gecko-dev/dom/base/nsJSUtils.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
#ifndef nsJSUtils_h__
#define nsJSUtils_h__
/**
* This is not a generated file. It contains common utility functions
* invoked from the JavaScript code generated from IDL interfaces.
* The goal of the utility functions is to cut down on the size of
* the generated code itself.
*/
#include "mozilla/Assertions.h"
#include "GeckoProfiler.h"
#include "jsapi.h"
#include "jsfriendapi.h"
#include "js/Conversions.h"
#include "nsString.h"
class nsIScriptContext;
class nsIScriptElement;
class nsIScriptGlobalObject;
class nsXBLPrototypeBinding;
namespace mozilla {
namespace dom {
class AutoJSAPI;
class Element;
} // namespace dom
} // namespace mozilla
class nsJSUtils
{
public:
static bool GetCallingLocation(JSContext* aContext, nsACString& aFilename,
uint32_t* aLineno = nullptr,
uint32_t* aColumn = nullptr);
static bool GetCallingLocation(JSContext* aContext, nsAString& aFilename,
uint32_t* aLineno = nullptr,
uint32_t* aColumn = nullptr);
/**
* Retrieve the inner window ID based on the given JSContext.
*
* @param JSContext aContext
* The JSContext from which you want to find the inner window ID.
*
* @returns uint64_t the inner window ID.
*/
static uint64_t GetCurrentlyRunningCodeInnerWindowID(JSContext *aContext);
static nsresult CompileFunction(mozilla::dom::AutoJSAPI& jsapi,
JS::AutoObjectVector& aScopeChain,
JS::CompileOptions& aOptions,
const nsACString& aName,
uint32_t aArgCount,
const char** aArgArray,
const nsAString& aBody,
JSObject** aFunctionObject);
// ExecutionContext is used to switch compartment.
class MOZ_STACK_CLASS ExecutionContext {
#ifdef MOZ_GECKO_PROFILER
// Register stack annotations for the Gecko profiler.
mozilla::AutoProfilerLabel mAutoProfilerLabel;
#endif
JSContext* mCx;
// Handles switching to our global's realm.
JSAutoRealm mRealm;
// Set to a valid handle if a return value is expected.
JS::Rooted<JS::Value> mRetValue;
// Scope chain in which the execution takes place.
JS::AutoObjectVector mScopeChain;
// returned value forwarded when we have to interupt the execution eagerly
// with mSkip.
nsresult mRv;
// Used to skip upcoming phases in case of a failure. In such case the
// result is carried by mRv.
bool mSkip;
// Should the result be serialized before being returned.
bool mCoerceToString;
// Encode the bytecode before it is being executed.
bool mEncodeBytecode;
#ifdef DEBUG
// Should we set the return value.
bool mWantsReturnValue;
bool mExpectScopeChain;
#endif
public:
// Enter compartment in which the code would be executed. The JSContext
// must come from an AutoEntryScript that has had
// TakeOwnershipOfErrorReporting() called on it.
ExecutionContext(JSContext* aCx, JS::Handle<JSObject*> aGlobal);
ExecutionContext(const ExecutionContext&) = delete;
ExecutionContext(ExecutionContext&&) = delete;
~ExecutionContext() {
// This flag is resetted, when the returned value is extracted.
MOZ_ASSERT(!mWantsReturnValue);
}
// The returned value would be converted to a string if the
// |aCoerceToString| is flag set.
ExecutionContext& SetCoerceToString(bool aCoerceToString) {
mCoerceToString = aCoerceToString;
return *this;
}
// When set, this flag records and encodes the bytecode as soon as it is
// being compiled, and before it is being executed. The bytecode can then be
// requested by using |JS::FinishIncrementalEncoding| with the mutable
// handle |aScript| argument of |CompileAndExec| or |JoinAndExec|.
ExecutionContext& SetEncodeBytecode(bool aEncodeBytecode) {
mEncodeBytecode = aEncodeBytecode;
return *this;
}
// Set the scope chain in which the code should be executed.
void SetScopeChain(const JS::AutoObjectVector& aScopeChain);
// Copy the returned value in the mutable handle argument, in case of a
// evaluation failure either during the execution or the conversion of the
// result to a string, the nsresult would be set to the corresponding result
// code, and the mutable handle argument would remain unchanged.
//
// The value returned in the mutable handle argument is part of the
// compartment given as argument to the ExecutionContext constructor. If the
// caller is in a different compartment, then the out-param value should be
// wrapped by calling |JS_WrapValue|.
MOZ_MUST_USE nsresult
ExtractReturnValue(JS::MutableHandle<JS::Value> aRetValue);
// After getting a notification that an off-thread compilation terminated,
// this function will take the result of the parser by moving it to the main
// thread before starting the execution of the script.
//
// The compiled script would be returned in the |aScript| out-param.
MOZ_MUST_USE nsresult JoinAndExec(JS::OffThreadToken** aOffThreadToken,
JS::MutableHandle<JSScript*> aScript);
// Compile a script contained in a SourceBuffer, and execute it.
nsresult CompileAndExec(JS::CompileOptions& aCompileOptions,
JS::SourceBufferHolder& aSrcBuf,
JS::MutableHandle<JSScript*> aScript);
// Compile a script contained in a string, and execute it.
nsresult CompileAndExec(JS::CompileOptions& aCompileOptions,
const nsAString& aScript);
// Decode a script contained in a buffer, and execute it.
MOZ_MUST_USE nsresult DecodeAndExec(JS::CompileOptions& aCompileOptions,
mozilla::Vector<uint8_t>& aBytecodeBuf,
size_t aBytecodeIndex);
// After getting a notification that an off-thread decoding terminated, this
// function will get the result of the decoder by moving it to the main
// thread before starting the execution of the script.
MOZ_MUST_USE nsresult DecodeJoinAndExec(JS::OffThreadToken** aOffThreadToken);
MOZ_MUST_USE nsresult DecodeBinASTJoinAndExec(JS::OffThreadToken** aOffThreadToken,
JS::MutableHandle<JSScript*> aScript);
// Decode a BinAST encoded script contained in a buffer, and execute it.
nsresult DecodeBinASTAndExec(JS::CompileOptions& aCompileOptions,
const uint8_t* aBuf, size_t aLength,
JS::MutableHandle<JSScript*> aScript);
};
static nsresult CompileModule(JSContext* aCx,
JS::SourceBufferHolder& aSrcBuf,
JS::Handle<JSObject*> aEvaluationGlobal,
JS::CompileOptions &aCompileOptions,
JS::MutableHandle<JSObject*> aModule);
static nsresult InitModuleSourceElement(JSContext* aCx,
JS::Handle<JSObject*> aModule,
nsIScriptElement* aElement);
static nsresult ModuleInstantiate(JSContext* aCx,
JS::Handle<JSObject*> aModule);
static nsresult ModuleEvaluate(JSContext* aCx,
JS::Handle<JSObject*> aModule);
// Returns false if an exception got thrown on aCx. Passing a null
// aElement is allowed; that wil produce an empty aScopeChain.
static bool GetScopeChainForElement(JSContext* aCx,
mozilla::dom::Element* aElement,
JS::AutoObjectVector& aScopeChain);
// Returns a scope chain suitable for XBL execution.
//
// This is by default GetScopeChainForElemenet, but will be different if the
// <binding> element had the simpleScopeChain attribute.
//
// This is to prevent footguns like bug 1446342.
static bool GetScopeChainForXBL(JSContext* aCx,
mozilla::dom::Element* aBoundElement,
const nsXBLPrototypeBinding& aProtoBinding,
JS::AutoObjectVector& aScopeChain);
static void ResetTimeZone();
};
template<typename T>
inline bool
AssignJSString(JSContext *cx, T &dest, JSString *s)
{
size_t len = js::GetStringLength(s);
static_assert(js::MaxStringLength < (1 << 28),
"Shouldn't overflow here or in SetCapacity");
if (MOZ_UNLIKELY(!dest.SetLength(len, mozilla::fallible))) {
JS_ReportOutOfMemory(cx);
return false;
}
return js::CopyStringChars(cx, dest.BeginWriting(), s, len);
}
inline void
AssignJSFlatString(nsAString &dest, JSFlatString *s)
{
size_t len = js::GetFlatStringLength(s);
static_assert(js::MaxStringLength < (1 << 28),
"Shouldn't overflow here or in SetCapacity");
dest.SetLength(len);
js::CopyFlatStringChars(dest.BeginWriting(), s, len);
}
class nsAutoJSString : public nsAutoString
{
public:
/**
* nsAutoJSString should be default constructed, which leaves it empty
* (this->IsEmpty()), and initialized with one of the init() methods below.
*/
nsAutoJSString() {}
bool init(JSContext* aContext, JSString* str)
{
return AssignJSString(aContext, *this, str);
}
bool init(JSContext* aContext, const JS::Value &v)
{
if (v.isString()) {
return init(aContext, v.toString());
}
// Stringify, making sure not to run script.
JS::Rooted<JSString*> str(aContext);
if (v.isObject()) {
str = JS_NewStringCopyZ(aContext, "[Object]");
} else {
JS::Rooted<JS::Value> rootedVal(aContext, v);
str = JS::ToString(aContext, rootedVal);
}
return str && init(aContext, str);
}
bool init(JSContext* aContext, jsid id)
{
JS::Rooted<JS::Value> v(aContext);
return JS_IdToValue(aContext, id, &v) && init(aContext, v);
}
bool init(const JS::Value &v);
~nsAutoJSString() {}
};
#endif /* nsJSUtils_h__ */