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Package token

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

Constants

const (
        LowestPrec  = 0 // non-operators
        UnaryPrec   = 6
        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.

type File

type File struct {
        // contains filtered or unexported fields
}

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

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

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

func (f *File) Base() int

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

func (*File) Line

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

func (f *File) LineCount() int

LineCount returns the number of lines in file f.

func (*File) MergeLine

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

func (f *File) Name() string

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

func (*File) Offset

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

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

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

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

func (*File) SetLines

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

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 (*File) SetLinesForContent

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

SetLinesForContent sets the line offsets for the given file content.

func (*File) Size

func (f *File) Size() int

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

type FileSet

type FileSet struct {
        // contains filtered or unexported fields
}

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

func NewFileSet

func NewFileSet() *FileSet

NewFileSet creates a new file set.

func (*FileSet) AddFile

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:

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

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

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

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

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

Position converts a Pos in the fileset into a general Position.

func (*FileSet) Read

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

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

Write calls encode to serialize the file set s.

type Pos

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, 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.

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

func (p Pos) IsValid() bool

IsValid returns true if the position is valid.

type Position

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)
}

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

func (pos *Position) IsValid() bool

IsValid returns true if the position is valid.

func (Position) String

func (pos Position) String() string

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

type Token

type Token int

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

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
)

The list of tokens.

func Lookup

func Lookup(ident string) 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; it returns false otherwise.

func (Token) IsLiteral

func (tok Token) IsLiteral() bool

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

func (Token) IsOperator

func (tok Token) IsOperator() bool

IsOperator returns true for tokens corresponding to operators and delimiters; it 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").