# The Parle\Lexer class

(PECL parle >= 0.5.1)

## Introduction

Single state lexer class. Lexemes can be defined on the fly. If the particular lexer instance is meant to be used with Parle\Parser, the token IDs need to be taken from there. Otherwise, arbitrary token IDs can be supplied. This lexer can give a certain performance advantage over Parle\RLexer, if no multiple states are required. Note, that Parle\RParser is not compatible with this lexer.

## Class synopsis

Parle\Lexer {
/* Constants */
const int ICASE = 1 ;
const int DOT_NOT_LF = 2 ;
const int DOT_NOT_CRLF = 4 ;
const int SKIP_WS = 8 ;
const int MATCH_ZERO_LEN = 16 ;
/* Properties */
public bool $bol = `FALSE` ;
public int $flags = 0 ;
public int $state = 0 ;
public int $marker = 0 ;
public int $cursor = 0 ;
/* Methods */
public advance ( ) : void
public build ( ) : void
public callout ( int `$id` , callable `$callback` ) : void
public consume ( string `$data` ) : void
public dump ( ) : void
public getToken ( ) : Parle\Token
public insertMacro ( string `$name` , string `$regex` ) : void
public push ( string `$regex` , int `$id` ) : void
public reset ( int `$pos` ) : void
}

## Predefined Constants

`Parle\Lexer::ICASE`

`Parle\Lexer::DOT_NOT_LF`

`Parle\Lexer::DOT_NOT_CRLF`

`Parle\Lexer::SKIP_WS`

`Parle\Lexer::MATCH_ZERO_LEN`

## Properties

bol

  Start of input flag.

flags

  Lexer flags.

state

  Current lexer state, readonly.

marker

  Position of the latest token match, readonly.

cursor

  Current input offset, readonly.

## Table of Contents

- Parle\Lexer::advance — Process next lexer rule
- Parle\Lexer::build — Finalize the lexer rule set
- Parle\Lexer::callout — Define token callback
- Parle\Lexer::consume — Pass the data for processing
- Parle\Lexer::dump — Dump the state machine
- Parle\Lexer::getToken — Retrieve the current token
- Parle\Lexer::insertMacro — Insert regex macro
- Parle\Lexer::push — Add a lexer rule
- Parle\Lexer::reset — Reset lexer