package token

Import Path
	go/token (on golang.org and go.dev)

Dependency Relation
	imports 6 packages, and imported by one package

Involved Source Files

	      position.go
	      serialize.go
	   d➜ token.go
		Package token defines constants representing the lexical tokens of the Go
		programming language and basic operations on tokens (printing, predicates).
Code Examples

	_retrievePositionInfo
		package main
		
		import (
			"fmt"
			"go/ast"
			"go/parser"
			"go/token"
		)
		
		func main() {
			fset := token.NewFileSet()
		
			const src = `package main
		
		import "fmt"
		
		import "go/token"
		
		//line :1:5
		type p = token.Pos
		
		const bad = token.NoPos
		
		//line fake.go:42:11
		func ok(pos p) bool {
			return pos != bad
		}
		
		/*line :7:9*/func main() {
			fmt.Println(ok(bad) == bad.IsValid())
		}
		`
		
			f, err := parser.ParseFile(fset, "main.go", src, 0)
			if err != nil {
				fmt.Println(err)
				return
			}
		
			// Print the location and kind of each declaration in f.
			for _, decl := range f.Decls {
				// Get the filename, line, and column back via the file set.
				// We get both the relative and absolute position.
				// The relative position is relative to the last line directive.
				// The absolute position is the exact position in the source.
				pos := decl.Pos()
				relPosition := fset.Position(pos)
				absPosition := fset.PositionFor(pos, false)
		
				// Either a FuncDecl or GenDecl, since we exit on error.
				kind := "func"
				if gen, ok := decl.(*ast.GenDecl); ok {
					kind = gen.Tok.String()
				}
		
				// If the relative and absolute positions differ, show both.
				fmtPosition := relPosition.String()
				if relPosition != absPosition {
					fmtPosition += "[" + absPosition.String() + "]"
				}
		
				fmt.Printf("%s: %s\n", fmtPosition, kind)
			}
		
		}


Package-Level Type Names (total 8, in which 5 are exported)

	/* sort exporteds by: alphabet | popularity */
	 type File (struct)
		A File is a handle for a file belonging to a FileSet.
		A File has a name, size, and line offset table.

		Fields (total 7, none are exported)
			/* 7 unexporteds ... *//* 7 unexporteds: */
			base int
				// Pos value range for this file is [base...base+size]

			infos []lineInfo
			lines []int
				// lines contains the offset of the first character for each line (the first entry is always 0)

			mutex sync.Mutex
				lines and infos are protected by mutex

			name string
				// file name as provided to AddFile

			set *FileSet
			size int
				// file size as provided to AddFile

		Methods (total 18, in which 16 are exported)
			(*T) 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.

			(*T) AddLineColumnInfo(offset int, filename string, line, column int)
				AddLineColumnInfo adds alternative file, line, and column 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.

				AddLineColumnInfo is typically used to register alternative position
				information for line directives such as //line filename:line:column.

			(*T) AddLineInfo(offset int, filename string, line int)
				AddLineInfo is like AddLineColumnInfo with a column = 1 argument.
				It is here for backward-compatibility for code prior to Go 1.11.

			(*T) Base() int
				Base returns the base offset of file f as registered with AddFile.

			(*T) 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.

			(*T) LineCount() int
				LineCount returns the number of lines in file f.

			(*T) LineStart(line int) Pos
				LineStart returns the Pos value of the start of the specified line.
				It ignores any alternative positions set using AddLineColumnInfo.
				LineStart panics if the 1-based line number is invalid.

			(*T) 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.

			(*T) Name() string
				Name returns the file name of file f as registered with AddFile.

			(*T) 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.

			(*T) 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.

			(*T) 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).

			(*T) 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.

			(*T) 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.

			(*T) SetLinesForContent(content []byte)
				SetLinesForContent sets the line offsets for the given file content.
				It ignores position-altering //line comments.

			(*T) Size() int
				Size returns the size of file f as registered with AddFile.

			/* 2 unexporteds ... *//* 2 unexporteds: */
			(*T) position(p Pos, adjusted bool) (pos Position)
			(*T) unpack(offset int, adjusted bool) (filename string, line, column int)
				unpack returns the filename and line and column number for a file offset.
				If adjusted is set, unpack will return the filename and line information
				possibly adjusted by //line comments; otherwise those comments are ignored.

		As Outputs Of (at least 3, in which 2 are exported)
			func (*FileSet).AddFile(filename string, base, size int) *File
			func (*FileSet).File(p Pos) (f *File)
			/* at least one unexported ... *//* at least one unexported: */
			func (*FileSet).file(p Pos) *File
		As Inputs Of (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			func searchFiles(a []*File, x int) int

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

		The byte offsets for each file in a file set are mapped into
		distinct (integer) intervals, one interval [base, base+size]
		per file. Base represents the first byte in the file, and size
		is the corresponding file size. A Pos value is a value in such
		an interval. By determining the interval a Pos value belongs
		to, the file, its file base, and thus the byte offset (position)
		the Pos value is representing can be computed.

		When adding a new file, a file base must be provided. That can
		be any integer value that is past the end of any interval of any
		file already in the file set. For convenience, FileSet.Base provides
		such a value, which is simply the end of the Pos interval of the most
		recently added file, plus one. Unless there is a need to extend an
		interval later, using the FileSet.Base should be used as argument
		for FileSet.AddFile.

		Fields (total 4, none are exported)
			/* 4 unexporteds ... *//* 4 unexporteds: */
			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

			mutex sync.RWMutex
				// protects the file set

		Methods (total 9, in which 8 are exported)
			(*T) 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:

					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.

			(*T) Base() int
				Base returns the minimum base offset that must be provided to
				AddFile when adding the next file.

			(*T) 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.

			(*T) 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.

			(*T) 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).

			(*T) 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.

			(*T) Read(decode func(interface{}) error) error
				Read calls decode to deserialize a file set into s; s must not be nil.

			(*T) Write(encode func(interface{}) error) error
				Write calls encode to serialize the file set s.

			/* one unexported ... *//* one unexported: */
			(*T) file(p Pos) *File
		As Outputs Of (at least one exported)
			func NewFileSet() *FileSet

	 type Pos int (basic type)
		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 a file is added to the file set.
		The difference between a Pos value and the corresponding file base
		corresponds to the byte offset of that position (represented by the Pos value)
		from the beginning of the file. Thus, the file base offset is the Pos value
		representing the first byte in the file.

		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.

		Methods (only one, which is exported)
			( T) IsValid() bool
				IsValid reports whether the position is valid.

		As Outputs Of (at least 2, both are exported)
			func (*File).LineStart(line int) Pos
			func (*File).Pos(offset int) Pos
		As Inputs Of (at least 9, in which 7 are exported)
			func (*File).Line(p Pos) int
			func (*File).Offset(p Pos) int
			func (*File).Position(p Pos) (pos Position)
			func (*File).PositionFor(p Pos, adjusted bool) (pos Position)
			func (*FileSet).File(p Pos) (f *File)
			func (*FileSet).Position(p Pos) (pos Position)
			func (*FileSet).PositionFor(p Pos, adjusted bool) (pos Position)
			/* 2+ unexporteds ... *//* 2+ unexporteds: */
			func (*File).position(p Pos, adjusted bool) (pos Position)
			func (*FileSet).file(p Pos) *File
		As Types Of (only one, which is exported)
			const NoPos

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

		Fields (total 4, all are exported)
			Column int
				// column number, starting at 1 (character count)

			Filename string
				// filename, if any

			Line int
				// line number, starting at 1

			Offset int
				// offset, starting at 0

		Methods (total 2, both are exported)
			(*T) IsValid() bool
				IsValid reports whether the position is valid.

			( T) String() string
				String returns a string in one of several forms:

					file:line:column    valid position with file name
					file:line           valid position with file name but no column (column == 0)
					line:column         valid position without file name
					line                valid position without file name and no column (column == 0)
					file                invalid position with file name
					-                   invalid position without file name

		Implements (at least 4, in which 1 are exported)
			 T : fmt.Stringer
			/* 3+ unexporteds ... *//* 3+ unexporteds: */
			 T : context.stringer
			 T : os/signal.stringer
			 T : runtime.stringer
		As Outputs Of (at least 5, in which 4 are exported)
			func (*File).Position(p Pos) (pos Position)
			func (*File).PositionFor(p Pos, adjusted bool) (pos Position)
			func (*FileSet).Position(p Pos) (pos Position)
			func (*FileSet).PositionFor(p Pos, adjusted bool) (pos Position)
			/* at least one unexported ... *//* at least one unexported: */
			func (*File).position(p Pos, adjusted bool) (pos Position)

	 type Token int (basic type)
		Token is the set of lexical tokens of the Go programming language.

		Methods (total 5, all are exported)
			( T) IsKeyword() bool
				IsKeyword returns true for tokens corresponding to keywords;
				it returns false otherwise.

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

			( T) IsOperator() bool
				IsOperator returns true for tokens corresponding to operators and
				delimiters; it returns false otherwise.

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

			( T) 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").

		Implements (at least 4, in which 1 are exported)
			 T : fmt.Stringer
			/* 3+ unexporteds ... *//* 3+ unexporteds: */
			 T : context.stringer
			 T : os/signal.stringer
			 T : runtime.stringer
		As Outputs Of (at least one exported)
			func Lookup(ident string) Token
		As Types Of (total 87, in which 81 are exported)
			const ADD
			const ADD_ASSIGN
			const AND
			const AND_ASSIGN
			const AND_NOT
			const AND_NOT_ASSIGN
			const ARROW
			const ASSIGN
			const BREAK
			const CASE
			const CHAN
			const CHAR
			const COLON
			const COMMA
			const COMMENT
			const CONST
			const CONTINUE
			const DEC
			const DEFAULT
			const DEFER
			const DEFINE
			const ELLIPSIS
			const ELSE
			const EOF
			const EQL
			const FALLTHROUGH
			const FLOAT
			const FOR
			const FUNC
			const GEQ
			const GO
			const GOTO
			const GTR
			const IDENT
			const IF
			const ILLEGAL
			const IMAG
			const IMPORT
			const INC
			const INT
			const INTERFACE
			const LAND
			const LBRACE
			const LBRACK
			const LEQ
			const LOR
			const LPAREN
			const LSS
			const MAP
			const MUL
			const MUL_ASSIGN
			const NEQ
			const NOT
			const OR
			const OR_ASSIGN
			const PACKAGE
			const PERIOD
			const QUO
			const QUO_ASSIGN
			const RANGE
			const RBRACE
			const RBRACK
			const REM
			const REM_ASSIGN
			const RETURN
			const RPAREN
			const SELECT
			const SEMICOLON
			const SHL
			const SHL_ASSIGN
			const SHR
			const SHR_ASSIGN
			const STRING
			const STRUCT
			const SUB
			const SUB_ASSIGN
			const SWITCH
			const TYPE
			const VAR
			const XOR
			const XOR_ASSIGN
			/* 6 unexporteds ... *//* 6 unexporteds: */
			const keyword_beg
			const keyword_end
			const literal_beg
			const literal_end
			const operator_beg
			const operator_end

	/* 3 unexporteds ... *//* 3 unexporteds: */
	 type lineInfo (struct)
		A lineInfo object describes alternative file, line, and column
		number information (such as provided via a //line directive)
		for a given file offset.

		Fields (total 4, all are exported)
			Column int
			Filename string
			Line int
			Offset int
				fields are exported to make them accessible to gob

		As Inputs Of (at least one unexported)
			/* at least one unexported ... *//* at least one unexported: */
			func searchLineInfos(a []lineInfo, x int) int

	 type serializedFile (struct)

		Fields (total 5, all are exported)
			Base int
			Infos []lineInfo
			Lines []int
			Name string
				fields correspond 1:1 to fields with same (lower-case) name in File

			Size int

	 type serializedFileSet (struct)

		Fields (total 2, both are exported)
			Base int
			Files []serializedFile


Package-Level Functions (total 9, in which 5 are exported)

	 func IsExported(name string) bool
		IsExported reports whether name starts with an upper-case letter.

	 func IsIdentifier(name string) bool
		IsIdentifier reports whether name is a Go identifier, that is, a non-empty
		string made up of letters, digits, and underscores, where the first character
		is not a digit. Keywords are not identifiers.

	 func IsKeyword(name string) bool
		IsKeyword reports whether name is a Go keyword, such as "func" or "return".

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

	 func NewFileSet() *FileSet
		NewFileSet creates a new file set.

	/* 4 unexporteds ... *//* 4 unexporteds: */
	 func init()
	 func searchFiles(a []*File, x int) int
	 func searchInts(a []int, x int) int
	 func searchLineInfos(a []lineInfo, x int) int
Package-Level Variables (total 2, neither is exported)

	/* 2 unexporteds ... *//* 2 unexporteds: */
	  var keywords map[string]Token
	  var tokens [86]string
Package-Level Constants (total 91, in which 85 are exported)

	const ADD Token = 12 // +
		Operators and delimiters

	const ADD_ASSIGN Token = 23 // +=
		The list of tokens.

	const AND Token = 17 // &
		The list of tokens.

	const AND_ASSIGN Token = 28 // &=
		The list of tokens.

	const AND_NOT Token = 22 // &^
		The list of tokens.

	const AND_NOT_ASSIGN Token = 33 // &^=
		The list of tokens.

	const ARROW Token = 36 // <-
		The list of tokens.

	const ASSIGN Token = 42 // =
		The list of tokens.

	const BREAK Token = 61
		Keywords

	const CASE Token = 62
		The list of tokens.

	const CHAN Token = 63
		The list of tokens.

	const CHAR Token = 8 // 'a'
		The list of tokens.

	const COLON Token = 58 // :
		The list of tokens.

	const COMMA Token = 52 // ,
		The list of tokens.

	const COMMENT Token = 2
		The list of tokens.

	const CONST Token = 64
		The list of tokens.

	const CONTINUE Token = 65
		The list of tokens.

	const DEC Token = 38 // --
		The list of tokens.

	const DEFAULT Token = 66
		The list of tokens.

	const DEFER Token = 67
		The list of tokens.

	const DEFINE Token = 47 // :=
		The list of tokens.

	const ELLIPSIS Token = 48 // ...
		The list of tokens.

	const ELSE Token = 68
		The list of tokens.

	const EOF Token = 1
		The list of tokens.

	const EQL Token = 39 // ==
		The list of tokens.

	const FALLTHROUGH Token = 69
		The list of tokens.

	const FLOAT Token = 6 // 123.45
		The list of tokens.

	const FOR Token = 70
		The list of tokens.

	const FUNC Token = 71
		The list of tokens.

	const GEQ Token = 46 // >=
		The list of tokens.

	const GO Token = 72
		The list of tokens.

	const GOTO Token = 73
		The list of tokens.

	const GTR Token = 41 // >
		The list of tokens.

	const HighestPrec = 7
		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.

	const IDENT Token = 4 // main
		Identifiers and basic type literals
		(these tokens stand for classes of literals)

	const IF Token = 74
		The list of tokens.

	const ILLEGAL Token = 0
		Special tokens

	const IMAG Token = 7 // 123.45i
		The list of tokens.

	const IMPORT Token = 75
		The list of tokens.

	const INC Token = 37 // ++
		The list of tokens.

	const INT Token = 5 // 12345
		The list of tokens.

	const INTERFACE Token = 76
		The list of tokens.

	const LAND Token = 34 // &&
		The list of tokens.

	const LBRACE Token = 51 // {
		The list of tokens.

	const LBRACK Token = 50 // [
		The list of tokens.

	const LEQ Token = 45 // <=
		The list of tokens.

	const LOR Token = 35 // ||
		The list of tokens.

	const LowestPrec = 0 // non-operators
		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.

	const LPAREN Token = 49 // (
		The list of tokens.

	const LSS Token = 40 // <
		The list of tokens.

	const MAP Token = 77
		The list of tokens.

	const MUL Token = 14 // *
		The list of tokens.

	const MUL_ASSIGN Token = 25 // *=
		The list of tokens.

	const NEQ Token = 44 // !=
		The list of tokens.

	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.

	const NOT Token = 43 // !
		The list of tokens.

	const OR Token = 18 // |
		The list of tokens.

	const OR_ASSIGN Token = 29 // |=
		The list of tokens.

	const PACKAGE Token = 78
		The list of tokens.

	const PERIOD Token = 53 // .
		The list of tokens.

	const QUO Token = 15 // /
		The list of tokens.

	const QUO_ASSIGN Token = 26 // /=
		The list of tokens.

	const RANGE Token = 79
		The list of tokens.

	const RBRACE Token = 56 // }
		The list of tokens.

	const RBRACK Token = 55 // ]
		The list of tokens.

	const REM Token = 16 // %
		The list of tokens.

	const REM_ASSIGN Token = 27 // %=
		The list of tokens.

	const RETURN Token = 80
		The list of tokens.

	const RPAREN Token = 54 // )
		The list of tokens.

	const SELECT Token = 81
		The list of tokens.

	const SEMICOLON Token = 57 // ;
		The list of tokens.

	const SHL Token = 20 // <<
		The list of tokens.

	const SHL_ASSIGN Token = 31 // <<=
		The list of tokens.

	const SHR Token = 21 // >>
		The list of tokens.

	const SHR_ASSIGN Token = 32 // >>=
		The list of tokens.

	const STRING Token = 9 // "abc"
		The list of tokens.

	const STRUCT Token = 82
		The list of tokens.

	const SUB Token = 13 // -
		The list of tokens.

	const SUB_ASSIGN Token = 24 // -=
		The list of tokens.

	const SWITCH Token = 83
		The list of tokens.

	const TYPE Token = 84
		The list of tokens.

	const UnaryPrec = 6
		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.

	const VAR Token = 85
		The list of tokens.

	const XOR Token = 19 // ^
		The list of tokens.

	const XOR_ASSIGN Token = 30 // ^=
		The list of tokens.

	/* 6 unexporteds ... *//* 6 unexporteds: */
	const keyword_beg Token = 60
		The list of tokens.

	const keyword_end Token = 86
		The list of tokens.

	const literal_beg Token = 3
		The list of tokens.

	const literal_end Token = 10
		The list of tokens.

	const operator_beg Token = 11
		The list of tokens.

	const operator_end Token = 59
		The list of tokens.

The pages are generated with Golds v0.3.2. (GOOS=linux GOARCH=amd64)
Golds is a Go 101 project developed by Tapir Liu.
PR and bug reports are welcome and can be submitted to the issue list.
Please follow @Go100and1 (reachable from the left QR code) to get the latest news of Golds.