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<?php
/*
** Copyright (C) 2001-2025 Zabbix SIA
**
** This program is free software: you can redistribute it and/or modify it under the terms of
** the GNU Affero General Public License as published by the Free Software Foundation, version 3.
**
** This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
** without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
** See the GNU Affero General Public License for more details.
**
** You should have received a copy of the GNU Affero General Public License along with this program.
** If not, see <https://www.gnu.org/licenses/>.
**/
abstract class CParser {
const PARSE_FAIL = -1;
const PARSE_SUCCESS = 0;
const PARSE_SUCCESS_CONT = 1;
protected $length = 0;
protected $match = '';
protected $error_source = false;
protected $error_pos = 0;
protected $error_msgs = [
'empty' => 'string is empty',
'unexpected_end' => 'unexpected end of string'
];
/**
* Try to parse the string starting from the given position.
*
* @param string $source string to parse
* @param int $pos position to start from
*
* @return int
*/
abstract public function parse($source, $pos = 0);
/**
* Returns length of the parsed element.
*
* @return int
*/
public function getLength() {
return $this->length;
}
/**
* Returns parsed element.
*
* @return string
*/
public function getMatch() {
return $this->match;
}
/**
* Returns the error message if string is invalid.
*
* @return string
*/
public function getError(): string {
if ($this->error_source === false) {
return '';
}
if (!isset($this->error_source[$this->error_pos])) {
return ($this->error_pos == 0) ? $this->error_msgs['empty'] : $this->error_msgs['unexpected_end'];
}
// The error message is prepared here to avoid extra calculations if the error message is not used.
return $this->errorPosMessage($this->error_source, $this->error_pos);
}
/**
* Save error source string and position for later use, when error will be retrieved.
*
* @param string $source
* @param int $pos
*/
protected function errorPos($source, $pos): void {
$this->error_source = $source;
$this->error_pos = $pos;
}
/**
* Clears error, when parse is used multiple times with same parser.
*/
protected function errorClear(): void {
$this->error_source = false;
$this->error_pos = 0;
}
/**
* Prepares error message for incorrect syntax at position.
*
* @param string $source
* @param int $pos
*
* @return string
*/
protected function errorPosMessage($source, $pos): string {
$maxChunkSize = 50;
$chunk = substr($source, $pos);
if (mb_strlen($chunk) > $maxChunkSize) {
$chunk = mb_substr($chunk, 0, $maxChunkSize) . ' ...';
}
return _s('incorrect syntax near "%1$s"', $chunk);
}
}
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