version: 1.10

package token

import "go/token"

Overview

Package token defines constants representing the lexical tokens of the Go
programming language and basic operations on tokens (printing, predicates).

Index

Package files

position.go serialize.go token.go

Constants

  1. const (
  2.     LowestPrec  = 0 // non-operators
  3.     UnaryPrec   = 6
  4.     HighestPrec = 7
  5. )

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 serves as “catch-all” precedence for selector,
indexing, and other operator and delimiter tokens.

type File

  1. type File struct {
  2.     // contains filtered or unexported fields
  3. }

A File is a handle for a file belonging to a FileSet. A File has a name, size,
and line offset table.

func (*File) AddLine

  1. func (f *File) AddLine(offset int)

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 (*File) AddLineInfo

  1. func (f *File) AddLineInfo(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 (*File) Base

  1. func (f *File) Base() int

Base returns the base offset of file f as registered with AddFile.

func (*File) Line

  1. func (f *File) Line(p Pos) int

Line returns the line number for the given file position p; p must be a Pos
value in that file or NoPos.

func (*File) LineCount

  1. func (f *File) LineCount() int

LineCount returns the number of lines in file f.

func (*File) MergeLine

  1. func (f *File) MergeLine(line int)

MergeLine merges a line with the following line. It is akin to replacing the
newline character at the end of the line with a space (to not change the
remaining offsets). To obtain the line number, consult e.g. Position.Line.
MergeLine will panic if given an invalid line number.

func (*File) Name

  1. func (f *File) Name() string

Name returns the file name of file f as registered with AddFile.

func (*File) Offset

  1. func (f *File) Offset(p Pos) int

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 (*File) Pos

  1. func (f *File) Pos(offset int) Pos

Pos returns the Pos value for the given file offset; the offset must be <=
f.Size(). f.Pos(f.Offset(p)) == p.

func (*File) Position

  1. func (f *File) Position(p Pos) (pos Position)

Position returns the Position value for the given file position p. Calling
f.Position(p) is equivalent to calling f.PositionFor(p, true).

func (*File) PositionFor

  1. func (f *File) PositionFor(p Pos, adjusted bool) (pos Position)

PositionFor returns the Position value for the given file position p. If
adjusted is set, the position may be adjusted by position-altering //line
comments; otherwise those comments are ignored. p must be a Pos value in f or
NoPos.

func (*File) SetLines

  1. func (f *File) SetLines(lines []int) bool

SetLines sets the line offsets for a file and reports whether it succeeded. 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. Callers must not mutate the provided slice after SetLines
returns.

func (*File) SetLinesForContent

  1. func (f *File) SetLinesForContent(content []byte)

SetLinesForContent sets the line offsets for the given file content. It ignores
position-altering //line comments.

func (*File) Size

  1. func (f *File) Size() int

Size returns the size of file f as registered with AddFile.

type FileSet

  1. type FileSet struct {
  2.     // contains filtered or unexported fields
  3. }

A FileSet represents a set of source files. Methods of file sets are
synchronized; multiple goroutines may invoke them concurrently.

func NewFileSet

  1. func NewFileSet() *FileSet

NewFileSet creates a new file set.

func (*FileSet) AddFile

  1. func (s *FileSet) AddFile(filename string, base, size int) *File

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. As a special case, if a negative base is provided, the current value
of the FileSet’s Base() is used instead.

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:

  1. 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 (*FileSet) Base

  1. func (s *FileSet) Base() int

Base returns the minimum base offset that must be provided to AddFile when
adding the next file.

func (*FileSet) File

  1. func (s *FileSet) File(p Pos) (f *File)

File returns the file that contains the position p. If no such file is found
(for instance for p == NoPos), the result is nil.

func (*FileSet) Iterate

  1. func (s *FileSet) Iterate(f func(*File) bool)

Iterate calls f for the files in the file set in the order they were added until
f returns false.

func (*FileSet) Position

  1. func (s *FileSet) Position(p Pos) (pos Position)

Position converts a Pos p in the fileset into a Position value. Calling
s.Position(p) is equivalent to calling s.PositionFor(p, true).

func (*FileSet) PositionFor

  1. func (s *FileSet) PositionFor(p Pos, adjusted bool) (pos Position)

PositionFor converts a Pos p in the fileset into a Position value. If adjusted
is set, the position may be adjusted by position-altering //line comments;
otherwise those comments are ignored. p must be a Pos value in s or NoPos.

func (*FileSet) Read

  1. func (s *FileSet) Read(decode func(interface{}) error) error

Read calls decode to deserialize a file set into s; s must not be nil.

func (*FileSet) Write

  1. func (s *FileSet) Write(encode func(interface{}) error) error

Write calls encode to serialize the file set s.

type Pos

  1. type Pos int

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 (measured in bytes), first
add the respective file to the current file set using 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.

  1. const NoPos Pos = 0

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.

func (Pos) IsValid

  1. func (p Pos) IsValid() bool

IsValid reports whether the position is valid.

type Position

  1. type Position struct {
  2.     Filename string // filename, if any
  3.     Offset   int    // offset, starting at 0
  4.     Line     int    // line number, starting at 1
  5.     Column   int    // column number, starting at 1 (byte count)
  6. }

Position describes an arbitrary source position including the file, line, and
column location. A Position is valid if the line number is > 0.

func (*Position) IsValid

  1. func (pos *Position) IsValid() bool

IsValid reports whether the position is valid.

func (Position) String

  1. func (pos Position) String() string

String returns a string in one of several forms:

  1. file:line:column    valid position with file name
  2. line:column         valid position without file name
  3. file                invalid position with file name
  4. -                   invalid position without file name

type Token

  1. type Token int

Token is the set of lexical tokens of the Go programming language.

  1. const (
  2.     // Special tokens
  3.     ILLEGAL Token = iota
  4.     EOF
  5.     COMMENT
  6.  
  7.     // Identifiers and basic type literals
  8.     // (these tokens stand for classes of literals)
  9.     IDENT  // main
  10.     INT    // 12345
  11.     FLOAT  // 123.45
  12.     IMAG   // 123.45i
  13.     CHAR   // 'a'
  14.     STRING // "abc"
  15.  
  16.     // Operators and delimiters
  17.     ADD // +
  18.     SUB // -
  19.     MUL // *
  20.     QUO // /
  21.     REM // %
  22.  
  23.     AND     // &
  24.     OR      // |
  25.     XOR     // ^
  26.     SHL     // <<
  27.     SHR     // >>
  28.     AND_NOT // &^
  29.  
  30.     ADD_ASSIGN // +=
  31.     SUB_ASSIGN // -=
  32.     MUL_ASSIGN // *=
  33.     QUO_ASSIGN // /=
  34.     REM_ASSIGN // %=
  35.  
  36.     AND_ASSIGN     // &=
  37.     OR_ASSIGN      // |=
  38.     XOR_ASSIGN     // ^=
  39.     SHL_ASSIGN     // <<=
  40.     SHR_ASSIGN     // >>=
  41.     AND_NOT_ASSIGN // &^=
  42.  
  43.     LAND  // &&
  44.     LOR   // ||
  45.     ARROW // <-
  46.     INC   // ++
  47.     DEC   // --
  48.  
  49.     EQL    // ==
  50.     LSS    // <
  51.     GTR    // >
  52.     ASSIGN // =
  53.     NOT    // !
  54.  
  55.     NEQ      // !=
  56.     LEQ      // <=
  57.     GEQ      // >=
  58.     DEFINE   // :=
  59.     ELLIPSIS // ...
  60.  
  61.     LPAREN // (
  62.     LBRACK // [
  63.     LBRACE // {
  64.     COMMA  // ,
  65.     PERIOD // .
  66.  
  67.     RPAREN    // )
  68.     RBRACK    // ]
  69.     RBRACE    // }
  70.     SEMICOLON // ;
  71.     COLON     // :
  72.  
  73.     // Keywords
  74.     BREAK
  75.     CASE
  76.     CHAN
  77.     CONST
  78.     CONTINUE
  79.  
  80.     DEFAULT
  81.     DEFER
  82.     ELSE
  83.     FALLTHROUGH
  84.     FOR
  85.  
  86.     FUNC
  87.     GO
  88.     GOTO
  89.     IF
  90.     IMPORT
  91.  
  92.     INTERFACE
  93.     MAP
  94.     PACKAGE
  95.     RANGE
  96.     RETURN
  97.  
  98.     SELECT
  99.     STRUCT
  100.     SWITCH
  101.     TYPE
  102.     VAR
  103. )

The list of tokens.

func Lookup

  1. func Lookup(ident string) Token

Lookup maps an identifier to its keyword token or IDENT (if not a keyword).

func (Token) IsKeyword

  1. func (tok Token) IsKeyword() bool

IsKeyword returns true for tokens corresponding to keywords; it returns false
otherwise.

func (Token) IsLiteral

  1. func (tok Token) IsLiteral() bool

IsLiteral returns true for tokens corresponding to identifiers and basic type
literals; it returns false otherwise.

func (Token) IsOperator

  1. func (tok Token) IsOperator() bool

IsOperator returns true for tokens corresponding to operators and delimiters; it
returns false otherwise.

func (Token) Precedence

  1. func (op Token) Precedence() int

Precedence returns the operator precedence of the binary operator op. If op is
not a binary operator, the result is LowestPrecedence.

func (Token) String

  1. func (tok Token) String() string

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”).