lexer

Documentation

Overview

Package lexer provides basic helpers to implement parsers

Index

• Constants
• Variables
• type Error
  • func (err Error) Error() string
  • func (err Error) Unwrap() error
• type Reader
  • func NewReader(r io.Reader) *Reader
  • func NewReaderBytes(b []byte) *Reader
  • func NewReaderString(s string) *Reader
  • func (b *Reader) Discard()
  • func (b *Reader) Emit() string
  • func (b *Reader) PeekRune() (rune, int, error)
  • func (b *Reader) ReadRune() (rune, int, error)
  • func (b *Reader) String() string
  • func (b *Reader) UnreadRune() error

Constants

const (
	// ReadBufferSize indicates the initial buffer size
	ReadBufferSize = 1 << 7 // 128B

	// DoublingBufferSizeLimit indicates when we stop doubling
	// and just add instead
	DoublingBufferSizeLimit = 1 << 17 // 128KiB
)

Variables

var (
	// ErrInvalidUnreadRune indicates UnreadRune() was calls after an
	// action other than a successful ReadRune()
	ErrInvalidUnreadRune = errors.New("invalid UnreadRune() call")
)

Types

type Error

type Error struct {
	Filename string
	Line     int
	Column   int

	Content string
	Err     error
}

Error represents a generic parsing error

func (Error) Error

func (err Error) Error() string

func (Error) Unwrap

func (err Error) Unwrap() error

type Reader

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

Reader is a RuneReader aimed at implementing text parsers

func NewReader

func NewReader(r io.Reader) *Reader

NewReader creates a new runes Reader using the given io.Reader

func NewReaderBytes

func NewReaderBytes(b []byte) *Reader

NewReaderBytes creates a new runes Reader using the given bytes

func NewReaderString

func NewReaderString(s string) *Reader

NewReaderString creates a new runes Reader using the given string

func (*Reader) Discard

func (b *Reader) Discard()

Discard removes from the buffer everything that has been Read

func (*Reader) Emit

func (b *Reader) Emit() string

Emit returns what's already being Read and discards it afterwards

func (*Reader) PeekRune

func (b *Reader) PeekRune() (rune, int, error)

PeekRune returns information about the next rune without moving the cursor

func (*Reader) ReadRune

func (b *Reader) ReadRune() (rune, int, error)

ReadRune reads the next rune

func (*Reader) String

func (b *Reader) String() string

String returns what's already Read but not yet emitted or discarded

func (*Reader) UnreadRune

func (b *Reader) UnreadRune() error

UnreadRune moves the cursor where it was before the last call to ReadRune