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File: classes/parser/parser.php

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  Classes of Gonzalo Chumillas  >  Ses Parser  >  classes/parser/parser.php  >  Download  
File: classes/parser/parser.php
Role: Class source
Content type: text/plain
Description: Parser class
Class: Ses Parser
Parse a string with an expression of any type
Author: By
Last change: _parse method has changed from "public" to "protected".
Date: 1 year ago
Size: 2,466 bytes
 

Contents

Class file image Download
<?php
require_once dirname(__DIR__) . "/parser/parser-exception.php";
require_once
dirname(__DIR__) . "/parser/tokenizer.php";

/**
 * class Parser
 * Parses a string.
 */
abstract class Parser extends Tokenizer {
   
/**
     * This flag indicates that we want to perform a "non-greedy" analysis.
     */
   
const UNGREEDY = 0x4;
   
   
/**
     * Flags.
     * @var int
     */
   
private $flags;
   
   
/**
     * @param string $str
     * @param int $flags = 0
     */
   
public function __construct($str, $flags = 0) {
       
parent::__construct($str);
       
$this->flags = $flags;
    }
   
   
/**
     * Parses a string.
     * @return mixed
     */
   
abstract protected function _parse();
   
   
/**
     * Tries to parse a string and throws an exception if unsuccessful.
     * This is the habitual use of the parser method:
     *
     * <code>
     * $p = new MyCustomParser($string);
     * try {
     * $info = $p->parse();
     * // .. more lines ..
     * } catch(ParserException $e) {
     * echo $e->getPrintableMessage();
     * }
     * </code>
     *
     * @throws Exception
     * @return mixed
     */
   
public function parse() {
       
$ungreedy = Parser::UNGREEDY & $this->flags;
       
$ret = $this->_parse();
       
        if (!
$ret || !$ungreedy && !$this->end()) {
            throw new
ParserException($this, "Unrecognized expression");
        }
       
        return
$ret;
    }
   
   
/**
     * Matches the string against a function and moves the offset forward if the function returns TRUE.
     * @param string $method_name Method name
     * @param array $args Additional arguments
     * @throws Exception
     * @return mixed
     */
   
protected function is($method_name, $args = NULL /* ... additional arguments */) {
        if (!
method_exists($this, $method_name)) {
            throw new
Exception("The method `$method_name` does not exist");
        }
       
        if (!
is_callable(array($this, $method_name))) {
            throw new
Exception("The method `$method_name` is inaccessible");
        }
       
       
$offset = $this->offset; // saves offset
       
$ret = call_user_func_array(array($this, $method_name), array_slice(func_get_args(), 1));
        if (!
$ret) {
           
$this->offset = $offset; // restores offset
       
}
       
        return
$ret;
    }
}