mirror of
https://gerrit.wikimedia.org/r/mediawiki/extensions/Echo
synced 2024-11-11 17:00:10 +00:00
1d7b766754
Detects changes to different parts of the document as independent from each other. Refactored parser passes all tests the previous parser passed plus a number of new tests which fail with the original parser. Change-Id: I65fdc6d9f922cbe9ff684332945def3776c70d30
313 lines
8.4 KiB
PHP
313 lines
8.4 KiB
PHP
<?php
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/**
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* MediaWiki Extension: Echo
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* This program is distributed WITHOUT ANY WARRANTY.
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*/
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/**
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*
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* @file
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* @ingroup Extensions
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* @author Erik Bernhardson
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*/
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/**
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* Calculates the individual sets of differences between two pieces of text
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* as individual groupings of add, subtract, and change actions. Internally
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* uses 0-indexing for positions. All results from the class are 1 indexed
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* to stay consistent with the origional diff output and the previous diff
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* parsing code.
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*/
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class EchoDiffParser {
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/**
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* @var integer $prefixLength The number of characters the diff prefixes a line with
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*/
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protected $prefixLength = 1;
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/**
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* @var array $left The text of the left side of the diff operation
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*/
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protected $left;
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/**
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* @var integer $leftPos The current position within the left text
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*/
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protected $leftPos;
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/**
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* @var array $right The text of the right side of the diff operation
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*/
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protected $right;
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/**
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* @var integer $rightPos The current position within the right text
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*/
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protected $rightPos;
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/**
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* @var array $changeSet Set of add, subtract, or change operations within the diff
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*/
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protected $changeSet;
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/**
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* Get the set of add, subtract, and change operations required to transform leftText into rightText
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*
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* @param string $leftText The left, or old, revision of the text
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* @param string $rightText The right, or new, revision of the text
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* @return array Array of arrays containing changes to individual groups of lines within the text
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* Each change consists of:
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* An 'action', one of:
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* - add
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* - subtract
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* - change
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* 'content' that was added or removed, or in the case
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* of a change, 'old_content' and 'new_content'
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* 'left_pos' and 'right_pos' (in 1-indexed lines) of the change.
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*/
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public function getChangeSet( $leftText, $rightText ) {
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/**
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* The internal diff utility, which is used when GNU diff is not available
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* prefixes lines with 2 characters instead of 1.
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* For more info see bug 41689.
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*/
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if ( self::usingInternalDiff() ) {
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$this->prefixLength = 2;
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} else {
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$this->prefixLength = 1;
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}
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$left = trim( $leftText ) . "\n";
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$right = trim( $rightText ) . "\n";
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$diff = wfDiff( $left, $right, '-u -w' );
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return $this->parse( $diff, $left, $right );
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}
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/**
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* Duplicates the check from the global wfDiff function to determine
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* if we are using internal or external diff utilities
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*/
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static protected function usingInternalDiff() {
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global $wgDiff;
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wfSuppressWarnings();
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$haveDiff = $wgDiff && file_exists( $wgDiff );
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wfRestoreWarnings();
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return !$haveDiff;
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}
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/**
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* Parse the unified diff output into an array of changes to individual groups of the text
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*
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* @param string $diff The unified diff output
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* @param string $left The left side of the diff used for sanity checks
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* @param string $right The right side of the diff used for sanity checks
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*/
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protected function parse( $diff, $left, $right ) {
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$this->left = explode( "\n", $left );
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$this->right = explode( "\n", $right );
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$diff = explode( "\n", $diff );
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$this->leftPos = 0;
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$this->rightPos = 0;
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$this->changeSet = array(
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'_info' => array(
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'lhs-length' => count( $this->left ),
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'rhs-length' => count( $this->right ),
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'lhs' => $this->left,
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'rhs' => $this->right,
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),
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);
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$change = null;
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foreach ( $diff as $line ) {
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$change = $this->parseLine( $line, $change );
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}
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if ( $change === null ) {
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return $this->changeSet;
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} else {
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return array_merge( $this->changeSet, $change->getChangeSet() );
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}
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}
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/**
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* Parse the next line of the unified diff output
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*
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* @param string $line The next line of the unified diff
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* @param EchoDiffGroup $change Changes the the immediately previous lines
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* @return EchoDiffGroup Changes to this line and any changed lines immediately previous
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*/
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protected function parseLine( $line, EchoDiffGroup $change = null ) {
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if ( $line ) {
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$op = $line[0];
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if ( strlen( $line ) > $this->prefixLength ) {
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$line = substr( $line, $this->prefixLength );
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} else {
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$line = '';
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}
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} else {
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$op = ' ';
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}
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switch( $op ) {
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case '@': // metadata
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if ( $change !== null ) {
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$this->changeSet = array_merge( $this->changeSet, $change->getChangeSet() );
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$change = null;
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}
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// @@ -start,numLines +start,numLines @@
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list( $at, $left, $right, $at ) = explode( ' ', $line );
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list( $this->leftPos ) = explode( ',', substr( $left, 1 ) );
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list( $this->rightPos ) = explode( ',', substr( $right, 1 ) );
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// -1 because diff is 1 indexed and we are 0 indexed
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$this->leftPos--;
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$this->rightPos--;
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break;
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case ' ': // No changes
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if ( $change !== null ) {
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$this->changeSet = array_merge( $this->changeSet, $change->getChangeSet() );
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$change = null;
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}
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$this->leftPos++;
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$this->rightPos++;
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break;
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case '-': // subtract
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if ( $this->left[$this->leftPos] !== $line ) {
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throw new MWException( 'Positional error: left' );
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}
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if ( $change === null ) {
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$change = new EchoDiffGroup( $this->leftPos, $this->rightPos );
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}
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$change->subtract( $line );
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$this->leftPos++;
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break;
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case '+': // add
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if ( $this->right[$this->rightPos] !== $line ) {
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throw new MWException( 'Positional error: right' );
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}
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if ( $change === null ) {
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$change = new EchoDiffGroup( $this->leftPos, $this->rightPos );
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}
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$change->add( $line );
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$this->rightPos++;
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break;
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default:
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throw new MWException( 'Unknown Diff Operation: ' . $op );
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}
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return $change;
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}
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}
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/**
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* Represents a single set of changes all effecting neighboring lines
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*/
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class EchoDiffGroup {
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/**
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* @var array The left and right position this change starts at
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*/
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protected $position;
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/**
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* @var array The lines that have been added
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*/
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protected $new = array();
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/**
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* @var array The lines that have been removed
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*/
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protected $old = array();
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/**
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* @param integer $leftPos The starting line number in the left text
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* @param integer $rightPos The starting line number in the right text
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*/
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public function __construct( $leftPos, $rightPos ) {
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// +1 due to the origional code use 1 indexing for this result
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$this->position = array(
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'right-pos' => $rightPos + 1,
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'left-pos' => $leftPos + 1,
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);
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}
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/**
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* @param string $line Line in the right text but not in the left
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*/
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public function add( $line ) {
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$this->new[] = $line;
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}
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/**
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* @param string $line Line in the left text but not in the right
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*/
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public function subtract( $line ) {
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$this->old[] = $line;
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}
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/**
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* @return array set of changes
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* Each change consists of:
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* An 'action', one of:
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* - add
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* - subtract
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* - change
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* 'content' that was added or removed, or in the case
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* of a change, 'old_content' and 'new_content'
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* 'left_pos' and 'right_pos' (in 1-indexed lines) of the change.
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*/
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public function getChangeSet() {
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$old = implode( "\n", $this->old );
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$new = implode( "\n", $this->new );
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$position = $this->position;
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$changeSet = array();
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// The implodes must come first because we consider array( '' ) to also be false
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// meaning a blank link replaced with content is an addition
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if ( $old && $new ) {
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$min = min( count( $this->old ), count( $this->new ) );
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$changeSet[] = $position + array(
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'action' => 'change',
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'old_content' => implode( "\n", array_slice( $this->old, 0, $min ) ),
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'new_content' => implode( "\n", array_slice( $this->new, 0, $min ) ),
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);
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$position['left-pos'] += $min;
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$position['right-pos'] += $min;
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$old = implode( "\n", array_slice( $this->old, $min ) );
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$new = implode( "\n", array_slice( $this->new, $min ) );
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}
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if ( $new ) {
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$changeSet[] = $position + array(
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'action' => 'add',
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'content' => $new,
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);
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} elseif ( $old ) {
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$changeSet[] = $position + array(
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'action' => 'subtract',
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'content' => $old,
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);
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}
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return $changeSet;
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}
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}
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