xarxaprod-wp-theme/vendor/mck89/peast/lib/Peast/Syntax/LSM.php

153 lines
4.5 KiB
PHP

<?php
/**
* This file is part of the Peast package
*
* (c) Marco Marchiò <marco.mm89@gmail.com>
*
* For the full copyright and license information refer to the LICENSE file
* distributed with this source code
*/
namespace Peast\Syntax;
/**
* Longest Sequence Matcher. Utility class used by the scanner to consume
* the longest sequence of character given a set of allowed characters sequences.
*
* @author Marco Marchiò <marco.mm89@gmail.com>
*/
class LSM
{
/**
* Internal sequences map
*
* @var array
*/
protected $map = array();
/**
* Encoding handle flag
*
* @var bool
*/
protected $handleEncoding = false;
/**
* Class constructor
*
* @param array $sequences Allowed characters sequences
* @param bool $handleEncoding True to handle encoding when matching
*/
function __construct($sequences, $handleEncoding = false)
{
$this->handleEncoding = $handleEncoding;
foreach ($sequences as $s) {
$this->add($s);
}
}
/**
* Adds a sequence
*
* @param string $sequence Sequence to add
*
* @return $this
*/
public function add($sequence)
{
if ($this->handleEncoding) {
$s = Utils::stringToUTF8Array($sequence);
$first = $s[0];
$len = count($s);
} else {
$first = $sequence[0];
$len = strlen($sequence);
}
if (!isset($this->map[$first])) {
$this->map[$first] = array(
"maxLen" => $len,
"map" => array($sequence)
);
} else {
$this->map[$first]["map"][] = $sequence;
$this->map[$first]["maxLen"] = max($this->map[$first]["maxLen"], $len);
}
return $this;
}
/**
* Removes a sequence
*
* @param string $sequence Sequence to remove
*
* @return $this
*/
public function remove($sequence)
{
if ($this->handleEncoding) {
$s = Utils::stringToUTF8Array($sequence);
$first = $s[0];
} else {
$first = $sequence[0];
}
if (isset($this->map[$first])) {
$len = $this->handleEncoding ? count($s) : strlen($sequence);
$this->map[$first]["map"] = array_diff(
$this->map[$first]["map"], array($sequence)
);
if (!count($this->map[$first]["map"])) {
unset($this->map[$first]);
} elseif ($this->map[$first]["maxLen"] === $len) {
// Recalculate the max length if necessary
foreach ($this->map[$first]["map"] as $m) {
$this->map[$first]["maxLen"] = max(
$this->map[$first]["maxLen"],
strlen($m)
);
}
}
}
return $this;
}
/**
* Executes the match. It returns an array where the first element is the
* number of consumed characters and the second element is the match. If
* no match is found it returns null.
*
* @param Scanner $scanner Scanner instance
* @param int $index Current index
* @param string $char Current character
*
* @return array|null
*/
public function match($scanner, $index, $char)
{
$consumed = 1;
$bestMatch = null;
if (isset($this->map[$char])) {
//If the character is present in the map and it has a max length of
//1, match immediately
if ($this->map[$char]["maxLen"] === 1) {
$bestMatch = array($consumed, $char);
} else {
//Otherwise consume a number of characters equal to the max
//length and find the longest match
$buffer = $char;
$map = $this->map[$char]["map"];
$maxLen = $this->map[$char]["maxLen"];
do {
if (in_array($buffer, $map)) {
$bestMatch = array($consumed, $buffer);
}
$nextChar = $scanner->charAt($index + $consumed);
if ($nextChar === null) {
break;
}
$buffer .= $nextChar;
$consumed++;
} while ($consumed <= $maxLen);
}
}
return $bestMatch;
}
}