Package token
import "go/token"
This package defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates).
Package files
token.goConstants
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 = 7
HighestPrec = 8
)
type Position
Token source positions are represented by a Position value. A Position is valid if the line number is > 0.
type Position struct {
Filename string // filename, if any
Offset int // byte offset, starting at 0
Line int // line number, starting at 1
Column int // column number, starting at 1 (character count)
}
func (*Position) IsValid
func (pos *Position) IsValid() bool
IsValid returns true if the position is valid.
func (*Position) Pos
func (pos *Position) Pos() Position
Pos is an accessor method for anonymous Position fields. It returns its receiver.
func (Position) String
func (pos Position) String() string
type Token
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
// 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"
// 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 // :
// 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
)
func Lookup
func Lookup(ident []byte) Token
Lookup maps an identifier to its keyword token or IDENT (if not a keyword).
func (Token) IsKeyword
func (tok Token) IsKeyword() bool
IsKeyword returns true for tokens corresponding to keywords; returns false otherwise.
func (Token) IsLiteral
func (tok Token) IsLiteral() bool
IsLiteral returns true for tokens corresponding to identifiers and basic type literals; returns false otherwise.
func (Token) IsOperator
func (tok Token) IsOperator() bool
IsOperator returns true for tokens corresponding to operators and delimiters; returns false otherwise.
func (Token) Precedence
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
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").