includes/libs/Diff/DiffFormatter.php
<?php
/**
* Base for diff rendering classes. Portions taken from phpwiki-1.3.3.
*
* Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
* You may copy this code freely under the conditions of the GPL.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup DifferenceEngine
*/
namespace Wikimedia\Diff;
use UnexpectedValueException;
/**
* Base class for diff formatters
*
* This class formats the diff in classic diff format.
* It is intended that this class be customized via inheritance,
* to obtain fancier outputs.
* @todo document
* @ingroup DifferenceEngine
*/
abstract class DiffFormatter {
/** @var int Number of leading context "lines" to preserve.
*
* This should be left at zero for this class, but subclasses
* may want to set this to other values.
*/
protected $leadingContextLines = 0;
/** @var int Number of trailing context "lines" to preserve.
*
* This should be left at zero for this class, but subclasses
* may want to set this to other values.
*/
protected $trailingContextLines = 0;
/** @var string The output buffer; holds the output while it is built. */
private $result = '';
/**
* Format a diff.
*
* @param Diff $diff
*
* @return string The formatted output.
*/
public function format( $diff ) {
$xi = $yi = 1;
$block = false;
$context = [];
$nlead = $this->leadingContextLines;
$ntrail = $this->trailingContextLines;
$this->startDiff();
// Initialize $x0 and $y0 to prevent IDEs from getting confused.
$x0 = $y0 = 0;
foreach ( $diff->edits as $edit ) {
if ( $edit->type == 'copy' ) {
if ( is_array( $block ) ) {
if ( count( $edit->orig ) <= $nlead + $ntrail ) {
$block[] = $edit;
} else {
if ( $ntrail ) {
$context = array_slice( $edit->orig, 0, $ntrail );
$block[] = new DiffOpCopy( $context );
}
$this->block( $x0, $ntrail + $xi - $x0,
$y0, $ntrail + $yi - $y0,
$block );
$block = false;
}
}
$context = $edit->orig;
} else {
if ( !is_array( $block ) ) {
$context = array_slice( $context, count( $context ) - $nlead );
$x0 = $xi - count( $context );
$y0 = $yi - count( $context );
$block = [];
if ( $context ) {
$block[] = new DiffOpCopy( $context );
}
}
$block[] = $edit;
}
if ( $edit->orig ) {
$xi += count( $edit->orig );
}
if ( $edit->closing ) {
$yi += count( $edit->closing );
}
}
if ( is_array( $block ) ) {
$this->block( $x0, $xi - $x0,
$y0, $yi - $y0,
$block );
}
$end = $this->endDiff();
return $end;
}
/**
* @param int $xbeg
* @param int $xlen
* @param int $ybeg
* @param int $ylen
* @param array &$edits
*/
protected function block( $xbeg, $xlen, $ybeg, $ylen, &$edits ) {
$this->startBlock( $this->blockHeader( $xbeg, $xlen, $ybeg, $ylen ) );
foreach ( $edits as $edit ) {
if ( $edit->type == 'copy' ) {
$this->context( $edit->orig );
} elseif ( $edit->type == 'add' ) {
$this->added( $edit->closing );
} elseif ( $edit->type == 'delete' ) {
$this->deleted( $edit->orig );
} elseif ( $edit->type == 'change' ) {
$this->changed( $edit->orig, $edit->closing );
} else {
throw new UnexpectedValueException( "Unknown edit type: {$edit->type}" );
}
}
$this->endBlock();
}
protected function startDiff() {
$this->result = '';
}
/**
* Writes a string to the output buffer.
*
* @param string $text
*/
protected function writeOutput( $text ) {
$this->result .= $text;
}
/**
* @return string
*/
protected function endDiff() {
$val = $this->result;
$this->result = '';
return $val;
}
/**
* @param int $xbeg
* @param int $xlen
* @param int $ybeg
* @param int $ylen
*
* @return string
*/
protected function blockHeader( $xbeg, $xlen, $ybeg, $ylen ) {
if ( $xlen > 1 ) {
$xbeg .= ',' . ( $xbeg + $xlen - 1 );
}
if ( $ylen > 1 ) {
$ybeg .= ',' . ( $ybeg + $ylen - 1 );
}
return $xbeg . ( $xlen ? ( $ylen ? 'c' : 'd' ) : 'a' ) . $ybeg;
}
/**
* Called at the start of a block of connected edits.
* This default implementation writes the header and a newline to the output buffer.
*
* @param string $header
*/
protected function startBlock( $header ) {
$this->writeOutput( $header . "\n" );
}
/**
* Called at the end of a block of connected edits.
* This default implementation does nothing.
*/
protected function endBlock() {
}
/**
* Writes all (optionally prefixed) lines to the output buffer, separated by newlines.
*
* @param string[] $lines
* @param string $prefix
*/
protected function lines( $lines, $prefix = ' ' ) {
foreach ( $lines as $line ) {
$this->writeOutput( "$prefix $line\n" );
}
}
/**
* @param string[] $lines
*/
protected function context( $lines ) {
$this->lines( $lines );
}
/**
* @param string[] $lines
*/
protected function added( $lines ) {
$this->lines( $lines, '>' );
}
/**
* @param string[] $lines
*/
protected function deleted( $lines ) {
$this->lines( $lines, '<' );
}
/**
* Writes the two sets of lines to the output buffer, separated by "---" and a newline.
*
* @param string[] $orig
* @param string[] $closing
*/
protected function changed( $orig, $closing ) {
$this->deleted( $orig );
$this->writeOutput( "---\n" );
$this->added( $closing );
}
}
/** @deprecated class alias since 1.41 */
class_alias( DiffFormatter::class, 'DiffFormatter' );