<?php
/**
* This file contains the Parser class.
*
* @author Gonzalo Chumillas <gonzalo@soloproyectos.com>
* @package parser
*/
require_once dirname(__DIR__) . "/parser/exceptions/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;
/**
* @var string|Parser
*/
private $target;
/**
* Flags.
* @var int
*/
private $flags;
/**
* @param string|Parser $target
* @param int $flags = 0
*/
public function __construct($target, $flags = 0) {
$this->target = $target;
$this->flags = $flags;
if ($this->target instanceof Parser) {
parent::__construct($target->getString(), $flags);
$this->offset = $target->getOffset();
} else {
parent::__construct($target, $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);
* $info = $p->parse();
* if (!$info) {
* echo "Invalid expression";
* }
* </code>
*
* @throws Exception
* @return mixed
*/
public function parse() {
$ungreedy = Parser::UNGREEDY & $this->flags;
$ret = $this->_parse();
if ($ret) {
if ($this->target instanceof Parser) {
$this->target->setOffset($this->offset);
} else
if (!$ungreedy && !$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;
}
}
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