<?php
/**
* This file is part of Soloproyectos common library.
*
* @author Gonzalo Chumillas <gchumillas@email.com>
* @license https://github.com/soloproyectos/php.common-libs/blob/master/LICENSE BSD 2-Clause License
* @link https://github.com/soloproyectos/php.common-libs
*/
namespace com\soloproyectos\common\text\parser;
use com\soloproyectos\common\text\parser\exception\TextParserException;
use com\soloproyectos\common\text\tokenizer\TextTokenizer;
/**
* class TextParser
*
* This class is for parsing purpose.
*
* @package Text\Parser
* @author Gonzalo Chumillas <gchumillas@email.com>
* @license https://github.com/soloproyectos/php.common-libs/blob/master/LICENSE BSD 2-Clause License
* @link https://github.com/soloproyectos/php.common-libs
*/
abstract class TextParser extends TextTokenizer
{
/**
* Non-geedy parsing.
* This flag indicates that we want to perform a "non-greedy" parsing. This flag
* is similar to the PCRE_UNGREEDY modifier in regular expressions.
*/
const UNGREEDY = 0x4;
/**
* String to be parsed or a TextParser object.
* @var string|TextParser
*/
private $_target;
/**
* Flags.
* @var integer
*/
private $_flags;
/**
* Constructor.
*
* @param string|TextParser $target Target object
* @param integer $flags Flags (default is 0, accepts: TextParser::UNGREEDY)
*/
public function __construct($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);
}
}
/**
* Evaluates an expression.
*
* This function is called by the 'TextParser::parse()' function.
*
* @see TextParser::parse()
* @return mixed
*/
abstract protected function evaluate();
/**
* Parses a string.
*
* This function parses a string and throws an exception if unsuccessful.
*
* For example:
* ```php
* // parses a string
* $p = new MyCustomParser($string);
* try {
* $info = $p->parse();
* } catch(TextParserException $e) {
* echo $e->getPrintableMessage();
* }
*
* if (!$info) {
* echo "This is not a valid expressión";
* } else {
* print_r($info);
* }
* ```
*
* @param string $string String target (default is "")
*
* @throws Exception
* @return mixed
*/
public function parse($string = "")
{
$this->offset = 0;
$this->string = func_num_args() > 0 ? $string : $this->string;
$ungreedy = TextParser::UNGREEDY & $this->_flags;
$ret = $this->evaluate();
if ($ret) {
if ($this->_target instanceof TextParser) {
$this->_target->setOffset($this->offset);
} elseif (!$ungreedy && !$this->end()) {
throw new TextParserException("Unrecognized expression", $this);
}
}
return $ret;
}
/**
* Does the next thing satisfies a given method?
*
* Matches the string against a function and moves the offset forward if the
* function returns true.
*
* @param string $methodName Method name
*
* @throws TextParserException
* @return mixed
*/
protected function is($methodName /*, $arg1, $arg2, $arg3 ... */)
{
if (!method_exists($this, $methodName)) {
throw new TextParserException(
"The method `$methodName` does not exist"
);
}
if (!is_callable(array($this, $methodName))) {
throw new TextParserException(
"The method `$methodName` is inaccessible"
);
}
// saves offset
$offset = $this->offset;
// calls user function
$ret = call_user_func_array(
array($this, $methodName),
array_slice(func_get_args(), 1)
);
// restores offset
if (!$ret) {
$this->offset = $offset;
}
return $ret;
}
}
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