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-rw-r--r--src/pkg/go/token/Makefile12
-rw-r--r--src/pkg/go/token/position.go424
-rw-r--r--src/pkg/go/token/position_test.go180
-rw-r--r--src/pkg/go/token/token.go310
4 files changed, 926 insertions, 0 deletions
diff --git a/src/pkg/go/token/Makefile b/src/pkg/go/token/Makefile
new file mode 100644
index 000000000..4a4e64dc8
--- /dev/null
+++ b/src/pkg/go/token/Makefile
@@ -0,0 +1,12 @@
+# Copyright 2009 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.
+
+include ../../../Make.inc
+
+TARG=go/token
+GOFILES=\
+ position.go\
+ token.go\
+
+include ../../../Make.pkg
diff --git a/src/pkg/go/token/position.go b/src/pkg/go/token/position.go
new file mode 100644
index 000000000..c559e19f8
--- /dev/null
+++ b/src/pkg/go/token/position.go
@@ -0,0 +1,424 @@
+// Copyright 2010 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.
+
+// TODO(gri) consider making this a separate package outside the go directory.
+
+package token
+
+import (
+ "fmt"
+ "sort"
+ "sync"
+)
+
+// Position describes an arbitrary source position
+// including the file, line, and column location.
+// A Position is valid if the line number is > 0.
+//
+type Position struct {
+ Filename string // filename, if any
+ Offset int // offset, starting at 0
+ Line int // line number, starting at 1
+ Column int // column number, starting at 1 (character count)
+}
+
+// IsValid returns true if the position is valid.
+func (pos *Position) IsValid() bool { return pos.Line > 0 }
+
+// String returns a string in one of several forms:
+//
+// file:line:column valid position with file name
+// line:column valid position without file name
+// file invalid position with file name
+// - invalid position without file name
+//
+func (pos Position) String() string {
+ s := pos.Filename
+ if pos.IsValid() {
+ if s != "" {
+ s += ":"
+ }
+ s += fmt.Sprintf("%d:%d", pos.Line, pos.Column)
+ }
+ if s == "" {
+ s = "-"
+ }
+ return s
+}
+
+// Pos is a compact encoding of a source position within a file set.
+// It can be converted into a Position for a more convenient, but much
+// larger, representation.
+//
+// The Pos value for a given file is a number in the range [base, base+size],
+// where base and size are specified when adding the file to the file set via
+// AddFile.
+//
+// To create the Pos value for a specific source offset, first add
+// the respective file to the current file set (via FileSet.AddFile)
+// and then call File.Pos(offset) for that file. Given a Pos value p
+// for a specific file set fset, the corresponding Position value is
+// obtained by calling fset.Position(p).
+//
+// Pos values can be compared directly with the usual comparison operators:
+// If two Pos values p and q are in the same file, comparing p and q is
+// equivalent to comparing the respective source file offsets. If p and q
+// are in different files, p < q is true if the file implied by p was added
+// to the respective file set before the file implied by q.
+//
+type Pos int
+
+// The zero value for Pos is NoPos; there is no file and line information
+// associated with it, and NoPos().IsValid() is false. NoPos is always
+// smaller than any other Pos value. The corresponding Position value
+// for NoPos is the zero value for Position.
+//
+const NoPos Pos = 0
+
+// IsValid returns true if the position is valid.
+func (p Pos) IsValid() bool {
+ return p != NoPos
+}
+
+func searchFiles(a []*File, x int) int {
+ return sort.Search(len(a), func(i int) bool { return a[i].base > x }) - 1
+}
+
+func (s *FileSet) file(p Pos) *File {
+ if f := s.last; f != nil && f.base <= int(p) && int(p) <= f.base+f.size {
+ return f
+ }
+ if i := searchFiles(s.files, int(p)); i >= 0 {
+ f := s.files[i]
+ // f.base <= int(p) by definition of searchFiles
+ if int(p) <= f.base+f.size {
+ s.last = f
+ return f
+ }
+ }
+ return nil
+}
+
+// File returns the file which contains the position p.
+// If no such file is found (for instance for p == NoPos),
+// the result is nil.
+//
+func (s *FileSet) File(p Pos) (f *File) {
+ if p != NoPos {
+ s.mutex.RLock()
+ f = s.file(p)
+ s.mutex.RUnlock()
+ }
+ return
+}
+
+func (f *File) position(p Pos) (pos Position) {
+ offset := int(p) - f.base
+ pos.Offset = offset
+ pos.Filename, pos.Line, pos.Column = f.info(offset)
+ return
+}
+
+// Position converts a Pos in the fileset into a general Position.
+func (s *FileSet) Position(p Pos) (pos Position) {
+ if p != NoPos {
+ // TODO(gri) consider optimizing the case where p
+ // is in the last file added, or perhaps
+ // looked at - will eliminate one level
+ // of search
+ s.mutex.RLock()
+ if f := s.file(p); f != nil {
+ pos = f.position(p)
+ }
+ s.mutex.RUnlock()
+ }
+ return
+}
+
+type lineInfo struct {
+ offset int
+ filename string
+ line int
+}
+
+// AddLineInfo adds alternative file and line number information for
+// a given file offset. The offset must be larger than the offset for
+// the previously added alternative line info and smaller than the
+// file size; otherwise the information is ignored.
+//
+// AddLineInfo is typically used to register alternative position
+// information for //line filename:line comments in source files.
+//
+func (f *File) AddLineInfo(offset int, filename string, line int) {
+ f.set.mutex.Lock()
+ if i := len(f.infos); i == 0 || f.infos[i-1].offset < offset && offset < f.size {
+ f.infos = append(f.infos, lineInfo{offset, filename, line})
+ }
+ f.set.mutex.Unlock()
+}
+
+// A File is a handle for a file belonging to a FileSet.
+// A File has a name, size, and line offset table.
+//
+type File struct {
+ set *FileSet
+ name string // file name as provided to AddFile
+ base int // Pos value range for this file is [base...base+size]
+ size int // file size as provided to AddFile
+
+ // lines and infos are protected by set.mutex
+ lines []int
+ infos []lineInfo
+}
+
+// Name returns the file name of file f as registered with AddFile.
+func (f *File) Name() string {
+ return f.name
+}
+
+// Base returns the base offset of file f as registered with AddFile.
+func (f *File) Base() int {
+ return f.base
+}
+
+// Size returns the size of file f as registered with AddFile.
+func (f *File) Size() int {
+ return f.size
+}
+
+// LineCount returns the number of lines in file f.
+func (f *File) LineCount() int {
+ f.set.mutex.RLock()
+ n := len(f.lines)
+ f.set.mutex.RUnlock()
+ return n
+}
+
+// AddLine adds the line offset for a new line.
+// The line offset must be larger than the offset for the previous line
+// and smaller than the file size; otherwise the line offset is ignored.
+//
+func (f *File) AddLine(offset int) {
+ f.set.mutex.Lock()
+ if i := len(f.lines); (i == 0 || f.lines[i-1] < offset) && offset < f.size {
+ f.lines = append(f.lines, offset)
+ }
+ f.set.mutex.Unlock()
+}
+
+// SetLines sets the line offsets for a file and returns true if successful.
+// The line offsets are the offsets of the first character of each line;
+// for instance for the content "ab\nc\n" the line offsets are {0, 3}.
+// An empty file has an empty line offset table.
+// Each line offset must be larger than the offset for the previous line
+// and smaller than the file size; otherwise SetLines fails and returns
+// false.
+//
+func (f *File) SetLines(lines []int) bool {
+ // verify validity of lines table
+ size := f.size
+ for i, offset := range lines {
+ if i > 0 && offset <= lines[i-1] || size <= offset {
+ return false
+ }
+ }
+
+ // set lines table
+ f.set.mutex.Lock()
+ f.lines = lines
+ f.set.mutex.Unlock()
+ return true
+}
+
+// SetLinesForContent sets the line offsets for the given file content.
+func (f *File) SetLinesForContent(content []byte) {
+ var lines []int
+ line := 0
+ for offset, b := range content {
+ if line >= 0 {
+ lines = append(lines, line)
+ }
+ line = -1
+ if b == '\n' {
+ line = offset + 1
+ }
+ }
+
+ // set lines table
+ f.set.mutex.Lock()
+ f.lines = lines
+ f.set.mutex.Unlock()
+}
+
+// Pos returns the Pos value for the given file offset;
+// the offset must be <= f.Size().
+// f.Pos(f.Offset(p)) == p.
+//
+func (f *File) Pos(offset int) Pos {
+ if offset > f.size {
+ panic("illegal file offset")
+ }
+ return Pos(f.base + offset)
+}
+
+// Offset returns the offset for the given file position p;
+// p must be a valid Pos value in that file.
+// f.Offset(f.Pos(offset)) == offset.
+//
+func (f *File) Offset(p Pos) int {
+ if int(p) < f.base || int(p) > f.base+f.size {
+ panic("illegal Pos value")
+ }
+ return int(p) - f.base
+}
+
+// Line returns the line number for the given file position p;
+// p must be a Pos value in that file or NoPos.
+//
+func (f *File) Line(p Pos) int {
+ // TODO(gri) this can be implemented much more efficiently
+ return f.Position(p).Line
+}
+
+// Position returns the Position value for the given file position p;
+// p must be a Pos value in that file or NoPos.
+//
+func (f *File) Position(p Pos) (pos Position) {
+ if p != NoPos {
+ if int(p) < f.base || int(p) > f.base+f.size {
+ panic("illegal Pos value")
+ }
+ pos = f.position(p)
+ }
+ return
+}
+
+func searchInts(a []int, x int) int {
+ // This function body is a manually inlined version of:
+ //
+ // return sort.Search(len(a), func(i int) bool { return a[i] > x }) - 1
+ //
+ // With better compiler optimizations, this may not be needed in the
+ // future, but at the moment this change improves the go/printer
+ // benchmark performance by ~30%. This has a direct impact on the
+ // speed of gofmt and thus seems worthwhile (2011-04-29).
+ i, j := 0, len(a)
+ for i < j {
+ h := i + (j-i)/2 // avoid overflow when computing h
+ // i ≤ h < j
+ if a[h] <= x {
+ i = h + 1
+ } else {
+ j = h
+ }
+ }
+ return i - 1
+}
+
+func searchLineInfos(a []lineInfo, x int) int {
+ return sort.Search(len(a), func(i int) bool { return a[i].offset > x }) - 1
+}
+
+// info returns the file name, line, and column number for a file offset.
+func (f *File) info(offset int) (filename string, line, column int) {
+ filename = f.name
+ if i := searchInts(f.lines, offset); i >= 0 {
+ line, column = i+1, offset-f.lines[i]+1
+ }
+ if len(f.infos) > 0 {
+ // almost no files have extra line infos
+ if i := searchLineInfos(f.infos, offset); i >= 0 {
+ alt := &f.infos[i]
+ filename = alt.filename
+ if i := searchInts(f.lines, alt.offset); i >= 0 {
+ line += alt.line - i - 1
+ }
+ }
+ }
+ return
+}
+
+// A FileSet represents a set of source files.
+// Methods of file sets are synchronized; multiple goroutines
+// may invoke them concurrently.
+//
+type FileSet struct {
+ mutex sync.RWMutex // protects the file set
+ base int // base offset for the next file
+ files []*File // list of files in the order added to the set
+ last *File // cache of last file looked up
+}
+
+// NewFileSet creates a new file set.
+func NewFileSet() *FileSet {
+ s := new(FileSet)
+ s.base = 1 // 0 == NoPos
+ return s
+}
+
+// Base returns the minimum base offset that must be provided to
+// AddFile when adding the next file.
+//
+func (s *FileSet) Base() int {
+ s.mutex.RLock()
+ b := s.base
+ s.mutex.RUnlock()
+ return b
+
+}
+
+// AddFile adds a new file with a given filename, base offset, and file size
+// to the file set s and returns the file. Multiple files may have the same
+// name. The base offset must not be smaller than the FileSet's Base(), and
+// size must not be negative.
+//
+// Adding the file will set the file set's Base() value to base + size + 1
+// as the minimum base value for the next file. The following relationship
+// exists between a Pos value p for a given file offset offs:
+//
+// int(p) = base + offs
+//
+// with offs in the range [0, size] and thus p in the range [base, base+size].
+// For convenience, File.Pos may be used to create file-specific position
+// values from a file offset.
+//
+func (s *FileSet) AddFile(filename string, base, size int) *File {
+ s.mutex.Lock()
+ defer s.mutex.Unlock()
+ if base < s.base || size < 0 {
+ panic("illegal base or size")
+ }
+ // base >= s.base && size >= 0
+ f := &File{s, filename, base, size, []int{0}, nil}
+ base += size + 1 // +1 because EOF also has a position
+ if base < 0 {
+ panic("token.Pos offset overflow (> 2G of source code in file set)")
+ }
+ // add the file to the file set
+ s.base = base
+ s.files = append(s.files, f)
+ s.last = f
+ return f
+}
+
+// Files returns the files added to the file set.
+func (s *FileSet) Files() <-chan *File {
+ ch := make(chan *File)
+ go func() {
+ for i := 0; ; i++ {
+ var f *File
+ s.mutex.RLock()
+ if i < len(s.files) {
+ f = s.files[i]
+ }
+ s.mutex.RUnlock()
+ if f == nil {
+ break
+ }
+ ch <- f
+ }
+ close(ch)
+ }()
+ return ch
+}
diff --git a/src/pkg/go/token/position_test.go b/src/pkg/go/token/position_test.go
new file mode 100644
index 000000000..30bec5991
--- /dev/null
+++ b/src/pkg/go/token/position_test.go
@@ -0,0 +1,180 @@
+// Copyright 2010 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 token
+
+import (
+ "fmt"
+ "testing"
+)
+
+func checkPos(t *testing.T, msg string, p, q Position) {
+ if p.Filename != q.Filename {
+ t.Errorf("%s: expected filename = %q; got %q", msg, q.Filename, p.Filename)
+ }
+ if p.Offset != q.Offset {
+ t.Errorf("%s: expected offset = %d; got %d", msg, q.Offset, p.Offset)
+ }
+ if p.Line != q.Line {
+ t.Errorf("%s: expected line = %d; got %d", msg, q.Line, p.Line)
+ }
+ if p.Column != q.Column {
+ t.Errorf("%s: expected column = %d; got %d", msg, q.Column, p.Column)
+ }
+}
+
+func TestNoPos(t *testing.T) {
+ if NoPos.IsValid() {
+ t.Errorf("NoPos should not be valid")
+ }
+ var fset *FileSet
+ checkPos(t, "nil NoPos", fset.Position(NoPos), Position{})
+ fset = NewFileSet()
+ checkPos(t, "fset NoPos", fset.Position(NoPos), Position{})
+}
+
+var tests = []struct {
+ filename string
+ source []byte // may be nil
+ size int
+ lines []int
+}{
+ {"a", []byte{}, 0, []int{}},
+ {"b", []byte("01234"), 5, []int{0}},
+ {"c", []byte("\n\n\n\n\n\n\n\n\n"), 9, []int{0, 1, 2, 3, 4, 5, 6, 7, 8}},
+ {"d", nil, 100, []int{0, 5, 10, 20, 30, 70, 71, 72, 80, 85, 90, 99}},
+ {"e", nil, 777, []int{0, 80, 100, 120, 130, 180, 267, 455, 500, 567, 620}},
+ {"f", []byte("package p\n\nimport \"fmt\""), 23, []int{0, 10, 11}},
+ {"g", []byte("package p\n\nimport \"fmt\"\n"), 24, []int{0, 10, 11}},
+ {"h", []byte("package p\n\nimport \"fmt\"\n "), 25, []int{0, 10, 11, 24}},
+}
+
+func linecol(lines []int, offs int) (int, int) {
+ prevLineOffs := 0
+ for line, lineOffs := range lines {
+ if offs < lineOffs {
+ return line, offs - prevLineOffs + 1
+ }
+ prevLineOffs = lineOffs
+ }
+ return len(lines), offs - prevLineOffs + 1
+}
+
+func verifyPositions(t *testing.T, fset *FileSet, f *File, lines []int) {
+ for offs := 0; offs < f.Size(); offs++ {
+ p := f.Pos(offs)
+ offs2 := f.Offset(p)
+ if offs2 != offs {
+ t.Errorf("%s, Offset: expected offset %d; got %d", f.Name(), offs, offs2)
+ }
+ line, col := linecol(lines, offs)
+ msg := fmt.Sprintf("%s (offs = %d, p = %d)", f.Name(), offs, p)
+ checkPos(t, msg, f.Position(f.Pos(offs)), Position{f.Name(), offs, line, col})
+ checkPos(t, msg, fset.Position(p), Position{f.Name(), offs, line, col})
+ }
+}
+
+func makeTestSource(size int, lines []int) []byte {
+ src := make([]byte, size)
+ for _, offs := range lines {
+ if offs > 0 {
+ src[offs-1] = '\n'
+ }
+ }
+ return src
+}
+
+func TestPositions(t *testing.T) {
+ const delta = 7 // a non-zero base offset increment
+ fset := NewFileSet()
+ for _, test := range tests {
+ // verify consistency of test case
+ if test.source != nil && len(test.source) != test.size {
+ t.Errorf("%s: inconsistent test case: expected file size %d; got %d", test.filename, test.size, len(test.source))
+ }
+
+ // add file and verify name and size
+ f := fset.AddFile(test.filename, fset.Base()+delta, test.size)
+ if f.Name() != test.filename {
+ t.Errorf("expected filename %q; got %q", test.filename, f.Name())
+ }
+ if f.Size() != test.size {
+ t.Errorf("%s: expected file size %d; got %d", f.Name(), test.size, f.Size())
+ }
+ if fset.File(f.Pos(0)) != f {
+ t.Errorf("%s: f.Pos(0) was not found in f", f.Name())
+ }
+
+ // add lines individually and verify all positions
+ for i, offset := range test.lines {
+ f.AddLine(offset)
+ if f.LineCount() != i+1 {
+ t.Errorf("%s, AddLine: expected line count %d; got %d", f.Name(), i+1, f.LineCount())
+ }
+ // adding the same offset again should be ignored
+ f.AddLine(offset)
+ if f.LineCount() != i+1 {
+ t.Errorf("%s, AddLine: expected unchanged line count %d; got %d", f.Name(), i+1, f.LineCount())
+ }
+ verifyPositions(t, fset, f, test.lines[0:i+1])
+ }
+
+ // add lines with SetLines and verify all positions
+ if ok := f.SetLines(test.lines); !ok {
+ t.Errorf("%s: SetLines failed", f.Name())
+ }
+ if f.LineCount() != len(test.lines) {
+ t.Errorf("%s, SetLines: expected line count %d; got %d", f.Name(), len(test.lines), f.LineCount())
+ }
+ verifyPositions(t, fset, f, test.lines)
+
+ // add lines with SetLinesForContent and verify all positions
+ src := test.source
+ if src == nil {
+ // no test source available - create one from scratch
+ src = makeTestSource(test.size, test.lines)
+ }
+ f.SetLinesForContent(src)
+ if f.LineCount() != len(test.lines) {
+ t.Errorf("%s, SetLinesForContent: expected line count %d; got %d", f.Name(), len(test.lines), f.LineCount())
+ }
+ verifyPositions(t, fset, f, test.lines)
+ }
+}
+
+func TestLineInfo(t *testing.T) {
+ fset := NewFileSet()
+ f := fset.AddFile("foo", fset.Base(), 500)
+ lines := []int{0, 42, 77, 100, 210, 220, 277, 300, 333, 401}
+ // add lines individually and provide alternative line information
+ for _, offs := range lines {
+ f.AddLine(offs)
+ f.AddLineInfo(offs, "bar", 42)
+ }
+ // verify positions for all offsets
+ for offs := 0; offs <= f.Size(); offs++ {
+ p := f.Pos(offs)
+ _, col := linecol(lines, offs)
+ msg := fmt.Sprintf("%s (offs = %d, p = %d)", f.Name(), offs, p)
+ checkPos(t, msg, f.Position(f.Pos(offs)), Position{"bar", offs, 42, col})
+ checkPos(t, msg, fset.Position(p), Position{"bar", offs, 42, col})
+ }
+}
+
+func TestFiles(t *testing.T) {
+ fset := NewFileSet()
+ for i, test := range tests {
+ fset.AddFile(test.filename, fset.Base(), test.size)
+ j := 0
+ for g := range fset.Files() {
+ if g.Name() != tests[j].filename {
+ t.Errorf("expected filename = %s; got %s", tests[j].filename, g.Name())
+ }
+ j++
+ }
+ if j != i+1 {
+ t.Errorf("expected %d files; got %d", i+1, j)
+ }
+ }
+}
diff --git a/src/pkg/go/token/token.go b/src/pkg/go/token/token.go
new file mode 100644
index 000000000..557374052
--- /dev/null
+++ b/src/pkg/go/token/token.go
@@ -0,0 +1,310 @@
+// Copyright 2009 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 token defines constants representing the lexical tokens of the Go
+// programming language and basic operations on tokens (printing, predicates).
+//
+package token
+
+import "strconv"
+
+// Token is the set of lexical tokens of the Go programming language.
+type Token int
+
+// The list of tokens.
+const (
+ // Special tokens
+ ILLEGAL Token = iota
+ EOF
+ COMMENT
+
+ literal_beg
+ // Identifiers and basic type literals
+ // (these tokens stand for classes of literals)
+ IDENT // main
+ INT // 12345
+ FLOAT // 123.45
+ IMAG // 123.45i
+ CHAR // 'a'
+ STRING // "abc"
+ literal_end
+
+ operator_beg
+ // Operators and delimiters
+ ADD // +
+ SUB // -
+ MUL // *
+ QUO // /
+ REM // %
+
+ AND // &
+ OR // |
+ XOR // ^
+ SHL // <<
+ SHR // >>
+ AND_NOT // &^
+
+ ADD_ASSIGN // +=
+ SUB_ASSIGN // -=
+ MUL_ASSIGN // *=
+ QUO_ASSIGN // /=
+ REM_ASSIGN // %=
+
+ AND_ASSIGN // &=
+ OR_ASSIGN // |=
+ XOR_ASSIGN // ^=
+ SHL_ASSIGN // <<=
+ SHR_ASSIGN // >>=
+ AND_NOT_ASSIGN // &^=
+
+ LAND // &&
+ LOR // ||
+ ARROW // <-
+ INC // ++
+ DEC // --
+
+ EQL // ==
+ LSS // <
+ GTR // >
+ ASSIGN // =
+ NOT // !
+
+ NEQ // !=
+ LEQ // <=
+ GEQ // >=
+ DEFINE // :=
+ ELLIPSIS // ...
+
+ LPAREN // (
+ LBRACK // [
+ LBRACE // {
+ COMMA // ,
+ PERIOD // .
+
+ RPAREN // )
+ RBRACK // ]
+ RBRACE // }
+ SEMICOLON // ;
+ COLON // :
+ operator_end
+
+ keyword_beg
+ // 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
+ keyword_end
+)
+
+var tokens = [...]string{
+ ILLEGAL: "ILLEGAL",
+
+ EOF: "EOF",
+ COMMENT: "COMMENT",
+
+ IDENT: "IDENT",
+ INT: "INT",
+ FLOAT: "FLOAT",
+ IMAG: "IMAG",
+ CHAR: "CHAR",
+ STRING: "STRING",
+
+ ADD: "+",
+ SUB: "-",
+ MUL: "*",
+ QUO: "/",
+ REM: "%",
+
+ AND: "&",
+ OR: "|",
+ XOR: "^",
+ SHL: "<<",
+ SHR: ">>",
+ AND_NOT: "&^",
+
+ ADD_ASSIGN: "+=",
+ SUB_ASSIGN: "-=",
+ MUL_ASSIGN: "*=",
+ QUO_ASSIGN: "/=",
+ REM_ASSIGN: "%=",
+
+ AND_ASSIGN: "&=",
+ OR_ASSIGN: "|=",
+ XOR_ASSIGN: "^=",
+ SHL_ASSIGN: "<<=",
+ SHR_ASSIGN: ">>=",
+ AND_NOT_ASSIGN: "&^=",
+
+ LAND: "&&",
+ LOR: "||",
+ ARROW: "<-",
+ INC: "++",
+ DEC: "--",
+
+ EQL: "==",
+ LSS: "<",
+ GTR: ">",
+ ASSIGN: "=",
+ NOT: "!",
+
+ NEQ: "!=",
+ LEQ: "<=",
+ GEQ: ">=",
+ DEFINE: ":=",
+ ELLIPSIS: "...",
+
+ LPAREN: "(",
+ LBRACK: "[",
+ LBRACE: "{",
+ COMMA: ",",
+ PERIOD: ".",
+
+ RPAREN: ")",
+ RBRACK: "]",
+ RBRACE: "}",
+ SEMICOLON: ";",
+ COLON: ":",
+
+ 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",
+}
+
+// String returns the string corresponding to the token tok.
+// For operators, delimiters, and keywords the string is the actual
+// token character sequence (e.g., for the token ADD, the string is
+// "+"). For all other tokens the string corresponds to the token
+// constant name (e.g. for the token IDENT, the string is "IDENT").
+//
+func (tok Token) String() string {
+ s := ""
+ if 0 <= tok && tok < Token(len(tokens)) {
+ s = tokens[tok]
+ }
+ if s == "" {
+ s = "token(" + strconv.Itoa(int(tok)) + ")"
+ }
+ return s
+}
+
+// A set of constants for precedence-based expression parsing.
+// Non-operators have lowest precedence, followed by operators
+// starting with precedence 1 up to unary operators. The highest
+// precedence corresponds serves as "catch-all" precedence for
+// selector, indexing, and other operator and delimiter tokens.
+//
+const (
+ LowestPrec = 0 // non-operators
+ UnaryPrec = 6
+ HighestPrec = 7
+)
+
+// Precedence returns the operator precedence of the binary
+// operator op. If op is not a binary operator, the result
+// is LowestPrecedence.
+//
+func (op Token) Precedence() int {
+ switch op {
+ case LOR:
+ return 1
+ case LAND:
+ return 2
+ case EQL, NEQ, LSS, LEQ, GTR, GEQ:
+ return 3
+ case ADD, SUB, OR, XOR:
+ return 4
+ case MUL, QUO, REM, SHL, SHR, AND, AND_NOT:
+ return 5
+ }
+ return LowestPrec
+}
+
+var keywords map[string]Token
+
+func init() {
+ keywords = make(map[string]Token)
+ for i := keyword_beg + 1; i < keyword_end; i++ {
+ keywords[tokens[i]] = i
+ }
+}
+
+// Lookup maps an identifier to its keyword token or IDENT (if not a keyword).
+//
+func Lookup(ident []byte) Token {
+ // TODO Maps with []byte key are illegal because []byte does not
+ // support == . Should find a more efficient solution eventually.
+ if tok, is_keyword := keywords[string(ident)]; is_keyword {
+ return tok
+ }
+ return IDENT
+}
+
+// Predicates
+
+// IsLiteral returns true for tokens corresponding to identifiers
+// and basic type literals; returns false otherwise.
+//
+func (tok Token) IsLiteral() bool { return literal_beg < tok && tok < literal_end }
+
+// IsOperator returns true for tokens corresponding to operators and
+// delimiters; returns false otherwise.
+//
+func (tok Token) IsOperator() bool { return operator_beg < tok && tok < operator_end }
+
+// IsKeyword returns true for tokens corresponding to keywords;
+// returns false otherwise.
+//
+func (tok Token) IsKeyword() bool { return keyword_beg < tok && tok < keyword_end }
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-22 03:06:38 +0000