CGAbstractMethod):
    """
    Abstract base class for codegen of implementation-only (no
    declaration) static methods.
    """
    def __init__(self, descriptor, name, returnType, args):
        CGAbstractMethod.__init__(self, descriptor, name, returnType, args,
                                  inline=False, static=True)
    def declare(self):
        # We only have implementation
        return ""

class CGAbstractClassHook(CGAbstractStaticMethod):
    """
    Meant for implementing JSClass hooks, like Finalize or Trace. Does very raw
    'this' unwrapping as it assumes that the unwrapped type is always known.
    """
    def __init__(self, descriptor, name, returnType, args):
        CGAbstractStaticMethod.__init__(self, descriptor, name, returnType,
                                        args)

    def definition_body_prologue(self):
        return """
  %s* self = UnwrapDOMObject<%s>(obj);
""" % (self.descriptor.nativeType, self.descriptor.nativeType)

    def definition_body(self):
        return self.definition_body_prologue() + self.generate_code()

    def generate_code(self):
        # Override me
        assert(False)

class CGAddPropertyHook(CGAbstractClassHook):
    """
    A hook for addProperty, used to preserve our wrapper from GC.
    """
    def __init__(self, descriptor):
        args = [Argument('JSContext*', 'cx'), Argument('JSHandleObject', 'obj'),
                Argument('JSHandleId', 'id'), Argument('jsval*', 'vp')]
        CGAbstractClassHook.__init__(self, descriptor, ADDPROPERTY_HOOK_NAME,
                                     'JSBool', args)

    def generate_code(self):
        # FIXME https://bugzilla.mozilla.org/show_bug.cgi?id=774279
        # Using a real trace hook might enable us to deal with non-nsISupports
        # wrappercached things here.
        assert self.descriptor.nativeIsISupports
        return """  nsContentUtils::PreserveWrapper(reinterpret_cast<nsISupports*>(self), self);
  return true;"""

class CGClassFinalizeHook(CGAbstractClassHook):
    """
    A hook for finalize, used to release our native object.
    """
    def __init__(self, descriptor):
        args = [Argument('JSFreeOp*', 'fop'), Argument('JSObject*', 'obj')]
        CGAbstractClassHook.__init__(self, descriptor, FINALIZE_HOOK_NAME,
                                     'void', args)

    def generate_code(self):
        if self.descriptor.customFinalize:
            return """  if (self) {
    self->%s(%s);
  }""" % (self.name, self.args[0].name)
        clearWrapper = "self->ClearWrapper();\n  " if self.descriptor.wrapperCache else ""
        if self.descriptor.workers:
            release = "self->Release();"
        else:
            assert self.descriptor.nativeIsISupports
            release = """XPCJSRuntime *rt = nsXPConnect::GetRuntimeInstance();
  if (rt) {
    rt->DeferredRelease(reinterpret_cast<nsISupports*>(self));
  } else {
    NS_RELEASE(self);
  }"""
        return """
  %s%s""" % (clearWrapper, release)

class CGClassTraceHook(CGAbstractClassHook):
    """
    A hook to trace through our native object; used for GC and CC
    """
    def __init__(self, descriptor):
        args = [Argument('JSTracer*', 'trc'), Argument('JSObject*', 'obj')]
        CGAbstractClassHook.__init__(self, descriptor, TRACE_HOOK_NAME, 'void',
                                     args)

    def generate_code(self):
        return """  if (self) {
    self->%s(%s);
  }""" % (self.name, self.args[0].name)

class CGClassConstructHook(CGAbstractStaticMethod):
    """
    JS-visible constructor for our objects
    """
    def __init__(self, descriptor):
        args = [Argument('JSContext*', 'cx'), Argument('unsigned', 'argc'), Argument('JS::Value*', 'vp')]
        CGAbstractStaticMethod.__init__(self, descriptor, CONSTRUCT_HOOK_NAME,
                                        'JSBool', args)
        self._ctor = self.descriptor.interface.ctor()

    def define(self):
        if not self._ctor:
            return ""
        return CGAbstractStaticMethod.define(self)

    def definition_body(self):
        return self.generate_code()

    def generate_code(self):
        preamble = """
  JSObject* obj = JS_GetGlobalForObject(cx, JSVAL_TO_OBJECT(JS_CALLEE(cx, vp)));
"""
        if self.descriptor.workers:
            preArgs = ["cx", "obj"]
        else:
            preamble += """
  nsISupports* global;
  xpc_qsSelfRef globalRef;
  {
    nsresult rv;
    JS::Value val = OBJECT_TO_JSVAL(obj);
    rv = xpc_qsUnwrapArg<nsISupports>(cx, val, &global, &globalRef.ptr, &val);
    if (NS_FAILED(rv)) {
      return Throw<true>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);
    }
  }
"""
            preArgs = ["global"]

        name = self._ctor.identifier.name
        nativeName = MakeNativeName(self.descriptor.binaryNames.get(name, name))
        callGenerator = CGMethodCall(preArgs, nativeName, True,
                                     self.descriptor, self._ctor)
        return preamble + callGenerator.define();

class CGClassHasInstanceHook(CGAbstractStaticMethod):
    def __init__(self, descriptor):
        args = [Argument('JSContext*', 'cx'), Argument('JSHandleObject', 'obj'),
                Argument('const jsval*', 'v'), Argument('JSBool*', 'bp')]
        CGAbstractStaticMethod.__init__(self, descriptor, HASINSTANCE_HOOK_NAME,
                                        'JSBool', args)

    def define(self):
        if not self.descriptor.hasInstanceInterface:
            return ""
        return CGAbstractStaticMethod.define(self)

    def definition_body(self):
        return self.generate_code()

    def generate_code(self):
        return """  if (!v->isObject()) {
    *bp = false;
    return true;
  }

  jsval protov;
  if (!JS_GetProperty(cx, obj, "prototype", &protov))
    return false;
  if (!protov.isObject()) {
    JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_BAD_PROTOTYPE,
                         "%s");
    return false;
  }
  JSObject *objProto = &protov.toObject();

  JSObject* instance = &v->toObject();
  JSObject* proto = JS_GetPrototype(instance);
  while (proto) {
    if (proto == objProto) {
      *bp = true;
      return true;
    }
    proto = JS_GetPrototype(proto);
  }

  nsISupports* native =
    nsContentUtils::XPConnect()->GetNativeOfWrapper(cx, instance);
  nsCOMPtr<%s> qiResult = do_QueryInterface(native);
  *bp = !!qiResult;
  return true;
""" % (self.descriptor.name, self.descriptor.hasInstanceInterface)

def isChromeOnly(m):
    return m.getExtendedAttribute("ChromeOnly")

class PropertyDefiner:
    """
    A common superclass for defining things on prototype objects.

    Subclasses should implement generateArray to generate the actual arrays of
    things we're defining.  They should also set self.chrome to the list of
    things exposed to chrome and self.regular to the list of things exposed to
    web pages.  self.chrome must be a superset of self.regular but also include
    all the ChromeOnly stuff.
    """
    def __init__(self, descriptor, name):
        self.descriptor = descriptor
        self.name = name
        # self.prefCacheData will store an array of (prefname, bool*)
        # pairs for our bool var caches.  generateArray will fill it
        # in as needed.
        self.prefCacheData = []
    def hasChromeOnly(self):
        return len(self.chrome) > len(self.regular)
    def hasNonChromeOnly(self):
        return len(self.regular) > 0
    def variableName(self, chrome):
        if chrome and self.hasChromeOnly():
            return "sChrome" + self.name
        if self.hasNonChromeOnly():
            return "s" + self.name
        return "NULL"
    def usedForXrays(self, chrome):
        # We only need Xrays for methods and attributes.  And we only need them
        # for the non-chrome ones if we have no chromeonly things.  Otherwise
        # (we have chromeonly attributes) we need Xrays for the chrome
        # methods/attributes.  Finally, in workers there are no Xrays.
        return ((self.name is "Methods" or self.name is "Attributes") and
                chrome == self.hasChromeOnly() and
                not self.descriptor.workers)

    def __str__(self):
        # We only need to generate id arrays for things that will end
        # up used via ResolveProperty or EnumerateProperties.
        str = self.generateArray(self.regular, self.variableName(False),
                                 self.usedForXrays(False))
        if self.hasChromeOnly():
            str += self.generateArray(self.chrome, self.variableName(True),
                                      self.usedForXrays(True))
        return str

    @staticmethod
    def getControllingPref(interfaceMember):
        prefName = interfaceMember.getExtendedAttribute("Pref")
        if prefName is None:
            return None
        # It's a list of strings
        assert(len(prefName) is 1)
        assert(prefName[0] is not None)
        return prefName[0]

    def generatePrefableArray(self, array, name, specTemplate, specTerminator,
                              specType, getPref, getDataTuple, doIdArrays):
        """
        This method generates our various arrays.

        array is an array of interface members as passed to generateArray

        name is the name as passed to generateArray

        specTemplate is a template for each entry of the spec array

        specTerminator is a terminator for the spec array (inserted every time
          our controlling pref changes and at the end of the array)

        specType is the actual typename of our spec

        getPref is a callback function that takes an array entry and returns
          the corresponding pref value.

        getDataTuple is a callback function that takes an array entry and
          returns a tuple suitable for substitution into specTemplate.
        """

        # We want to generate a single list of specs, but with specTerminator
        # inserted at every point where the pref name controlling the member
        # changes.  That will make sure the order of the properties as exposed
        # on the interface and interface prototype objects does not change when
        # pref control is added to members while still allowing us to define all
        # the members in the smallest number of JSAPI calls.
        assert(len(array) is not 0)
        lastPref = getPref(array[0]) # So we won't put a specTerminator
                                     # at the very front of the list.
        specs = []
        prefableSpecs = []
        if doIdArrays:
            prefableIds = []

        prefableTemplate = '  { true, &%s[%d] }'
        prefCacheTemplate = '&%s[%d].enabled'
        def switchToPref(props, pref):
            # Remember the info about where our pref-controlled
            # booleans live.
            if pref is not None:
                props.prefCacheData.append(
                    (pref, prefCacheTemplate % (name, len(prefableSpecs)))
                    )
            # Set up pointers to the new sets of specs and ids
            # inside prefableSpecs and prefableIds
            prefableSpecs.append(prefableTemplate %
                                 (name + "_specs", len(specs)))

        switchToPref(self, lastPref)

        for member in array:
            curPref = getPref(member)
            if lastPref != curPref:
                # Terminate previous list
                specs.append(specTerminator)
                # And switch to our new pref
                switchToPref(self, curPref)
                lastPref = curPref
            # And the actual spec
            specs.append(specTemplate % getDataTuple(member))
        specs.append(specTerminator)
        prefableSpecs.append("  { false, NULL }");

        arrays = (("static %s %s_specs[] = {\n" +
                   ',\n'.join(specs) + "\n" +
                   "};\n\n" +
                   "static Prefable<%s> %s[] = {\n" +
                   ',\n'.join(prefableSpecs) + "\n" +
                   "};\n\n") % (specType, name, specType, name))
        if doIdArrays:
            arrays += ("static jsid %s_ids[%i] = { JSID_VOID };\n\n" %
                       (name, len(specs)))
        return arrays


# The length of a method is the maximum of the lengths of the
# argument lists of all its overloads.
def methodLength(method):
    signatures = method.signatures()
    return max([len(arguments) for (retType, arguments) in signatures])

class MethodDefiner(PropertyDefiner):
    """
    A class for defining methods on a prototype object.
    """
    def __init__(self, descriptor, name, static):
        PropertyDefiner.__init__(self, descriptor, name)

        methods = [m for m in descriptor.interface.members if
                   m.isMethod() and m.isStatic() == static]
        self.chrome = [{"name": m.identifier.name,
                        "length": methodLength(m),
                        "flags": "JSPROP_ENUMERATE",
                        "pref": PropertyDefiner.getControllingPref(m) }
                       for m in methods]
        self.regular = [{"name": m.identifier.name,
                         "length": methodLength(m),
                         "flags": "JSPROP_ENUMERATE",
                         "pref": PropertyDefiner.getControllingPref(m) }
                        for m in methods if not isChromeOnly(m)]
        if not descriptor.interface.parent and not static and not descriptor.workers:
            self.chrome.append({"name": 'QueryInterface',
                                "length": 1,
                                "flags": "0",
                                "pref": None })
            self.regular.append({"name": 'QueryInterface',
                                 "length": 1,
                                 "flags": "0",
                                 "pref": None })

        if static:
            if not descriptor.interface.hasInterfaceObject():
                # static methods go on the interface object
                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()
        else:
            if not descriptor.interface.hasInterfacePrototypeObject():
                # non-static methods go on the interface prototype object
                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()

    def generateArray(self, array, name, doIdArrays):
        if len(array) == 0:
            return ""

        def pref(m):
            return m["pref"]

        def specData(m):
            return (m["name"], m["name"], m["length"], m["flags"])

        return self.generatePrefableArray(
            array, name,
            '  JS_FN("%s", %s, %s, %s)',
            '  JS_FS_END',
            'JSFunctionSpec',
            pref, specData, doIdArrays)

class AttrDefiner(PropertyDefiner):
    def __init__(self, descriptor, name):
        PropertyDefiner.__init__(self, descriptor, name)
        self.name = name
        self.chrome = [m for m in descriptor.interface.members if m.isAttr()]
        self.regular = [m for m in self.chrome if not isChromeOnly(m)]

    def generateArray(self, array, name, doIdArrays):
        if len(array) == 0:
            return ""

        def flags(attr):
            flags = "JSPROP_SHARED | JSPROP_ENUMERATE"
            if generateNativeAccessors:
                flags = "JSPROP_NATIVE_ACCESSORS | " + flags
            elif attr.readonly:
                return "JSPROP_READONLY | " + flags
            return flags

        def getter(attr):
            return "get_" + attr.identifier.name

        def setter(attr):
            if attr.readonly:
                return "NULL"
            return "set_" + attr.identifier.name

        def specData(attr):
            return (attr.identifier.name, flags(attr), getter(attr),
                    setter(attr))

        return self.generatePrefableArray(
            array, name,
            '  { "%s", 0, %s, (JSPropertyOp)%s, (JSStrictPropertyOp)%s }',
            '  { 0, 0, 0, 0, 0 }',
            'JSPropertySpec',
            PropertyDefiner.getControllingPref, specData, doIdArrays)

class ConstDefiner(PropertyDefiner):
    """
    A class for definining constants on the interface object
    """
    def __init__(self, descriptor, name):
        PropertyDefiner.__init__(self, descriptor, name)
        self.name = name
        self.chrome = [m for m in descriptor.interface.members if m.isConst()]
        self.regular = [m for m in self.chrome if not isChromeOnly(m)]

    def generateArray(self, array, name, doIdArrays):
        if len(array) == 0:
            return ""

        def specData(const):
            return (const.identifier.name,
                    convertConstIDLValueToJSVal(const.value))

        return self.generatePrefableArray(
            array, name,
            '  { "%s", %s }',
            '  { 0, JSVAL_VOID }',
            'ConstantSpec',
            PropertyDefiner.getControllingPref, specData, doIdArrays)

class PropertyArrays():
    def __init__(self, descriptor):
        self.staticMethods = MethodDefiner(descriptor, "StaticMethods", True)
        self.methods = MethodDefiner(descriptor, "Methods", False)
        self.attrs = AttrDefiner(descriptor, "Attributes")
        self.consts = ConstDefiner(descriptor, "Constants")

    @staticmethod
    def arrayNames():
        return [ "staticMethods", "methods", "attrs", "consts" ]

    @staticmethod
    def xrayRelevantArrayNames():
        return [ "methods", "attrs" ]

    def hasChromeOnly(self):
        return reduce(lambda b, a: b or getattr(self, a).hasChromeOnly(),
                      self.arrayNames(), False)
    def variableNames(self, chrome):
        names = {}
        for array in self.arrayNames():
            names[array] = getattr(self, array).variableName(chrome)
        return names
    def __str__(self):
        define = ""
        for array in self.arrayNames():
            define += str(getattr(self, array))
        return define

class CGCreateInterfaceObjectsMethod(CGAbstractMethod):
    """
    Generate the CreateInterfaceObjects method for an interface descriptor.

    properties should be a PropertyArrays instance.
    """
    def __init__(self, descriptor, properties):
        args = [Argument('JSContext*', 'aCx'), Argument('JSObject*', 'aGlobal'),
                Argument('JSObject*', 'aReceiver')]
        CGAbstractMethod.__init__(self, descriptor, 'CreateInterfaceObjects', 'JSObject*', args)
        self.properties = properties
    def definition_body(self):
        protoChain = self.descriptor.prototypeChain
        if len(protoChain) == 1:
            getParentProto = "JS_GetObjectPrototype(aCx, aGlobal)"
        else:
            parentProtoName = self.descriptor.prototypeChain[-2]
            getParentProto = ("%s::GetProtoObject(aCx, aGlobal, aReceiver)" %
                              toBindingNamespace(parentProtoName))

        needInterfaceObject = self.descriptor.interface.hasInterfaceObject()
        needInterfacePrototypeObject = self.descriptor.interface.hasInterfacePrototypeObject()

        # if we don't need to create anything, why are we generating this?
        assert needInterfaceObject or needInterfacePrototypeObject

        idsToInit = []
        # There is no need to init any IDs in workers, because worker bindings
        # don't have Xrays.
        if not self.descriptor.workers:
            for var in self.properties.xrayRelevantArrayNames():
                props = getattr(self.properties, var)
                # We only have non-chrome ids to init if we have no chrome ids.
                if props.hasChromeOnly():
                    idsToInit.append(props.variableName(True))
                elif props.hasNonChromeOnly():
                    idsToInit.append(props.variableName(False))
        if len(idsToInit) > 0:
            initIds = CGList(
                [CGGeneric("!InitIds(aCx, %s, %s_ids)" % (varname, varname)) for
                 varname in idsToInit], ' ||\n')
            if len(idsToInit) > 1:
                initIds = CGWrapper(initIds, pre="(", post=")", reindent=True)
            initIds = CGList(
                [CGGeneric("%s_ids[0] == JSID_VOID &&" % idsToInit[0]), initIds],
                "\n")
            initIds = CGWrapper(initIds, pre="if (", post=") {", reindent=True)
            initIds = CGList(
                [initIds,
                 CGGeneric(("  %s_ids[0] = JSID_VOID;\n"
                            "  return NULL;") % idsToInit[0]),
                 CGGeneric("}")],
                "\n")
        else:
            initIds = None

        prefCacheData = []
        for var in self.properties.arrayNames():
            props = getattr(self.properties, var)
            prefCacheData.extend(props.prefCacheData)
        if len(prefCacheData) is not 0:
            prefCacheData = [
                CGGeneric('Preferences::AddBoolVarCache(%s, "%s");' % (ptr, pref)) for
                (pref, ptr) in prefCacheData]
            prefCache = CGWrapper(CGIndenter(CGList(prefCacheData, "\n")),
                                  pre=("static bool sPrefCachesInited = false;\n"
                                       "if (!sPrefCachesInited) {\n"
                                       "  sPrefCachesInited = true;\n"),
                                  post="\n}")
        else:
            prefCache = None
            
        getParentProto = ("JSObject* parentProto = %s;\n"
                          "if (!parentProto) {\n"
                          "  return NULL;\n"
                          "}") % getParentProto

        needInterfaceObjectClass = (needInterfaceObject and
                                    self.descriptor.hasInstanceInterface)
        needConstructor = (needInterfaceObject and
                           not self.descriptor.hasInstanceInterface)
        if self.descriptor.interface.ctor():
            constructHook = CONSTRUCT_HOOK_NAME
            constructArgs = methodLength(self.descriptor.interface.ctor())
        else:
            constructHook = "ThrowingConstructorWorkers" if self.descriptor.workers else "ThrowingConstructor"
            constructArgs = 0

        call = CGGeneric(("return dom::CreateInterfaceObjects(aCx, aGlobal, aReceiver, parentProto,\n"
                          "                                   %s, %s, %s, %d,\n"
                          "                                   %%(methods)s, %%(attrs)s, %%(consts)s, %%(staticMethods)s,\n"
                          "                                   %s);") % (
            "&PrototypeClass" if needInterfacePrototypeObject else "NULL",
            "&InterfaceObjectClass" if needInterfaceObjectClass else "NULL",
            constructHook if needConstructor else "NULL",
            constructArgs,
            '"' + self.descriptor.interface.identifier.name + '"' if needInterfaceObject else "NULL"))

        if self.properties.hasChromeOnly():
            if self.descriptor.workers:
                accessCheck = "mozilla::dom::workers::GetWorkerPrivateFromContext(aCx)->IsChromeWorker()"
            else:
                accessCheck = "xpc::AccessCheck::isChrome(js::GetObjectCompartment(aGlobal))"
            accessCheck = "if (" + accessCheck + ") {\n"
            chrome = CGWrapper(CGGeneric((CGIndenter(call).define() % self.properties.variableNames(True))),
                               pre=accessCheck, post="\n}")
        else:
            chrome = None

        functionBody = CGList(
            [CGGeneric(getParentProto), initIds, prefCache, chrome,
             CGGeneric(call.define() % self.properties.variableNames(False))],
            "\n\n")
        return CGIndenter(functionBody).define()

class CGGetPerInterfaceObject(CGAbstractMethod):
    """
    A method for getting a per-interface object (a prototype object or interface
    constructor object).
    """
    def __init__(self, descriptor, name, idPrefix=""):
        args = [Argument('JSContext*', 'aCx'), Argument('JSObject*', 'aGlobal'),
                Argument('JSObject*', 'aReceiver')]
        CGAbstractMethod.__init__(self, descriptor, name,
                                  'JSObject*', args, inline=True)
        self.id = idPrefix + "id::" + self.descriptor.name
    def definition_body(self):
        return """

  /* aGlobal and aReceiver are usually the same, but they can be different
     too. For example a sandbox often has an xray wrapper for a window as the
     prototype of the sandbox's global. In that case aReceiver is the xray
     wrapper and aGlobal is the sandbox's global.
   */

  /* Make sure our global is sane.  Hopefully we can remove this sometime */
  if (!(js::GetObjectClass(aGlobal)->flags & JSCLASS_DOM_GLOBAL)) {
    return NULL;
  }
  /* Check to see whether the interface objects are already installed */
  JSObject** protoOrIfaceArray = GetProtoOrIfaceArray(aGlobal);
  JSObject* cachedObject = protoOrIfaceArray[%s];
  if (!cachedObject) {
    protoOrIfaceArray[%s] = cachedObject = CreateInterfaceObjects(aCx, aGlobal, aReceiver);
  }

  /* cachedObject might _still_ be null, but that's OK */
  return cachedObject;""" % (self.id, self.id)

class CGGetProtoObjectMethod(CGGetPerInterfaceObject):
    """
    A method for getting the interface prototype object.
    """
    def __init__(self, descriptor):
        CGGetPerInterfaceObject.__init__(self, descriptor, "GetProtoObject",
                                         "prototypes::")
    def definition_body(self):
        return """
  /* Get the interface prototype object for this class.  This will create the
     object as needed. */""" + CGGetPerInterfaceObject.definition_body(self)

class CGGetConstructorObjectMethod(CGGetPerInterfaceObject):
    """
    A method for getting the interface constructor object.
    """
    def __init__(self, descriptor):
        CGGetPerInterfaceObject.__init__(self, descriptor, "GetConstructorObject",
                                         "constructors::")
    def definition_body(self):
        return """
  /* Get the interface object for this class.  This will create the object as
     needed. */""" + CGGetPerInterfaceObject.definition_body(self)

def CheckPref(descriptor, globalName, varName, retval, wrapperCache = None):
    """
    Check whether bindings should be enabled for this descriptor.  If not, set
    varName to false and return retval.
    """
    if not descriptor.prefable:
        return ""
    if wrapperCache:
       wrapperCache = "      %s->ClearIsDOMBinding();\n" % (wrapperCache)
    else:
        wrapperCache = ""
    return """
  {
    XPCWrappedNativeScope* scope =
      XPCWrappedNativeScope::FindInJSObjectScope(aCx, %s);
    if (!scope) {
      return %s;
    }

    if (!scope->ExperimentalBindingsEnabled()) {
%s      %s = false;
      return %s;
    }
  }
""" % (globalName, retval, wrapperCache, varName, retval)

class CGDefineDOMInterfaceMethod(CGAbstractMethod):
    """
    A method for resolve hooks to try to lazily define the interface object for
    a given interface.
    """
    def __init__(self, descriptor):
        args = [Argument('JSContext*', 'aCx'), Argument('JSObject*', 'aReceiver'),
                Argument('bool*', 'aEnabled')]
        CGAbstractMethod.__init__(self, descriptor, 'DefineDOMInterface', 'bool', args)

    def declare(self):
        if self.descriptor.workers:
            return ''
        return CGAbstractMethod.declare(self)

    def define(self):
        if self.descriptor.workers:
            return ''
        return CGAbstractMethod.define(self)

    def definition_body(self):
        if self.descriptor.interface.hasInterfacePrototypeObject():
            # We depend on GetProtoObject defining an interface constructor
            # object as needed.
            getter = "GetProtoObject"
        else:
            getter = "GetConstructorObject"

        return ("  JSObject* global = JS_GetGlobalForObject(aCx, aReceiver);\n" +
                CheckPref(self.descriptor, "global", "*aEnabled", "false") + 
                """
  *aEnabled = true;
  return !!%s(aCx, global, aReceiver);""" % (getter))

class CGWrapMethod(CGAbstractMethod):
    def __init__(self, descriptor):
        # XXX can we wrap if we don't have an interface prototype object?
        assert descriptor.interface.hasInterfacePrototypeObject()
        args = [Argument('JSContext*', 'aCx'), Argument('JSObject*', 'aScope'),
                Argument(descriptor.nativeType + '*', 'aObject'),
                Argument('bool*', 'aTriedToWrap')]
        CGAbstractMethod.__init__(self, descriptor, 'Wrap', 'JSObject*', args)

    def definition_body(self):
        if self.descriptor.workers:
            return """
  *aTriedToWrap = true;
  return aObject->GetJSObject();"""

        return """
  *aTriedToWrap = true;

  JSObject* parent = WrapNativeParent(aCx, aScope, aObject->GetParentObject());
  if (!parent) {
    return NULL;
  }

  JSAutoEnterCompartment ac;
  if (js::GetGlobalForObjectCrossCompartment(parent) != aScope) {
    if (!ac.enter(aCx, parent)) {
      return NULL;
    }
  }

  JSObject* global = JS_GetGlobalForObject(aCx, parent);
%s
  JSObject* proto = GetProtoObject(aCx, global, global);
  if (!proto) {
    return NULL;
  }

  JSObject* obj = JS_NewObject(aCx, &Class.mBase, proto, parent);
  if (!obj) {
    return NULL;
  }

  js::SetReservedSlot(obj, DOM_OBJECT_SLOT, PRIVATE_TO_JSVAL(aObject));
  NS_ADDREF(aObject);

  aObject->SetWrapper(obj);

  return obj;""" % (CheckPref(self.descriptor, "global", "*aTriedToWrap", "NULL", "aObject"))

class CGWrapNonWrapperCacheMethod(CGAbstractMethod):
    def __init__(self, descriptor):
        # XXX can we wrap if we don't have an interface prototype object?
        assert descriptor.interface.hasInterfacePrototypeObject()
        args = [Argument('JSContext*', 'aCx'), Argument('JSObject*', 'aScope'),
                Argument(descriptor.nativeType + '*', 'aObject')]
        CGAbstractMethod.__init__(self, descriptor, 'Wrap', 'JSObject*', args)

    def definition_body(self):
        return """
  JSObject* global = JS_GetGlobalForObject(aCx, aScope);
  JSObject* proto = GetProtoObject(aCx, global, global);
  if (!proto) {
    return NULL;
  }

  JSObject* obj = JS_NewObject(aCx, &Class.mBase, proto, global);
  if (!obj) {
    return NULL;
  }

  js::SetReservedSlot(obj, DOM_OBJECT_SLOT, PRIVATE_TO_JSVAL(aObject));
  NS_ADDREF(aObject);

  return obj;"""

builtinNames = {
    IDLType.Tags.bool: 'bool',
    IDLType.Tags.int8: 'int8_t',
    IDLType.Tags.int16: 'int16_t',
    IDLType.Tags.int32: 'int32_t',
    IDLType.Tags.int64: 'int64_t',
    IDLType.Tags.uint8: 'uint8_t',
    IDLType.Tags.uint16: 'uint16_t',
    IDLType.Tags.uint32: 'uint32_t',
    IDLType.Tags.uint64: 'uint64_t',
    IDLType.Tags.float: 'float',
    IDLType.Tags.double: 'double'
}

class CastableObjectUnwrapper():
    """
    A class for unwrapping an object named by the "source" argument
    based on the passed-in descriptor and storing it in a variable
    called by the name in the "target" argument.

    codeOnFailure is the code to run if unwrapping fails.
    """
    def __init__(self, descriptor, source, target, codeOnFailure):
        assert descriptor.castable
        self.substitution = { "type" : descriptor.nativeType,
                              "protoID" : "prototypes::id::" + descriptor.name,
                              "source" : source,
                              "target" : target,
                              "codeOnFailure" : CGIndenter(CGGeneric(codeOnFailure), 4).define() }

    def __str__(self):
        return string.Template(
"""{
  nsresult rv = UnwrapObject<${protoID}, ${type}>(cx, ${source}, ${target});
  if (NS_FAILED(rv)) {
${codeOnFailure}
  }
}""").substitute(self.substitution)

class FailureFatalCastableObjectUnwrapper(CastableObjectUnwrapper):
    """
    As CastableObjectUnwrapper, but defaulting to throwing if unwrapping fails
    """
    def __init__(self, descriptor, source, target):
        CastableObjectUnwrapper.__init__(self, descriptor, source, target,
                                         "return Throw<%s>(cx, rv);" %
                                         toStringBool(not descriptor.workers))

class CallbackObjectUnwrapper:
    """
    A class for unwrapping objects implemented in JS.

    |source| is the JSObject we want to use in native code.
    |target| is an nsCOMPtr of the appropriate type in which we store the result.
    """
    def __init__(self, descriptor, source, target, codeOnFailure=None):
        if codeOnFailure is None:
            codeOnFailure = ("return Throw<%s>(cx, rv);" %
                             toStringBool(not descriptor.workers))
        self.descriptor = descriptor
        self.substitution = { "nativeType" : descriptor.nativeType,
                              "source" : source,
                              "target" : target,
                              "codeOnFailure" : CGIndenter(CGGeneric(codeOnFailure)).define() }

    def __str__(self):
        if self.descriptor.workers:
            return string.Template(
                "${target} = ${source};"
                ).substitute(self.substitution)

        return string.Template(
            """nsresult rv;
XPCCallContext ccx(JS_CALLER, cx);
if (!ccx.IsValid()) {
  rv = NS_ERROR_XPC_BAD_CONVERT_JS;
${codeOnFailure}
}

const nsIID& iid = NS_GET_IID(${nativeType});
nsRefPtr<nsXPCWrappedJS> wrappedJS;
rv = nsXPCWrappedJS::GetNewOrUsed(ccx, ${source}, iid,
                                  NULL, getter_AddRefs(wrappedJS));
if (NS_FAILED(rv) || !wrappedJS) {
${codeOnFailure}
}

// Use a temp nsCOMPtr for the null-check, because ${target} might be
// OwningNonNull, not an nsCOMPtr.
nsCOMPtr<${nativeType}> tmp = do_QueryObject(wrappedJS.get());
if (!tmp) {
${codeOnFailure}
}
${target} = tmp.forget();""").substitute(self.substitution)

def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
                                    isDefinitelyObject=False,
                                    isMember=False,
                                    isOptional=False,
                                    invalidEnumValueFatal=True):
    """
    Get a template for converting a JS value to a native object based on the
    given type and descriptor.  If failureCode is given, then we're actually
    testing whether we can convert the argument to the desired type.  That
    means that failures to convert due to the JS value being the wrong type of
    value need to use failureCode instead of throwing exceptions.  Failures to
    convert that are due to JS exceptions (from toString or valueOf methods) or
    out of memory conditions need to throw exceptions no matter what
    failureCode is.

    If isDefinitelyObject is True, that means we know the value
    isObject() and we have no need to recheck that.

    if isMember is True, we're being converted from a property of some
    JS object, not from an actual method argument, so we can't rely on
    our jsval being rooted or outliving us in any way.

    If isOptional is true, then we are doing conversion of an optional
    argument with no default value.

    The return value from this function is a tuple consisting of four things:

    1)  A string representing the conversion code.  This will have template
        substitution performed on it as follows:

          ${val} replaced by an expression for the JS::Value in question
          ${valPtr} is a pointer to the JS::Value in question
          ${holderName} replaced by the holder's name, if any
          ${declName} replaced by the declaration's name

    2)  A CGThing representing the native C++ type we're converting to
        (declType).  This is allowed to be None if the conversion code is
        supposed to be used as-is.
    3)  A CGThing representing the type of a "holder" (holderType) which will
        hold a possible reference to the C++ thing whose type we returned in #1,
        or None if no such holder is needed.
    4)  A boolean indicating whether the caller has to do optional-argument handling.
        This will only be true if isOptional is true and if the returned template
        expects both declType and holderType to be wrapped in Optional<>, with
        ${declName} and ${holderName} adjusted to point to the Value() of the
        Optional, and Construct() calls to be made on the Optional<>s as needed.

    ${declName} must be in scope before the generated code is entered.

    If holderType is not None then ${holderName} must be in scope
    before the generated code is entered.
    """

    # A helper function for dealing with failures due to the JS value being the
    # wrong type of value
    def onFailure(failureCode, isWorker):
        return CGWrapper(CGGeneric(
                failureCode or
                "return Throw<%s>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);"
                % toStringBool(isWorker)), post="\n")

    # A helper function for wrapping up the template body for
    # possibly-nullable objecty stuff
    def wrapObjectTemplate(templateBody, isDefinitelyObject, type,
                           codeToSetNull, isWorker, failureCode=None):
        if not isDefinitelyObject:
            # Handle the non-object cases by wrapping up the whole
            # thing in an if cascade.
            templateBody = (
                "if (${val}.isObject()) {\n" +
                CGIndenter(CGGeneric(templateBody)).define() + "\n")
            if type.nullable():
                templateBody += (
                    "} else if (${val}.isNullOrUndefined()) {\n"
                    "  %s;\n" % codeToSetNull)
            templateBody += (
                "} else {\n" +
                CGIndenter(onFailure(failureCode, isWorker)).define() +
                "}")
        return templateBody

    if type.isArray():
        raise TypeError("Can't handle array arguments yet")

    if type.isSequence():
        if isMember:
            # XXXbz we probably _could_ handle this; we just have to be careful
            # with reallocation behavior for arrays.  In particular, if we have
            # a return value that's a sequence of dictionaries of sequences,
            # that will cause us to have an nsTArray containing objects with
            # nsAutoTArray members, which is a recipe for badness as the
            # outermost array is resized.
            raise TypeError("Can't handle unrooted sequences")
        if failureCode is not None:
            raise TypeError("Can't handle sequences when failureCode is not None")
        nullable = type.nullable();
        # Be very careful not to change "type": we need it later
        if nullable:
            elementType = type.inner.inner
        else:
            elementType = type.inner
        # We don't know anything about the object-ness of the things
        # we wrap, so don't pass through isDefinitelyObject
        (elementTemplate, elementDeclType,
         elementHolderType, dealWithOptional) = getJSToNativeConversionTemplate(
            elementType, descriptorProvider, isMember=True)
        if dealWithOptional:
            raise TypeError("Shouldn't have optional things in sequences")
        if elementHolderType is not None:
            raise TypeError("Shouldn't need holders for sequences")

        typeName = CGWrapper(elementDeclType, pre="Sequence< ", post=" >")
        if nullable:
            typeName = CGWrapper(typeName, pre="Nullable< ", post=" >")
            arrayRef = "${declName}.Value()"
        else:
            arrayRef = "${declName}"
        # If we're optional, the const will come from the Optional
        mutableTypeName = typeName
        if not isOptional:
            typeName = CGWrapper(typeName, pre="const ")

        templateBody = ("""JSObject* seq = &${val}.toObject();\n
if (!IsArrayLike(cx, seq)) {
  return Throw<%s>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);
}
uint32_t length;
// JS_GetArrayLength actually works on all objects
if (!JS_GetArrayLength(cx, seq, &length)) {
  return false;
}
Sequence< %s > &arr = const_cast< Sequence< %s >& >(%s);
if (!arr.SetCapacity(length)) {
  return Throw<%s>(cx, NS_ERROR_OUT_OF_MEMORY);
}
for (uint32_t i = 0; i < length; ++i) {
  jsval temp;
  if (!JS_GetElement(cx, seq, i, &temp)) {
    return false;
  }
""" % (toStringBool(descriptorProvider.workers),
       elementDeclType.define(),
       elementDeclType.define(),
       arrayRef,
       toStringBool(descriptorProvider.workers)))

        templateBody += CGIndenter(CGGeneric(
                string.Template(elementTemplate).substitute(
                    {
                        "val" : "temp",
                        "valPtr": "&temp",
                        "declName" : "(*arr.AppendElement())"
                        }
                    ))).define()

        templateBody += "\n}"
        templateBody = wrapObjectTemplate(templateBody, isDefinitelyObject,
                                          type,
                                          "const_cast< %s & >(${declName}).SetNull()" % mutableTypeName.define(),
                                          descriptorProvider.workers)
        return (templateBody, typeName, None, isOptional)

    if type.isUnion():
        if isMember:
            raise TypeError("Can't handle unions as members, we have a "
                            "holderType")

        nullable = type.nullable();
        if nullable:
            type = type.inner

        unionArgumentObj = "${holderName}"
        if isOptional or nullable:
            unionArgumentObj += ".ref()"

        memberTypes = type.flatMemberTypes

        interfaceMemberTypes = filter(lambda t: t.isNonCallbackInterface(), memberTypes)
        if len(interfaceMemberTypes) > 0:
            interfaceObject = []
            for memberType in interfaceMemberTypes:
                if type.isGeckoInterface():
                    name = memberType.inner.identifier.name
                else:
                    name = memberType.name
                interfaceObject.append(CGGeneric("(failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext" % (unionArgumentObj, name)))
            interfaceObject = CGWrapper(CGList(interfaceObject, " ||\n"), pre="done = ", post=";\n", reindent=True)
        else:
            interfaceObject = None

        arrayObjectMemberTypes = filter(lambda t: t.isArray() or t.isSequence(), memberTypes)
        if len(arrayObjectMemberTypes) > 0:
            assert len(arrayObjectMemberTypes) == 1
            memberType = arrayObjectMemberTypes[0]
            name = memberType.name
            arrayObject = CGGeneric("done = (failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext;" % (unionArgumentObj, name))
            # XXX Now we're supposed to check for an array or a platform object
            # that supports indexed properties... skip that last for now. It's a
            # bit of a pain.
            arrayObject = CGWrapper(CGIndenter(arrayObject),
                                    pre="if (IsArrayLike(cx, &argObj)) {\n",
                                    post="}")
        else:
            arrayObject = None

        dateObjectMemberTypes = filter(lambda t: t.isDate(), memberTypes)
        if len(dateObjectMemberTypes) > 0:
            assert len(dateObjectMemberTypes) == 1
            memberType = dateObjectMemberTypes[0]
            name = memberType.name
            dateObject = CGGeneric("%s.SetTo%s(cx, ${val}, ${valPtr});\n"
                                   "done = true;" % (unionArgumentObj, name))
            dateObject = CGWrapper(CGIndenter(dateObject),
                                   pre="if (JS_ObjectIsDate(cx, &argObj)) {\n",
                                   post="\n}")
        else:
            dateObject = None

        callbackMemberTypes = filter(lambda t: t.isCallback() or t.isCallbackInterface(), memberTypes)
        if len(callbackMemberTypes) > 0:
            assert len(callbackMemberTypes) == 1
            memberType = callbackMemberTypes[0]
            name = memberType.name
            callbackObject = CGGeneric("done = (failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext;" % (unionArgumentObj, name))
        else:
            callbackObject = None

        dictionaryMemberTypes = filter(lambda t: t.isDictionary(), memberTypes)
        if len(dictionaryMemberTypes) > 0:
            raise TypeError("No support for unwrapping dictionaries as member "
                            "of a union")
        else:
            dictionaryObject = None

        if callbackObject or dictionaryObject:
            nonPlatformObject = CGList([callbackObject, dictionaryObject], "\n")
            nonPlatformObject = CGWrapper(CGIndenter(nonPlatformObject),
                                          pre="if (!IsPlatformObject(cx, &argObj)) {\n",
                                          post="\n}")
        else:
            nonPlatformObject = None

        objectMemberTypes = filter(lambda t: t.isObject(), memberTypes)
        if len(objectMemberTypes) > 0:
            object = CGGeneric("%s.SetToObject(&argObj);\n"
                               "done = true;" % unionArgumentObj)
        else:
            object = None

        hasObjectTypes = interfaceObject or arrayObject or dateObject or nonPlatformObject or object
        if hasObjectTypes:
            # If we try more specific object types first then we need to check
            # whether that succeeded before converting to object.
            if object and (interfaceObject or arrayObject or dateObject or nonPlatformObject):
                object = CGWrapper(CGIndenter(object), pre="if (!done) {\n",
                                   post=("\n}"))

            if arrayObject or dateObject or nonPlatformObject:
                # An object can be both an array object and not a platform
                # object, but we shouldn't have both in the union's members
                # because they are not distinguishable.
                assert not (arrayObject and nonPlatformObject)
                templateBody = CGList([arrayObject, dateObject, nonPlatformObject], " else ")
            else:
                templateBody = None
            if interfaceObject:
                if templateBody:
                    templateBody = CGList([templateBody, object], "\n")
                    templateBody = CGWrapper(CGIndenter(templateBody),
                                             pre="if (!done) {\n", post=("\n}"))
                templateBody = CGList([interfaceObject, templateBody], "\n")
            else:
                templateBody = CGList([templateBody, object], "\n")

            if any([arrayObject, dateObject, nonPlatformObject, object]):
                templateBody.prepend(CGGeneric("JSObject& argObj = ${val}.toObject();"))
            templateBody = CGWrapper(CGIndenter(templateBody),
                                     pre="if (${val}.isObject()) {\n",
                                     post="\n}")
        else:
            templateBody = CGGeneric()

        otherMemberTypes = filter(lambda t: t.isString() or t.isEnum(),
                                  memberTypes)
        otherMemberTypes.extend(t for t in memberTypes if t.isPrimitive())
        if len(otherMemberTypes) > 0:
            assert len(otherMemberTypes) == 1
            memberType = otherMemberTypes[0]
            if memberType.isEnum():
                name = memberType.inner.identifier.name
            else:
                name = memberType.name
            other = CGGeneric("done = (failed = !%s.TrySetTo%s(cx, ${val}, ${valPtr}, tryNext)) || !tryNext;" % (unionArgumentObj, name))
            if hasObjectTypes:
                other = CGWrapper(CGIndenter(other), "{\n", post="\n}")
                if object:
                    join = " else "
                else:
                    other = CGWrapper(other, pre="if (!done) ")
                    join = "\n"
                templateBody = CGList([templateBody, other], join)
        else:
            other = None

        templateBody = CGWrapper(templateBody, pre="bool done = false, failed = false, tryNext;\n")
        throw = CGGeneric("if (failed) {\n"
                          "  return false;\n"
                          "}\n"
                          "if (!done) {\n"
                          "  return Throw<%s>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);\n"
                          "}" % toStringBool(descriptorProvider.workers))
        templateBody = CGWrapper(CGIndenter(CGList([templateBody, throw], "\n")), pre="{\n", post="\n}")

        typeName = type.name
        argumentTypeName = typeName + "Argument"
        if nullable:
            typeName = "Nullable<" + typeName + " >"
        if isOptional:
            nonConstDecl = "const_cast<Optional<" + typeName + " >& >(${declName})"
        else:
            nonConstDecl = "const_cast<" + typeName + "& >(${declName})"
            typeName = "const " + typeName

        def handleNull(templateBody, setToNullVar):
            null = CGGeneric("if (${val}.isNullOrUndefined()) {\n"
                             "  %s.SetNull();\n"
                             "}" % setToNullVar)
            templateBody = CGWrapper(CGIndenter(templateBody), pre="{\n", post="\n}")
            return CGList([null, templateBody], " else ")

        if type.hasNullableType:
            templateBody = handleNull(templateBody, unionArgumentObj)

        declType = CGGeneric(typeName)
        holderType = CGGeneric(argumentTypeName)
        if isOptional:
            mutableDecl = nonConstDecl + ".Value()"
            declType = CGWrapper(declType, pre="const Optional<", post=" >")
            holderType = CGWrapper(holderType, pre="Maybe<", post=" >")
            constructDecl = CGGeneric(nonConstDecl + ".Construct();")
            if nullable:
                constructHolder = CGGeneric("${holderName}.construct(%s.SetValue());" % mutableDecl)
            else:
                constructHolder = CGGeneric("${holderName}.construct(${declName}.Value());")
        else:
            mutableDecl = nonConstDecl
            constructDecl = None
            if nullable:
                holderType = CGWrapper(holderType, pre="Maybe<", post=" >")
                constructHolder = CGGeneric("${holderName}.construct(%s.SetValue());" % mutableDecl)
            else:
                constructHolder = CGWrapper(holderType, post=" ${holderName}(${declName});")
                holderType = None

        templateBody = CGList([constructHolder, templateBody], "\n")
        if nullable:
            templateBody = handleNull(templateBody, mutableDecl)
        templateBody = CGList([constructDecl, templateBody], "\n")

        return templateBody.define(), declType, holderType, False

    if type.isGeckoInterface():
        descriptor = descriptorProvider.getDescriptor(
            type.unroll().inner.identifier.name)
        # This is an interface that we implement as a concrete class
        # or an XPCOM interface.

        # Allow null pointers for nullable types and old-binding classes
        argIsPointer = type.nullable() or type.unroll().inner.isExternal()

        # Sequences and non-worker callbacks have to hold a strong ref to the
        # thing being passed down.
        forceOwningType = (descriptor.interface.isCallback() and
                           not descriptor.workers) or isMember

        typeName = descriptor.nativeType
        typePtr = typeName + "*"

        # Compute a few things:
        #  - declType is the type we want to return as the first element of our
        #    tuple.
        #  - holderType is the type we want to return as the third element
        #    of our tuple.

        # Set up some sensible defaults for these things insofar as we can.
        holderType = None
        if argIsPointer:
            if forceOwningType:
                declType = "nsRefPtr<" + typeName + ">"
            else:
                declType = typePtr
        else:
            if forceOwningType:
                declType = "OwningNonNull<" + typeName + ">"
            else:
                declType = "NonNull<" + typeName + ">"

        templateBody = ""
        if descriptor.castable:
            if descriptor.prefable:
                raise TypeError("We don't support prefable castable object "
                                "arguments (like %s), because we don't know "
                                "how to handle them being preffed off" %
                                descriptor.interface.identifier.name)
            if failureCode is not None:
                templateBody += str(CastableObjectUnwrapper(
                        descriptor,
                        "&${val}.toObject()",
                        "${declName}",
                        failureCode))
            else:
                templateBody += str(FailureFatalCastableObjectUnwrapper(
                        descriptor,
                        "&${val}.toObject()",
                        "${declName}"))
        elif descriptor.interface.isCallback():
            templateBody += str(CallbackObjectUnwrapper(
                    descriptor,
                    "&${val}.toObject()",
                    "${declName}",
                    codeOnFailure=failureCode))
        elif descriptor.workers:
            templateBody += "${declName} = &${val}.toObject();"
        else:
            # Either external, or new-binding non-castable.  We always have a
            # holder for these, because we don't actually know whether we have
            # to addref when unwrapping or not.  So we just pass an
            # getter_AddRefs(nsRefPtr) to XPConnect and if we'll need a release
            # it'll put a non-null pointer in there.
            if forceOwningType:
                # Don't return a holderType in this case; our declName
                # will just own stuff.
                templateBody += "nsRefPtr<" + typeName + "> ${holderName};\n"
            else:
                holderType = "nsRefPtr<" + typeName + ">"
            templateBody += (
                "jsval tmpVal = ${val};\n" +
                typePtr + " tmp;\n"
                "if (NS_FAILED(xpc_qsUnwrapArg<" + typeName + ">(cx, ${val}, &tmp, static_cast<" + typeName + "**>(getter_AddRefs(${holderName})), &tmpVal))) {\n")
            templateBody += CGIndenter(onFailure(failureCode,
                                                 descriptor.workers)).define()
            templateBody += ("}\n"
                "MOZ_ASSERT(tmp);\n")

            if not isDefinitelyObject:
                # Our tmpVal will go out of scope, so we can't rely on it
                # for rooting
                templateBody += (
                    "if (tmpVal != ${val} && !${holderName}) {\n"
                    "  // We have to have a strong ref, because we got this off\n"
                    "  // some random object that might get GCed\n"
                    "  ${holderName} = tmp;\n"
                    "}\n")

            # And store our tmp, before it goes out of scope.
            templateBody += "${declName} = tmp;"

        templateBody = wrapObjectTemplate(templateBody, isDefinitelyObject,
                                          type, "${declName} = NULL",
                                          descriptor.workers, failureCode)

        declType = CGGeneric(declType)
        if holderType is not None:
            holderType = CGGeneric(holderType)
        return (templateBody, declType, holderType, isOptional)

    if type.isSpiderMonkeyInterface():
        if isMember:
            raise TypeError("Can't handle member arraybuffers or "
                            "arraybuffer views because making sure all the "
                            "objects are properly rooted is hard")
        name = type.name
        if type.isArrayBuffer():
            jsname = "ArrayBufferObject"
        elif type.isArrayBufferView():
            jsname = "ArrayBufferViewObject"
        else:
            jsname = type.name

        # By default, we use a Maybe<> to hold our typed array.  And in the optional
        # non-nullable case we want to pass Optional<TypedArray> to consumers, not
        # Optional<NonNull<TypedArray> >, so jump though some hoops to do that.
        holderType = "Maybe<%s>" % name
        constructLoc = "${holderName}"
        constructMethod = "construct"
        if type.nullable():
            if isOptional:
                declType = "const Optional<" + name + "*>"
            else:
                declType = name + "*"
        else:
            if isOptional:
                declType = "const Optional<" + name + ">"
                # We don't need a holder in this case
                holderType = None
                constructLoc = "(const_cast<Optional<" + name + ">& >(${declName}))"
                constructMethod = "Construct"
            else:
                declType = "NonNull<" + name + ">"
        template = (
            "if (!JS_Is%s(&${val}.toObject(), cx)) {\n"
            "%s" # No newline here because onFailure() handles that
            "}\n"
            "%s.%s(cx, &${val}.toObject());\n" %
            (jsname, CGIndenter(onFailure(failureCode, descriptorProvider.workers)).define(),
             constructLoc, constructMethod))
        nullableTarget = ""
        if type.nullable():
            if isOptional:
                mutableDecl = "(const_cast<Optional<" + name + "*>& >(${declName}))"
                template += "%s.Construct();\n" % mutableDecl
                nullableTarget = "%s.Value()" % mutableDecl
            else:
                nullableTarget = "${declName}"
            template += "%s = ${holderName}.addr();" % nullableTarget
        elif not isOptional:
            template += "${declName} = ${holderName}.addr();"
        template = wrapObjectTemplate(template, isDefinitelyObject, type,
                                      "%s = NULL" % nullableTarget,
                                      descriptorProvider.workers,
                                      failureCode)

        if holderType is not None:
            holderType = CGGeneric(holderType)
        # We handle all the optional stuff ourselves; no need for caller to do it.
        return (template, CGGeneric(declType), holderType, False)

    if type.isString():
        # XXXbz Need to figure out string behavior based on extended args?  Also, how to
        # detect them?

        # For nullable strings that are not otherwise annotated, null
        # and undefined become null strings.
        if type.nullable():
            nullBehavior = "eNull"
            undefinedBehavior = "eNull"
        else:
            nullBehavior = "eStringify"
            undefinedBehavior = "eStringify"

        if isMember:
            # We have to make a copy, because our jsval may well not
            # live as long as our string needs to.
            declType = CGGeneric("nsString")
            return (
                "{\n"
                "  FakeDependentString str;\n"
                "  if (!ConvertJSValueToString(cx, ${val}, ${valPtr}, %s, %s, str)) {\n"
                "    return false;\n"
                "  }\n"
                "  ${declName} = str;\n"
                "}\n" %
                (nullBehavior, undefinedBehavior),
            declType, None,
            isOptional)

        if isOptional:
            declType = "Optional<nsAString>"
        else:
            declType = "NonNull<nsAString>"
        return (
            "if (!ConvertJSValueToString(cx, ${val}, ${valPtr}, %s, %s, ${holderName})) {\n"
            "  return false;\n"
            "}\n"
            "const_cast<%s&>(${declName}) = &${holderName};" %
            (nullBehavior, undefinedBehavior, declType),
            CGGeneric("const " + declType), CGGeneric("FakeDependentString"),
            # No need to deal with Optional here; we have handled it already
            False)

    if type.isEnum():
        if type.nullable():
            raise TypeError("We don't support nullable enumerated arguments "
                            "yet")
        enum = type.inner.identifier.name
        if invalidEnumValueFatal:
            handleInvalidEnumValueCode = "  MOZ_ASSERT(index >= 0);\n"
        else:
            handleInvalidEnumValueCode = (
                "  if (index < 0) {\n"
                "    return true;\n"
                "  }\n")
            
        return (
            "{\n"
            "  bool ok;\n"
            "  int index = FindEnumStringIndex<%(invalidEnumValueFatal)s>(cx, ${val}, %(values)s, \"%(enumtype)s\", &ok);\n"
            "  if (!ok) {\n"
            "    return false;\n"
            "  }\n"
            "%(handleInvalidEnumValueCode)s"
            "  ${declName} = static_cast<%(enumtype)s>(index);\n"
            "}" % { "enumtype" : enum,
                      "values" : enum + "Values::strings",
       "invalidEnumValueFatal" : toStringBool(invalidEnumValueFatal),
  "handleInvalidEnumValueCode" : handleInvalidEnumValueCode },
            CGGeneric(enum), None, isOptional)

    if type.isCallback():
        if isMember:
            raise TypeError("Can't handle member callbacks; need to sort out "
                            "rooting issues")
        # XXXbz we're going to assume that callback types are always
        # nullable and always have [TreatNonCallableAsNull] for now.
        return (
            "if (${val}.isObject() && JS_ObjectIsCallable(cx, &${val}.toObject())) {\n"
            "  ${declName} = &${val}.toObject();\n"
            "} else {\n"
            "  ${declName} = NULL;\n"
            "}", CGGeneric("JSObject*"), None, isOptional)

    if type.isAny():
        if isMember:
            raise TypeError("Can't handle member 'any'; need to sort out "
                            "rooting issues")
        return ("${declName} = ${val};", CGGeneric("JS::Value"), None, isOptional)

    if type.isObject():
        if isMember:
            raise TypeError("Can't handle member 'object'; need to sort out "
                            "rooting issues")
        template = wrapObjectTemplate("${declName} = &${val}.toObject();",
                                      isDefinitelyObject, type,
                                      "${declName} = NULL",
                                      descriptorProvider.workers, failureCode)
        if type.nullable():
            declType = CGGeneric("JSObject*")
        else:
            declType = CGGeneric("NonNull<JSObject>")
        return (template, declType, None, isOptional)

    if type.isDictionary():
        if failureCode is not None:
            raise TypeError("Can't handle dictionaries when failureCode is not None")
        # There are no nullable dictionaries
        assert not type.nullable()
        # All optional dictionaries always have default values, so we
        # should be able to assume not isOptional here.
        assert not isOptional

        typeName = CGDictionary.makeDictionaryName(type.inner,
                                                   descriptorProvider.workers)
        actualTypeName = typeName
        selfRef = "${declName}"

        declType = CGGeneric(actualTypeName)

        # If we're a member of something else, the const
        # will come from the Optional or our container.
        if not isMember:
            declType = CGWrapper(declType, pre="const ")
            selfRef = "const_cast<%s&>(%s)" % (typeName, selfRef)

        template = ("if (!%s.Init(cx, ${val})) {\n"
                    "  return false;\n"
                    "}" % selfRef)

        return (template, declType, None, False)

    if not type.isPrimitive():
        raise TypeError("Need conversion for argument type '%s'" % type)

    # XXXbz need to add support for [EnforceRange] and [Clamp]
    typeName = builtinNames[type.tag()]
    if type.nullable():
        return ("if (${val}.isNullOrUndefined()) {\n"
                "  ${declName}.SetNull();\n"
                "} else if (!ValueToPrimitive<" + typeName + ">(cx, ${val}, &${declName}.SetValue())) {\n"
                "  return false;\n"
                "}", CGGeneric("Nullable<" + typeName + ">"), None, isOptional)
    else:
        return ("if (!ValueToPrimitive<" + typeName + ">(cx, ${val}, &${declName})) {\n"
                "  return false;\n"
                "}", CGGeneric(typeName), None, isOptional)

def instantiateJSToNativeConversionTemplate(templateTuple, replacements,
                                            argcAndIndex=None):
    """
    Take a tuple as returned by getJSToNativeConversionTemplate and a set of
    replacements as required by the strings in such a tuple, and generate code
    to convert into stack C++ types.

    If argcAndIndex is not None it must be a dict that can be used to
    replace ${argc} and ${index}, where ${index} is the index of this
    argument (0-based) and ${argc} is the total number of arguments.
    """
    (templateBody, declType, holderType, dealWithOptional) = templateTuple

    if dealWithOptional and argcAndIndex is None:
        raise TypeError("Have to deal with optional things, but don't know how")
    if argcAndIndex is not None and declType is None:
        raise TypeError("Need to predeclare optional things, so they will be "
                        "outside the check for big enough arg count!");

    result = CGList([], "\n")
    # Make a copy of "replacements" since we may be about to start modifying it
    replacements = dict(replacements)
    originalHolderName = replacements["holderName"]
    if holderType is not None:
        if dealWithOptional:
            replacements["holderName"] = (
                "const_cast< %s & >(%s.Value())" %
                (holderType.define(), originalHolderName))
            mutableHolderType = CGWrapper(holderType, pre="Optional< ", post=" >")
            holderType = CGWrapper(mutableHolderType, pre="const ")
        result.append(
            CGList([holderType, CGGeneric(" "),
                    CGGeneric(originalHolderName),
                    CGGeneric(";")]))

    originalDeclName = replacements["declName"]
    if declType is not None:
        if dealWithOptional:
            replacements["declName"] = (
                "const_cast< %s & >(%s.Value())" %
                (declType.define(), originalDeclName))
            mutableDeclType = CGWrapper(declType, pre="Optional< ", post=" >")
            declType = CGWrapper(mutableDeclType, pre="const ")
        result.append(
            CGList([declType, CGGeneric(" "),
                    CGGeneric(originalDeclName),
                    CGGeneric(";")]))

    conversion = CGGeneric(
            string.Template(templateBody).substitute(replacements)
            )

    if argcAndIndex is not None:
        if dealWithOptional:
            declConstruct = CGIndenter(
                CGGeneric("const_cast< %s &>(%s).Construct();" %
                          (mutableDeclType.define(), originalDeclName)))
            if holderType is not None:
                holderConstruct = CGIndenter(
                    CGGeneric("const_cast< %s &>(%s).Construct();" %
                              (mutableHolderType.define(), originalHolderName)))
            else:
                holderConstruct = None
        else:
            declConstruct = None
            holderConstruct = None

        conversion = CGList(
            [CGGeneric(
                    string.Template("if (${index} < ${argc}) {").substitute(
                        argcAndIndex
                        )),
             declConstruct,
             holderConstruct,
             CGIndenter(conversion),
             CGGeneric("}")],
            "\n")

    result.append(conversion)
    # Add an empty CGGeneric to get an extra newline after the argument
    # conversion.
    result.append(CGGeneric(""))
    return result;

def convertConstIDLValueToJSVal(value):
    if isinstance(value, IDLNullValue):
        return "JSVAL_NULL"
    tag = value.type.tag()
    if tag in [IDLType.Tags.int8, IDLType.Tags.uint8, IDLType.Tags.int16,
               IDLType.Tags.uint16, IDLType.Tags.int32]:
        return "INT_TO_JSVAL(%s)" % (value.value)
    if tag == IDLType.Tags.uint32:
        return "UINT_TO_JSVAL(%s)" % (value.value)
    if tag in [IDLType.Tags.int64, IDLType.Tags.uint64]:
        return "DOUBLE_TO_JSVAL(%s)" % (value.value)
    if tag == IDLType.Tags.bool:
        return "JSVAL_TRUE" if value.value else "JSVAL_FALSE"
    if tag in [IDLType.Tags.float, IDLType.Tags.double]:
        return "DOUBLE_TO_JSVAL(%s)" % (value.value)
    raise TypeError("Const value of unhandled type: " + value.type)

def convertIDLDefaultValueToJSVal(value):
    if value.type:
        tag = value.type.tag()
        if (tag == IDLType.Tags.domstring and
            (not value.type.nullable() or not isinstance(value, IDLNullValue))):
            assert False # Not implemented!
    return convertConstIDLValueToJSVal(value)

class CGArgumentConverter(CGThing):
    """
    A class that takes an IDL argument object, its index in the
    argument list, and the argv and argc strings and generates code to
    unwrap the argument to the right native type.
    """
    def __init__(self, argument, index, argv, argc, descriptorProvider,
                 invalidEnumValueFatal=True):
        CGThing.__init__(self)
        self.argument = argument
        # XXXbz should optional jsval args get JSVAL_VOID? What about
        # others?
        replacer = {
            "index" : index,
            "argc" : argc,
            "argv" : argv
            }
        self.replacementVariables = {
            "declName" : "arg%d" % index,
            "holderName" : ("arg%d" % index) + "_holder"
            }
        if argument.optional and argument.defaultValue:
            replacer["defaultValue"] = convertIDLDefaultValueToJSVal(argument.defaultValue)
            self.replacementVariables["val"] = string.Template(
                "(${index} < ${argc} ? ${argv}[${index}] : ${defaultValue})"
                ).substitute(replacer)
            self.replacementVariables["valPtr"] = string.Template(
                "(${index} < ${argc} ? &${argv}[${index}] : NULL)"
                ).substitute(replacer)
        else:
            self.replacementVariables["val"] = string.Template(
                "${argv}[${index}]"
                ).substitute(replacer)
            self.replacementVariables["valPtr"] = (
                "&" + self.replacementVariables["val"])
        self.descriptorProvider = descriptorProvider
        if self.argument.optional and not self.argument.defaultValue:
            self.argcAndIndex = replacer
        else:
            self.argcAndIndex = None
        self.invalidEnumValueFatal = invalidEnumValueFatal

    def define(self):
        return instantiateJSToNativeConversionTemplate(
            getJSToNativeConversionTemplate(self.argument.type,
                                            self.descriptorProvider,
                                            isOptional=(self.argcAndIndex is not None),
                                            invalidEnumValueFatal=self.invalidEnumValueFatal),
            self.replacementVariables,
            self.argcAndIndex).define()

def getWrapTemplateForType(type, descriptorProvider, result, successCode,
                           isCreator):
    """
    Reflect a C++ value stored in "result", of IDL type "type" into JS.  The
    "successCode" is the code to run once we have successfully done the
    conversion.  The resulting string should be used with string.Template, it
    needs the following keys when substituting: jsvalPtr/jsvalRef/obj.
    """
    haveSuccessCode = successCode is not None
    if not haveSuccessCode:
        successCode = "return true;"

    def setValue(value, callWrapValue=False):
        """
        Returns the code to set the jsval to value. If "callWrapValue" is true
        JS_WrapValue will be called on the jsval.
        """
        if not callWrapValue:
            tail = successCode
        elif haveSuccessCode:
            tail = ("if (!JS_WrapValue(cx, ${jsvalPtr})) {\n" +
                    "  return false;\n" +
                    "}\n" +
                    successCode)
        else:
            tail = "return JS_WrapValue(cx, ${jsvalPtr});"
        return ("${jsvalRef} = %s;\n" +
                tail) % (value)

    def wrapAndSetPtr(wrapCall, failureCode=None):
        """
        Returns the code to set the jsval by calling "wrapCall". "failureCode"
        is the code to run if calling "wrapCall" fails 
        """
        if failureCode is None:
            if not haveSuccessCode:
                return "return " + wrapCall + ";"
            failureCode = "return false;"
        str = ("if (!%s) {\n" +
               CGIndenter(CGGeneric(failureCode)).define() + "\n" +
               "}\n" +
               successCode) % (wrapCall)
        return str
    
    if type is None or type.isVoid():
        return setValue("JSVAL_VOID")

    if type.isArray():
        raise TypeError("Can't handle array return values yet")

    if type.isSequence():
        if type.nullable():
            # Nullable sequences are Nullable< nsTArray<T> >
            return """
if (%s.IsNull()) {
%s
}
%s""" % (result, CGIndenter(CGGeneric(setValue("JSVAL_NULL"))).define(),
         getWrapTemplateForType(type.inner, descriptorProvider,
                                "%s.Value()" % result, successCode,
                                isCreator))

        # Now do non-nullable sequences.  We use setting the element
        # in the array as our succcess code because when we succeed in
        # wrapping that's what we should do.
        innerTemplate = wrapForType(
            type.inner, descriptorProvider,
            {
                'result' :  "%s[i]" % result,
                'successCode': ("if (!JS_SetElement(cx, returnArray, i, &tmp)) {\n"
                                "  return false;\n"
                                "}"),
                'jsvalRef': "tmp",
                'jsvalPtr': "&tmp",
                'isCreator': isCreator
                }
            )
        innerTemplate = CGIndenter(CGGeneric(innerTemplate)).define()
        return ("""
uint32_t length = %s.Length();
JSObject *returnArray = JS_NewArrayObject(cx, length, NULL);
if (!returnArray) {
  return false;
}
jsval tmp;
for (uint32_t i = 0; i < length; ++i) {
%s
}\n""" % (result, innerTemplate)) + setValue("JS::ObjectValue(*returnArray)")

    if type.isGeckoInterface():
        descriptor = descriptorProvider.getDescriptor(type.unroll().inner.identifier.name)
        if type.nullable():
            wrappingCode = ("if (!%s) {\n" % (result) +
                            CGIndenter(CGGeneric(setValue("JSVAL_NULL"))).define() + "\n" +
                            "}\n")
        else:
            wrappingCode = ""
        if descriptor.castable and not type.unroll().inner.isExternal():
            if descriptor.wrapperCache:
                wrapMethod = "WrapNewBindingObject"
            else:
                if not isCreator:
                    raise MethodNotCreatorError(descriptor.interface.identifier.name)
                wrapMethod = "WrapNewBindingNonWrapperCachedObject"
            wrap = "%s(cx, ${obj}, %s, ${jsvalPtr})" % (wrapMethod, result)
            # We don't support prefable stuff in workers.
            assert(not descriptor.prefable or not descriptor.workers)
            if not descriptor.prefable:
                # Non-prefable bindings can only fail to wrap as a new-binding object
                # if they already threw an exception.  Same thing for
                # non-prefable bindings.
                failed = ("MOZ_ASSERT(JS_IsExceptionPending(cx));\n" +
                          "return false;")
            else:
                # Try old-style wrapping for bindings which might be preffed off.
                failed = wrapAndSetPtr("HandleNewBindingWrappingFailure(cx, ${obj}, %s, ${jsvalPtr})" % result)
            wrappingCode += wrapAndSetPtr(wrap, failed)
        else:
            if descriptor.notflattened:
                getIID = "&NS_GET_IID(%s), " % descriptor.nativeType
            else:
                getIID = ""
            wrap = "WrapObject(cx, ${obj}, %s, %s${jsvalPtr})" % (result, getIID)
            wrappingCode += wrapAndSetPtr(wrap)
        return wrappingCode

    if type.isString():
        if type.nullable():
            return wrapAndSetPtr("xpc::StringToJsval(cx, %s, ${jsvalPtr})" % result)
        else:
            return wrapAndSetPtr("xpc::NonVoidStringToJsval(cx, %s, ${jsvalPtr})" % result)

    if type.isEnum():
        if type.nullable():
            raise TypeError("We don't support nullable enumerated return types "
                            "yet")
        return """MOZ_ASSERT(uint32_t(%(result)s) < ArrayLength(%(strings)s));
JSString* %(resultStr)s = JS_NewStringCopyN(cx, %(strings)s[uint32_t(%(result)s)].value, %(strings)s[uint32_t(%(result)s)].length);
if (!%(resultStr)s) {
  return false;
}
""" % { "result" : result,
        "resultStr" : result + "_str",
        "strings" : type.inner.identifier.name + "Values::strings" } + setValue("JS::StringValue(%s_str)" % result)

    if type.isCallback():
        assert not type.isInterface()
        # XXXbz we're going to assume that callback types are always
        # nullable and always have [TreatNonCallableAsNull] for now.
        # See comments in WrapNewBindingObject explaining why we need
        # to wrap here.
        return setValue("JS::ObjectOrNullValue(%s)" % result, True)

    if type.tag() == IDLType.Tags.any:
        # See comments in WrapNewBindingObject explaining why we need
        # to wrap here.
        return setValue(result, True)

    if type.isObject():
        # See comments in WrapNewBindingObject explaining why we need
        # to wrap here.
        if type.nullable():
            toValue = "JS::ObjectOrNullValue(%s)"
        else:
            toValue = "JS::ObjectValue(*%s)"
        return setValue(toValue % result, True)

    if not type.isPrimitive():
        raise TypeError("Need to learn to wrap %s" % type)

    if type.nullable():
        return ("if (%s.IsNull()) {\n" % result +
                CGIndenter(CGGeneric(setValue("JSVAL_NULL"))).define() + "\n" +
                "}\n" +
                getWrapTemplateForType(type.inner, descriptorProvider,
                                       "%s.Value()" % result, successCode,
                                       isCreator))
    
    tag = type.tag()
    
    if tag in [IDLType.Tags.int8, IDLType.Tags.uint8, IDLType.Tags.int16,
               IDLType.Tags.uint16, IDLType.Tags.int32]:
        return setValue("INT_TO_JSVAL(int32_t(%s))" % result)

    elif tag in [IDLType.Tags.int64, IDLType.Tags.uint64, IDLType.Tags.float,
                 IDLType.Tags.double]:
        # XXXbz will cast to double do the "even significand" thing that webidl
        # calls for for 64-bit ints?  Do we care?
        return wrapAndSetPtr("JS_NewNumberValue(cx, double(%s), ${jsvalPtr})" % result)

    elif tag == IDLType.Tags.uint32:
        return setValue("UINT_TO_JSVAL(%s)" % result)

    elif tag == IDLType.Tags.bool:
        return setValue("BOOLEAN_TO_JSVAL(%s)" % result)

    else:
        raise TypeError("Need to learn to wrap primitive: %s" % type)

def wrapForType(type, descriptorProvider, templateValues):
    """
    Reflect a C++ value of IDL type "type" into JS.  TemplateValues is a dict
    that should contain:

      * 'jsvalRef': a C++ reference to the jsval in which to store the result of
                    the conversion
      * 'jsvalPtr': a C++ pointer to the jsval in which to store the result of
                    the conversion
      * 'obj' (optional): the name of the variable that contains the JSObject to
                          use as a scope when wrapping, if not supplied 'obj'
                          will be used as the name
      * 'result' (optional): the name of the variable in which the C++ value is
                             stored, if not supplied 'result' will be used as
                             the name
      * 'successCode' (optional): the code to run once we have successfully done
                                  the conversion, if not supplied 'return true;'
                                  will be used as the code
      * 'isCreator' (optional): If true, we're wrapping for the return value of
                                a [Creator] method.  Assumed false if not set.
    """
    wrap = getWrapTemplateForType(type, descriptorProvider,
                                  templateValues.get('result', 'result'),
                                  templateValues.get('successCode', None),
                                  templateValues.get('isCreator', False))

    defaultValues = {'obj': 'obj'}
    return string.Template(wrap).substitute(defaultValues, **templateValues)

def typeNeedsCx(type):
    return (type is not None and
            (type.isCallback() or type.isAny() or type.isObject() or
             (type.isUnion() and
              any(typeNeedsCx(t) for t in type.unroll().flatMemberTypes))))

# Returns a CGThing containing the type of the return value, or None
# if there is no need for a return value.
def getRetvalDeclarationForType(returnType, descriptorProvider,
                                resultAlreadyAddRefed):
    if returnType is None or returnType.isVoid():
        # Nothing to declare
        return None
    if returnType.isPrimitive() and returnType.tag() in builtinNames:
        result = CGGeneric(builtinNames[returnType.tag()])
        if returnType.nullable():
            result = CGWrapper(result, pre="Nullable<", post=">")
        return result
    if returnType.isString():
        return CGGeneric("nsString")
    if returnType.isEnum():
        if returnType.nullable():
            raise TypeError("We don't support nullable enum return values")
        return CGGeneric(returnType.inner.identifier.name)
    if returnType.isGeckoInterface():
        result = CGGeneric(descriptorProvider.getDescriptor(
            returnType.unroll().inner.identifier.name).nativeType)
        if resultAlreadyAddRefed:
            result = CGWrapper(result, pre="nsRefPtr<", post=">")
        else:
            result = CGWrapper(result, post="*")
        return result
    if returnType.isCallback():
        # XXXbz we're going to assume that callback types are always
        # nullable for now.
        return CGGeneric("JSObject*")
    if returnType.isAny():
        return CGGeneric("JS::Value")
    if returnType.isObject():
        return CGGeneric("JSObject*")
    if returnType.isSequence():
        nullable = returnType.nullable()
        if nullable:
            returnType = returnType.inner
        # If our result is already addrefed, use the right type in the
        # sequence argument here.
        result = getRetvalDeclarationForType(returnType.inner,
                                             descriptorProvider,
                                             resultAlreadyAddRefed)
        result = CGWrapper(result, pre="nsTArray< ", post=" >")
        if nullable:
            result = CGWrapper(result, pre="Nullable< ", post=" >")
        return result
    raise TypeError("Don't know how to declare return value for %s" %
                    returnType)

def isResultAlreadyAddRefed(descriptor, extendedAttributes):
    # Default to already_AddRefed on the main thread, raw pointer in workers
    return not descriptor.workers and not 'resultNotAddRefed' in extendedAttributes

class CGCallGenerator(CGThing):
    """
    A class to generate an actual call to a C++ object.  Assumes that the C++
    object is stored in a variable named "self".
    """
    def __init__(self, errorReport, arguments, argsPre, returnType,
                 extendedAttributes, descriptorProvider, nativeMethodName, static):
        CGThing.__init__(self)

        isFallible = errorReport is not None

        args = CGList([CGGeneric(arg) for arg in argsPre], ", ")
        for (i, a) in enumerate(arguments):
            arg = "arg" + str(i)
            # This is a workaround for a bug in Apple's clang.
            if a.type.isObject() and not a.type.nullable() and not a.optional:
                arg = "(JSObject&)" + arg
            args.append(CGGeneric(arg))
        resultOutParam = (returnType is not None and
                          (returnType.isString() or returnType.isSequence()))
        # Return values that go in outparams go here
        if resultOutParam:
            args.append(CGGeneric("result"))
        if isFallible:
            args.append(CGGeneric("rv"))

        resultAlreadyAddRefed = isResultAlreadyAddRefed(descriptorProvider,
                                                        extendedAttributes)
        result = getRetvalDeclarationForType(returnType,
                                             descriptorProvider,
                                             resultAlreadyAddRefed)
        needsCx = (typeNeedsCx(returnType) or
                   any(typeNeedsCx(a.type) for a in arguments) or
                   'implicitJSContext' in extendedAttributes)

        if not "cx" in argsPre and needsCx:
            args.prepend(CGGeneric("cx"))

        # Build up our actual call
        self.cgRoot = CGList([], "\n")

        call = CGGeneric(nativeMethodName)
        if static:
            call = CGWrapper(call, pre="%s::" % (descriptorProvider.getDescriptor(
                returnType.unroll().inner.identifier.name).nativeType))
        else: 
            call = CGWrapper(call, pre="self->")
        call = CGList([call, CGWrapper(args, pre="(", post=");")])
        if result is not None:
            result = CGWrapper(result, post=" result;")
            self.cgRoot.prepend(result)
            if not resultOutParam:
                call = CGWrapper(call, pre="result = ")

        call = CGWrapper(call)
        self.cgRoot.append(call)

        if isFallible:
            self.cgRoot.prepend(CGGeneric("ErrorResult rv;"))
            self.cgRoot.append(CGGeneric("if (rv.Failed()) {"))
            self.cgRoot.append(CGIndenter(CGGeneric(errorReport)))
            self.cgRoot.append(CGGeneric("}"))

    def define(self):
        return self.cgRoot.define()

class MethodNotCreatorError(Exception):
    def __init__(self, typename):
        self.typename = typename

class CGPerSignatureCall(CGThing):
    """
    This class handles the guts of generating code for a particular
    call signature.  A call signature consists of four things:

    1) A return type, which can be None to indicate that there is no
       actual return value (e.g. this is an attribute setter) or an
       IDLType if there's an IDL type involved (including |void|).
    2) An argument list, which is allowed to be empty.
    3) A name of a native method to call.
    4) Whether or not this method is static.

    We also need to know whether this is a method or a getter/setter
    to do error reporting correctly.

    The idlNode parameter can be either a method or an attr. We can query
    |idlNode.identifier| in both cases, so we can be agnostic between the two.
    """
    # XXXbz For now each entry in the argument list is either an
    # IDLArgument or a FakeArgument, but longer-term we may want to
    # have ways of flagging things like JSContext* or optional_argc in
    # there.

    def __init__(self, returnType, argsPre, arguments, nativeMethodName, static,
                 descriptor, idlNode, argConversionStartsAt=0,
                 getter=False, setter=False):
        CGThing.__init__(self)
        self.returnType = returnType
        self.descriptor = descriptor
        self.idlNode = idlNode
        self.extendedAttributes = descriptor.getExtendedAttributes(idlNode,
                                                                   getter=getter,
                                                                   setter=setter)
        self.argsPre = argsPre
        self.arguments = arguments
        self.argCount = len(arguments)
        if self.argCount > argConversionStartsAt:
            # Insert our argv in there
            cgThings = [CGGeneric(self.getArgvDecl())]
        else:
            cgThings = []
        cgThings.extend([CGArgumentConverter(arguments[i], i, self.getArgv(),
                                             self.getArgc(), self.descriptor,
                                             invalidEnumValueFatal=not setter) for
                         i in range(argConversionStartsAt, self.argCount)])

        cgThings.append(CGCallGenerator(
                    self.getErrorReport() if self.isFallible() else None,
                    self.arguments, self.argsPre, returnType,
                    self.extendedAttributes, descriptor, nativeMethodName,
                    static))
        self.cgRoot = CGList(cgThings, "\n")

    def getArgv(self):
        return "argv" if self.argCount > 0 else ""
    def getArgvDecl(self):
        return "\nJS::Value* argv = JS_ARGV(cx, vp);\n"
    def getArgc(self):
        return "argc"

    def isFallible(self):
        return not 'infallible' in self.extendedAttributes

    def wrap_return_value(self):
        isCreator = self.idlNode.getExtendedAttribute("Creator") is not None
        if isCreator:
            # We better be returning addrefed things!
            assert isResultAlreadyAddRefed(self.descriptor,
                                           self.extendedAttributes)

        resultTemplateValues = { 'jsvalRef': '*vp', 'jsvalPtr': 'vp',
                                 'isCreator': isCreator}
        try:
            return wrapForType(self.returnType, self.descriptor,
                               resultTemplateValues)
        except MethodNotCreatorError, err:
            assert not isCreator
            raise TypeError("%s being returned from non-creator method or property %s.%s" %
                            (err.typename,
                             self.descriptor.interface.identifier.name,
                             self.idlNode.identifier.name))

    def getErrorReport(self):
        return 'return ThrowMethodFailedWithDetails<%s>(cx, rv, "%s", "%s");'\
               % (toStringBool(not self.descriptor.workers),
                  self.descriptor.interface.identifier.name,
                  self.idlNode.identifier.name)

    def define(self):
        return (self.cgRoot.define() + "\n" + self.wrap_return_value())

class CGSwitch(CGList):
    """
    A class to generate code for a switch statement.

    Takes three constructor arguments: an expression, a list of cases,
    and an optional default.

    Each case is a CGCase.  The default is a CGThing for the body of
    the default case, if any.
    """
    def __init__(self, expression, cases, default=None):
        CGList.__init__(self, [CGIndenter(c) for c in cases], "\n")
        self.prepend(CGWrapper(CGGeneric(expression),
                               pre="switch (", post=") {"));
        if default is not None:
            self.append(
                CGIndenter(
                    CGWrapper(
                        CGIndenter(default),
                        pre="default: {\n",
                        post="\n  break;\n}"
                        )
                    )
                )
                        
        self.append(CGGeneric("}"))

class CGCase(CGList):
    """
    A class to generate code for a case statement.

    Takes three constructor arguments: an expression, a CGThing for
    the body (allowed to be None if there is no body), and an optional
    argument (defaulting to False) for whether to fall through.
    """
    def __init__(self, expression, body, fallThrough=False):
        CGList.__init__(self, [], "\n")
        self.append(CGWrapper(CGGeneric(expression), pre="case ", post=": {"))
        bodyList = CGList([body], "\n")
        if fallThrough:
            bodyList.append(CGGeneric("/* Fall through */"))
        else:
            bodyList.append(CGGeneric("break;"))
        self.append(CGIndenter(bodyList));
        self.append(CGGeneric("}"))

class CGMethodCall(CGThing):
    """
    A class to generate selection of a method signature from a set of
    signatures and generation of a call to that signature.
    """
    def __init__(self, argsPre, nativeMethodName, static, descriptor, method):
        CGThing.__init__(self)

        methodName = '"%s.%s"' % (descriptor.interface.identifier.name, method.identifier.name)

        def requiredArgCount(signature):
            arguments = signature[1]
            if len(arguments) == 0:
                return 0
            requiredArgs = len(arguments)
            while requiredArgs and arguments[requiredArgs-1].optional:
                requiredArgs -= 1
            return requiredArgs

        def getPerSignatureCall(signature, argConversionStartsAt=0):
            return CGPerSignatureCall(signature[0], argsPre, signature[1],
                                      nativeMethodName, static, descriptor,
                                      method, argConversionStartsAt)
            

        signatures = method.signatures()
        if len(signatures) == 1:
            # Special case: we can just do a per-signature method call
            # here for our one signature and not worry about switching
            # on anything.
            signature = signatures[0]
            self.cgRoot = CGList([ CGIndenter(getPerSignatureCall(signature)) ])
            requiredArgs = requiredArgCount(signature)


            if requiredArgs > 0:
                code = (
                    "if (argc < %d) {\n"
                    "  return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, %s);\n"
                    "}" % (requiredArgs, methodName))
                self.cgRoot.prepend(
                    CGWrapper(CGIndenter(CGGeneric(code)), pre="\n", post="\n"))
            return

        # Need to find the right overload
        maxArgCount = method.maxArgCount
        allowedArgCounts = method.allowedArgCounts

        argCountCases = []
        for argCount in allowedArgCounts:
            possibleSignatures = method.signaturesForArgCount(argCount)
            if len(possibleSignatures) == 1:
                # easy case!
                signature = possibleSignatures[0]

                # (possibly) important optimization: if signature[1] has >
                # argCount arguments and signature[1][argCount] is optional and
                # there is only one signature for argCount+1, then the
                # signature for argCount+1 is just ourselves and we can fall
                # through.
                if (len(signature[1]) > argCount and
                    signature[1][argCount].optional and
                    (argCount+1) in allowedArgCounts and
                    len(method.signaturesForArgCount(argCount+1)) == 1):
                    argCountCases.append(
                        CGCase(str(argCount), None, True))
                else:
                    argCountCases.append(
                        CGCase(str(argCount), getPerSignatureCall(signature)))
                continue

            distinguishingIndex = method.distinguishingIndexForArgCount(argCount)

            # We can't handle unions at the distinguishing index.
            for (returnType, args) in possibleSignatures:
                if args[distinguishingIndex].type.isUnion():
                    raise TypeError("No support for unions as distinguishing "
                                    "arguments yet: %s",
                                    args[distinguishingIndex].location)

            # Convert all our arguments up to the distinguishing index.
            # Doesn't matter which of the possible signatures we use, since
            # they all have the same types up to that point; just use
            # possibleSignatures[0]
            caseBody = [CGGeneric("JS::Value* argv_start = JS_ARGV(cx, vp);")]
            caseBody.extend([ CGArgumentConverter(possibleSignatures[0][1][i],
                                                  i, "argv_start", "argc",
                                                  descriptor) for i in
                              range(0, distinguishingIndex) ])

            # Select the right overload from our set.
            distinguishingArg = "argv_start[%d]" % distinguishingIndex

            def pickFirstSignature(condition, filterLambda):
                sigs = filter(filterLambda, possibleSignatures)
                assert len(sigs) < 2
                if len(sigs) > 0:
                    if condition is None:
                        caseBody.append(
                            getPerSignatureCall(sigs[0], distinguishingIndex))
                    else:
                        caseBody.append(CGGeneric("if (" + condition + ") {"))
                        caseBody.append(CGIndenter(
                                getPerSignatureCall(sigs[0], distinguishingIndex)))
                        caseBody.append(CGGeneric("}"))
                    return True
                return False

            # First check for null or undefined
            pickFirstSignature("%s.isNullOrUndefined()" % distinguishingArg,
                               lambda s: (s[1][distinguishingIndex].type.nullable() or
                                          s[1][distinguishingIndex].type.isDictionary()))

            # Now check for distinguishingArg being an object that implements a
            # non-callback interface.  That includes typed arrays and
            # arraybuffers.
            interfacesSigs = [
                s for s in possibleSignatures
                if (s[1][distinguishingIndex].type.isObject() or
                    s[1][distinguishingIndex].type.isNonCallbackInterface()) ]
            # There might be more than one of these; we need to check
            # which ones we unwrap to.
            
            if len(interfacesSigs) > 0:
                # The spec says that we should check for "platform objects
                # implementing an interface", but it's enough to guard on these
                # being an object.  The code for unwrapping non-callback
                # interfaces and typed arrays will just bail out and move on to
                # the next overload if the object fails to unwrap correctly.  We
                # could even not do the isObject() check up front here, but in
                # cases where we have multiple object overloads it makes sense
                # to do it only once instead of for each overload.  That will
                # also allow the unwrapping test to skip having to do codegen
                # for the null-or-undefined case, which we already handled
                # above.
                caseBody.append(CGGeneric("if (%s.isObject()) {" %
                                          (distinguishingArg)))
                for sig in interfacesSigs:
                    caseBody.append(CGIndenter(CGGeneric("do {")));
                    type = sig[1][distinguishingIndex].type

                    # The argument at index distinguishingIndex can't possibly
                    # be unset here, because we've already checked that argc is
                    # large enough that we can examine this argument.
                    testCode = instantiateJSToNativeConversionTemplate(
                        getJSToNativeConversionTemplate(type, descriptor,
                                                        failureCode="break;",
                                                        isDefinitelyObject=True),
                        {
                            "declName" : "arg%d" % distinguishingIndex,
                            "holderName" : ("arg%d" % distinguishingIndex) + "_holder",
                            "val" : distinguishingArg
                            })

                    # Indent by 4, since we need to indent further than our "do" statement
                    caseBody.append(CGIndenter(testCode, 4));
                    # If we got this far, we know we unwrapped to the right
                    # interface, so just do the call.  Start conversion with
                    # distinguishingIndex + 1, since we already converted
                    # distinguishingIndex.
                    caseBody.append(CGIndenter(
                            getPerSignatureCall(sig, distinguishingIndex + 1), 4))
                    caseBody.append(CGIndenter(CGGeneric("} while (0);")))

                caseBody.append(CGGeneric("}"))

            # XXXbz Now we're supposed to check for distinguishingArg being
            # an array or a platform object that supports indexed
            # properties... skip that last for now.  It's a bit of a pain.
            pickFirstSignature("%s.isObject() && IsArrayLike(cx, &%s.toObject())" %
                               (distinguishingArg, distinguishingArg),
                               lambda s:
                                   (s[1][distinguishingIndex].type.isArray() or
                                    s[1][distinguishingIndex].type.isSequence() or
                                    s[1][distinguishingIndex].type.isObject()))

            # Check for Date objects
            # XXXbz Do we need to worry about security wrappers around the Date?
            pickFirstSignature("%s.isObject() && JS_ObjectIsDate(cx, &%s.toObject())" %
                               (distinguishingArg, distinguishingArg),
                               lambda s: (s[1][distinguishingIndex].type.isDate() or
                                          s[1][distinguishingIndex].type.isObject()))

            # Check for vanilla JS objects
            # XXXbz Do we need to worry about security wrappers?
            pickFirstSignature("%s.isObject() && !IsPlatformObject(cx, &%s.toObject())" %
                               (distinguishingArg, distinguishingArg),
                               lambda s: (s[1][distinguishingIndex].type.isCallback() or
                                          s[1][distinguishingIndex].type.isCallbackInterface() or
                                          s[1][distinguishingIndex].type.isDictionary() or
                                          s[1][distinguishingIndex].type.isObject()))

            # The remaining cases are mutually exclusive.  The
            # pickFirstSignature calls are what change caseBody
            # Check for strings or enums
            if pickFirstSignature(None,
                                  lambda s: (s[1][distinguishingIndex].type.isString() or
                                             s[1][distinguishingIndex].type.isEnum())):
                pass
            # Check for primitives
            elif pickFirstSignature(None,
                                    lambda s: s[1][distinguishingIndex].type.isPrimitive()):
                pass
            # Check for "any"
            elif pickFirstSignature(None,
                                    lambda s: s[1][distinguishingIndex].type.isAny()):
                pass
            else:
                # Just throw; we have no idea what we're supposed to
                # do with this.
                caseBody.append(CGGeneric("return Throw<%s>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);" %
                                          toStringBool(not descriptor.workers)))

            argCountCases.append(CGCase(str(argCount),
                                        CGList(caseBody, "\n")))

        overloadCGThings = []
        overloadCGThings.append(
            CGGeneric("unsigned argcount = NS_MIN(argc, %du);" %
                      maxArgCount))
        overloadCGThings.append(
            CGSwitch("argcount",
                     argCountCases,
                     CGGeneric("return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, %s);\n" % methodName)))
        overloadCGThings.append(
            CGGeneric('MOZ_NOT_REACHED("We have an always-returning default case");\n'
                      'return false;'))
        self.cgRoot = CGWrapper(CGIndenter(CGList(overloadCGThings, "\n")),
                                pre="\n")

    def define(self):
        return self.cgRoot.define()

class CGGetterSetterCall(CGPerSignatureCall):
    """
    A class to generate a native object getter or setter call for a
    particular IDL getter or setter.
    """
    def __init__(self, returnType, arguments, nativeMethodName, descriptor,
                 attr, getter=False, setter=False):
        assert bool(getter) != bool(setter)
        CGPerSignatureCall.__init__(self, returnType, [], arguments,
                                    nativeMethodName, False, descriptor, attr,
                                    getter=getter, setter=setter)
    def getArgv(self):
        if generateNativeAccessors:
            return CGPerSignatureCall.getArgv(self)
        return "vp"

class CGGetterCall(CGGetterSetterCall):
    """
    A class to generate a native object getter call for a particular IDL
    getter.
    """
    def __init__(self, returnType, nativeMethodName, descriptor, attr):
        CGGetterSetterCall.__init__(self, returnType, [], nativeMethodName,
                                    descriptor, attr, getter=True)
    def getArgc(self):
        if generateNativeAccessors:
            return CGGetterSetterCall.getArgc()
        return "0"
    def getArgvDecl(self):
        if generateNativeAccessors:
            return CGPerSignatureCall.getArgvDecl(self)
        # We just get our stuff from vp
        return ""

class FakeArgument():
    def __init__(self, type):
        self.type = type
        self.optional = False

class CGSetterCall(CGGetterSetterCall):
    """
    A class to generate a native object setter call for a particular IDL
    setter.
    """
    def __init__(self, argType, nativeMethodName, descriptor, attr):
        CGGetterSetterCall.__init__(self, None, [FakeArgument(argType)],
                                    nativeMethodName, descriptor, attr,
                                    setter=True)
    def wrap_return_value(self):
        if generateNativeAccessors:
            return CGGetterSetterCall.wrap_return_value(self)
        # We have no return value
        return "\nreturn true;"
    def getArgc(self):
        if generateNativeAccessors:
            return CGGetterSetterCall.getArgc(self)
        return "1"
    def getArgvDecl(self):
        if generateNativeAccessors:
            return (CGPerSignatureCall.getArgvDecl(self) +
                    "jsval undef = JS::UndefinedValue();\n"
                    "if (argc == 0) {\n"
                    "  argv = &undef;\n"
                    "  argc = 1;\n"
                    "}")
        # We just get our stuff from vp
        return ""

class CGAbstractBindingMethod(CGAbstractStaticMethod):
    """
    Common class to generate the JSNatives for all our methods, getters, and
    setters.  This will generate the function declaration and unwrap the
    |this| object.  Subclasses are expected to override the generate_code
    function to do the rest of the work.  This function should return a
    CGThing which is already properly indented.
    """
    def __init__(self, descriptor, name, args):
        CGAbstractStaticMethod.__init__(self, descriptor, name, "JSBool", args)

    def definition_body(self):
        unwrapThis = CGIndenter(CGGeneric(
            str(FailureFatalCastableObjectUnwrapper(self.descriptor,
                                                    "obj", "self"))))
        return CGList([ self.getThis(), unwrapThis,
                        self.generate_code() ], "\n").define()

    def getThis(self):
        return CGIndenter(
            CGGeneric("JSObject* obj = JS_THIS_OBJECT(cx, vp);\n"
                      "if (!obj) {\n"
                      "  return false;\n"
                      "}\n"
                      "\n"
                      "%s* self;" % self.descriptor.nativeType))

    def generate_code(self):
        assert(False) # Override me

def MakeNativeName(name):
    return name[0].upper() + name[1:]

class CGNativeMethod(CGAbstractBindingMethod):
    """
    A class for generating the C++ code for an IDL method..
    """
    def __init__(self, descriptor, method):
        self.method = method
        baseName = method.identifier.name
        args = [Argument('JSContext*', 'cx'), Argument('unsigned', 'argc'),
                Argument('JS::Value*', 'vp')]
        CGAbstractBindingMethod.__init__(self, descriptor, baseName, args)
    def generate_code(self):
        name = self.method.identifier.name
        nativeName = MakeNativeName(self.descriptor.binaryNames.get(name, name))
        return CGMethodCall([], nativeName, self.method.isStatic(),
                            self.descriptor, self.method)

class CGNativeGetter(CGAbstractBindingMethod):
    """
    A class for generating the C++ code for an IDL attribute getter.
    """
    def __init__(self, descriptor, attr):
        self.attr = attr
        name = 'get_' + attr.identifier.name
        if generateNativeAccessors:
            args = [Argument('JSContext*', 'cx'), Argument('unsigned', 'argc'),
                    Argument('JS::Value*', 'vp')]
        else:
            args = [Argument('JSContext*', 'cx'), Argument('JSHandleObject', 'obj'),
                    Argument('JSHandleId', 'id'), Argument('JS::Value*', 'vp')]
        CGAbstractBindingMethod.__init__(self, descriptor, name, args)

    def getThis(self):
        if generateNativeAccessors:
            return CGAbstractBindingMethod.getThis(self)
        return CGIndenter(
            CGGeneric("%s* self;" % self.descriptor.nativeType))

    def generate_code(self):
        name = self.attr.identifier.name
        nativeName = "Get" + MakeNativeName(self.descriptor.binaryNames.get(name, name))
        return CGIndenter(CGGetterCall(self.attr.type, nativeName, self.descriptor,
                                       self.attr))

class CGNativeSetter(CGAbstractBindingMethod):
    """
    A class for generating the C++ code for an IDL attribute setter.
    """
    def __init__(self, descriptor, attr):
        self.attr = attr
        baseName = attr.identifier.name
        name = 'set_' + attr.identifier.name
        if generateNativeAccessors:
            args = [Argument('JSContext*', 'cx'), Argument('unsigned', 'argc'),
                    Argument('JS::Value*', 'vp')]
        else:
            args = [Argument('JSContext*', 'cx'), Argument('JSHandleObject', 'obj'),
                    Argument('JSHandleId', 'id'), Argument('JSBool', 'strict'),
                    Argument('JS::Value*', 'vp')]
        CGAbstractBindingMethod.__init__(self, descriptor, name, args)

    def getThis(self):
        if generateNativeAccessors:
            return CGAbstractBindingMethod.getThis(self)
        return CGIndenter(
            CGGeneric("%s* self;" % self.descriptor.nativeType))

    def generate_code(self):
        name = self.attr.identifier.name
        nativeName = "Set" + MakeNativeName(self.descriptor.binaryNames.get(name, name))
        return CGIndenter(CGSetterCall(self.attr.type, nativeName, self.descriptor,
                                       self.attr))

def getEnumValueName(value):
    # Some enum values can be empty strings.  Others might have weird
    # characters in them.  Deal with the former by returning "_empty",
    # deal with possible name collisions from that by throwing if the
    # enum value is actually "_empty", and throw on any value
    # containing chars other than [a-z] or '-' for now. Replace '-' with '_'.
    value = value.replace('-', '_')
    if value == "_empty":
        raise SyntaxError('"_empty" is not an IDL enum value we support yet')
    if value == "":
        return "_empty"
    if not re.match("^[a-z_]+$", value):
        raise SyntaxError('Enum value "' + value + '" contains characters '
                          'outside [a-z_]')
    return MakeNativeName(value)

class CGEnum(CGThing):
    def __init__(self, enum):
        CGThing.__init__(self)
        self.enum = enum

    def declare(self):
        return """
  enum valuelist {
    %s
  };

  extern const EnumEntry strings[%d];
""" % (",\n    ".join(map(getEnumValueName, self.enum.values())),
       len(self.enum.values()) + 1)

    def define(self):
        return """
  const EnumEntry strings[%d] = {
    %s,
    { NULL, 0 }
  };
""" % (len(self.enum.values()) + 1,
       ",\n    ".join(['{"' + val + '", ' + str(len(val)) + '}' for val in self.enum.values()]))

def getUnionAccessorSignatureType(type, descriptorProvider):
    """
    Returns the types that are used in the getter and setter signatures for
    union types
    """
    if type.isArray():
        raise TypeError("Can't handle array arguments yet")

    if type.isSequence():
        nullable = type.nullable();
        if nullable:
            type = type.inner.inner
        else:
            type = type.inner
        (elementTemplate, elementDeclType,
         elementHolderType, dealWithOptional) = getJSToNativeConversionTemplate(
            type, descriptorProvider, isSequenceMember=True)
        typeName = CGWrapper(elementDeclType, pre="Sequence< ", post=" >&")
        if nullable:
            typeName = CGWrapper(typeName, pre="Nullable< ", post=" >&")

        return typeName

    if type.isUnion():
        typeName = CGGeneric(type.name)
        if type.nullable():
            typeName = CGWrapper(typeName, pre="Nullable< ", post=" >&")

        return typeName

    if type.isGeckoInterface():
        descriptor = descriptorProvider.getDescriptor(
            type.unroll().inner.identifier.name)
        typeName = CGGeneric(descriptor.nativeType)
        # Allow null pointers for nullable types and old-binding classes
        if type.nullable() or type.unroll().inner.isExternal():
            typeName = CGWrapper(typeName, post="*")
        else:
            typeName = CGWrapper(typeName, post="&")
        return typeName

    if type.isSpiderMonkeyInterface():
        typeName = CGGeneric(type.name)
        if type.nullable():
            typeName = CGWrapper(typeName, post="*")
        else:
            typeName = CGWrapper(typeName, post="&")
        return typeName

    if type.isString():
        return CGGeneric("const nsAString&")

    if type.isEnum():
        if type.nullable():
            raise TypeError("We don't support nullable enumerated arguments or "
                            "union members yet")
        return CGGeneric(type.inner.identifier.name)

    if type.isCallback():
        return CGGeneric("JSObject*")

    if type.isAny():
        return CGGeneric("JS::Value")

    if type.isObject():
        typeName = CGGeneric("JSObject")
        if type.nullable():
            typeName = CGWrapper(typeName, post="*")
        else:
            typeName = CGWrapper(typeName, post="&")
        return typeName

    if not type.isPrimitive():
        raise TypeError("Need native type for argument type '%s'" % str(type))

    typeName = CGGeneric(builtinNames[type.tag()])
    if type.nullable():
        typeName = CGWrapper(typeName, pre="Nullable< ", post=" >&")
    return typeName

def getUnionTypeTemplateVars(type, descriptorProvider):
    # For dictionaries and sequences we need to pass None as the failureCode
    # for getJSToNativeConversionTemplate.
    # Also, for dictionaries we would need to handle conversion of
    # null/undefined to the dictionary correctly.
    if type.isDictionary() or type.isSequence():
        raise TypeError("Can't handle dictionaries or sequences in unions")

    if type.isGeckoInterface():
        name = type.inner.identifier.name
    elif type.isEnum():
        name = type.inner.identifier.name
    elif type.isArray() or type.isSequence():
        name = str(type)
    else:
        name = type.name

    tryNextCode = """tryNext = true;
return true;"""
    if type.isGeckoInterface():
         tryNextCode = ("""if (mUnion.mType != mUnion.eUninitialized) {
  mUnion.Destroy%s();
}""" % name) + tryNextCode
    (template, declType, holderType,
     dealWithOptional) = getJSToNativeConversionTemplate(
        type, descriptorProvider, failureCode=tryNextCode,
        isDefinitelyObject=True)

    # This is ugly, but UnionMember needs to call a constructor with no
    # arguments so the type can't be const.
    structType = declType.define()
    if structType.startswith("const "):
        structType = structType[6:]
    externalType = getUnionAccessorSignatureType(type, descriptorProvider).define()

    if type.isObject():
        setter = CGGeneric("void SetToObject(JSObject* obj)\n"
                           "{\n"
                           "  mUnion.mValue.mObject.SetValue() = obj;\n"
                           "  mUnion.mType = mUnion.eObject;\n"
                           "}")
    else:
        jsConversion = string.Template(template).substitute(
            {
                "val": "value",
                "valPtr": "pvalue",
                "declName": "SetAs" + name + "()",
                "holderName": "m" + name + "Holder"
                }
            )
        jsConversion = CGWrapper(CGGeneric(jsConversion),
                                 post="\n"
                                      "return true;")
        setter = CGWrapper(CGIndenter(jsConversion),
                           pre="bool TrySetTo" + name + "(JSContext* cx, const JS::Value& value, JS::Value* pvalue, bool& tryNext)\n"
                               "{\n"
                               "  tryNext = false;\n",
                           post="\n"
                                "}")

    return {
                "name": name,
                "structType": structType,
                "externalType": externalType,
                "setter": CGIndenter(setter).define(),
                "holderType": holderType.define() if holderType else None
                }

def mapTemplate(template, templateVarArray):
    return map(lambda v: string.Template(template).substitute(v),
               templateVarArray)

class CGUnionStruct(CGThing):
    def __init__(self, type, descriptorProvider):
        CGThing.__init__(self)
        self.type = type.unroll()
        self.descriptorProvider = descriptorProvider

    def declare(self):
        templateVars = map(lambda t: getUnionTypeTemplateVars(t, self.descriptorProvider),
                           self.type.flatMemberTypes)

        callDestructors = []
        enumValues = []
        methods = []
        if self.type.hasNullableType:
            callDestructors.append("      case eNull:\n"
                                   "        break;")
            enumValues.append("eNull")
            methods.append("""  bool IsNull() const
  {
    return mType == eNull;
  }""")

        destructorTemplate = """  void Destroy${name}()
  {
    MOZ_ASSERT(Is${name}(), "Wrong type!");
    mValue.m${name}.Destroy();
    mType = eUninitialized;
  }"""
        destructors = mapTemplate(destructorTemplate, templateVars)
        callDestructors.extend(mapTemplate("      case e${name}:\n"
                                           "         Destroy${name}();\n"
                                           "         break;", templateVars))
        enumValues.extend(mapTemplate("e${name}", templateVars))
        methodTemplate = """  bool Is${name}() const
  {
    return mType == e${name};
  }
  ${externalType} GetAs${name}() const
  {
    MOZ_ASSERT(Is${name}(), "Wrong type!");
    // The cast to ${externalType} is needed to work around a bug in Apple's
    // clang compiler, for some reason it doesn't call |S::operator T&| when
    // casting S<T> to T& and T is forward declared.
    return (${externalType})mValue.m${name}.Value();
  }
  ${structType}& SetAs${name}()
  {
    mType = e${name};
    return mValue.m${name}.SetValue();
  }"""
        methods.extend(mapTemplate(methodTemplate, templateVars))
        values = mapTemplate("UnionMember<${structType} > m${name};", templateVars)
        return string.Template("""
class ${structName} {
public:
  ${structName}() : mType(eUninitialized)
  {
  }
  ~${structName}()
  {
    switch (mType) {
${callDestructors}
      case eUninitialized:
        break;
    }
  }

${methods}

private:
  friend class ${structName}Argument;

${destructors}

  enum Type {
    eUninitialized,
    ${enumValues}
  };
  union Value {
    ${values}
  };

  Type mType;
  Value mValue;
};

""").substitute(
    {
       "structName": self.type.__str__(),
       "callDestructors": "\n".join(callDestructors),
       "destructors": "\n".join(destructors),
       "methods": "\n\n".join(methods),
       "enumValues": ",\n    ".join(enumValues),
       "values": "\n    ".join(values),
       })

    def define(self):
        return """
"""

class CGUnionConversionStruct(CGThing):
    def __init__(self, type, descriptorProvider):
        CGThing.__init__(self)
        self.type = type.unroll()
        self.descriptorProvider = descriptorProvider

    def declare(self):
        setters = []

        if self.type.hasNullableType:
            setters.append("""  bool SetNull()
  {
    mUnion.mType = mUnion.eNull;
    return true;
  }""")

        templateVars = map(lambda t: getUnionTypeTemplateVars(t, self.descriptorProvider),
                           self.type.flatMemberTypes)
        structName = self.type.__str__()

        setters.extend(mapTemplate("${setter}", templateVars))
        private = "\n".join(mapTemplate("""  ${structType}& SetAs${name}()
  {
    mUnion.mType = mUnion.e${name};
    return mUnion.mValue.m${name}.SetValue();
  }""", templateVars))
        private += "\n\n"
        holders = filter(lambda v: v["holderType"] is not None, templateVars)
        if len(holders) > 0:
            private += "\n".join(mapTemplate("  ${holderType} m${name}Holder;", holders))
            private += "\n\n"
        private += "  " + structName + "& mUnion;"
        return string.Template("""
class ${structName}Argument {
public:
  ${structName}Argument(const ${structName}& aUnion) : mUnion(const_cast<${structName}&>(aUnion))
  {
  }

${setters}

private:
${private}
};
""").substitute({"structName": structName,
       "setters": "\n\n".join(setters),
       "private": private
       })

    def define(self):
        return """
"""

class ClassItem:
    """ Use with CGClass """
    def __init__(self, name, visibility):
        self.name = name
        self.visibility = visibility
    def declare(self, cgClass):
        assert False
    def define(self, cgClass):
        assert False

class ClassBase(ClassItem):
    def __init__(self, name, visibility='public'):
        ClassItem.__init__(self, name, visibility)
    def declare(self, cgClass):
        return '%s %s' % (self.visibility, self.name)
    def define(self, cgClass):
        # Only in the header
        return ''

class ClassMethod(ClassItem):
    def __init__(self, name, returnType, args, inline=False, static=False,
                 virtual=False, const=False, bodyInHeader=False,
                 templateArgs=None, visibility='public', body=None):
        self.returnType = returnType
        self.args = args
        self.inline = inline or bodyInHeader
        self.static = static
        self.virtual = virtual
        self.const = const
        self.bodyInHeader = bodyInHeader
        self.templateArgs = templateArgs
        self.body = body
        ClassItem.__init__(self, name, visibility)

    def getDecorators(self, declaring):
        decorators = []
        if self.inline:
            decorators.append('inline')
        if declaring:
            if self.static:
                decorators.append('static')
            if self.virtual:
                decorators.append('virtual')
        if decorators:
            return ' '.join(decorators) + ' '
        return ''

    def getBody(self):
        # Override me or pass a string to constructor
        assert self.body is not None
        return self.body

    def declare(self, cgClass):
        templateClause = 'template <%s>\n' % ', '.join(self.templateArgs) \
                         if self.bodyInHeader and self.templateArgs else ''
        args = ', '.join([str(a) for a in self.args])
        if self.bodyInHeader:
            body = CGIndenter(CGGeneric(self.getBody())).define()
            body = '\n{\n' + body + '\n}'
        else:
           body = ';'

        return string.Template("""${templateClause}${decorators}${returnType}
${name}(${args})${const}${body}
""").substitute({ 'templateClause': templateClause,
                  'decorators': self.getDecorators(True),
                  'returnType': self.returnType,
                  'name': self.name,
                  'const': ' const' if self.const else '',
                  'args': args,
                  'body': body })

    def define(self, cgClass):
        if self.bodyInHeader:
            return ''

        templateArgs = cgClass.templateArgs
        if templateArgs:
            if cgClass.templateSpecialization:
                templateArgs = \
                    templateArgs[len(cgClass.templateSpecialization):]

        if templateArgs:
            templateClause = \
                'template <%s>\n' % ', '.join([str(a) for a in templateArgs])
        else:
            templateClause = ''

        args = ', '.join([str(a) for a in self.args])

        body = CGIndenter(CGGeneric(self.getBody())).define()

        return string.Template("""${templateClause}${decorators}${returnType}
${className}::${name}(${args})${const}
{
${body}
}\n
""").substitute({ 'templateClause': templateClause,
                  'decorators': self.getDecorators(False),
                  'returnType': self.returnType,
                  'className': cgClass.getNameString(),
                  'name': self.name,
                  'args': args,
                  'const': ' const' if self.const else '',
                  'body': body })

class ClassMember(ClassItem):
    def __init__(self, name, type, visibility="private", static=False,
                 body=None):
        self.type = type;
        self.static = static
        self.body = body
        ClassItem.__init__(self, name, visibility)

    def getBody(self):
        assert self.body is not None
        return self.body

    def declare(self, cgClass):
        return '%s%s %s;\n' % ('static ' if self.static else '', self.type,
                               self.name)

    def define(self, cgClass):
        if not self.static:
            return ''
        return '%s %s::%s = %s;\n' % (self.type, cgClass.getNameString(),
                                      self.name, self.getBody())

class ClassTypedef(ClassItem):
    def __init__(self, name, type, visibility="public"):
        self.type = type
        ClassItem.__init__(self, name, visibility)

    def declare(self, cgClass):
        return 'typedef %s %s;\n' % (self.type, self.name)

    def define(self, cgClass):
        # Only goes in the header
        return ''

class ClassEnum(ClassItem):
    def __init__(self, name, entries, values=None, visibility="public"):
        self.entries = entries
        self.values = values
        ClassItem.__init__(self, name, visibility)

    def declare(self, cgClass):
        entries = []
        for i in range(0, len(self.entries)):
            if i >= len(self.values):
                entry = '%s' % self.entries[i]
            else:
                entry = '%s = %s' % (self.entries[i], self.values[i])
            entries.append(entry)
        name = '' if not self.name else ' ' + self.name
        return 'enum%s\n{\n  %s\n};\n' % (name, ',\n  '.join(entries))

    def define(self, cgClass):
        # Only goes in the header
        return ''

class CGClass(CGThing):
    def __init__(self, name, bases=[], members=[], methods=[], typedefs = [],
                 enums=[], templateArgs=[], templateSpecialization=[],
                 isStruct=False, indent=''):
        CGThing.__init__(self)
        self.name = name
        self.bases = bases
        self.members = members
        self.methods = methods
        self.typedefs = typedefs
        self.enums = enums
        self.templateArgs = templateArgs
        self.templateSpecialization = templateSpecialization
        self.isStruct = isStruct
        self.indent = indent
        self.defaultVisibility ='public' if isStruct else 'private'

    def getNameString(self):
        className = self.name
        if self.templateSpecialization:
            className = className + \
                '<%s>' % ', '.join([str(a) for a
                                    in self.templateSpecialization])
        return className

    def declare(self):
        result = ''
        if self.templateArgs:
            templateArgs = [str(a) for a in self.templateArgs]
            templateArgs = templateArgs[len(self.templateSpecialization):]
            result = result + self.indent + 'template <%s>\n' \
                     % ','.join([str(a) for a in templateArgs])

        type = 'struct' if self.isStruct else 'class'

        if self.templateSpecialization:
            specialization = \
                '<%s>' % ', '.join([str(a) for a in self.templateSpecialization])
        else:
            specialization = ''

        result = result + '%s%s %s%s' \
                 % (self.indent, type, self.name, specialization)

        if self.bases:
            result = result + ' : %s' % ', '.join([d.declare(self) for d in self.bases])

        result = result + '\n%s{\n' % self.indent

        def declareMembers(cgClass, memberList, defaultVisibility, itemCount,
                           separator=''):
            members = { 'private': [], 'protected': [], 'public': [] }

            for member in memberList:
                members[member.visibility].append(member)


            if defaultVisibility == 'public':
                order = [ 'public', 'protected', 'private' ]
            else:
                order = [ 'private', 'protected', 'public' ]

            result = ''

            lastVisibility = defaultVisibility
            for visibility in order:
                list = members[visibility]
                if list:
                    if visibility != lastVisibility:
                        if itemCount:
                            result = result + '\n'
                        result = result + visibility + ':\n'
                        itemCount = 0
                    for member in list:
                        if itemCount != 0:
                            result = result + separator
                        declaration = member.declare(cgClass)
                        declaration = CGIndenter(CGGeneric(declaration)).define()
                        result = result + declaration
                        itemCount = itemCount + 1
                    lastVisibility = visibility
            return (result, lastVisibility, itemCount)

        order = [(self.enums, ''), (self.typedefs, ''), (self.members, ''),
                 (self.methods, '\n')]

        lastVisibility = self.defaultVisibility
        itemCount = 0
        for (memberList, separator) in order:
            (memberString, lastVisibility, itemCount) = \
                declareMembers(self, memberList, lastVisibility, itemCount,
                               separator)
            if self.indent:
                memberString = CGIndenter(CGGeneric(memberString),
                                          len(self.indent)).define()
            result = result + memberString

        result = result + self.indent + '};\n\n'
        return result

    def define(self):
        def defineMembers(cgClass, memberList, itemCount, separator=''):
            result = ''
            for member in memberList:
                if itemCount != 0:
                    result = result + separator
                result = result + member.define(cgClass)
                itemCount = itemCount + 1
            return (result, itemCount)

        order = [(self.members, '\n'), (self.methods, '\n')]

        result = ''
        itemCount = 0
        for (memberList, separator) in order:
            (memberString, itemCount) = defineMembers(self, memberList,
                                                      itemCount, separator)
            result = result + memberString
        return result

class CGResolveProperty(CGAbstractMethod):
    def __init__(self, descriptor, properties):
        args = [Argument('JSContext*', 'cx'), Argument('JSObject*', 'wrapper'),
                Argument('jsid', 'id'), Argument('bool', 'set'),
                Argument('JSPropertyDescriptor*', 'desc')]
        CGAbstractMethod.__init__(self, descriptor, "ResolveProperty", "bool", args)
        self.properties = properties
    def definition_body(self):
        str = ""

        varNames = self.properties.variableNames(True)

        methods = self.properties.methods
        if methods.hasNonChromeOnly() or methods.hasChromeOnly():
            str += """  // %(methods)s has an end-of-list marker at the end that we ignore
  for (size_t prefIdx = 0; prefIdx < ArrayLength(%(methods)s)-1; ++prefIdx) {
    MOZ_ASSERT(%(methods)s[prefIdx].specs);
    if (%(methods)s[prefIdx].enabled) {
      // Set i to be the index into our full list of ids/specs that we're
      // looking at now.
      size_t i = %(methods)s[prefIdx].specs - %(methods)s_specs;
      for ( ; %(methods)s_ids[i] != JSID_VOID; ++i) {
        if (id == %(methods)s_ids[i]) {
          JSFunction *fun = JS_NewFunctionById(cx, %(methods)s_specs[i].call, %(methods)s_specs[i].nargs, 0, wrapper, id);
          if (!fun)
              return false;
          JSObject *funobj = JS_GetFunctionObject(fun);
          desc->value.setObject(*funobj);
          desc->attrs = %(methods)s_specs[i].flags;
          desc->obj = wrapper;
          desc->setter = nsnull;
          desc->getter = nsnull;
          return true;
        }
      }
    }
  }

""" % varNames

        attrs = self.properties.attrs
        if attrs.hasNonChromeOnly() or attrs.hasChromeOnly():
            str += """  // %(attrs)s has an end-of-list marker at the end that we ignore
  for (size_t prefIdx = 0; prefIdx < ArrayLength(%(attrs)s)-1; ++prefIdx) {
    MOZ_ASSERT(%(attrs)s[prefIdx].specs);
    if (%(attrs)s[prefIdx].enabled) {
      // Set i to be the index into our full list of ids/specs that we're
      // looking at now.
      size_t i = %(attrs)s[prefIdx].specs - %(attrs)s_specs;;
      for ( ; %(attrs)s_ids[i] != JSID_VOID; ++i) {
        if (id == %(attrs)s_ids[i]) {
          desc->attrs = %(attrs)s_specs[i].flags;
          desc->obj = wrapper;
          desc->setter = %(attrs)s_specs[i].setter;
          desc->getter = %(attrs)s_specs[i].getter;
          return true;
        }
      }
    }
  }

""" % varNames

        return str + "  return true;"

class CGEnumerateProperties(CGAbstractMethod):
    def __init__(self, descriptor, properties):
        args = [Argument('JS::AutoIdVector&', 'props')]
        CGAbstractMethod.__init__(self, descriptor, "EnumerateProperties", "bool", args)
        self.properties = properties
    def definition_body(self):
        str = ""

        varNames = self.properties.variableNames(True)

        methods = self.properties.methods
        if methods.hasNonChromeOnly() or methods.hasChromeOnly():
            str += """  // %(methods)s has an end-of-list marker at the end that we ignore
  for (size_t prefIdx = 0; prefIdx < ArrayLength(%(methods)s)-1; ++prefIdx) {
    MOZ_ASSERT(%(methods)s[prefIdx].specs);
    if (%(methods)s[prefIdx].enabled) {
      // Set i to be the index into our full list of ids/specs that we're
      // looking at now.
      size_t i = %(methods)s[prefIdx].specs - %(methods)s_specs;
      for ( ; %(methods)s_ids[i] != JSID_VOID; ++i) {
        if ((%(methods)s_specs[i].flags & JSPROP_ENUMERATE) &&
            !props.append(%(methods)s_ids[i])) {
          return false;
        }
      }
    }
  }

""" % varNames

        attrs = self.properties.attrs
        if attrs.hasNonChromeOnly() or attrs.hasChromeOnly():
            str += """  // %(attrs)s has an end-of-list marker at the end that we ignore
  for (size_t prefIdx = 0; prefIdx < ArrayLength(%(attrs)s)-1; ++prefIdx) {
    MOZ_ASSERT(%(attrs)s[prefIdx].specs);
    if (%(attrs)s[prefIdx].enabled) {
      // Set i to be the index into our full list of ids/specs that we're
      // looking at now.
      size_t i = %(attrs)s[prefIdx].specs - %(attrs)s_specs;;
      for ( ; %(attrs)s_ids[i] != JSID_VOID; ++i) {
        if ((%(attrs)s_specs[i].flags & JSPROP_ENUMERATE) &&
            !props.append(%(attrs)s_ids[i])) {
          return false;
        }
      }
    }
  }

""" % varNames

        return str + "  return true;"

class CGPrototypeTraitsClass(CGClass):
    def __init__(self, descriptor, indent=''):
        templateArgs = [Argument('prototypes::ID', 'PrototypeID')]
        templateSpecialization = ['prototypes::id::' + descriptor.name]
        enums = [ClassEnum('', ['Depth'],
                           [descriptor.interface.inheritanceDepth()])]
        typedefs = [ClassTypedef('NativeType', descriptor.nativeType)]
        CGClass.__init__(self, 'PrototypeTraits', indent=indent,
                         templateArgs=templateArgs,
                         templateSpecialization=templateSpecialization,
                         enums=enums, typedefs=typedefs, isStruct=True)

class CGPrototypeIDMapClass(CGClass):
    def __init__(self, descriptor, indent=''):
        templateArgs = [Argument('class', 'ConcreteClass')]
        templateSpecialization = [descriptor.nativeType]
        enums = [ClassEnum('', ['PrototypeID'],
                           ['prototypes::id::' + descriptor.name])]
        CGClass.__init__(self, 'PrototypeIDMap', indent=indent,
                         templateArgs=templateArgs,
                         templateSpecialization=templateSpecialization,
                         enums=enums, isStruct=True)

class CGClassForwardDeclare(CGThing):
    def __init__(self, name, isStruct=False):
        CGThing.__init__(self)
        self.name = name
        self.isStruct = isStruct
    def declare(self):
        type = 'struct' if self.isStruct else 'class'
        return '%s %s;\n' % (type, self.name)
    def define(self):
        # Header only
        return ''

def stripTrailingWhitespace(text):
    lines = text.splitlines()
    for i in range(len(lines)):
        lines[i] = lines[i].rstrip()
    return '\n'.join(lines)

class CGDescriptor(CGThing):
    def __init__(self, descriptor):
        CGThing.__init__(self)

        assert not descriptor.concrete or descriptor.interface.hasInterfacePrototypeObject()

        cgThings = []
        if descriptor.interface.hasInterfacePrototypeObject():
            cgThings.extend([CGNativeMethod(descriptor, m) for m in
                             descriptor.interface.members if
                             m.isMethod() and not m.isStatic()])
            cgThings.extend([CGNativeGetter(descriptor, a) for a in
                             descriptor.interface.members if a.isAttr()])
            cgThings.extend([CGNativeSetter(descriptor, a) for a in
                             descriptor.interface.members if
                             a.isAttr() and not a.readonly])

        if descriptor.concrete:
            if not descriptor.workers and descriptor.wrapperCache:
                cgThings.append(CGAddPropertyHook(descriptor))

            # Always have a finalize hook, regardless of whether the class wants a
            # custom hook.
            cgThings.append(CGClassFinalizeHook(descriptor))

            # Only generate a trace hook if the class wants a custom hook.
            if (descriptor.customTrace):
                cgThings.append(CGClassTraceHook(descriptor))

        if descriptor.concrete or descriptor.interface.hasInterfacePrototypeObject():
            cgThings.append(CGNativePropertyHooks(descriptor))
        if descriptor.concrete:
            cgThings.append(CGDOMJSClass(descriptor))

        if descriptor.interface.hasInterfaceObject():
            cgThings.append(CGClassConstructHook(descriptor))
            cgThings.append(CGClassHasInstanceHook(descriptor))
            cgThings.append(CGInterfaceObjectJSClass(descriptor))

        if descriptor.interface.hasInterfacePrototypeObject():
            cgThings.append(CGPrototypeJSClass(descriptor))

        properties = PropertyArrays(descriptor)
        cgThings.append(CGGeneric(define=str(properties)))
        cgThings.append(CGCreateInterfaceObjectsMethod(descriptor, properties))
        if descriptor.interface.hasInterfacePrototypeObject():
            cgThings.append(CGIndenter(CGGetProtoObjectMethod(descriptor)))
        else:
            cgThings.append(CGIndenter(CGGetConstructorObjectMethod(descriptor)))

        # Set up our Xray callbacks as needed.  Note that we don't need to do
        # it in workers.
        if ((descriptor.concrete or
             descriptor.interface.hasInterfacePrototypeObject()) and
            not descriptor.workers):
            cgThings.append(CGResolveProperty(descriptor, properties))
            cgThings.append(CGEnumerateProperties(descriptor, properties))

        if descriptor.interface.hasInterfaceObject():
            cgThings.append(CGDefineDOMInterfaceMethod(descriptor))

        if descriptor.concrete:
            if descriptor.wrapperCache:
                cgThings.append(CGWrapMethod(descriptor))
            else:
                cgThings.append(CGWrapNonWrapperCacheMethod(descriptor))

        cgThings = CGList(cgThings)
        cgThings = CGWrapper(cgThings, post='\n')
        self.cgRoot = CGWrapper(CGNamespace(toBindingNamespace(descriptor.name),
                                            cgThings),
                                post='\n')

    def declare(self):
        return self.cgRoot.declare()
    def define(self):
        return self.cgRoot.define()

class CGNamespacedEnum(CGThing):
    def __init__(self, namespace, enumName, names, values, comment=""):

        if not values:
            values = []

        # Account for explicit enum values.
        entries = []
        for i in range(0, len(names)):
            if len(values) > i and values[i] is not None:
                entry = "%s = %s" % (names[i], values[i])
            else:
                entry = names[i]
            entries.append(entry)

        # Append a Count.
        entries.append('_' + enumName + '_Count')

        # Indent.
        entries = ['  ' + e for e in entries]

        # Build the enum body.
        enumstr = comment + 'enum %s\n{\n%s\n};\n' % (enumName, ',\n'.join(entries))
        curr = CGGeneric(declare=enumstr)

        # Add some whitespace padding.
        curr = CGWrapper(curr, pre='\n',post='\n')

        # Add the namespace.
        curr = CGNamespace(namespace, curr)

        # Add the typedef
        typedef = '\ntypedef %s::%s %s;\n\n' % (namespace, enumName, enumName)
        curr = CGList([curr, CGGeneric(declare=typedef)])

        # Save the result.
        self.node = curr

    def declare(self):
        return self.node.declare()
    def define(self):
        assert False # Only for headers.

class CGDictionary(CGThing):
    def __init__(self, dictionary, descriptorProvider):
        self.dictionary = dictionary;
        self.workers = descriptorProvider.workers
        if dictionary.parent:
            parentCGThing = CGDictionary(dictionary.parent, descriptorProvider)
            self.generatable = parentCGThing.generatable
            if not self.generatable:
                # Nothing else to do here
                return
        else:
            self.generatable = True
        # Getting a conversion template for interface types can fail
        # if we don't have a relevant descriptor when self.workers is True.
        # If that happens, just mark ourselves as not being
        # generatable and move on.
        try:
            self.memberInfo = [
                (member,
                 getJSToNativeConversionTemplate(member.type,
                                                 descriptorProvider,
                                                 isMember=True,
                                                 isOptional=(not member.defaultValue)))
                for member in dictionary.members ]
        except NoSuchDescriptorError, err:
            if not self.workers:
                raise err
            self.generatable = False

    def declare(self):
        if not self.generatable:
            return ""
        d = self.dictionary
        if d.parent:
            inheritance = ": public %s " % self.makeClassName(d.parent)
        else:
            inheritance = ""
        memberDecls = ["  %s %s;" %
                       (self.getMemberType(m), m[0].identifier.name)
                       for m in self.memberInfo]

        return (string.Template(
                "struct ${selfName} ${inheritance}{\n"
                "  ${selfName}() {}\n"
                "  bool Init(JSContext* cx, const JS::Value& val);\n"
                "\n" +
                "\n".join(memberDecls) + "\n"
                "private:\n"
                "  // Disallow copy-construction\n"
                "  ${selfName}(const ${selfName}&) MOZ_DELETE;\n"
                "  static bool InitIds(JSContext* cx);\n"
                "  static bool initedIds;\n" +
                "\n".join("  static jsid " +
                          self.makeIdName(m.identifier.name) + ";" for
                          m in d.members) + "\n"
                "};").substitute( { "selfName": self.makeClassName(d),
                                    "inheritance": inheritance }))

    def define(self):
        if not self.generatable:
            return ""
        d = self.dictionary
        if d.parent:
            initParent = ("// Per spec, we init the parent's members first\n"
                          "if (!%s::Init(cx, val)) {\n"
                          "  return false;\n"
                          "}\n" % self.makeClassName(d.parent))
        else:
            initParent = ""

        memberInits = [CGIndenter(self.getMemberConversion(m)).define()
                       for m in self.memberInfo]
        idinit = [CGGeneric('!InternJSString(cx, %s, "%s")' %
                            (m.identifier.name + "_id", m.identifier.name))
                  for m in d.members]
        idinit = CGList(idinit, " ||\n")
        idinit = CGWrapper(idinit, pre="if (",
                           post=(") {\n"
                                 "  return false;\n"
                                 "}"),
                           reindent=True)

        return string.Template(
            "bool ${selfName}::initedIds = false;\n" +
            "\n".join("jsid ${selfName}::%s = JSID_VOID;" %
                      self.makeIdName(m.identifier.name)
                      for m in d.members) + "\n"
            "\n"
            "bool\n"
            "${selfName}::InitIds(JSContext* cx)\n"
            "{\n"
            "  MOZ_ASSERT(!initedIds);\n"
            "${idInit}\n"
            "  initedIds = true;\n"
            "  return true;\n"
            "}\n"
            "\n"
            "bool\n"
            "${selfName}::Init(JSContext* cx, const JS::Value& val)\n"
            "{\n"
            "  if (!initedIds && !InitIds(cx)) {\n"
            "    return false;\n"
            "  }\n"
            "${initParent}"
            "  JSBool found;\n"
            "  JS::Value temp;\n"
            "  bool isNull = val.isNullOrUndefined();\n"
            "  if (!isNull && !val.isObject()) {\n"
            "    return Throw<${isMainThread}>(cx, NS_ERROR_XPC_BAD_CONVERT_JS);\n"
            "  }\n"
            "\n"
            "${initMembers}\n"
            "  return true;\n"
            "}").substitute({
                "selfName": self.makeClassName(d),
                "initParent": CGIndenter(CGGeneric(initParent)).define(),
                "initMembers": "\n\n".join(memberInits),
                "idInit": CGIndenter(idinit).define(),
                "isMainThread": toStringBool(not self.workers)
                })

    @staticmethod
    def makeDictionaryName(dictionary, workers):
        suffix = "Workers" if workers else ""
        return dictionary.identifier.name + suffix

    def makeClassName(self, dictionary):
        return self.makeDictionaryName(dictionary, self.workers)

    def getMemberType(self, memberInfo):
        (member, (templateBody, declType,
                  holderType, dealWithOptional)) = memberInfo
        # We can't handle having a holderType here
        assert holderType is None
        if dealWithOptional:
            declType = CGWrapper(declType, pre="Optional< ", post=" >")
        return declType.define()

    def getMemberConversion(self, memberInfo):
        (member, (templateBody, declType,
                  holderType, dealWithOptional)) = memberInfo
        replacements = { "val": "temp",
                         "valPtr": "&temp",
                         # Use this->%s to refer to members, because we don't
                         # control the member names and want to make sure we're
                         # talking about the member, not some local that
                         # shadows the member.  Another option would be to move
                         # the guts of init to a static method which is passed
                         # an explicit reference to our dictionary object, so
                         # we couldn't screw this up even if we wanted to....
                         "declName": ("(this->%s)" % member.identifier.name),
                         # We need a holder name for external interfaces, but
                         # it's scoped down to the conversion so we can just use
                         # anything we want.
                         "holderName": "holder"}
        # We can't handle having a holderType here
        assert holderType is None
        if dealWithOptional:
            replacements["declName"] = "(" + replacements["declName"] + ".Value())"

        conversionReplacements = {
            "propId" : self.makeIdName(member.identifier.name),
            "prop": "(this->%s)" % member.identifier.name,
            "convert": string.Template(templateBody).substitute(replacements)
            }
        conversion = ("if (isNull) {\n"
                      "  found = false;\n"
                      "} else if (!JS_HasPropertyById(cx, &val.toObject(), ${propId}, &found)) {\n"
                      "  return false;\n"
                      "}\n")
        if member.defaultValue:
            conversion += (
                "if (found) {\n"
                "  if (!JS_GetPropertyById(cx, &val.toObject(), ${propId}, &temp)) {\n"
                "    return false;\n"
                "  }\n"
                "} else {\n"
                "  temp = ${defaultVal};\n"
                "}\n"
                "${convert}")
            conversionReplacements["defaultVal"] = (
                convertIDLDefaultValueToJSVal(member.defaultValue))
        else:
            conversion += (
                "if (found) {\n"
                "  ${prop}.Construct();\n"
                "  if (!JS_GetPropertyById(cx, &val.toObject(), ${propId}, &temp)) {\n"
                "    return false;\n"
                "  }\n"
                "${convert}\n"
                "}")
            conversionReplacements["convert"] = CGIndenter(
                CGGeneric(conversionReplacements["convert"])).define()
        
        return CGGeneric(
            string.Template(conversion).substitute(conversionReplacements)
            )

    @staticmethod
    def makeIdName(name):
        return name + "_id"

class CGRegisterProtos(CGAbstractMethod):
    def __init__(self, config):
        CGAbstractMethod.__init__(self, None, 'Register', 'void',
                                  [Argument('nsScriptNameSpaceManager*', 'aNameSpaceManager')])
        self.config = config

    def _defineMacro(self):
       return """
#define REGISTER_PROTO(_dom_class) \\
  aNameSpaceManager->RegisterDefineDOMInterface(NS_LITERAL_STRING(#_dom_class), _dom_class##Binding::DefineDOMInterface);\n\n"""
    def _undefineMacro(self):
        return "\n#undef REGISTER_PROTO"
    def _registerProtos(self):
        lines = ["REGISTER_PROTO(%s);" % desc.name
                 for desc in self.config.getDescriptors(hasInterfaceObject=True,
                                                        isExternal=False,
                                                        workers=False,
                                                        register=True)]
        return '\n'.join(lines) + '\n'
    def definition_body(self):
        return self._defineMacro() + self._registerProtos() + self._undefineMacro()

class CGBindingRoot(CGThing):
    """
    Root codegen class for binding generation. Instantiate the class, and call
    declare or define to generate header or cpp code (respectively).
    """
    def __init__(self, config, prefix, webIDLFile):
        descriptors = config.getDescriptors(webIDLFile=webIDLFile,
                                            hasInterfaceOrInterfacePrototypeObject=True)
        dictionaries = config.getDictionaries(webIDLFile)

        forwardDeclares = [CGClassForwardDeclare('XPCWrappedNativeScope')]

        descriptorsForForwardDeclaration = list(descriptors)
        for dictionary in dictionaries:
            curDict = dictionary
            ifacemembers = []
            while curDict:
                ifacemembers.extend([m.type.unroll().inner for m
                                     in curDict.members
                                     if m.type.unroll().isInterface()])
                curDict = curDict.parent
            # Put in all the non-worker descriptors
            descriptorsForForwardDeclaration.extend(
                [config.getDescriptor(iface.identifier.name, False) for
                 iface in ifacemembers])
            # And now the worker ones.  But these may not exist, so we
            # have to be more careful.
            for iface in ifacemembers:
                try:
                    descriptorsForForwardDeclaration.append(
                        config.getDescriptor(iface.identifier.name, True))
                except NoSuchDescriptorError:
                    # just move along
                    pass

        for x in descriptorsForForwardDeclaration:
            nativeType = x.nativeType
            components = x.nativeType.split('::')
            className = components[-1]
            # JSObject is a struct, not a class
            declare = CGClassForwardDeclare(className, className is "JSObject")
            if len(components) > 1:
                declare = CGNamespace.build(components[:-1],
                                            CGWrapper(declare, declarePre='\n',
                                                      declarePost='\n'),
                                            declareOnly=True)
            forwardDeclares.append(CGWrapper(declare, declarePost='\n'))

        forwardDeclares = CGList(forwardDeclares)

        descriptorsWithPrototype = filter(lambda d: d.interface.hasInterfacePrototypeObject(),
                                          descriptors)
        traitsClasses = [CGPrototypeTraitsClass(d) for d in descriptorsWithPrototype]

        # We must have a 1:1 mapping here, skip for prototypes that have more
        # than one concrete class implementation.
        traitsClasses.extend([CGPrototypeIDMapClass(d) for d in descriptorsWithPrototype
                              if d.uniqueImplementation])

        # Wrap all of that in our namespaces.
        if len(traitsClasses) > 0:
            traitsClasses = CGNamespace.build(['mozilla', 'dom'],
                                     CGWrapper(CGList(traitsClasses),
                                               declarePre='\n'),
                                               declareOnly=True)
            traitsClasses = CGWrapper(traitsClasses, declarePost='\n')
        else:
            traitsClasses = None

        # Do codegen for all the enums
        def makeEnum(e):
            return CGNamespace.build([e.identifier.name + "Values"],
                                     CGEnum(e))
        def makeEnumTypedef(e):
            return CGGeneric(declare=("typedef %sValues::valuelist %s;\n" %
                                      (e.identifier.name, e.identifier.name)))
        cgthings = [ fun(e) for e in config.getEnums(webIDLFile)
                     for fun in [makeEnum, makeEnumTypedef] ]

        # Do codegen for all the dictionaries.  We have to be a bit careful
        # here, because we have to generate these in order from least derived to
        # most derived so that class inheritance works out.
        #
        # XXXbz this will fail if we have two webidl files A and B such that A
        # declares a dictionary which inherits from a dictionary in B and B
        # declares a dictionary (possibly a different one!) that inherits from a
        # dictionary in A.  The good news is that I expect this to never happen.
        reSortedDictionaries = []
        while len(dictionaries) != 0:
            toMove = [d for d in dictionaries if d.parent not in dictionaries]
            dictionaries = [d for d in dictionaries if d.parent in dictionaries]
            reSortedDictionaries.extend(toMove)

        dictionaries = reSortedDictionaries
        cgthings.extend([CGDictionary(d, config.getDescriptorProvider(True))
                         for d in dictionaries])
        cgthings.extend([CGDictionary(d, config.getDescriptorProvider(False))
                         for d in dictionaries])

        # Do codegen for all the descriptors
        cgthings.extend([CGDescriptor(x) for x in descriptors])

        # And make sure we have the right number of newlines at the end
        curr = CGWrapper(CGList(cgthings, "\n\n"), post="\n\n")

        # Wrap all of that in our namespaces.
        curr = CGNamespace.build(['mozilla', 'dom'],
                                 CGWrapper(curr, pre="\n"))

        curr = CGList([forwardDeclares,
                       CGWrapper(CGGeneric("using namespace mozilla::dom;"),
                                 defineOnly=True),
                       traitsClasses, curr],
                      "\n")

        # Add header includes.
        curr = CGHeaders(descriptors,
                         dictionaries,
                         ['mozilla/dom/BindingUtils.h',
                          'mozilla/dom/DOMJSClass.h'],
                         ['mozilla/dom/Nullable.h',
                          'PrimitiveConversions.h',
                          'XPCQuickStubs.h',
                          'nsDOMQS.h',
                          'AccessCheck.h',
                          'WorkerPrivate.h',
                          'nsContentUtils.h',
                          'mozilla/Preferences.h',
                          # Have to include nsDOMQS.h to get fast arg unwrapping
                          # for old-binding things with castability.
                          'nsDOMQS.h'
                          ],
                         curr)

        # Add include guards.
        curr = CGIncludeGuard(prefix, curr)

        # Add the auto-generated comment.
        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)

        # Store the final result.
        self.root = curr

    def declare(self):
        return stripTrailingWhitespace(self.root.declare())
    def define(self):
        return stripTrailingWhitespace(self.root.define())


class GlobalGenRoots():
    """
    Roots for global codegen.

    To generate code, call the method associated with the target, and then
    call the appropriate define/declare method.
    """

    @staticmethod
    def PrototypeList(config):

        # Prototype ID enum.
        protos = [d.name for d in config.getDescriptors(hasInterfacePrototypeObject=True)]
        idEnum = CGNamespacedEnum('id', 'ID', protos, [0])
        idEnum = CGList([idEnum])
        idEnum.append(CGGeneric(declare="const unsigned MaxProtoChainLength = " +
                                str(config.maxProtoChainLength) + ";\n\n"))

        # Wrap all of that in our namespaces.
        idEnum = CGNamespace.build(['mozilla', 'dom', 'prototypes'],
                                   CGWrapper(idEnum, pre='\n'))
        idEnum = CGWrapper(idEnum, post='\n')

        curr = CGList([idEnum])

        # Constructor ID enum.
        constructors = [d.name for d in config.getDescriptors(hasInterfaceObject=True,
                                                              hasInterfacePrototypeObject=False)]
        idEnum = CGNamespacedEnum('id', 'ID', constructors, [0])

        # Wrap all of that in our namespaces.
        idEnum = CGNamespace.build(['mozilla', 'dom', 'constructors'],
                                   CGWrapper(idEnum, pre='\n'))
        idEnum = CGWrapper(idEnum, post='\n')

        curr.append(idEnum)

        traitsDecl = CGGeneric(declare="""
template <prototypes::ID PrototypeID>
struct PrototypeTraits;

template <class ConcreteClass>
struct PrototypeIDMap;
""")

        traitsDecl = CGNamespace.build(['mozilla', 'dom'],
                                        CGWrapper(traitsDecl, post='\n'))

        curr.append(traitsDecl)

        # Add include guards.
        curr = CGIncludeGuard('PrototypeList', curr)

        # Add the auto-generated comment.
        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)

        # Done.
        return curr

    @staticmethod
    def RegisterBindings(config):

        # TODO - Generate the methods we want
        curr = CGRegisterProtos(config)

        # Wrap all of that in our namespaces.
        curr = CGNamespace.build(['mozilla', 'dom'],
                                 CGWrapper(curr, post='\n'))
        curr = CGWrapper(curr, post='\n')

        # Add the includes
        defineIncludes = [CGHeaders.getDeclarationFilename(desc.interface)
                          for desc in config.getDescriptors(hasInterfaceObject=True,
                                                            workers=False,
                                                            register=True)]
        defineIncludes.append('nsScriptNameSpaceManager.h')
        curr = CGHeaders([], [], [], defineIncludes, curr)

        # Add include guards.
        curr = CGIncludeGuard('RegisterBindings', curr)

        # Done.
        return curr

    @staticmethod
    def UnionTypes(config):

        (includes, declarations, unions) = UnionTypes(config.getDescriptors())
        includes.add("mozilla/dom/BindingUtils.h")

        # Wrap all of that in our namespaces.
        curr = CGNamespace.build(['mozilla', 'dom'], unions)

        curr = CGWrapper(curr, post='\n')

        namespaces = []
        stack = [CGList([])]
        for (clazz, isStruct) in SortedTuples(declarations):
            elements = clazz.split("::")
            clazz = CGClassForwardDeclare(elements.pop(), isStruct=isStruct)
            i = 0
            if len(elements) > 0:
                common = min(len(namespaces), len(elements))
                while i < common and namespaces[i] == elements[i]:
                    i += 1

            # pop all the namespaces that should be closed
            namespaces = namespaces[:i]

            # add all the namespaces that should be opened
            for j, namespace in enumerate(elements[i:]):
                namespaces.append(namespace)
                # every CGNamespace that we add holds a CGList
                list = CGList([])
                # add the new namespace to the list on top of the stack
                stack[i + j].append(CGNamespace(namespace, list))
                # set the top of the namespace stack to the list of the new
                # namespace
                stack[i + j + 1:] = [list]

            stack[len(elements)].append(clazz)

        curr = CGList([stack[0], curr], "\n")

        curr = CGHeaders([], [], includes, [], curr)

        # Add include guards.
        curr = CGIncludeGuard('UnionTypes', curr)

        # Done.
        return curr

    @staticmethod
    def UnionConversions(config):

        unions = UnionConversions(config.getDescriptors())

        # Wrap all of that in our namespaces.
        curr = CGNamespace.build(['mozilla', 'dom'], unions)

        curr = CGWrapper(curr, post='\n')

        curr = CGHeaders([], [], ["nsDebug.h", "mozilla/dom/UnionTypes.h", "nsDOMQS.h"], [], curr)

        # Add include guards.
        curr = CGIncludeGuard('UnionConversions', curr)

        # Done.
        return curr