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<?php |
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/** |
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* AhoCorasick PHP Library |
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* |
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* A PHP implementation of the Aho-Corasick string matching algorithm. |
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* |
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* Alfred V. Aho and Margaret J. Corasick, "Efficient string matching: |
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* an aid to bibliographic search", CACM, 18(6):333-340, June 1975. |
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* |
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* @link http://xlinux.nist.gov/dads//HTML/ahoCorasick.html |
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* @link https://en.wikipedia.org/wiki/Aho-Corasick_string_matching_algorithm |
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* |
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* Copyright (C) 2015 Ori Livneh <[email protected]> |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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* |
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* @file |
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* @author Ori Livneh <[email protected]> |
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*/ |
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|
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namespace AhoCorasick; |
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|
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/** |
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* This class extends MultiStringMatcher, adding search and replace |
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* functionality. |
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*/ |
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class MultiStringReplacer extends MultiStringMatcher { |
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|
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/** @var array Mapping of states to outputs. **/ |
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protected $replacePairs = []; |
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|
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/** |
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* Constructor. |
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* |
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* @param array $replacePairs array of ( 'from' => 'to' ) replacement pairs. |
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*/ |
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public function __construct( array $replacePairs ) { |
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foreach ( $replacePairs as $keyword => $replacement ) { |
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if ( $keyword !== '' ) { |
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$this->replacePairs[$keyword] = $replacement; |
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} |
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} |
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parent::__construct( array_keys( $this->replacePairs ) ); |
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} |
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|
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/** |
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* Search and replace a set of keywords in some text. |
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* |
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* @param string $text The string to search in. |
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* @return string The input text with replacements. |
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* |
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* @par Example: |
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* @code |
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* $replacer = new MultiStringReplacer( array( 'csh' => 'sea shells' ) ); |
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* $replacer->searchAndReplace( 'She sells csh by the sea shore.' ); |
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* // result: 'She sells sea shells by the sea shore.' |
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* @endcode |
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*/ |
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public function searchAndReplace( $text ) { |
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$state = 0; |
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$length = strlen( $text ); |
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$matches = []; |
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for ( $i = 0; $i < $length; $i++ ) { |
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$ch = $text[$i]; |
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$state = $this->nextState( $state, $ch ); |
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foreach ( $this->outputs[$state] as $match ) { |
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$offset = $i - $this->searchKeywords[$match] + 1; |
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$matches[$offset] = $match; |
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} |
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} |
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ksort( $matches ); |
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|
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$buf = ''; |
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$lastInsert = 0; |
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foreach ( $matches as $offset => $match ) { |
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if ( $offset >= $lastInsert ) { |
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$buf .= substr( $text, $lastInsert, $offset - $lastInsert ); |
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$buf .= $this->replacePairs[$match]; |
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$lastInsert = $offset + $this->searchKeywords[$match]; |
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} |
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} |
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$buf .= substr( $text, $lastInsert ); |
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|
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return $buf; |
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} |
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} |
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|
