From c8683ff7977c526fb48ae007971fed16ef32ff62 Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Fri, 4 Mar 2016 17:09:08 -0800 Subject: [PATCH] cmd/compile/internal/syntax: fast Go syntax trees, initial commit. Syntax tree nodes, scanner, parser, basic printers. Builds syntax trees for entire Go std lib at a rate of ~1.8M lines/s in warmed up state (MacMini, 2.3 GHz Intel Core i7, 8GB RAM): $ go test -run StdLib -fast parsed 1074617 lines (2832 files) in 579.66364ms (1853863 lines/s) allocated 282.212Mb (486.854Mb/s) PASS Change-Id: Ie26d9a7bf4e5ff07457aedfcc9b89f0eba72ae3f Reviewed-on: https://go-review.googlesource.com/27195 Run-TryBot: Matthew Dempsky Reviewed-by: Robert Griesemer --- misc/nacl/testzip.proto | 4 + src/cmd/compile/internal/syntax/dumper.go | 212 ++ .../compile/internal/syntax/dumper_test.go | 22 + src/cmd/compile/internal/syntax/nodes.go | 425 ++++ src/cmd/compile/internal/syntax/parser.go | 2062 +++++++++++++++++ .../compile/internal/syntax/parser_test.go | 157 ++ src/cmd/compile/internal/syntax/printer.go | 942 ++++++++ .../compile/internal/syntax/printer_test.go | 24 + src/cmd/compile/internal/syntax/scanner.go | 651 ++++++ .../compile/internal/syntax/scanner_test.go | 354 +++ src/cmd/compile/internal/syntax/source.go | 177 ++ src/cmd/compile/internal/syntax/syntax.go | 61 + src/cmd/compile/internal/syntax/tokens.go | 263 +++ 13 files changed, 5354 insertions(+) create mode 100644 src/cmd/compile/internal/syntax/dumper.go create mode 100644 src/cmd/compile/internal/syntax/dumper_test.go create mode 100644 src/cmd/compile/internal/syntax/nodes.go create mode 100644 src/cmd/compile/internal/syntax/parser.go create mode 100644 src/cmd/compile/internal/syntax/parser_test.go create mode 100644 src/cmd/compile/internal/syntax/printer.go create mode 100644 src/cmd/compile/internal/syntax/printer_test.go create mode 100644 src/cmd/compile/internal/syntax/scanner.go create mode 100644 src/cmd/compile/internal/syntax/scanner_test.go create mode 100644 src/cmd/compile/internal/syntax/source.go create mode 100644 src/cmd/compile/internal/syntax/syntax.go create mode 100644 src/cmd/compile/internal/syntax/tokens.go diff --git a/misc/nacl/testzip.proto b/misc/nacl/testzip.proto index 8a8784c8be..bb7b39d8ca 100644 --- a/misc/nacl/testzip.proto +++ b/misc/nacl/testzip.proto @@ -18,6 +18,10 @@ go src=.. asm testdata + + compile + internal + syntax + parser.go doc main.go pkg.go diff --git a/src/cmd/compile/internal/syntax/dumper.go b/src/cmd/compile/internal/syntax/dumper.go new file mode 100644 index 0000000000..bb369fc705 --- /dev/null +++ b/src/cmd/compile/internal/syntax/dumper.go @@ -0,0 +1,212 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This file implements printing of syntax tree structures. + +package syntax + +import ( + "fmt" + "io" + "reflect" + "unicode" + "unicode/utf8" +) + +// Fdump dumps the structure of the syntax tree rooted at n to w. +// It is intended for debugging purposes; no specific output format +// is guaranteed. +func Fdump(w io.Writer, n Node) (err error) { + p := dumper{ + output: w, + ptrmap: make(map[Node]int), + last: '\n', // force printing of line number on first line + } + + defer func() { + if e := recover(); e != nil { + err = e.(localError).err // re-panics if it's not a localError + } + }() + + if n == nil { + p.printf("nil\n") + return + } + p.dump(reflect.ValueOf(n), n) + p.printf("\n") + + return +} + +type dumper struct { + output io.Writer + ptrmap map[Node]int // node -> dump line number + indent int // current indentation level + last byte // last byte processed by Write + line int // current line number +} + +var indentBytes = []byte(". ") + +func (p *dumper) Write(data []byte) (n int, err error) { + var m int + for i, b := range data { + // invariant: data[0:n] has been written + if b == '\n' { + m, err = p.output.Write(data[n : i+1]) + n += m + if err != nil { + return + } + } else if p.last == '\n' { + p.line++ + _, err = fmt.Fprintf(p.output, "%6d ", p.line) + if err != nil { + return + } + for j := p.indent; j > 0; j-- { + _, err = p.output.Write(indentBytes) + if err != nil { + return + } + } + } + p.last = b + } + if len(data) > n { + m, err = p.output.Write(data[n:]) + n += m + } + return +} + +// localError wraps locally caught errors so we can distinguish +// them from genuine panics which we don't want to return as errors. +type localError struct { + err error +} + +// printf is a convenience wrapper that takes care of print errors. +func (p *dumper) printf(format string, args ...interface{}) { + if _, err := fmt.Fprintf(p, format, args...); err != nil { + panic(localError{err}) + } +} + +// dump prints the contents of x. +// If x is the reflect.Value of a struct s, where &s +// implements Node, then &s should be passed for n - +// this permits printing of the unexported span and +// comments fields of the embedded isNode field by +// calling the Span() and Comment() instead of using +// reflection. +func (p *dumper) dump(x reflect.Value, n Node) { + switch x.Kind() { + case reflect.Interface: + if x.IsNil() { + p.printf("nil") + return + } + p.dump(x.Elem(), nil) + + case reflect.Ptr: + if x.IsNil() { + p.printf("nil") + return + } + + // special cases for identifiers w/o attached comments (common case) + if x, ok := x.Interface().(*Name); ok { + p.printf(x.Value) + return + } + + p.printf("*") + // Fields may share type expressions, and declarations + // may share the same group - use ptrmap to keep track + // of nodes that have been printed already. + if ptr, ok := x.Interface().(Node); ok { + if line, exists := p.ptrmap[ptr]; exists { + p.printf("(Node @ %d)", line) + return + } + p.ptrmap[ptr] = p.line + n = ptr + } + p.dump(x.Elem(), n) + + case reflect.Slice: + if x.IsNil() { + p.printf("nil") + return + } + p.printf("%s (%d entries) {", x.Type(), x.Len()) + if x.Len() > 0 { + p.indent++ + p.printf("\n") + for i, n := 0, x.Len(); i < n; i++ { + p.printf("%d: ", i) + p.dump(x.Index(i), nil) + p.printf("\n") + } + p.indent-- + } + p.printf("}") + + case reflect.Struct: + typ := x.Type() + + // if span, ok := x.Interface().(lexical.Span); ok { + // p.printf("%s", &span) + // return + // } + + p.printf("%s {", typ) + p.indent++ + + first := true + if n != nil { + p.printf("\n") + first = false + // p.printf("Span: %s\n", n.Span()) + // if c := *n.Comments(); c != nil { + // p.printf("Comments: ") + // p.dump(reflect.ValueOf(c), nil) // a Comment is not a Node + // p.printf("\n") + // } + } + + for i, n := 0, typ.NumField(); i < n; i++ { + // Exclude non-exported fields because their + // values cannot be accessed via reflection. + if name := typ.Field(i).Name; isExported(name) { + if first { + p.printf("\n") + first = false + } + p.printf("%s: ", name) + p.dump(x.Field(i), nil) + p.printf("\n") + } + } + + p.indent-- + p.printf("}") + + default: + switch x := x.Interface().(type) { + case string: + // print strings in quotes + p.printf("%q", x) + default: + p.printf("%v", x) + } + } +} + +func isExported(name string) bool { + ch, _ := utf8.DecodeRuneInString(name) + return unicode.IsUpper(ch) +} diff --git a/src/cmd/compile/internal/syntax/dumper_test.go b/src/cmd/compile/internal/syntax/dumper_test.go new file mode 100644 index 0000000000..fd38e7ca78 --- /dev/null +++ b/src/cmd/compile/internal/syntax/dumper_test.go @@ -0,0 +1,22 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "os" + "testing" +) + +func TestDump(t *testing.T) { + if testing.Short() { + t.Skip("skipping test in short mode") + } + + ast, err := ReadFile(*src, nil, 0) + if err != nil { + t.Fatal(err) + } + Fdump(os.Stdout, ast) +} diff --git a/src/cmd/compile/internal/syntax/nodes.go b/src/cmd/compile/internal/syntax/nodes.go new file mode 100644 index 0000000000..4e264c1e82 --- /dev/null +++ b/src/cmd/compile/internal/syntax/nodes.go @@ -0,0 +1,425 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +// ---------------------------------------------------------------------------- +// Nodes + +type Node interface { + aNode() +} + +type node struct { + doc *Comment // nil means no comment(s) attached + pos uint32 + line uint32 +} + +func (*node) aNode() {} + +func (n *node) init(p *parser) { + n.pos = uint32(p.pos) + n.line = uint32(p.line) +} + +// ---------------------------------------------------------------------------- +// Files + +type File struct { + PkgName *Name + DeclList []Decl + Pragmas []Pragma + Lines int + node +} + +type Pragma struct { + Line int + Text string +} + +// ---------------------------------------------------------------------------- +// Declarations + +type ( + Decl interface { + Node + aDecl() + } + + ImportDecl struct { + LocalPkgName *Name // including "."; nil means no rename present + Path *BasicLit + Group *Group // nil means not part of a group + decl + } + + ConstDecl struct { + NameList []*Name + Type Expr // nil means no type + Values Expr // nil means no values + Group *Group // nil means not part of a group + decl + } + + TypeDecl struct { + Name *Name + Type Expr + Group *Group // nil means not part of a group + decl + } + + VarDecl struct { + NameList []*Name + Type Expr // nil means no type + Values Expr // nil means no values + Group *Group // nil means not part of a group + decl + } + + FuncDecl struct { + Attr map[string]bool // go:attr map + Recv *Field // nil means regular function + Name *Name + Type *FuncType + Body []Stmt // nil means no body (forward declaration) + decl + } +) + +type decl struct{ node } + +func (*decl) aDecl() {} + +// All declarations belonging to the same group point to the same Group node. +type Group struct { + dummy int // not empty so we are guaranteed different Group instances +} + +// ---------------------------------------------------------------------------- +// Expressions + +type ( + Expr interface { + Node + aExpr() + } + + // Value + Name struct { + Value string + expr + } + + // Value + BasicLit struct { + Value string + Kind LitKind + expr + } + + // Type { ElemList[0], ElemList[1], ... } + CompositeLit struct { + Type Expr // nil means no literal type + ElemList []Expr + NKeys int // number of elements with keys + expr + } + + // Key: Value + KeyValueExpr struct { + Key, Value Expr + expr + } + + // func Type { Body } + FuncLit struct { + Type *FuncType + Body []Stmt + expr + } + + // (X) + ParenExpr struct { + X Expr + expr + } + + // X.Sel + SelectorExpr struct { + X Expr + Sel *Name + expr + } + + // X[Index] + IndexExpr struct { + X Expr + Index Expr + expr + } + + // X[Index[0] : Index[1] : Index[2]] + SliceExpr struct { + X Expr + Index [3]Expr + expr + } + + // X.(Type) + AssertExpr struct { + X Expr + // TODO(gri) consider using Name{"..."} instead of nil (permits attaching of comments) + Type Expr + expr + } + + Operation struct { + Op Operator + X, Y Expr // Y == nil means unary expression + expr + } + + // Fun(ArgList[0], ArgList[1], ...) + CallExpr struct { + Fun Expr + ArgList []Expr + HasDots bool // last argument is followed by ... + expr + } + + // ElemList[0], ElemList[1], ... + ListExpr struct { + ElemList []Expr + expr + } + + // [Len]Elem + ArrayType struct { + // TODO(gri) consider using Name{"..."} instead of nil (permits attaching of comments) + Len Expr // nil means Len is ... + Elem Expr + expr + } + + // []Elem + SliceType struct { + Elem Expr + expr + } + + // ...Elem + DotsType struct { + Elem Expr + expr + } + + // struct { FieldList[0] TagList[0]; FieldList[1] TagList[1]; ... } + StructType struct { + FieldList []*Field + TagList []*BasicLit // i >= len(TagList) || TagList[i] == nil means no tag for field i + expr + } + + // Name Type + // Type + Field struct { + Name *Name // nil means anonymous field/parameter (structs/parameters), or embedded interface (interfaces) + Type Expr // field names declared in a list share the same Type (identical pointers) + node + } + + // interface { MethodList[0]; MethodList[1]; ... } + InterfaceType struct { + MethodList []*Field + expr + } + + FuncType struct { + ParamList []*Field + ResultList []*Field + expr + } + + // map[Key]Value + MapType struct { + Key Expr + Value Expr + expr + } + + // chan Elem + // <-chan Elem + // chan<- Elem + ChanType struct { + Dir ChanDir // 0 means no direction + Elem Expr + expr + } +) + +type expr struct{ node } + +func (*expr) aExpr() {} + +type ChanDir uint + +const ( + _ ChanDir = iota + SendOnly + RecvOnly +) + +// ---------------------------------------------------------------------------- +// Statements + +type ( + Stmt interface { + Node + aStmt() + } + + SimpleStmt interface { + Stmt + aSimpleStmt() + } + + EmptyStmt struct { + simpleStmt + } + + LabeledStmt struct { + Label *Name + Stmt Stmt + stmt + } + + BlockStmt struct { + Body []Stmt + stmt + } + + ExprStmt struct { + X Expr + simpleStmt + } + + SendStmt struct { + Chan, Value Expr // Chan <- Value + simpleStmt + } + + DeclStmt struct { + DeclList []Decl + stmt + } + + AssignStmt struct { + Op Operator // 0 means no operation + Lhs, Rhs Expr // Rhs == ImplicitOne means Lhs++ (Op == Add) or Lhs-- (Op == Sub) + simpleStmt + } + + BranchStmt struct { + Tok token // Break, Continue, Fallthrough, or Goto + Label *Name + stmt + } + + CallStmt struct { + Tok token // Go or Defer + Call *CallExpr + stmt + } + + ReturnStmt struct { + Results Expr // nil means no explicit return values + stmt + } + + IfStmt struct { + Init SimpleStmt + Cond Expr + Then []Stmt + Else Stmt // either *IfStmt or *BlockStmt + stmt + } + + ForStmt struct { + Init SimpleStmt // incl. *RangeClause + Cond Expr + Post SimpleStmt + Body []Stmt + stmt + } + + SwitchStmt struct { + Init SimpleStmt + Tag Expr + Body []*CaseClause + stmt + } + + SelectStmt struct { + Body []*CommClause + stmt + } +) + +type ( + RangeClause struct { + Lhs Expr // nil means no Lhs = or Lhs := + Def bool // means := + X Expr // range X + simpleStmt + } + + TypeSwitchGuard struct { + // TODO(gri) consider using Name{"..."} instead of nil (permits attaching of comments) + Lhs *Name // nil means no Lhs := + X Expr // X.(type) + expr + } + + CaseClause struct { + Cases Expr // nil means default clause + Body []Stmt + node + } + + CommClause struct { + Comm SimpleStmt // send or receive stmt; nil means default clause + Body []Stmt + node + } +) + +type stmt struct{ node } + +func (stmt) aStmt() {} + +type simpleStmt struct { + stmt +} + +func (simpleStmt) aSimpleStmt() {} + +// ---------------------------------------------------------------------------- +// Comments + +type CommentKind uint + +const ( + Above CommentKind = iota + Below + Left + Right +) + +type Comment struct { + Kind CommentKind + Text string + Next *Comment +} diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go new file mode 100644 index 0000000000..f267d4b2c9 --- /dev/null +++ b/src/cmd/compile/internal/syntax/parser.go @@ -0,0 +1,2062 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "fmt" + "io" + "strings" +) + +const debug = false +const trace = false + +type parser struct { + scanner + + fnest int // function nesting level (for error handling) + xnest int // expression nesting level (for complit ambiguity resolution) + indent []byte // tracing support + + nerrors int // error count +} + +func (p *parser) init(src io.Reader, errh ErrorHandler) { + p.scanner.init(src, func(pos, line int, msg string) { + p.nerrors++ + if !debug && errh != nil { + errh(pos, line, msg) + return + } + panic(fmt.Sprintf("%d: %s\n", line, msg)) + }) + + p.fnest = 0 + p.xnest = 0 + p.indent = nil + + p.nerrors = 0 +} + +func (p *parser) got(tok token) bool { + if p.tok == tok { + p.next() + return true + } + return false +} + +func (p *parser) want(tok token) { + if !p.got(tok) { + p.syntax_error("expecting " + tok.String()) + p.advance() + } +} + +// ---------------------------------------------------------------------------- +// Error handling + +// syntax_error reports a syntax error at the current line. +func (p *parser) syntax_error(msg string) { + if trace { + defer p.trace("syntax_error (" + msg + ")")() + } + + if p.tok == _EOF && p.nerrors > 0 { + return // avoid meaningless follow-up errors + } + + // add punctuation etc. as needed to msg + switch { + case msg == "": + // nothing to do + case strings.HasPrefix(msg, "in"), strings.HasPrefix(msg, "at"), strings.HasPrefix(msg, "after"): + msg = " " + msg + case strings.HasPrefix(msg, "expecting"): + msg = ", " + msg + default: + // plain error - we don't care about current token + p.error("syntax error: " + msg) + return + } + + // determine token string + var tok string + switch p.tok { + case _Name, _Literal: + tok = p.lit + case _Operator: + tok = p.op.String() + case _AssignOp: + tok = p.op.String() + "=" + case _IncOp: + tok = p.op.String() + tok += tok + default: + tok = tokstring(p.tok) + } + + p.error("syntax error: unexpected " + tok + msg) +} + +// Like syntax_error, but reports error at given line rather than current lexer line. +func (p *parser) syntax_error_at(lineno uint32, msg string) { + // TODO(gri) fix this + // defer func(lineno int32) { + // lexlineno = lineno + // }(lexlineno) + // lexlineno = lineno + p.syntax_error(msg) +} + +// The stopset contains keywords that start a statement. +// They are good synchronization points in case of syntax +// errors and (usually) shouldn't be skipped over. +const stopset uint64 = 1<<_Break | + 1<<_Const | + 1<<_Continue | + 1<<_Defer | + 1<<_Fallthrough | + 1<<_For | + 1<<_Func | + 1<<_Go | + 1<<_Goto | + 1<<_If | + 1<<_Return | + 1<<_Select | + 1<<_Switch | + 1<<_Type | + 1<<_Var + +// Advance consumes tokens until it finds a token of the stopset or followlist. +// The stopset is only considered if we are inside a function (p.fnest > 0). +// The followlist is the list of valid tokens that can follow a production; +// if it is empty, exactly one token is consumed to ensure progress. +func (p *parser) advance(followlist ...token) { + if len(followlist) == 0 { + p.next() + return + } + + // compute follow set + // TODO(gri) the args are constants - do as constant expressions? + var followset uint64 = 1 << _EOF // never skip over EOF + for _, tok := range followlist { + followset |= 1 << tok + } + + for !(contains(followset, p.tok) || p.fnest > 0 && contains(stopset, p.tok)) { + p.next() + } +} + +func tokstring(tok token) string { + switch tok { + case _EOF: + return "EOF" + case _Comma: + return "comma" + case _Semi: + return "semicolon or newline" + } + return tok.String() +} + +// usage: defer p.trace(msg)() +func (p *parser) trace(msg string) func() { + fmt.Printf("%5d: %s%s (\n", p.line, p.indent, msg) + const tab = ". " + p.indent = append(p.indent, tab...) + return func() { + p.indent = p.indent[:len(p.indent)-len(tab)] + if x := recover(); x != nil { + panic(x) // skip print_trace + } + fmt.Printf("%5d: %s)\n", p.line, p.indent) + } +} + +// ---------------------------------------------------------------------------- +// Package files +// +// Parse methods are annotated with matching Go productions as appropriate. +// The annotations are intended as guidelines only since a single Go grammar +// rule may be covered by multiple parse methods and vice versa. + +// SourceFile = PackageClause ";" { ImportDecl ";" } { TopLevelDecl ";" } . +func (p *parser) file() *File { + if trace { + defer p.trace("file")() + } + + f := new(File) + f.init(p) + + // PackageClause + p.want(_Package) + f.PkgName = p.name() + p.want(_Semi) + + // don't bother continuing if package clause has errors + if p.nerrors > 0 { + return nil + } + + // { ImportDecl ";" } + for p.got(_Import) { + f.DeclList = p.appendGroup(f.DeclList, p.importDecl) + p.want(_Semi) + } + + // { TopLevelDecl ";" } + for p.tok != _EOF { + switch p.tok { + case _Const: + p.next() + f.DeclList = p.appendGroup(f.DeclList, p.constDecl) + + case _Type: + p.next() + f.DeclList = p.appendGroup(f.DeclList, p.typeDecl) + + case _Var: + p.next() + f.DeclList = p.appendGroup(f.DeclList, p.varDecl) + + case _Func: + p.next() + f.DeclList = append(f.DeclList, p.funcDecl()) + + default: + if p.tok == _Lbrace && len(f.DeclList) > 0 && emptyFuncDecl(f.DeclList[len(f.DeclList)-1]) { + // opening { of function declaration on next line + p.syntax_error("unexpected semicolon or newline before {") + } else { + p.syntax_error("non-declaration statement outside function body") + } + p.advance(_Const, _Type, _Var, _Func) + continue + } + + if p.tok != _EOF && !p.got(_Semi) { + p.syntax_error("after top level declaration") + p.advance(_Const, _Type, _Var, _Func) + } + } + // p.tok == _EOF + + f.Lines = p.source.line + f.Pragmas = p.pragmas + + return f +} + +func emptyFuncDecl(dcl Decl) bool { + f, ok := dcl.(*FuncDecl) + return ok && f.Body == nil +} + +// ---------------------------------------------------------------------------- +// Declarations + +// appendGroup(f) = f | "(" { f ";" } ")" . +func (p *parser) appendGroup(list []Decl, f func(*Group) Decl) []Decl { + if p.got(_Lparen) { + g := new(Group) + for p.tok != _EOF && p.tok != _Rparen { + list = append(list, f(g)) + if !p.osemi(_Rparen) { + break + } + } + p.want(_Rparen) + return list + } + + return append(list, f(nil)) +} + +func (p *parser) importDecl(group *Group) Decl { + if trace { + defer p.trace("importDecl")() + } + + d := new(ImportDecl) + d.init(p) + + switch p.tok { + case _Name: + d.LocalPkgName = p.name() + case _Dot: + n := new(Name) + n.init(p) + n.Value = "." + d.LocalPkgName = n + p.next() + } + if p.tok == _Literal && p.kind == StringLit { + d.Path = p.oliteral() + } else { + p.syntax_error("missing import path; require quoted string") + p.advance(_Semi, _Rparen) + } + d.Group = group + + return d +} + +// ConstSpec = IdentifierList [ [ Type ] "=" ExpressionList ] . +func (p *parser) constDecl(group *Group) Decl { + if trace { + defer p.trace("constDecl")() + } + + d := new(ConstDecl) + d.init(p) + + d.NameList = p.nameList(p.name()) + if p.tok != _EOF && p.tok != _Semi && p.tok != _Rparen { + d.Type = p.tryType() + if p.got(_Assign) { + d.Values = p.exprList() + } + } + d.Group = group + + return d +} + +// TypeSpec = identifier Type . +func (p *parser) typeDecl(group *Group) Decl { + if trace { + defer p.trace("typeDecl")() + } + + d := new(TypeDecl) + d.init(p) + + d.Name = p.name() + d.Type = p.tryType() + if d.Type == nil { + p.syntax_error("in type declaration") + p.advance(_Semi, _Rparen) + } + d.Group = group + + return d +} + +// VarSpec = IdentifierList ( Type [ "=" ExpressionList ] | "=" ExpressionList ) . +func (p *parser) varDecl(group *Group) Decl { + if trace { + defer p.trace("varDecl")() + } + + d := new(VarDecl) + d.init(p) + + d.NameList = p.nameList(p.name()) + if p.got(_Assign) { + d.Values = p.exprList() + } else { + d.Type = p.type_() + if p.got(_Assign) { + d.Values = p.exprList() + } + } + d.Group = group + + return d +} + +// FunctionDecl = "func" FunctionName ( Function | Signature ) . +// FunctionName = identifier . +// Function = Signature FunctionBody . +// MethodDecl = "func" Receiver MethodName ( Function | Signature ) . +// Receiver = Parameters . +func (p *parser) funcDecl() *FuncDecl { + if trace { + defer p.trace("funcDecl")() + } + + f := new(FuncDecl) + f.init(p) + + if p.tok == _Lparen { + rcvr := p.paramList() + switch len(rcvr) { + case 0: + p.error("method has no receiver") + return nil // TODO(gri) better solution + case 1: + f.Recv = rcvr[0] + default: + p.error("method has multiple receivers") + return nil // TODO(gri) better solution + } + } + + if p.tok != _Name { + p.syntax_error("expecting name or (") + p.advance(_Lbrace, _Semi) + return nil + } + + // TODO(gri) check for regular functions only + // if name.Sym.Name == "init" { + // name = renameinit() + // if params != nil || result != nil { + // p.error("func init must have no arguments and no return values") + // } + // } + + // if localpkg.Name == "main" && name.Name == "main" { + // if params != nil || result != nil { + // p.error("func main must have no arguments and no return values") + // } + // } + + f.Name = p.name() + f.Type = p.funcType() + f.Body = p.funcBody() + + // TODO(gri) deal with function properties + // if noescape && body != nil { + // p.error("can only use //go:noescape with external func implementations") + // } + + return f +} + +// ---------------------------------------------------------------------------- +// Expressions + +func (p *parser) expr() Expr { + if trace { + defer p.trace("expr")() + } + + return p.binaryExpr(0) +} + +// Expression = UnaryExpr | Expression binary_op Expression . +func (p *parser) binaryExpr(prec int) Expr { + // don't trace binaryExpr - only leads to overly nested trace output + + x := p.unaryExpr() + for (p.tok == _Operator || p.tok == _Star) && p.prec > prec { + t := new(Operation) + t.init(p) + t.Op = p.op + t.X = x + tprec := p.prec + p.next() + t.Y = p.binaryExpr(tprec) + x = t + } + return x +} + +// UnaryExpr = PrimaryExpr | unary_op UnaryExpr . +func (p *parser) unaryExpr() Expr { + if trace { + defer p.trace("unaryExpr")() + } + + switch p.tok { + case _Operator, _Star: + switch p.op { + case Mul, Add, Sub, Not, Xor: + x := new(Operation) + x.init(p) + x.Op = p.op + p.next() + x.X = p.unaryExpr() + return x + + case And: + p.next() + x := new(Operation) + x.init(p) + x.Op = And + // unaryExpr may have returned a parenthesized composite literal + // (see comment in operand) - remove parentheses if any + x.X = unparen(p.unaryExpr()) + return x + } + + case _Arrow: + // receive op (<-x) or receive-only channel (<-chan E) + p.next() + + // If the next token is _Chan we still don't know if it is + // a channel (<-chan int) or a receive op (<-chan int(ch)). + // We only know once we have found the end of the unaryExpr. + + x := p.unaryExpr() + + // There are two cases: + // + // <-chan... => <-x is a channel type + // <-x => <-x is a receive operation + // + // In the first case, <- must be re-associated with + // the channel type parsed already: + // + // <-(chan E) => (<-chan E) + // <-(chan<-E) => (<-chan (<-E)) + + if x, ok := x.(*ChanType); ok { + // x is a channel type => re-associate <- + dir := SendOnly + t := x + for ok && dir == SendOnly { + dir = t.Dir + if dir == RecvOnly { + // t is type <-chan E but <-<-chan E is not permitted + // (report same error as for "type _ <-<-chan E") + p.syntax_error("unexpected <-, expecting chan") + // already progressed, no need to advance + } + t.Dir = RecvOnly + t, ok = t.Elem.(*ChanType) + } + if dir == SendOnly { + // channel dir is <- but channel element E is not a channel + // (report same error as for "type _ <-chan<-E") + p.syntax_error(fmt.Sprintf("unexpected %v, expecting chan", t)) + // already progressed, no need to advance + } + return x + } + + // x is not a channel type => we have a receive op + return &Operation{Op: Recv, X: x} + } + + return p.pexpr(false) +} + +// callStmt parses call-like statements that can be preceded by 'defer' and 'go'. +func (p *parser) callStmt() *CallStmt { + if trace { + defer p.trace("callStmt")() + } + + s := new(CallStmt) + s.init(p) + s.Tok = p.tok + p.next() + + x := p.pexpr(p.tok == _Lparen) // keep_parens so we can report error below + switch x := x.(type) { + case *CallExpr: + s.Call = x + case *ParenExpr: + p.error(fmt.Sprintf("expression in %s must not be parenthesized", s.Tok)) + // already progressed, no need to advance + default: + p.error(fmt.Sprintf("expression in %s must be function call", s.Tok)) + // already progressed, no need to advance + } + + return s // TODO(gri) should we return nil in case of failure? +} + +// Operand = Literal | OperandName | MethodExpr | "(" Expression ")" . +// Literal = BasicLit | CompositeLit | FunctionLit . +// BasicLit = int_lit | float_lit | imaginary_lit | rune_lit | string_lit . +// OperandName = identifier | QualifiedIdent. +func (p *parser) operand(keep_parens bool) Expr { + if trace { + defer p.trace("operand " + p.tok.String())() + } + + switch p.tok { + case _Name: + return p.name() + + case _Literal: + return p.oliteral() + + case _Lparen: + p.next() + p.xnest++ + x := p.expr() // expr_or_type + p.xnest-- + p.want(_Rparen) + + // Optimization: Record presence of ()'s only where needed + // for error reporting. Don't bother in other cases; it is + // just a waste of memory and time. + + // Parentheses are not permitted on lhs of := . + // switch x.Op { + // case ONAME, ONONAME, OPACK, OTYPE, OLITERAL, OTYPESW: + // keep_parens = true + // } + + // Parentheses are not permitted around T in a composite + // literal T{}. If the next token is a {, assume x is a + // composite literal type T (it may not be, { could be + // the opening brace of a block, but we don't know yet). + if p.tok == _Lbrace { + keep_parens = true + } + + // Parentheses are also not permitted around the expression + // in a go/defer statement. In that case, operand is called + // with keep_parens set. + if keep_parens { + x = &ParenExpr{X: x} + } + return x + + case _Func: + p.next() + t := p.funcType() + if p.tok == _Lbrace { + p.fnest++ + p.xnest++ + f := new(FuncLit) + f.init(p) + f.Type = t + f.Body = p.funcBody() + p.xnest-- + p.fnest-- + return f + } + return t + + case _Lbrack, _Chan, _Map, _Struct, _Interface: + return p.type_() // othertype + + case _Lbrace: + // common case: p.header is missing simpleStmt before { in if, for, switch + p.syntax_error("missing operand") + // '{' will be consumed in pexpr - no need to consume it here + return nil + + default: + p.syntax_error("expecting expression") + p.advance() + return nil + } + + // Syntactically, composite literals are operands. Because a complit + // type may be a qualified identifier which is handled by pexpr + // (together with selector expressions), complits are parsed there + // as well (operand is only called from pexpr). +} + +// PrimaryExpr = +// Operand | +// Conversion | +// PrimaryExpr Selector | +// PrimaryExpr Index | +// PrimaryExpr Slice | +// PrimaryExpr TypeAssertion | +// PrimaryExpr Arguments . +// +// Selector = "." identifier . +// Index = "[" Expression "]" . +// Slice = "[" ( [ Expression ] ":" [ Expression ] ) | +// ( [ Expression ] ":" Expression ":" Expression ) +// "]" . +// TypeAssertion = "." "(" Type ")" . +// Arguments = "(" [ ( ExpressionList | Type [ "," ExpressionList ] ) [ "..." ] [ "," ] ] ")" . +func (p *parser) pexpr(keep_parens bool) Expr { + if trace { + defer p.trace("pexpr")() + } + + x := p.operand(keep_parens) + +loop: + for { + switch p.tok { + case _Dot: + p.next() + switch p.tok { + case _Name: + // pexpr '.' sym + t := new(SelectorExpr) + t.init(p) + t.X = x + t.Sel = p.name() + x = t + + case _Lparen: + p.next() + if p.got(_Type) { + t := new(TypeSwitchGuard) + t.init(p) + t.X = x + x = t + } else { + t := new(AssertExpr) + t.init(p) + t.X = x + t.Type = p.expr() + x = t + } + p.want(_Rparen) + + default: + p.syntax_error("expecting name or (") + p.advance(_Semi, _Rparen) + } + + case _Lbrack: + p.next() + p.xnest++ + + var i Expr + if p.tok != _Colon { + i = p.expr() + if p.got(_Rbrack) { + // x[i] + t := new(IndexExpr) + t.init(p) + t.X = x + t.Index = i + x = t + p.xnest-- + break + } + } + + // x[i:... + t := new(SliceExpr) + t.init(p) + t.X = x + t.Index[0] = i + p.want(_Colon) + if p.tok != _Colon && p.tok != _Rbrack { + // x[i:j... + t.Index[1] = p.expr() + } + if p.got(_Colon) { + // x[i:j:...] + if t.Index[1] == nil { + p.error("middle index required in 3-index slice") + } + if p.tok != _Rbrack { + // x[i:j:k... + t.Index[2] = p.expr() + } else { + p.error("final index required in 3-index slice") + } + } + p.want(_Rbrack) + + x = t + p.xnest-- + + case _Lparen: + // call or conversion + // convtype '(' expr ocomma ')' + c := new(CallExpr) + c.init(p) + c.Fun = x + c.ArgList, c.HasDots = p.argList() + x = c + + case _Lbrace: + // operand may have returned a parenthesized complit + // type; accept it but complain if we have a complit + t := unparen(x) + // determine if '{' belongs to a complit or a compound_stmt + complit_ok := false + switch t.(type) { + case *Name, *SelectorExpr: + if p.xnest >= 0 { + // x is considered a comptype + complit_ok = true + } + case *ArrayType, *SliceType, *StructType, *MapType: + // x is a comptype + complit_ok = true + } + if !complit_ok { + break loop + } + if t != x { + p.syntax_error("cannot parenthesize type in composite literal") + // already progressed, no need to advance + } + n := p.complitexpr() + n.Type = x + x = n + + default: + break loop + } + } + + return x +} + +// Element = Expression | LiteralValue . +func (p *parser) bare_complitexpr() Expr { + if trace { + defer p.trace("bare_complitexpr")() + } + + if p.tok == _Lbrace { + // '{' start_complit braced_keyval_list '}' + return p.complitexpr() + } + + return p.expr() +} + +// LiteralValue = "{" [ ElementList [ "," ] ] "}" . +func (p *parser) complitexpr() *CompositeLit { + if trace { + defer p.trace("complitexpr")() + } + + x := new(CompositeLit) + x.init(p) + + p.want(_Lbrace) + p.xnest++ + + for p.tok != _EOF && p.tok != _Rbrace { + // value + e := p.bare_complitexpr() + if p.got(_Colon) { + // key ':' value + l := new(KeyValueExpr) + l.init(p) + l.Key = e + l.Value = p.bare_complitexpr() + e = l + x.NKeys++ + } + x.ElemList = append(x.ElemList, e) + if !p.ocomma(_Rbrace) { + break + } + } + + p.xnest-- + p.want(_Rbrace) + + return x +} + +// ---------------------------------------------------------------------------- +// Types + +func (p *parser) type_() Expr { + if trace { + defer p.trace("type_")() + } + + if typ := p.tryType(); typ != nil { + return typ + } + + p.syntax_error("") + p.advance() + return nil +} + +func indirect(typ Expr) Expr { + return &Operation{Op: Mul, X: typ} +} + +// tryType is like type_ but it returns nil if there was no type +// instead of reporting an error. +// +// Type = TypeName | TypeLit | "(" Type ")" . +// TypeName = identifier | QualifiedIdent . +// TypeLit = ArrayType | StructType | PointerType | FunctionType | InterfaceType | +// SliceType | MapType | Channel_Type . +func (p *parser) tryType() Expr { + if trace { + defer p.trace("tryType")() + } + + switch p.tok { + case _Star: + // ptrtype + p.next() + return indirect(p.type_()) + + case _Arrow: + // recvchantype + p.next() + p.want(_Chan) + t := new(ChanType) + t.init(p) + t.Dir = RecvOnly + t.Elem = p.chanElem() + return t + + case _Func: + // fntype + p.next() + return p.funcType() + + case _Lbrack: + // '[' oexpr ']' ntype + // '[' _DotDotDot ']' ntype + p.next() + p.xnest++ + if p.got(_Rbrack) { + // []T + p.xnest-- + t := new(SliceType) + t.init(p) + t.Elem = p.type_() + return t + } + + // [n]T + t := new(ArrayType) + t.init(p) + if !p.got(_DotDotDot) { + t.Len = p.expr() + } + p.want(_Rbrack) + p.xnest-- + t.Elem = p.type_() + return t + + case _Chan: + // _Chan non_recvchantype + // _Chan _Comm ntype + p.next() + t := new(ChanType) + t.init(p) + if p.got(_Arrow) { + t.Dir = SendOnly + } + t.Elem = p.chanElem() + return t + + case _Map: + // _Map '[' ntype ']' ntype + p.next() + p.want(_Lbrack) + t := new(MapType) + t.init(p) + t.Key = p.type_() + p.want(_Rbrack) + t.Value = p.type_() + return t + + case _Struct: + return p.structType() + + case _Interface: + return p.interfaceType() + + case _Name: + return p.dotname(p.name()) + + case _Lparen: + p.next() + t := p.type_() + p.want(_Rparen) + return t + } + + return nil +} + +func (p *parser) funcType() *FuncType { + if trace { + defer p.trace("funcType")() + } + + typ := new(FuncType) + typ.init(p) + typ.ParamList = p.paramList() + typ.ResultList = p.funcResult() + return typ +} + +func (p *parser) chanElem() Expr { + if trace { + defer p.trace("chanElem")() + } + + if typ := p.tryType(); typ != nil { + return typ + } + + p.syntax_error("missing channel element type") + // assume element type is simply absent - don't advance + return nil +} + +func (p *parser) dotname(name *Name) Expr { + if trace { + defer p.trace("dotname")() + } + + if p.got(_Dot) { + s := new(SelectorExpr) + s.init(p) + s.X = name + s.Sel = p.name() + return s + } + return name +} + +// StructType = "struct" "{" { FieldDecl ";" } "}" . +func (p *parser) structType() *StructType { + if trace { + defer p.trace("structType")() + } + + typ := new(StructType) + typ.init(p) + + p.want(_Struct) + p.want(_Lbrace) + for p.tok != _EOF && p.tok != _Rbrace { + p.fieldDecl(typ) + if !p.osemi(_Rbrace) { + break + } + } + p.want(_Rbrace) + + return typ +} + +// InterfaceType = "interface" "{" { MethodSpec ";" } "}" . +func (p *parser) interfaceType() *InterfaceType { + if trace { + defer p.trace("interfaceType")() + } + + typ := new(InterfaceType) + typ.init(p) + + p.want(_Interface) + p.want(_Lbrace) + for p.tok != _EOF && p.tok != _Rbrace { + if m := p.methodDecl(); m != nil { + typ.MethodList = append(typ.MethodList, m) + } + if !p.osemi(_Rbrace) { + break + } + } + p.want(_Rbrace) + + return typ +} + +// FunctionBody = Block . +func (p *parser) funcBody() []Stmt { + if trace { + defer p.trace("funcBody")() + } + + if p.got(_Lbrace) { + p.fnest++ + body := p.stmtList() + p.fnest-- + p.want(_Rbrace) + if body == nil { + body = []Stmt{new(EmptyStmt)} + } + return body + } + + return nil +} + +// Result = Parameters | Type . +func (p *parser) funcResult() []*Field { + if trace { + defer p.trace("funcResult")() + } + + if p.tok == _Lparen { + return p.paramList() + } + + if result := p.tryType(); result != nil { + f := new(Field) + f.init(p) + f.Type = result + return []*Field{f} + } + + return nil +} + +func (p *parser) addField(styp *StructType, name *Name, typ Expr, tag *BasicLit) { + if tag != nil { + for i := len(styp.FieldList) - len(styp.TagList); i > 0; i-- { + styp.TagList = append(styp.TagList, nil) + } + styp.TagList = append(styp.TagList, tag) + } + + f := new(Field) + f.init(p) + f.Name = name + f.Type = typ + styp.FieldList = append(styp.FieldList, f) + + if debug && tag != nil && len(styp.FieldList) != len(styp.TagList) { + panic("inconsistent struct field list") + } +} + +// FieldDecl = (IdentifierList Type | AnonymousField) [ Tag ] . +// AnonymousField = [ "*" ] TypeName . +// Tag = string_lit . +func (p *parser) fieldDecl(styp *StructType) { + if trace { + defer p.trace("fieldDecl")() + } + + var name *Name + switch p.tok { + case _Name: + name = p.name() + if p.tok == _Dot || p.tok == _Literal || p.tok == _Semi || p.tok == _Rbrace { + // embed oliteral + typ := p.qualifiedName(name) + tag := p.oliteral() + p.addField(styp, nil, typ, tag) + return + } + + // new_name_list ntype oliteral + names := p.nameList(name) + typ := p.type_() + tag := p.oliteral() + + for _, name := range names { + p.addField(styp, name, typ, tag) + } + + case _Lparen: + p.next() + if p.tok == _Star { + // '(' '*' embed ')' oliteral + p.next() + typ := indirect(p.qualifiedName(nil)) + p.want(_Rparen) + tag := p.oliteral() + p.addField(styp, nil, typ, tag) + p.error("cannot parenthesize embedded type") + + } else { + // '(' embed ')' oliteral + typ := p.qualifiedName(nil) + p.want(_Rparen) + tag := p.oliteral() + p.addField(styp, nil, typ, tag) + p.error("cannot parenthesize embedded type") + } + + case _Star: + p.next() + if p.got(_Lparen) { + // '*' '(' embed ')' oliteral + typ := indirect(p.qualifiedName(nil)) + p.want(_Rparen) + tag := p.oliteral() + p.addField(styp, nil, typ, tag) + p.error("cannot parenthesize embedded type") + + } else { + // '*' embed oliteral + typ := indirect(p.qualifiedName(nil)) + tag := p.oliteral() + p.addField(styp, nil, typ, tag) + } + + default: + p.syntax_error("expecting field name or embedded type") + p.advance(_Semi, _Rbrace) + } +} + +func (p *parser) oliteral() *BasicLit { + if p.tok == _Literal { + b := new(BasicLit) + b.init(p) + b.Value = p.lit + b.Kind = p.kind + p.next() + return b + } + return nil +} + +// MethodSpec = MethodName Signature | InterfaceTypeName . +// MethodName = identifier . +// InterfaceTypeName = TypeName . +func (p *parser) methodDecl() *Field { + if trace { + defer p.trace("methodDecl")() + } + + switch p.tok { + case _Name: + name := p.name() + + // accept potential name list but complain + hasNameList := false + for p.got(_Comma) { + p.name() + hasNameList = true + } + if hasNameList { + p.syntax_error("name list not allowed in interface type") + // already progressed, no need to advance + } + + f := new(Field) + f.init(p) + if p.tok != _Lparen { + // packname + f.Type = p.qualifiedName(name) + return f + } + + f.Name = name + f.Type = p.funcType() + return f + + case _Lparen: + p.next() + f := new(Field) + f.init(p) + f.Type = p.qualifiedName(nil) + p.want(_Rparen) + p.error("cannot parenthesize embedded type") + return f + + default: + p.syntax_error("") + p.advance(_Semi, _Rbrace) + return nil + } +} + +// ParameterDecl = [ IdentifierList ] [ "..." ] Type . +func (p *parser) paramDecl() *Field { + if trace { + defer p.trace("paramDecl")() + } + + f := new(Field) + f.init(p) + + switch p.tok { + case _Name: + f.Name = p.name() + switch p.tok { + case _Name, _Star, _Arrow, _Func, _Lbrack, _Chan, _Map, _Struct, _Interface, _Lparen: + // sym name_or_type + f.Type = p.type_() + + case _DotDotDot: + // sym dotdotdot + f.Type = p.dotsType() + + case _Dot: + // name_or_type + // from dotname + f.Type = p.dotname(f.Name) + f.Name = nil + } + + case _Arrow, _Star, _Func, _Lbrack, _Chan, _Map, _Struct, _Interface, _Lparen: + // name_or_type + f.Type = p.type_() + + case _DotDotDot: + // dotdotdot + f.Type = p.dotsType() + + default: + p.syntax_error("expecting )") + p.advance(_Comma, _Rparen) + return nil + } + + return f +} + +// ...Type +func (p *parser) dotsType() *DotsType { + if trace { + defer p.trace("dotsType")() + } + + t := new(DotsType) + t.init(p) + + p.want(_DotDotDot) + t.Elem = p.tryType() + if t.Elem == nil { + p.error("final argument in variadic function missing type") + } + + return t +} + +// Parameters = "(" [ ParameterList [ "," ] ] ")" . +// ParameterList = ParameterDecl { "," ParameterDecl } . +func (p *parser) paramList() (list []*Field) { + if trace { + defer p.trace("paramList")() + } + + p.want(_Lparen) + + var named int // number of parameters that have an explicit name and type + for p.tok != _EOF && p.tok != _Rparen { + if par := p.paramDecl(); par != nil { + if debug && par.Name == nil && par.Type == nil { + panic("parameter without name or type") + } + if par.Name != nil && par.Type != nil { + named++ + } + list = append(list, par) + } + if !p.ocomma(_Rparen) { + break + } + } + + // distribute parameter types + if named == 0 { + // all unnamed => found names are named types + for _, par := range list { + if typ := par.Name; typ != nil { + par.Type = typ + par.Name = nil + } + } + } else if named != len(list) { + // some named => all must be named + var typ Expr + for i := len(list) - 1; i >= 0; i-- { + if par := list[i]; par.Type != nil { + typ = par.Type + if par.Name == nil { + typ = nil // error + } + } else { + par.Type = typ + } + if typ == nil { + p.syntax_error("mixed named and unnamed function parameters") + break + } + } + } + + p.want(_Rparen) + return +} + +// ---------------------------------------------------------------------------- +// Statements + +// We represent x++, x-- as assignments x += ImplicitOne, x -= ImplicitOne. +// ImplicitOne should not be used elsewhere. +var ImplicitOne = &BasicLit{Value: "1"} + +// SimpleStmt = EmptyStmt | ExpressionStmt | SendStmt | IncDecStmt | Assignment | ShortVarDecl . +// +// simpleStmt may return missing_stmt if labelOk is set. +func (p *parser) simpleStmt(lhs Expr, rangeOk bool) SimpleStmt { + if trace { + defer p.trace("simpleStmt")() + } + + if rangeOk && p.got(_Range) { + // _Range expr + if debug && lhs != nil { + panic("invalid call of simpleStmt") + } + return p.rangeClause(nil, false) + } + + if lhs == nil { + lhs = p.exprList() + } + + if _, ok := lhs.(*ListExpr); !ok && p.tok != _Assign && p.tok != _Define { + // expr + switch p.tok { + case _AssignOp: + // lhs op= rhs + op := p.op + p.next() + return p.newAssignStmt(op, lhs, p.expr()) + + case _IncOp: + // lhs++ or lhs-- + op := p.op + p.next() + return p.newAssignStmt(op, lhs, ImplicitOne) + + case _Arrow: + // lhs <- rhs + p.next() + s := new(SendStmt) + s.init(p) + s.Chan = lhs + s.Value = p.expr() + return s + + default: + // expr + return &ExprStmt{X: lhs} + } + } + + // expr_list + switch p.tok { + case _Assign: + p.next() + + if rangeOk && p.got(_Range) { + // expr_list '=' _Range expr + return p.rangeClause(lhs, false) + } + + // expr_list '=' expr_list + return p.newAssignStmt(0, lhs, p.exprList()) + + case _Define: + //lno := lineno + p.next() + + if rangeOk && p.got(_Range) { + // expr_list ':=' range expr + return p.rangeClause(lhs, true) + } + + // expr_list ':=' expr_list + rhs := p.exprList() + + if x, ok := rhs.(*TypeSwitchGuard); ok { + switch lhs := lhs.(type) { + case *Name: + x.Lhs = lhs + case *ListExpr: + p.error(fmt.Sprintf("argument count mismatch: %d = %d", len(lhs.ElemList), 1)) + default: + // TODO(mdempsky): Have Expr types implement Stringer? + p.error(fmt.Sprintf("invalid variable name %s in type switch", lhs)) + } + return &ExprStmt{X: x} + } + + return p.newAssignStmt(Def, lhs, rhs) + + default: + p.syntax_error("expecting := or = or comma") + p.advance(_Semi, _Rbrace) + return nil + } +} + +func (p *parser) rangeClause(lhs Expr, def bool) *RangeClause { + r := new(RangeClause) + r.init(p) + r.Lhs = lhs + r.Def = def + r.X = p.expr() + return r +} + +func (p *parser) newAssignStmt(op Operator, lhs, rhs Expr) *AssignStmt { + a := new(AssignStmt) + a.init(p) + a.Op = op + a.Lhs = lhs + a.Rhs = rhs + return a +} + +func (p *parser) labeledStmt(label *Name) Stmt { + if trace { + defer p.trace("labeledStmt")() + } + + var ls Stmt // labeled statement + if p.tok != _Rbrace && p.tok != _EOF { + ls = p.stmt() + if ls == missing_stmt { + // report error at line of ':' token + p.syntax_error_at(label.line, "missing statement after label") + // we are already at the end of the labeled statement - no need to advance + return missing_stmt + } + } + + s := new(LabeledStmt) + s.init(p) + s.Label = label + s.Stmt = ls + return s +} + +func (p *parser) blockStmt() *BlockStmt { + if trace { + defer p.trace("blockStmt")() + } + + s := new(BlockStmt) + s.init(p) + p.want(_Lbrace) + s.Body = p.stmtList() + p.want(_Rbrace) + + return s +} + +func (p *parser) declStmt(f func(*Group) Decl) *DeclStmt { + if trace { + defer p.trace("declStmt")() + } + + s := new(DeclStmt) + s.init(p) + + p.next() // _Const, _Type, or _Var + s.DeclList = p.appendGroup(nil, f) + + return s +} + +func (p *parser) forStmt() Stmt { + if trace { + defer p.trace("forStmt")() + } + + s := new(ForStmt) + s.init(p) + + p.want(_For) + s.Init, s.Cond, s.Post = p.header(true) + s.Body = p.stmtBody("for clause") + + return s +} + +// stmtBody parses if and for statement bodies. +func (p *parser) stmtBody(context string) []Stmt { + if trace { + defer p.trace("stmtBody")() + } + + if !p.got(_Lbrace) { + p.syntax_error("missing { after " + context) + p.advance(_Name, _Rbrace) + } + + body := p.stmtList() + p.want(_Rbrace) + + return body +} + +func (p *parser) header(forStmt bool) (init SimpleStmt, cond Expr, post SimpleStmt) { + if p.tok == _Lbrace { + return + } + + outer := p.xnest + p.xnest = -1 + + if p.tok != _Semi { + // accept potential varDecl but complain + if p.got(_Var) { + p.error("var declaration not allowed in initializer") + } + init = p.simpleStmt(nil, forStmt) + // If we have a range clause, we are done. + if _, ok := init.(*RangeClause); ok { + p.xnest = outer + return + } + } + + var condStmt SimpleStmt + if p.got(_Semi) { + if forStmt { + if p.tok != _Semi { + condStmt = p.simpleStmt(nil, false) + } + p.want(_Semi) + if p.tok != _Lbrace { + post = p.simpleStmt(nil, false) + } + } else if p.tok != _Lbrace { + condStmt = p.simpleStmt(nil, false) + } + } else { + condStmt = init + init = nil + } + + // unpack condStmt + switch s := condStmt.(type) { + case nil: + // nothing to do + case *ExprStmt: + cond = s.X + default: + p.error("invalid condition, tag, or type switch guard") + } + + p.xnest = outer + return +} + +func (p *parser) ifStmt() *IfStmt { + if trace { + defer p.trace("ifStmt")() + } + + s := new(IfStmt) + s.init(p) + + p.want(_If) + s.Init, s.Cond, _ = p.header(false) + if s.Cond == nil { + p.error("missing condition in if statement") + } + + s.Then = p.stmtBody("if clause") + + if p.got(_Else) { + if p.tok == _If { + s.Else = p.ifStmt() + } else { + s.Else = p.blockStmt() + } + } + + return s +} + +func (p *parser) switchStmt() *SwitchStmt { + if trace { + defer p.trace("switchStmt")() + } + + p.want(_Switch) + s := new(SwitchStmt) + s.init(p) + + s.Init, s.Tag, _ = p.header(false) + + if !p.got(_Lbrace) { + p.syntax_error("missing { after switch clause") + p.advance(_Case, _Default, _Rbrace) + } + for p.tok != _EOF && p.tok != _Rbrace { + s.Body = append(s.Body, p.caseClause()) + } + p.want(_Rbrace) + + return s +} + +func (p *parser) selectStmt() *SelectStmt { + if trace { + defer p.trace("selectStmt")() + } + + p.want(_Select) + s := new(SelectStmt) + s.init(p) + + if !p.got(_Lbrace) { + p.syntax_error("missing { after select clause") + p.advance(_Case, _Default, _Rbrace) + } + for p.tok != _EOF && p.tok != _Rbrace { + s.Body = append(s.Body, p.commClause()) + } + p.want(_Rbrace) + + return s +} + +func (p *parser) caseClause() *CaseClause { + if trace { + defer p.trace("caseClause")() + } + + c := new(CaseClause) + c.init(p) + + switch p.tok { + case _Case: + p.next() + c.Cases = p.exprList() + + case _Default: + p.next() + + default: + p.syntax_error("expecting case or default or }") + p.advance(_Case, _Default, _Rbrace) + } + + p.want(_Colon) + c.Body = p.stmtList() + + return c +} + +func (p *parser) commClause() *CommClause { + if trace { + defer p.trace("commClause")() + } + + c := new(CommClause) + c.init(p) + + switch p.tok { + case _Case: + p.next() + lhs := p.exprList() + + if _, ok := lhs.(*ListExpr); !ok && p.tok == _Arrow { + // lhs <- x + } else { + // lhs + // lhs = <-x + // lhs := <-x + if p.tok == _Assign || p.tok == _Define { + // TODO(gri) check that lhs has at most 2 entries + } else if p.tok == _Colon { + // TODO(gri) check that lhs has at most 1 entry + } else { + panic("unimplemented") + } + } + + c.Comm = p.simpleStmt(lhs, false) + + case _Default: + p.next() + + default: + p.syntax_error("expecting case or default or }") + p.advance(_Case, _Default, _Rbrace) + } + + p.want(_Colon) + c.Body = p.stmtList() + + return c +} + +// TODO(gri) find a better solution +var missing_stmt Stmt = new(EmptyStmt) // = Nod(OXXX, nil, nil) + +// Statement = +// Declaration | LabeledStmt | SimpleStmt | +// GoStmt | ReturnStmt | BreakStmt | ContinueStmt | GotoStmt | +// FallthroughStmt | Block | IfStmt | SwitchStmt | SelectStmt | ForStmt | +// DeferStmt . +// +// stmt may return missing_stmt. +func (p *parser) stmt() Stmt { + if trace { + defer p.trace("stmt " + p.tok.String())() + } + + // Most statements (assignments) start with an identifier; + // look for it first before doing anything more expensive. + if p.tok == _Name { + lhs := p.exprList() + if label, ok := lhs.(*Name); ok && p.got(_Colon) { + return p.labeledStmt(label) + } + return p.simpleStmt(lhs, false) + } + + switch p.tok { + case _Lbrace: + return p.blockStmt() + + case _Var: + return p.declStmt(p.varDecl) + + case _Const: + return p.declStmt(p.constDecl) + + case _Type: + return p.declStmt(p.typeDecl) + + case _Operator, _Star: + switch p.op { + case Add, Sub, Mul, And, Xor, Not: + return p.simpleStmt(nil, false) // unary operators + } + + case _Literal, _Func, _Lparen, // operands + _Lbrack, _Struct, _Map, _Chan, _Interface, // composite types + _Arrow: // receive operator + return p.simpleStmt(nil, false) + + case _For: + return p.forStmt() + + case _Switch: + return p.switchStmt() + + case _Select: + return p.selectStmt() + + case _If: + return p.ifStmt() + + case _Fallthrough: + p.next() + s := new(BranchStmt) + s.init(p) + s.Tok = _Fallthrough + return s + // // will be converted to OFALL + // stmt := Nod(OXFALL, nil, nil) + // stmt.Xoffset = int64(block) + // return stmt + + case _Break, _Continue: + tok := p.tok + p.next() + s := new(BranchStmt) + s.init(p) + s.Tok = tok + if p.tok == _Name { + s.Label = p.name() + } + return s + + case _Go, _Defer: + return p.callStmt() + + case _Goto: + p.next() + s := new(BranchStmt) + s.init(p) + s.Tok = _Goto + s.Label = p.name() + return s + // stmt := Nod(OGOTO, p.new_name(p.name()), nil) + // stmt.Sym = dclstack // context, for goto restrictions + // return stmt + + case _Return: + p.next() + s := new(ReturnStmt) + s.init(p) + if p.tok != _Semi && p.tok != _Rbrace { + s.Results = p.exprList() + } + return s + + case _Semi: + s := new(EmptyStmt) + s.init(p) + return s + } + + return missing_stmt +} + +// StatementList = { Statement ";" } . +func (p *parser) stmtList() (l []Stmt) { + if trace { + defer p.trace("stmtList")() + } + + for p.tok != _EOF && p.tok != _Rbrace && p.tok != _Case && p.tok != _Default { + s := p.stmt() + if s == missing_stmt { + break + } + l = append(l, s) + // customized version of osemi: + // ';' is optional before a closing ')' or '}' + if p.tok == _Rparen || p.tok == _Rbrace { + continue + } + if !p.got(_Semi) { + p.syntax_error("at end of statement") + p.advance(_Semi, _Rbrace) + } + } + return +} + +// Arguments = "(" [ ( ExpressionList | Type [ "," ExpressionList ] ) [ "..." ] [ "," ] ] ")" . +func (p *parser) argList() (list []Expr, hasDots bool) { + if trace { + defer p.trace("argList")() + } + + p.want(_Lparen) + p.xnest++ + + for p.tok != _EOF && p.tok != _Rparen { + list = append(list, p.expr()) // expr_or_type + hasDots = p.got(_DotDotDot) + if !p.ocomma(_Rparen) || hasDots { + break + } + } + + p.xnest-- + p.want(_Rparen) + + return +} + +// ---------------------------------------------------------------------------- +// Common productions + +func (p *parser) name() *Name { + // no tracing to avoid overly verbose output + + n := new(Name) + n.init(p) + + if p.tok == _Name { + n.Value = p.lit + p.next() + } else { + n.Value = "_" + p.syntax_error("expecting name") + p.advance() + } + + return n +} + +// IdentifierList = identifier { "," identifier } . +// The first name must be provided. +func (p *parser) nameList(first *Name) []*Name { + if trace { + defer p.trace("nameList")() + } + + if debug && first == nil { + panic("first name not provided") + } + + l := []*Name{first} + for p.got(_Comma) { + l = append(l, p.name()) + } + + return l +} + +// The first name may be provided, or nil. +func (p *parser) qualifiedName(name *Name) Expr { + if trace { + defer p.trace("qualifiedName")() + } + + switch { + case name != nil: + // name is provided + case p.tok == _Name: + name = p.name() + default: + name = new(Name) + name.init(p) + p.syntax_error("expecting name") + p.advance(_Dot, _Semi, _Rbrace) + } + + return p.dotname(name) +} + +// ExpressionList = Expression { "," Expression } . +func (p *parser) exprList() Expr { + if trace { + defer p.trace("exprList")() + } + + x := p.expr() + if p.got(_Comma) { + list := []Expr{x, p.expr()} + for p.got(_Comma) { + list = append(list, p.expr()) + } + t := new(ListExpr) + t.init(p) // TODO(gri) what is the correct thing here? + t.ElemList = list + x = t + } + return x +} + +// osemi parses an optional semicolon. +func (p *parser) osemi(follow token) bool { + switch p.tok { + case _Semi: + p.next() + return true + + case _Rparen, _Rbrace: + // semicolon is optional before ) or } + return true + } + + p.syntax_error("expecting semicolon, newline, or " + tokstring(follow)) + p.advance(follow) + return false +} + +// ocomma parses an optional comma. +func (p *parser) ocomma(follow token) bool { + switch p.tok { + case _Comma: + p.next() + return true + + case _Rparen, _Rbrace: + // comma is optional before ) or } + return true + } + + p.syntax_error("expecting comma or " + tokstring(follow)) + p.advance(follow) + return false +} + +// unparen removes all parentheses around an expression. +func unparen(x Expr) Expr { + for { + p, ok := x.(*ParenExpr) + if !ok { + break + } + x = p.X + } + return x +} diff --git a/src/cmd/compile/internal/syntax/parser_test.go b/src/cmd/compile/internal/syntax/parser_test.go new file mode 100644 index 0000000000..12fc019414 --- /dev/null +++ b/src/cmd/compile/internal/syntax/parser_test.go @@ -0,0 +1,157 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "bytes" + "flag" + "fmt" + "io/ioutil" + "path/filepath" + "runtime" + "strings" + "sync" + "testing" + "time" +) + +var fast = flag.Bool("fast", false, "parse package files in parallel") +var src = flag.String("src", "parser.go", "source file to parse") +var verify = flag.Bool("verify", false, "verify idempotent printing") + +func TestParse(t *testing.T) { + _, err := ReadFile(*src, nil, 0) + if err != nil { + t.Fatal(err) + } +} + +func TestStdLib(t *testing.T) { + if testing.Short() { + t.Skip("skipping test in short mode") + } + + var m1 runtime.MemStats + runtime.ReadMemStats(&m1) + start := time.Now() + + type parseResult struct { + filename string + lines int + } + + results := make(chan parseResult) + go func() { + for _, dir := range []string{ + runtime.GOROOT(), + //"/Users/gri/src", + } { + walkDirs(t, dir, func(filename string) { + if debug { + fmt.Printf("parsing %s\n", filename) + } + ast, err := ReadFile(filename, nil, 0) + if err != nil { + t.Fatal(err) + } + if *verify { + verifyPrint(filename, ast) + } + results <- parseResult{filename, ast.Lines} + }) + } + close(results) + }() + + var count, lines int + for res := range results { + count++ + lines += res.lines + if testing.Verbose() { + fmt.Printf("%5d %s (%d lines)\n", count, res.filename, res.lines) + } + } + + dt := time.Since(start) + var m2 runtime.MemStats + runtime.ReadMemStats(&m2) + dm := float64(m2.TotalAlloc-m1.TotalAlloc) / 1e6 + + fmt.Printf("parsed %d lines (%d files) in %v (%d lines/s)\n", lines, count, dt, int64(float64(lines)/dt.Seconds())) + fmt.Printf("allocated %.3fMb (%.3fMb/s)\n", dm, dm/dt.Seconds()) +} + +func walkDirs(t *testing.T, dir string, action func(string)) { + fis, err := ioutil.ReadDir(dir) + if err != nil { + t.Error(err) + return + } + + var files, dirs []string + for _, fi := range fis { + if fi.Mode().IsRegular() { + if strings.HasSuffix(fi.Name(), ".go") { + path := filepath.Join(dir, fi.Name()) + files = append(files, path) + } + } else if fi.IsDir() && fi.Name() != "testdata" { + path := filepath.Join(dir, fi.Name()) + if !strings.Contains(path, "go/test") { + dirs = append(dirs, path) + } + } + } + + if *fast { + var wg sync.WaitGroup + wg.Add(len(files)) + for _, filename := range files { + go func(filename string) { + defer wg.Done() + action(filename) + }(filename) + } + wg.Wait() + } else { + for _, filename := range files { + action(filename) + } + } + + for _, dir := range dirs { + walkDirs(t, dir, action) + } +} + +func verifyPrint(filename string, ast1 *File) { + var buf1 bytes.Buffer + _, err := Fprint(&buf1, ast1, true) + if err != nil { + panic(err) + } + + ast2, err := ReadBytes(buf1.Bytes(), nil, 0) + if err != nil { + panic(err) + } + + var buf2 bytes.Buffer + _, err = Fprint(&buf2, ast2, true) + if err != nil { + panic(err) + } + + if bytes.Compare(buf1.Bytes(), buf2.Bytes()) != 0 { + fmt.Printf("--- %s ---\n", filename) + fmt.Printf("%s\n", buf1.Bytes()) + fmt.Println() + + fmt.Printf("--- %s ---\n", filename) + fmt.Printf("%s\n", buf2.Bytes()) + fmt.Println() + panic("not equal") + } +} diff --git a/src/cmd/compile/internal/syntax/printer.go b/src/cmd/compile/internal/syntax/printer.go new file mode 100644 index 0000000000..0cacf1e5d4 --- /dev/null +++ b/src/cmd/compile/internal/syntax/printer.go @@ -0,0 +1,942 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This file implements printing of syntax trees in source format. + +package syntax + +import ( + "bytes" + "fmt" + "io" + "strings" +) + +// TODO(gri) Consider removing the linebreaks flag from this signature. +// Its likely rarely used in common cases. + +func Fprint(w io.Writer, x Node, linebreaks bool) (n int, err error) { + p := printer{ + output: w, + linebreaks: linebreaks, + } + + defer func() { + n = p.written + if e := recover(); e != nil { + err = e.(localError).err // re-panics if it's not a localError + } + }() + + p.print(x) + p.flush(_EOF) + + return +} + +func String(n Node) string { + var buf bytes.Buffer + _, err := Fprint(&buf, n, false) + if err != nil { + panic(err) // TODO(gri) print something sensible into buf instead + } + return buf.String() +} + +type ctrlSymbol int + +const ( + none ctrlSymbol = iota + semi + blank + newline + indent + outdent + // comment + // eolComment +) + +type whitespace struct { + last token + kind ctrlSymbol + //text string // comment text (possibly ""); valid if kind == comment +} + +type printer struct { + output io.Writer + written int // number of bytes written + linebreaks bool // print linebreaks instead of semis + + indent int // current indentation level + nlcount int // number of consecutive newlines + + pending []whitespace // pending whitespace + lastTok token // last token (after any pending semi) processed by print +} + +// write is a thin wrapper around p.output.Write +// that takes care of accounting and error handling. +func (p *printer) write(data []byte) { + n, err := p.output.Write(data) + p.written += n + if err != nil { + panic(localError{err}) + } +} + +var ( + tabBytes = []byte("\t\t\t\t\t\t\t\t") + newlineByte = []byte("\n") + blankByte = []byte(" ") +) + +func (p *printer) writeBytes(data []byte) { + if len(data) == 0 { + panic("expected non-empty []byte") + } + if p.nlcount > 0 && p.indent > 0 { + // write indentation + n := p.indent + for n > len(tabBytes) { + p.write(tabBytes) + n -= len(tabBytes) + } + p.write(tabBytes[:n]) + } + p.write(data) + p.nlcount = 0 +} + +func (p *printer) writeString(s string) { + p.writeBytes([]byte(s)) +} + +// If impliesSemi returns true for a non-blank line's final token tok, +// a semicolon is automatically inserted. Vice versa, a semicolon may +// be omitted in those cases. +func impliesSemi(tok token) bool { + switch tok { + case _Name, + _Break, _Continue, _Fallthrough, _Return, + /*_Inc, _Dec,*/ _Rparen, _Rbrack, _Rbrace: // TODO(gri) fix this + return true + } + return false +} + +// TODO(gri) provide table of []byte values for all tokens to avoid repeated string conversion + +func lineComment(text string) bool { + return strings.HasPrefix(text, "//") +} + +func (p *printer) addWhitespace(kind ctrlSymbol, text string) { + p.pending = append(p.pending, whitespace{p.lastTok, kind /*text*/}) + switch kind { + case semi: + p.lastTok = _Semi + case newline: + p.lastTok = 0 + // TODO(gri) do we need to handle /*-style comments containing newlines here? + } +} + +func (p *printer) flush(next token) { + // eliminate semis and redundant whitespace + sawNewline := next == _EOF + sawParen := next == _Rparen || next == _Rbrace + for i := len(p.pending) - 1; i >= 0; i-- { + switch p.pending[i].kind { + case semi: + k := semi + if sawParen { + sawParen = false + k = none // eliminate semi + } else if sawNewline && impliesSemi(p.pending[i].last) { + sawNewline = false + k = none // eliminate semi + } + p.pending[i].kind = k + case newline: + sawNewline = true + case blank, indent, outdent: + // nothing to do + // case comment: + // // A multi-line comment acts like a newline; and a "" + // // comment implies by definition at least one newline. + // if text := p.pending[i].text; strings.HasPrefix(text, "/*") && strings.ContainsRune(text, '\n') { + // sawNewline = true + // } + // case eolComment: + // // TODO(gri) act depending on sawNewline + default: + panic("unreachable") + } + } + + // print pending + prev := none + for i := range p.pending { + switch p.pending[i].kind { + case none: + // nothing to do + case semi: + p.writeString(";") + p.nlcount = 0 + prev = semi + case blank: + if prev != blank { + // at most one blank + p.writeBytes(blankByte) + p.nlcount = 0 + prev = blank + } + case newline: + const maxEmptyLines = 1 + if p.nlcount <= maxEmptyLines { + p.write(newlineByte) + p.nlcount++ + prev = newline + } + case indent: + p.indent++ + case outdent: + p.indent-- + if p.indent < 0 { + panic("negative indentation") + } + // case comment: + // if text := p.pending[i].text; text != "" { + // p.writeString(text) + // p.nlcount = 0 + // prev = comment + // } + // // TODO(gri) should check that line comments are always followed by newline + default: + panic("unreachable") + } + } + + p.pending = p.pending[:0] // re-use underlying array +} + +func mayCombine(prev token, next byte) (b bool) { + return // for now + // switch prev { + // case lexical.Int: + // b = next == '.' // 1. + // case lexical.Add: + // b = next == '+' // ++ + // case lexical.Sub: + // b = next == '-' // -- + // case lexical.Quo: + // b = next == '*' // /* + // case lexical.Lss: + // b = next == '-' || next == '<' // <- or << + // case lexical.And: + // b = next == '&' || next == '^' // && or &^ + // } + // return +} + +func (p *printer) print(args ...interface{}) { + for i := 0; i < len(args); i++ { + switch x := args[i].(type) { + case nil: + // we should not reach here but don't crash + + case Node: + p.printNode(x) + + case token: + // _Name implies an immediately following string + // argument which is the actual value to print. + var s string + if x == _Name { + i++ + if i >= len(args) { + panic("missing string argument after _Name") + } + s = args[i].(string) + } else { + s = x.String() + } + + // TODO(gri) This check seems at the wrong place since it doesn't + // take into account pending white space. + if mayCombine(p.lastTok, s[0]) { + panic("adjacent tokens combine without whitespace") + } + + if x == _Semi { + // delay printing of semi + p.addWhitespace(semi, "") + } else { + p.flush(x) + p.writeString(s) + p.nlcount = 0 + p.lastTok = x + } + + case Operator: + if x != 0 { + p.flush(_Operator) + p.writeString(x.String()) + } + + case ctrlSymbol: + switch x { + case none, semi /*, comment*/ : + panic("unreachable") + case newline: + // TODO(gri) need to handle mandatory newlines after a //-style comment + if !p.linebreaks { + x = blank + } + } + p.addWhitespace(x, "") + + // case *Comment: // comments are not Nodes + // p.addWhitespace(comment, x.Text) + + default: + panic(fmt.Sprintf("unexpected argument %v (%T)", x, x)) + } + } +} + +func (p *printer) printNode(n Node) { + // ncom := *n.Comments() + // if ncom != nil { + // // TODO(gri) in general we cannot make assumptions about whether + // // a comment is a /*- or a //-style comment since the syntax + // // tree may have been manipulated. Need to make sure the correct + // // whitespace is emitted. + // for _, c := range ncom.Alone { + // p.print(c, newline) + // } + // for _, c := range ncom.Before { + // if c.Text == "" || lineComment(c.Text) { + // panic("unexpected empty line or //-style 'before' comment") + // } + // p.print(c, blank) + // } + // } + + p.printRawNode(n) + + // if ncom != nil && len(ncom.After) > 0 { + // for i, c := range ncom.After { + // if i+1 < len(ncom.After) { + // if c.Text == "" || lineComment(c.Text) { + // panic("unexpected empty line or //-style non-final 'after' comment") + // } + // } + // p.print(blank, c) + // } + // //p.print(newline) + // } +} + +func (p *printer) printRawNode(n Node) { + switch n := n.(type) { + // expressions and types + case *Name: + p.print(_Name, n.Value) // _Name requires actual value following immediately + + case *BasicLit: + p.print(_Name, n.Value) // _Name requires actual value following immediately + + case *FuncLit: + p.print(n.Type, blank) + p.printBody(n.Body) + + case *CompositeLit: + if n.Type != nil { + p.print(n.Type) + } + p.print(_Lbrace) + if n.NKeys > 0 && n.NKeys == len(n.ElemList) { + p.printExprLines(n.ElemList) + } else { + p.printExprList(n.ElemList) + } + p.print(_Rbrace) + + case *ParenExpr: + p.print(_Lparen, n.X, _Rparen) + + case *SelectorExpr: + p.print(n.X, _Dot, n.Sel) + + case *IndexExpr: + p.print(n.X, _Lbrack, n.Index, _Rbrack) + + case *SliceExpr: + p.print(n.X, _Lbrack) + if i := n.Index[0]; i != nil { + p.printNode(i) + } + p.print(_Colon) + if j := n.Index[1]; j != nil { + p.printNode(j) + } + if k := n.Index[2]; k != nil { + p.print(_Colon, k) + } + p.print(_Rbrack) + + case *AssertExpr: + p.print(n.X, _Dot, _Lparen) + if n.Type != nil { + p.printNode(n.Type) + } else { + p.print(_Type) + } + p.print(_Rparen) + + case *CallExpr: + p.print(n.Fun, _Lparen) + p.printExprList(n.ArgList) + if n.HasDots { + p.print(_DotDotDot) + } + p.print(_Rparen) + + case *Operation: + if n.Y == nil { + // unary expr + p.print(n.Op) + // if n.Op == lexical.Range { + // p.print(blank) + // } + p.print(n.X) + } else { + // binary expr + // TODO(gri) eventually take precedence into account + // to control possibly missing parentheses + p.print(n.X, blank, n.Op, blank, n.Y) + } + + case *KeyValueExpr: + p.print(n.Key, _Colon, blank, n.Value) + + case *ListExpr: + p.printExprList(n.ElemList) + + case *ArrayType: + var len interface{} = _DotDotDot + if n.Len != nil { + len = n.Len + } + p.print(_Lbrack, len, _Rbrack, n.Elem) + + case *SliceType: + p.print(_Lbrack, _Rbrack, n.Elem) + + case *DotsType: + p.print(_DotDotDot, n.Elem) + + case *StructType: + p.print(_Struct) + if len(n.FieldList) > 0 && p.linebreaks { + p.print(blank) + } + p.print(_Lbrace) + if len(n.FieldList) > 0 { + p.print(newline, indent) + p.printFieldList(n.FieldList, n.TagList) + p.print(outdent, newline) + } + p.print(_Rbrace) + + case *FuncType: + p.print(_Func) + p.printSignature(n) + + case *InterfaceType: + p.print(_Interface) + if len(n.MethodList) > 0 && p.linebreaks { + p.print(blank) + } + p.print(_Lbrace) + if len(n.MethodList) > 0 { + p.print(newline, indent) + p.printMethodList(n.MethodList) + p.print(outdent, newline) + } + p.print(_Rbrace) + + case *MapType: + p.print(_Map, _Lbrack, n.Key, _Rbrack, n.Value) + + case *ChanType: + if n.Dir == RecvOnly { + p.print(_Arrow) + } + p.print(_Chan) + if n.Dir == SendOnly { + p.print(_Arrow) + } + p.print(blank, n.Elem) + + // statements + case *DeclStmt: + p.printDecl(n.DeclList) + + case *EmptyStmt: + // nothing to print + + case *LabeledStmt: + p.print(outdent, n.Label, _Colon, indent, newline, n.Stmt) + + case *ExprStmt: + p.print(n.X) + + case *SendStmt: + p.print(n.Chan, blank, _Arrow, blank, n.Value) + + case *AssignStmt: + p.print(n.Lhs) + if n.Rhs == ImplicitOne { + // TODO(gri) This is going to break the mayCombine + // check once we enable that again. + p.print(n.Op, n.Op) // ++ or -- + } else { + p.print(blank, n.Op, _Assign, blank) + p.print(n.Rhs) + } + + case *CallStmt: + p.print(n.Tok, blank, n.Call) + + case *ReturnStmt: + p.print(_Return) + if n.Results != nil { + p.print(blank, n.Results) + } + + case *BranchStmt: + p.print(n.Tok) + if n.Label != nil { + p.print(blank, n.Label) + } + + case *BlockStmt: + p.printBody(n.Body) + + case *IfStmt: + p.print(_If, blank) + if n.Init != nil { + p.print(n.Init, _Semi, blank) + } + p.print(n.Cond, blank) + p.printBody(n.Then) + if n.Else != nil { + p.print(blank, _Else, blank, n.Else) + } + + case *SwitchStmt: + p.print(_Switch, blank) + if n.Init != nil { + p.print(n.Init, _Semi, blank) + } + if n.Tag != nil { + p.print(n.Tag, blank) + } + p.printSwitchBody(n.Body) + + case *TypeSwitchGuard: + if n.Lhs != nil { + p.print(n.Lhs, blank, _Define, blank) + } + p.print(n.X, _Dot, _Lparen, _Type, _Rparen) + + case *SelectStmt: + p.print(_Select, blank) // for now + p.printSelectBody(n.Body) + + case *RangeClause: + if n.Lhs != nil { + tok := _Assign + if n.Def { + tok = _Define + } + p.print(n.Lhs, blank, tok, blank) + } + p.print(_Range, blank, n.X) + + case *ForStmt: + p.print(_For, blank) + if n.Init == nil && n.Post == nil { + if n.Cond != nil { + p.print(n.Cond, blank) + } + } else { + if n.Init != nil { + p.print(n.Init) + // TODO(gri) clean this up + if _, ok := n.Init.(*RangeClause); ok { + p.print(blank) + p.printBody(n.Body) + break + } + } + p.print(_Semi, blank) + if n.Cond != nil { + p.print(n.Cond) + } + p.print(_Semi, blank) + if n.Post != nil { + p.print(n.Post, blank) + } + } + p.printBody(n.Body) + + case *ImportDecl: + if n.Group == nil { + p.print(_Import, blank) + } + if n.LocalPkgName != nil { + p.print(n.LocalPkgName, blank) + } + p.print(n.Path) + + case *ConstDecl: + if n.Group == nil { + p.print(_Const, blank) + } + p.printNameList(n.NameList) + if n.Type != nil { + p.print(blank, n.Type) + } + if n.Values != nil { + p.print(blank, _Assign, blank, n.Values) + } + + case *TypeDecl: + if n.Group == nil { + p.print(_Type, blank) + } + p.print(n.Name, blank, n.Type) + + case *VarDecl: + if n.Group == nil { + p.print(_Var, blank) + } + p.printNameList(n.NameList) + if n.Type != nil { + p.print(blank, n.Type) + } + if n.Values != nil { + p.print(blank, _Assign, blank, n.Values) + } + + case *FuncDecl: + p.print(_Func, blank) + if r := n.Recv; r != nil { + p.print(_Lparen) + if r.Name != nil { + p.print(r.Name, blank) + } + p.printNode(r.Type) + p.print(_Rparen, blank) + } + p.print(n.Name) + p.printSignature(n.Type) + if n.Body != nil { + p.print(blank) + p.printBody(n.Body) + } + + case *printGroup: + p.print(n.Tok, blank, _Lparen) + if len(n.Decls) > 0 { + p.print(newline, indent) + for _, d := range n.Decls { + p.printNode(d) + p.print(_Semi, newline) + } + p.print(outdent) + } + p.print(_Rparen) + + // files + case *File: + p.print(_Package, blank, n.PkgName) + if len(n.DeclList) > 0 { + p.print(_Semi, newline, newline) + p.printDeclList(n.DeclList) + } + + default: + panic(fmt.Sprintf("syntax.Iterate: unexpected node type %T", n)) + } +} + +func (p *printer) printFields(fields []*Field, tags []*BasicLit, i, j int) { + if i+1 == j && fields[i].Name == nil { + // anonymous field + p.printNode(fields[i].Type) + } else { + for k, f := range fields[i:j] { + if k > 0 { + p.print(_Comma, blank) + } + p.printNode(f.Name) + } + p.print(blank) + p.printNode(fields[i].Type) + } + if i < len(tags) && tags[i] != nil { + p.print(blank) + p.printNode(tags[i]) + } +} + +func (p *printer) printFieldList(fields []*Field, tags []*BasicLit) { + i0 := 0 + var typ Expr + for i, f := range fields { + if f.Name == nil || f.Type != typ { + if i0 < i { + p.printFields(fields, tags, i0, i) + p.print(_Semi, newline) + i0 = i + } + typ = f.Type + } + } + p.printFields(fields, tags, i0, len(fields)) +} + +func (p *printer) printMethodList(methods []*Field) { + for i, m := range methods { + if i > 0 { + p.print(_Semi, newline) + } + if m.Name != nil { + p.printNode(m.Name) + p.printSignature(m.Type.(*FuncType)) + } else { + p.printNode(m.Type) + } + } +} + +func (p *printer) printNameList(list []*Name) { + for i, x := range list { + if i > 0 { + p.print(_Comma, blank) + } + p.printNode(x) + } +} + +func (p *printer) printExprList(list []Expr) { + for i, x := range list { + if i > 0 { + p.print(_Comma, blank) + } + p.printNode(x) + } +} + +func (p *printer) printExprLines(list []Expr) { + if len(list) > 0 { + p.print(newline, indent) + for _, x := range list { + p.print(x, _Comma, newline) + } + p.print(outdent) + } +} + +func groupFor(d Decl) (token, *Group) { + switch d := d.(type) { + case *ImportDecl: + return _Import, d.Group + case *ConstDecl: + return _Const, d.Group + case *TypeDecl: + return _Type, d.Group + case *VarDecl: + return _Var, d.Group + case *FuncDecl: + return _Func, nil + default: + panic("unreachable") + } +} + +type printGroup struct { + node + Tok token + Decls []Decl +} + +func (p *printer) printDecl(list []Decl) { + tok, group := groupFor(list[0]) + + if group == nil { + if len(list) != 1 { + panic("unreachable") + } + p.printNode(list[0]) + return + } + + // if _, ok := list[0].(*EmptyDecl); ok { + // if len(list) != 1 { + // panic("unreachable") + // } + // // TODO(gri) if there are comments inside the empty + // // group, we may need to keep the list non-nil + // list = nil + // } + + // printGroup is here for consistent comment handling + // (this is not yet used) + var pg printGroup + // *pg.Comments() = *group.Comments() + pg.Tok = tok + pg.Decls = list + p.printNode(&pg) +} + +func (p *printer) printDeclList(list []Decl) { + i0 := 0 + var tok token + var group *Group + for i, x := range list { + if s, g := groupFor(x); g == nil || g != group { + if i0 < i { + p.printDecl(list[i0:i]) + p.print(_Semi, newline) + // print empty line between different declaration groups, + // different kinds of declarations, or between functions + if g != group || s != tok || s == _Func { + p.print(newline) + } + i0 = i + } + tok, group = s, g + } + } + p.printDecl(list[i0:]) +} + +func (p *printer) printSignature(sig *FuncType) { + p.printParameterList(sig.ParamList) + if list := sig.ResultList; list != nil { + p.print(blank) + if len(list) == 1 && list[0].Name == nil { + p.printNode(list[0].Type) + } else { + p.printParameterList(list) + } + } +} + +func (p *printer) printParameterList(list []*Field) { + p.print(_Lparen) + if len(list) > 0 { + for i, f := range list { + if i > 0 { + p.print(_Comma, blank) + } + if f.Name != nil { + p.printNode(f.Name) + if i+1 < len(list) { + f1 := list[i+1] + if f1.Name != nil && f1.Type == f.Type { + continue // no need to print type + } + } + p.print(blank) + } + p.printNode(f.Type) + } + } + p.print(_Rparen) +} + +func (p *printer) printStmtList(list []Stmt, braces bool) { + for i, x := range list { + p.print(x, _Semi) + if i+1 < len(list) { + p.print(newline) + } else if braces { + // Print an extra semicolon if the last statement is + // an empty statement and we are in a braced block + // because one semicolon is automatically removed. + if _, ok := x.(*EmptyStmt); ok { + p.print(x, _Semi) + } + } + } +} + +func (p *printer) printBody(list []Stmt) { + p.print(_Lbrace) + if len(list) > 0 { + p.print(newline, indent) + p.printStmtList(list, true) + p.print(outdent, newline) + } + p.print(_Rbrace) +} + +func (p *printer) printSwitchBody(list []*CaseClause) { + p.print(_Lbrace) + if len(list) > 0 { + p.print(newline) + for i, c := range list { + p.printCaseClause(c, i+1 == len(list)) + p.print(newline) + } + } + p.print(_Rbrace) +} + +func (p *printer) printSelectBody(list []*CommClause) { + p.print(_Lbrace) + if len(list) > 0 { + p.print(newline) + for i, c := range list { + p.printCommClause(c, i+1 == len(list)) + p.print(newline) + } + } + p.print(_Rbrace) +} + +func (p *printer) printCaseClause(c *CaseClause, braces bool) { + if c.Cases != nil { + p.print(_Case, blank, c.Cases) + } else { + p.print(_Default) + } + p.print(_Colon) + if len(c.Body) > 0 { + p.print(newline, indent) + p.printStmtList(c.Body, braces) + p.print(outdent) + } +} + +func (p *printer) printCommClause(c *CommClause, braces bool) { + if c.Comm != nil { + p.print(_Case, blank) + p.print(c.Comm) + } else { + p.print(_Default) + } + p.print(_Colon) + if len(c.Body) > 0 { + p.print(newline, indent) + p.printStmtList(c.Body, braces) + p.print(outdent) + } +} diff --git a/src/cmd/compile/internal/syntax/printer_test.go b/src/cmd/compile/internal/syntax/printer_test.go new file mode 100644 index 0000000000..e8c2201e60 --- /dev/null +++ b/src/cmd/compile/internal/syntax/printer_test.go @@ -0,0 +1,24 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "fmt" + "os" + "testing" +) + +func TestPrint(t *testing.T) { + if testing.Short() { + t.Skip("skipping test in short mode") + } + + ast, err := ReadFile(*src, nil, 0) + if err != nil { + t.Fatal(err) + } + Fprint(os.Stdout, ast, true) + fmt.Println() +} diff --git a/src/cmd/compile/internal/syntax/scanner.go b/src/cmd/compile/internal/syntax/scanner.go new file mode 100644 index 0000000000..0f0f1ead9a --- /dev/null +++ b/src/cmd/compile/internal/syntax/scanner.go @@ -0,0 +1,651 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "fmt" + "io" + "strings" + "unicode" + "unicode/utf8" +) + +type scanner struct { + source + nlsemi bool // if set '\n' and EOF translate to ';' + + // current token, valid after calling next() + pos, line int + tok token + lit string // valid if tok is _Name or _Literal + kind LitKind // valid if tok is _Literal + op Operator // valid if tok is _Operator, _AssignOp, or _IncOp + prec int // valid if tok is _Operator, _AssignOp, or _IncOp + + pragmas []Pragma +} + +func (s *scanner) init(src io.Reader, errh ErrorHandler) { + s.source.init(src, errh) + s.nlsemi = false +} + +func (s *scanner) next() { + nlsemi := s.nlsemi + s.nlsemi = false + +redo: + // skip white space + c := s.getr() + for c == ' ' || c == '\t' || c == '\n' && !nlsemi || c == '\r' { + c = s.getr() + } + + // token start + s.pos, s.line = s.source.pos0(), s.source.line0 + + if isLetter(c) || c >= utf8.RuneSelf && unicode.IsLetter(c) { + s.ident() + return + } + + switch c { + case -1: + if nlsemi { + s.tok = _Semi + break + } + s.tok = _EOF + + case '\n': + s.tok = _Semi + + case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': + s.number(c) + + case '"': + s.stdString() + + case '`': + s.rawString() + + case '\'': + s.rune() + + case '(': + s.tok = _Lparen + + case '[': + s.tok = _Lbrack + + case '{': + s.tok = _Lbrace + + case ',': + s.tok = _Comma + + case ';': + s.tok = _Semi + + case ')': + s.nlsemi = true + s.tok = _Rparen + + case ']': + s.nlsemi = true + s.tok = _Rbrack + + case '}': + s.nlsemi = true + s.tok = _Rbrace + + case ':': + if s.getr() == '=' { + s.tok = _Define + break + } + s.ungetr() + s.tok = _Colon + + case '.': + c = s.getr() + if isDigit(c) { + s.ungetr() + s.source.r0-- // make sure '.' is part of literal (line cannot have changed) + s.number('.') + break + } + if c == '.' { + c = s.getr() + if c == '.' { + s.tok = _DotDotDot + break + } + s.ungetr() + s.source.r0-- // make next ungetr work (line cannot have changed) + } + s.ungetr() + s.tok = _Dot + + case '+': + s.op, s.prec = Add, precAdd + c = s.getr() + if c != '+' { + goto assignop + } + s.nlsemi = true + s.tok = _IncOp + + case '-': + s.op, s.prec = Sub, precAdd + c = s.getr() + if c != '-' { + goto assignop + } + s.nlsemi = true + s.tok = _IncOp + + case '*': + s.op, s.prec = Mul, precMul + // don't goto assignop - want _Star token + if s.getr() == '=' { + s.tok = _AssignOp + break + } + s.ungetr() + s.tok = _Star + + case '/': + c = s.getr() + if c == '/' { + s.lineComment() + goto redo + } + if c == '*' { + s.fullComment() + if s.source.line > s.line && nlsemi { + // A multi-line comment acts like a newline; + // it translates to a ';' if nlsemi is set. + s.tok = _Semi + break + } + goto redo + } + s.op, s.prec = Div, precMul + goto assignop + + case '%': + s.op, s.prec = Rem, precMul + c = s.getr() + goto assignop + + case '&': + c = s.getr() + if c == '&' { + s.op, s.prec = AndAnd, precAndAnd + s.tok = _Operator + break + } + s.op, s.prec = And, precMul + if c == '^' { + s.op = AndNot + c = s.getr() + } + goto assignop + + case '|': + c = s.getr() + if c == '|' { + s.op, s.prec = OrOr, precOrOr + s.tok = _Operator + break + } + s.op, s.prec = Or, precAdd + goto assignop + + case '~': + s.error("bitwise complement operator is ^") + fallthrough + + case '^': + s.op, s.prec = Xor, precAdd + c = s.getr() + goto assignop + + case '<': + c = s.getr() + if c == '=' { + s.op, s.prec = Leq, precCmp + s.tok = _Operator + break + } + if c == '<' { + s.op, s.prec = Shl, precMul + c = s.getr() + goto assignop + } + if c == '-' { + s.tok = _Arrow + break + } + s.ungetr() + s.op, s.prec = Lss, precCmp + s.tok = _Operator + + case '>': + c = s.getr() + if c == '=' { + s.op, s.prec = Geq, precCmp + s.tok = _Operator + break + } + if c == '>' { + s.op, s.prec = Shr, precMul + c = s.getr() + goto assignop + } + s.ungetr() + s.op, s.prec = Gtr, precCmp + s.tok = _Operator + + case '=': + if s.getr() == '=' { + s.op, s.prec = Eql, precCmp + s.tok = _Operator + break + } + s.ungetr() + s.tok = _Assign + + case '!': + if s.getr() == '=' { + s.op, s.prec = Neq, precCmp + s.tok = _Operator + break + } + s.ungetr() + s.op, s.prec = Not, 0 + s.tok = _Operator + + default: + s.tok = 0 + s.error(fmt.Sprintf("invalid rune %q", c)) + goto redo + } + + return + +assignop: + if c == '=' { + s.tok = _AssignOp + return + } + s.ungetr() + s.tok = _Operator +} + +func isLetter(c rune) bool { + return 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || c == '_' +} + +func isDigit(c rune) bool { + return '0' <= c && c <= '9' +} + +func (s *scanner) ident() { + s.startLit() + + // accelerate common case (7bit ASCII) + c := s.getr() + for isLetter(c) || isDigit(c) { + c = s.getr() + } + + // general case + if c >= utf8.RuneSelf { + for unicode.IsLetter(c) || c == '_' || unicode.IsDigit(c) { + c = s.getr() + } + } + s.ungetr() + + lit := s.stopLit() + + // possibly a keyword + if len(lit) >= 2 { + if tok := keywordMap[hash(lit)]; tok != 0 && strbyteseql(tokstrings[tok], lit) { + s.nlsemi = contains(1<<_Break|1<<_Continue|1<<_Fallthrough|1<<_Return, tok) + s.tok = tok + return + } + } + + s.nlsemi = true + s.lit = string(lit) + s.tok = _Name +} + +// hash is a perfect hash function for keywords. +// It assumes that s has at least length 2. +func hash(s []byte) uint { + return (uint(s[0])<<4 ^ uint(s[1]) + uint(len(s))) & uint(len(keywordMap)-1) +} + +func strbyteseql(s string, b []byte) bool { + if len(s) == len(b) { + for i, b := range b { + if s[i] != b { + return false + } + } + return true + } + return false +} + +var keywordMap [1 << 6]token // size must be power of two + +func init() { + // populate keywordMap + for tok := _Break; tok <= _Var; tok++ { + h := hash([]byte(tokstrings[tok])) + if keywordMap[h] != 0 { + panic("imperfect hash") + } + keywordMap[h] = tok + } +} + +func (s *scanner) number(c rune) { + s.startLit() + + if c != '.' { + s.kind = IntLit // until proven otherwise + if c == '0' { + c = s.getr() + if c == 'x' || c == 'X' { + // hex + c = s.getr() + hasDigit := false + for isDigit(c) || 'a' <= c && c <= 'f' || 'A' <= c && c <= 'F' { + c = s.getr() + hasDigit = true + } + if !hasDigit { + s.error("malformed hex constant") + } + goto done + } + + // decimal 0, octal, or float + has8or9 := false + for isDigit(c) { + if c > '7' { + has8or9 = true + } + c = s.getr() + } + if c != '.' && c != 'e' && c != 'E' && c != 'i' { + // octal + if has8or9 { + s.error("malformed octal constant") + } + goto done + } + + } else { + // decimal or float + for isDigit(c) { + c = s.getr() + } + } + } + + // float + if c == '.' { + s.kind = FloatLit + c = s.getr() + for isDigit(c) { + c = s.getr() + } + } + + // exponent + if c == 'e' || c == 'E' { + s.kind = FloatLit + c = s.getr() + if c == '-' || c == '+' { + c = s.getr() + } + if !isDigit(c) { + s.error("malformed floating-point constant exponent") + } + for isDigit(c) { + c = s.getr() + } + } + + // complex + if c == 'i' { + s.kind = ImagLit + s.getr() + } + +done: + s.ungetr() + s.nlsemi = true + s.lit = string(s.stopLit()) + s.tok = _Literal +} + +func (s *scanner) stdString() { + s.startLit() + + for { + r := s.getr() + if r == '"' { + break + } + if r == '\\' { + s.escape('"') + continue + } + if r == '\n' { + s.ungetr() // assume newline is not part of literal + s.error("newline in string") + break + } + if r < 0 { + s.error_at(s.pos, s.line, "string not terminated") + break + } + } + + s.nlsemi = true + s.lit = string(s.stopLit()) + s.kind = StringLit + s.tok = _Literal +} + +func (s *scanner) rawString() { + s.startLit() + + for { + r := s.getr() + if r == '`' { + break + } + if r < 0 { + s.error_at(s.pos, s.line, "string not terminated") + break + } + } + // We leave CRs in the string since they are part of the + // literal (even though they are not part of the literal + // value). + + s.nlsemi = true + s.lit = string(s.stopLit()) + s.kind = StringLit + s.tok = _Literal +} + +func (s *scanner) rune() { + s.startLit() + + r := s.getr() + if r == '\'' { + s.error("empty character literal") + } else if r == '\n' { + s.ungetr() // assume newline is not part of literal + s.error("newline in character literal") + } else { + ok := true + if r == '\\' { + ok = s.escape('\'') + } + r = s.getr() + if r != '\'' { + // only report error if we're ok so far + if ok { + s.error("missing '") + } + s.ungetr() + } + } + + s.nlsemi = true + s.lit = string(s.stopLit()) + s.kind = RuneLit + s.tok = _Literal +} + +func (s *scanner) lineComment() { + // recognize pragmas + var prefix string + r := s.getr() + switch r { + case 'g': + prefix = "go:" + case 'l': + prefix = "line " + default: + goto skip + } + + s.startLit() + for _, m := range prefix { + if r != m { + s.stopLit() + goto skip + } + r = s.getr() + } + + for r >= 0 { + if r == '\n' { + s.ungetr() + break + } + r = s.getr() + } + s.pragmas = append(s.pragmas, Pragma{ + Line: s.line, + Text: strings.TrimSuffix(string(s.stopLit()), "\r"), + }) + return + +skip: + // consume line + for r != '\n' && r >= 0 { + r = s.getr() + } + s.ungetr() // don't consume '\n' - needed for nlsemi logic +} + +func (s *scanner) fullComment() { + for { + r := s.getr() + for r == '*' { + r = s.getr() + if r == '/' { + return + } + } + if r < 0 { + s.error_at(s.pos, s.line, "comment not terminated") + return + } + } +} + +func (s *scanner) escape(quote rune) bool { + var n int + var base, max uint32 + + c := s.getr() + switch c { + case 'a', 'b', 'f', 'n', 'r', 't', 'v', '\\', quote: + return true + case '0', '1', '2', '3', '4', '5', '6', '7': + n, base, max = 3, 8, 255 + case 'x': + c = s.getr() + n, base, max = 2, 16, 255 + case 'u': + c = s.getr() + n, base, max = 4, 16, unicode.MaxRune + case 'U': + c = s.getr() + n, base, max = 8, 16, unicode.MaxRune + default: + if c < 0 { + return true // complain in caller about EOF + } + s.error("unknown escape sequence") + return false + } + + var x uint32 + for i := n; i > 0; i-- { + d := base + switch { + case isDigit(c): + d = uint32(c) - '0' + case 'a' <= c && c <= 'f': + d = uint32(c) - ('a' - 10) + case 'A' <= c && c <= 'F': + d = uint32(c) - ('A' - 10) + } + if d >= base { + if c < 0 { + return true // complain in caller about EOF + } + if c != quote { + s.error(fmt.Sprintf("illegal character %#U in escape sequence", c)) + } else { + s.error("escape sequence incomplete") + } + s.ungetr() + return false + } + // d < base + x = x*base + d + c = s.getr() + } + s.ungetr() + + if x > max && n == 3 { + s.error(fmt.Sprintf("octal escape value > 255: %d", x)) + return false + } + + if x > max || 0xD800 <= x && x < 0xE000 /* surrogate range */ { + s.error("escape sequence is invalid Unicode code point") + return false + } + + return true +} diff --git a/src/cmd/compile/internal/syntax/scanner_test.go b/src/cmd/compile/internal/syntax/scanner_test.go new file mode 100644 index 0000000000..69e81aceca --- /dev/null +++ b/src/cmd/compile/internal/syntax/scanner_test.go @@ -0,0 +1,354 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "fmt" + "os" + "testing" +) + +func TestScanner(t *testing.T) { + if testing.Short() { + t.Skip("skipping test in short mode") + } + + src, err := os.Open("parser.go") + if err != nil { + t.Fatal(err) + } + defer src.Close() + + var s scanner + s.init(src, nil) + for { + s.next() + if s.tok == _EOF { + break + } + switch s.tok { + case _Name: + fmt.Println(s.line, s.tok, "=>", s.lit) + case _Operator: + fmt.Println(s.line, s.tok, "=>", s.op, s.prec) + default: + fmt.Println(s.line, s.tok) + } + } +} + +func TestTokens(t *testing.T) { + // make source + var buf []byte + for i, s := range sampleTokens { + buf = append(buf, "\t\t\t\t"[:i&3]...) // leading indentation + buf = append(buf, s.src...) // token + buf = append(buf, " "[:i&7]...) // trailing spaces + buf = append(buf, "/* foo */ // bar\n"...) // comments + } + + // scan source + var got scanner + got.init(&bytesReader{buf}, nil) + got.next() + for i, want := range sampleTokens { + nlsemi := false + + if got.line != i+1 { + t.Errorf("got line %d; want %d", got.line, i+1) + } + + if got.tok != want.tok { + t.Errorf("got tok = %s; want %s", got.tok, want.tok) + continue + } + + switch want.tok { + case _Name, _Literal: + if got.lit != want.src { + t.Errorf("got lit = %q; want %q", got.lit, want.src) + continue + } + nlsemi = true + + case _Operator, _AssignOp, _IncOp: + if got.op != want.op { + t.Errorf("got op = %s; want %s", got.op, want.op) + continue + } + if got.prec != want.prec { + t.Errorf("got prec = %s; want %s", got.prec, want.prec) + continue + } + nlsemi = want.tok == _IncOp + + case _Rparen, _Rbrack, _Rbrace, _Break, _Continue, _Fallthrough, _Return: + nlsemi = true + } + + if nlsemi { + got.next() + if got.tok != _Semi { + t.Errorf("got tok = %s; want ;", got.tok) + continue + } + } + + got.next() + } + + if got.tok != _EOF { + t.Errorf("got %q; want _EOF", got.tok) + } +} + +var sampleTokens = [...]struct { + tok token + src string + op Operator + prec int +}{ + // name samples + {_Name, "x", 0, 0}, + {_Name, "X123", 0, 0}, + {_Name, "foo", 0, 0}, + {_Name, "Foo123", 0, 0}, + {_Name, "foo_bar", 0, 0}, + {_Name, "_", 0, 0}, + {_Name, "_foobar", 0, 0}, + {_Name, "a۰۱۸", 0, 0}, + {_Name, "foo६४", 0, 0}, + {_Name, "bar９８７６", 0, 0}, + {_Name, "ŝ", 0, 0}, + {_Name, "ŝfoo", 0, 0}, + + // literal samples + {_Literal, "0", 0, 0}, + {_Literal, "1", 0, 0}, + {_Literal, "12345", 0, 0}, + {_Literal, "123456789012345678890123456789012345678890", 0, 0}, + {_Literal, "01234567", 0, 0}, + {_Literal, "0x0", 0, 0}, + {_Literal, "0xcafebabe", 0, 0}, + {_Literal, "0.", 0, 0}, + {_Literal, "0.e0", 0, 0}, + {_Literal, "0.e-1", 0, 0}, + {_Literal, "0.e+123", 0, 0}, + {_Literal, ".0", 0, 0}, + {_Literal, ".0E00", 0, 0}, + {_Literal, ".0E-0123", 0, 0}, + {_Literal, ".0E+12345678901234567890", 0, 0}, + {_Literal, ".45e1", 0, 0}, + {_Literal, "3.14159265", 0, 0}, + {_Literal, "1e0", 0, 0}, + {_Literal, "1e+100", 0, 0}, + {_Literal, "1e-100", 0, 0}, + {_Literal, "2.71828e-1000", 0, 0}, + {_Literal, "0i", 0, 0}, + {_Literal, "1i", 0, 0}, + {_Literal, "012345678901234567889i", 0, 0}, + {_Literal, "123456789012345678890i", 0, 0}, + {_Literal, "0.i", 0, 0}, + {_Literal, ".0i", 0, 0}, + {_Literal, "3.14159265i", 0, 0}, + {_Literal, "1e0i", 0, 0}, + {_Literal, "1e+100i", 0, 0}, + {_Literal, "1e-100i", 0, 0}, + {_Literal, "2.71828e-1000i", 0, 0}, + {_Literal, "'a'", 0, 0}, + {_Literal, "'\\000'", 0, 0}, + {_Literal, "'\\xFF'", 0, 0}, + {_Literal, "'\\uff16'", 0, 0}, + {_Literal, "'\\U0000ff16'", 0, 0}, + {_Literal, "`foobar`", 0, 0}, + {_Literal, "`foo\tbar`", 0, 0}, + {_Literal, "`\r`", 0, 0}, + + // operators + {_Operator, "||", OrOr, precOrOr}, + + {_Operator, "&&", AndAnd, precAndAnd}, + + {_Operator, "==", Eql, precCmp}, + {_Operator, "!=", Neq, precCmp}, + {_Operator, "<", Lss, precCmp}, + {_Operator, "<=", Leq, precCmp}, + {_Operator, ">", Gtr, precCmp}, + {_Operator, ">=", Geq, precCmp}, + + {_Operator, "+", Add, precAdd}, + {_Operator, "-", Sub, precAdd}, + {_Operator, "|", Or, precAdd}, + {_Operator, "^", Xor, precAdd}, + + {_Star, "*", Mul, precMul}, + {_Operator, "/", Div, precMul}, + {_Operator, "%", Rem, precMul}, + {_Operator, "&", And, precMul}, + {_Operator, "&^", AndNot, precMul}, + {_Operator, "<<", Shl, precMul}, + {_Operator, ">>", Shr, precMul}, + + // assignment operations + {_AssignOp, "+=", Add, precAdd}, + {_AssignOp, "-=", Sub, precAdd}, + {_AssignOp, "|=", Or, precAdd}, + {_AssignOp, "^=", Xor, precAdd}, + + {_AssignOp, "*=", Mul, precMul}, + {_AssignOp, "/=", Div, precMul}, + {_AssignOp, "%=", Rem, precMul}, + {_AssignOp, "&=", And, precMul}, + {_AssignOp, "&^=", AndNot, precMul}, + {_AssignOp, "<<=", Shl, precMul}, + {_AssignOp, ">>=", Shr, precMul}, + + // other operations + {_IncOp, "++", Add, precAdd}, + {_IncOp, "--", Sub, precAdd}, + {_Assign, "=", 0, 0}, + {_Define, ":=", 0, 0}, + {_Arrow, "<-", 0, 0}, + + // delimiters + {_Lparen, "(", 0, 0}, + {_Lbrack, "[", 0, 0}, + {_Lbrace, "{", 0, 0}, + {_Rparen, ")", 0, 0}, + {_Rbrack, "]", 0, 0}, + {_Rbrace, "}", 0, 0}, + {_Comma, ",", 0, 0}, + {_Semi, ";", 0, 0}, + {_Colon, ":", 0, 0}, + {_Dot, ".", 0, 0}, + {_DotDotDot, "...", 0, 0}, + + // keywords + {_Break, "break", 0, 0}, + {_Case, "case", 0, 0}, + {_Chan, "chan", 0, 0}, + {_Const, "const", 0, 0}, + {_Continue, "continue", 0, 0}, + {_Default, "default", 0, 0}, + {_Defer, "defer", 0, 0}, + {_Else, "else", 0, 0}, + {_Fallthrough, "fallthrough", 0, 0}, + {_For, "for", 0, 0}, + {_Func, "func", 0, 0}, + {_Go, "go", 0, 0}, + {_Goto, "goto", 0, 0}, + {_If, "if", 0, 0}, + {_Import, "import", 0, 0}, + {_Interface, "interface", 0, 0}, + {_Map, "map", 0, 0}, + {_Package, "package", 0, 0}, + {_Range, "range", 0, 0}, + {_Return, "return", 0, 0}, + {_Select, "select", 0, 0}, + {_Struct, "struct", 0, 0}, + {_Switch, "switch", 0, 0}, + {_Type, "type", 0, 0}, + {_Var, "var", 0, 0}, +} + +func TestScanErrors(t *testing.T) { + for _, test := range []struct { + src, msg string + pos, line int + }{ + // Note: Positions for lexical errors are the earliest position + // where the error is apparent, not the beginning of the respective + // token. + + // rune-level errors + {"fo\x00o", "invalid NUL character", 2, 1}, + {"foo\n\ufeff bar", "invalid BOM in the middle of the file", 4, 2}, + {"foo\n\n\xff ", "invalid UTF-8 encoding", 5, 3}, + + // token-level errors + {"x + ~y", "bitwise complement operator is ^", 4, 1}, + {"foo$bar = 0", "invalid rune '$'", 3, 1}, + {"const x = 0xyz", "malformed hex constant", 12, 1}, + {"0123456789", "malformed octal constant", 10, 1}, + {"0123456789. /* foobar", "comment not terminated", 12, 1}, // valid float constant + {"0123456789e0 /*\nfoobar", "comment not terminated", 13, 1}, // valid float constant + {"var a, b = 08, 07\n", "malformed octal constant", 13, 1}, + {"(x + 1.0e+x)", "malformed floating-point constant exponent", 10, 1}, + + {`''`, "empty character literal", 1, 1}, + {"'\n", "newline in character literal", 1, 1}, + {`'\`, "missing '", 2, 1}, + {`'\'`, "missing '", 3, 1}, + {`'\x`, "missing '", 3, 1}, + {`'\x'`, "escape sequence incomplete", 3, 1}, + {`'\y'`, "unknown escape sequence", 2, 1}, + {`'\x0'`, "escape sequence incomplete", 4, 1}, + {`'\00'`, "escape sequence incomplete", 4, 1}, + {`'\377' /*`, "comment not terminated", 7, 1}, // valid octal escape + {`'\378`, "illegal character U+0038 '8' in escape sequence", 4, 1}, + {`'\400'`, "octal escape value > 255: 256", 5, 1}, + {`'xx`, "missing '", 2, 1}, + + {"\"\n", "newline in string", 1, 1}, + {`"`, "string not terminated", 0, 1}, + {`"foo`, "string not terminated", 0, 1}, + {"`", "string not terminated", 0, 1}, + {"`foo", "string not terminated", 0, 1}, + {"/*/", "comment not terminated", 0, 1}, + {"/*\n\nfoo", "comment not terminated", 0, 1}, + {"/*\n\nfoo", "comment not terminated", 0, 1}, + {`"\`, "string not terminated", 0, 1}, + {`"\"`, "string not terminated", 0, 1}, + {`"\x`, "string not terminated", 0, 1}, + {`"\x"`, "escape sequence incomplete", 3, 1}, + {`"\y"`, "unknown escape sequence", 2, 1}, + {`"\x0"`, "escape sequence incomplete", 4, 1}, + {`"\00"`, "escape sequence incomplete", 4, 1}, + {`"\377" /*`, "comment not terminated", 7, 1}, // valid octal escape + {`"\378"`, "illegal character U+0038 '8' in escape sequence", 4, 1}, + {`"\400"`, "octal escape value > 255: 256", 5, 1}, + + {`s := "foo\z"`, "unknown escape sequence", 10, 1}, + {`s := "foo\z00\nbar"`, "unknown escape sequence", 10, 1}, + {`"\x`, "string not terminated", 0, 1}, + {`"\x"`, "escape sequence incomplete", 3, 1}, + {`var s string = "\x"`, "escape sequence incomplete", 18, 1}, + {`return "\Uffffffff"`, "escape sequence is invalid Unicode code point", 18, 1}, + + // former problem cases + {"package p\n\n\xef", "invalid UTF-8 encoding", 11, 3}, + } { + var s scanner + nerrors := 0 + s.init(&bytesReader{[]byte(test.src)}, func(pos, line int, msg string) { + nerrors++ + // only check the first error + if nerrors == 1 { + if msg != test.msg { + t.Errorf("%q: got msg = %q; want %q", test.src, msg, test.msg) + } + if pos != test.pos { + t.Errorf("%q: got pos = %d; want %d", test.src, pos, test.pos) + } + if line != test.line { + t.Errorf("%q: got line = %d; want %d", test.src, line, test.line) + } + } else if nerrors > 1 { + t.Errorf("%q: got unexpected %q at pos = %d, line = %d", test.src, msg, pos, line) + } + }) + + for { + s.next() + if s.tok == _EOF { + break + } + } + + if nerrors == 0 { + t.Errorf("%q: got no error; want %q", test.src, test.msg) + } + } +} diff --git a/src/cmd/compile/internal/syntax/source.go b/src/cmd/compile/internal/syntax/source.go new file mode 100644 index 0000000000..87c22fcc26 --- /dev/null +++ b/src/cmd/compile/internal/syntax/source.go @@ -0,0 +1,177 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "fmt" + "io" + "unicode/utf8" +) + +// buf [...read...|...|...unread...|s|...free...] +// ^ ^ ^ ^ +// | | | | +// suf r0 r w + +type source struct { + src io.Reader + errh ErrorHandler + + // source buffer + buf [4 << 10]byte + offs int // source offset of buf + r0, r, w int // previous/current read and write buf positions, excluding sentinel + line0, line int // previous/current line + err error // pending io error + + // literal buffer + lit []byte // literal prefix + suf int // literal suffix; suf >= 0 means we are scanning a literal +} + +func (s *source) init(src io.Reader, errh ErrorHandler) { + s.src = src + s.errh = errh + + s.buf[0] = utf8.RuneSelf // terminate with sentinel + s.offs = 0 + s.r0, s.r, s.w = 0, 0, 0 + s.line0, s.line = 1, 1 + s.err = nil + + s.lit = s.lit[:0] + s.suf = -1 +} + +func (s *source) error(msg string) { + s.error_at(s.pos0(), s.line0, msg) +} + +func (s *source) error_at(pos, line int, msg string) { + if s.errh != nil { + s.errh(pos, line, msg) + return + } + panic(fmt.Sprintf("%d: %s", line, msg)) +} + +// pos0 returns the byte position of the last character read. +func (s *source) pos0() int { + return s.offs + s.r0 +} + +func (s *source) ungetr() { + s.r, s.line = s.r0, s.line0 +} + +func (s *source) getr() rune { +redo: + s.r0, s.line0 = s.r, s.line + + // We could avoid at least one test that is always taken in the + // for loop below by duplicating the common case code (ASCII) + // here since we always have at least the sentinel (utf8.RuneSelf) + // in the buffer. Measure and optimize if necessary. + + // make sure we have at least one rune in buffer, or we are at EOF + for s.r+utf8.UTFMax > s.w && !utf8.FullRune(s.buf[s.r:s.w]) && s.err == nil && s.w-s.r < len(s.buf) { + s.fill() // s.w-s.r < len(s.buf) => buffer is not full + } + + // common case: ASCII and enough bytes + // (invariant: s.buf[s.w] == utf8.RuneSelf) + if b := s.buf[s.r]; b < utf8.RuneSelf { + s.r++ + if b == 0 { + s.error("invalid NUL character") + goto redo + } + if b == '\n' { + s.line++ + } + return rune(b) + } + + // EOF + if s.r == s.w { + if s.err != io.EOF { + s.error(s.err.Error()) + } + return -1 + } + + // uncommon case: not ASCII + r, w := utf8.DecodeRune(s.buf[s.r:s.w]) + s.r += w + + if r == utf8.RuneError && w == 1 { + s.error("invalid UTF-8 encoding") + goto redo + } + + // BOM's are only allowed as the first character in a file + const BOM = 0xfeff + if r == BOM { + if s.r0 > 0 { // s.r0 is always > 0 after 1st character (fill will set it to 1) + s.error("invalid BOM in the middle of the file") + } + goto redo + } + + return r +} + +func (s *source) fill() { + // Slide unread bytes to beginning but preserve last read char + // (for one ungetr call) plus one extra byte (for a 2nd ungetr + // call, only for ".." character sequence and float literals + // starting with "."). + if s.r0 > 1 { + // save literal prefix, if any + // (We see at most one ungetr call while reading + // a literal, so make sure s.r0 remains in buf.) + if s.suf >= 0 { + s.lit = append(s.lit, s.buf[s.suf:s.r0]...) + s.suf = 1 // == s.r0 after slide below + } + s.offs += s.r0 - 1 + r := s.r - s.r0 + 1 // last read char plus one byte + s.w = r + copy(s.buf[r:], s.buf[s.r:s.w]) + s.r = r + s.r0 = 1 + } + + // read more data: try a limited number of times + for i := 100; i > 0; i-- { + n, err := s.src.Read(s.buf[s.w : len(s.buf)-1]) // -1 to leave space for sentinel + if n < 0 { + panic("negative read") // incorrect underlying io.Reader implementation + } + s.w += n + if n > 0 || err != nil { + s.buf[s.w] = utf8.RuneSelf // sentinel + if err != nil { + s.err = err + } + return + } + } + + s.err = io.ErrNoProgress +} + +func (s *source) startLit() { + s.suf = s.r0 + s.lit = s.lit[:0] // reuse lit +} + +func (s *source) stopLit() []byte { + lit := s.buf[s.suf:s.r] + if len(s.lit) > 0 { + lit = append(s.lit, lit...) + } + s.suf = -1 // no pending literal + return lit +} diff --git a/src/cmd/compile/internal/syntax/syntax.go b/src/cmd/compile/internal/syntax/syntax.go new file mode 100644 index 0000000000..85dddaa47f --- /dev/null +++ b/src/cmd/compile/internal/syntax/syntax.go @@ -0,0 +1,61 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import ( + "fmt" + "io" + "os" +) + +type Mode uint + +type ErrorHandler func(pos, line int, msg string) + +// TODO(gri) These need a lot more work. + +func ReadFile(filename string, errh ErrorHandler, mode Mode) (*File, error) { + src, err := os.Open(filename) + if err != nil { + return nil, err + } + defer src.Close() + return Read(src, errh, mode) +} + +type bytesReader struct { + data []byte +} + +func (r *bytesReader) Read(p []byte) (int, error) { + if len(r.data) > 0 { + n := copy(p, r.data) + r.data = r.data[n:] + return n, nil + } + return 0, io.EOF +} + +func ReadBytes(src []byte, errh ErrorHandler, mode Mode) (*File, error) { + return Read(&bytesReader{src}, errh, mode) +} + +func Read(src io.Reader, errh ErrorHandler, mode Mode) (*File, error) { + var p parser + p.init(src, errh) + + p.next() + ast := p.file() + + if errh == nil && p.nerrors > 0 { + return nil, fmt.Errorf("%d syntax errors", p.nerrors) + } + + return ast, nil +} + +func Write(w io.Writer, n *File) error { + panic("unimplemented") +} diff --git a/src/cmd/compile/internal/syntax/tokens.go b/src/cmd/compile/internal/syntax/tokens.go new file mode 100644 index 0000000000..bd0118a141 --- /dev/null +++ b/src/cmd/compile/internal/syntax/tokens.go @@ -0,0 +1,263 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package syntax + +import "fmt" + +type token uint + +const ( + _ token = iota + _EOF + + // names and literals + _Name + _Literal + + // operators and operations + _Operator // excluding '*' (_Star) + _AssignOp + _IncOp + _Assign + _Define + _Arrow + _Star + + // delimitors + _Lparen + _Lbrack + _Lbrace + _Rparen + _Rbrack + _Rbrace + _Comma + _Semi + _Colon + _Dot + _DotDotDot + + // keywords + _Break + _Case + _Chan + _Const + _Continue + _Default + _Defer + _Else + _Fallthrough + _For + _Func + _Go + _Goto + _If + _Import + _Interface + _Map + _Package + _Range + _Return + _Select + _Struct + _Switch + _Type + _Var + + tokenCount +) + +const ( + // for BranchStmt + Break = _Break + Continue = _Continue + Fallthrough = _Fallthrough + Goto = _Goto + + // for CallStmt + Go = _Go + Defer = _Defer +) + +var tokstrings = [...]string{ + // source control + _EOF: "EOF", + + // names and literals + _Name: "name", + _Literal: "literal", + + // operators and operations + _Operator: "op", + _AssignOp: "op=", + _IncOp: "opop", + _Assign: "=", + _Define: ":=", + _Arrow: "<-", + _Star: "*", + + // delimitors + _Lparen: "(", + _Lbrack: "[", + _Lbrace: "{", + _Rparen: ")", + _Rbrack: "]", + _Rbrace: "}", + _Comma: ",", + _Semi: ";", + _Colon: ":", + _Dot: ".", + _DotDotDot: "...", + + // keywords + _Break: "break", + _Case: "case", + _Chan: "chan", + _Const: "const", + _Continue: "continue", + _Default: "default", + _Defer: "defer", + _Else: "else", + _Fallthrough: "fallthrough", + _For: "for", + _Func: "func", + _Go: "go", + _Goto: "goto", + _If: "if", + _Import: "import", + _Interface: "interface", + _Map: "map", + _Package: "package", + _Range: "range", + _Return: "return", + _Select: "select", + _Struct: "struct", + _Switch: "switch", + _Type: "type", + _Var: "var", +} + +func (tok token) String() string { + var s string + if 0 <= tok && int(tok) < len(tokstrings) { + s = tokstrings[tok] + } + if s == "" { + s = fmt.Sprintf("", tok) + } + return s +} + +// Make sure we have at most 64 tokens so we can use them in a set. +const _ uint64 = 1 << (tokenCount - 1) + +// contains reports whether tok is in tokset. +func contains(tokset uint64, tok token) bool { + return tokset&(1< + Geq // >= + + // precAdd + Add // + + Sub // - + Or // | + Xor // ^ + + // precMul + Mul // * + Div // / + Rem // % + And // & + AndNot // &^ + Shl // << + Shr // >> +) + +var opstrings = [...]string{ + // prec == 0 + Def: ":", // : in := + Not: "!", + Recv: "<-", + + // precOrOr + OrOr: "||", + + // precAndAnd + AndAnd: "&&", + + // precCmp + Eql: "==", + Neq: "!=", + Lss: "<", + Leq: "<=", + Gtr: ">", + Geq: ">=", + + // precAdd + Add: "+", + Sub: "-", + Or: "|", + Xor: "^", + + // precMul + Mul: "*", + Div: "/", + Rem: "%", + And: "&", + AndNot: "&^", + Shl: "<<", + Shr: ">>", +} + +func (op Operator) String() string { + var s string + if 0 <= op && int(op) < len(opstrings) { + s = opstrings[op] + } + if s == "" { + s = fmt.Sprintf("", op) + } + return s +} + +// Operator precedences +const ( + _ = iota + precOrOr + precAndAnd + precCmp + precAdd + precMul +)