lex

Documentation

Overview

Package lex implements lexing for the CTM data format.

Index

• type ErrorInfo
  • func (e ErrorInfo) Error() string
• type Lexeme
  • func (l Lexeme) Match(t Type, v string) bool
  • func (l Lexeme) String() string
• type Lexer
  • func NewLexer(r io.Reader) *Lexer
  • func (lx *Lexer) Lexeme() *Lexeme
• type Type
  • func (t Type) String() string
  • func (t Type) Terminal() bool

Types

type ErrorInfo

type ErrorInfo struct {
	Message    string
	Inner      error
	Start, End lex.Position
}

ErrorInfo desribes an lexical error along with the position in a source where the error occurred.

func (ErrorInfo) Error

func (e ErrorInfo) Error() string

type Lexeme

type Lexeme struct {
	Type       Type
	Value      string
	Start, End lex.Position
	// ErrMessage is set only when Type==Error.
	ErrMessage string
	// ErrInner is set only when Type==Error.
	ErrInner error
}

Lexeme describes a lexical CTM atom, including its position in a source text.

func (Lexeme) Match

func (l Lexeme) Match(t Type, v string) bool

func (Lexeme) String

func (l Lexeme) String() string

type Lexer

type Lexer struct {
	*lex.RuneScanner
	// contains filtered or unexported fields
}

Lexer supports lexing a CTM source into lexical atoms.

func NewLexer

func NewLexer(r io.Reader) *Lexer

NewLexer creates a lexer that can read lexical CTM atoms from r.

func (*Lexer) Lexeme

func (lx *Lexer) Lexeme() *Lexeme

Lexeme returns the next lexical CTM atom, and never returns nil.

At the end of available input, Lexeme returns a Lexeme with Type==EOF. If an error is encountered, a Lexeme is returned with Type==Error.

type Type

type Type int

Type identifies the type of lexemes read from a CTM source.

const (
	Error Type = iota
	Break
	Comment
	Delimiter
	EOF
	IRI
	Name
	Number
	Space
	String
)

func (Type) String

func (t Type) String() string

func (Type) Terminal

func (t Type) Terminal() bool

Terminal returns true if t indicates that reading should stop.