includes/diff/DiffFormatter.php

   1 <?php
   2 /**
   3  * Base for diff rendering classes. Portions taken from phpwiki-1.3.3.
   4  *
   5  * Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
   6  * You may copy this code freely under the conditions of the GPL.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup DifferenceEngine
  25  */
  26
  27 /**
  28  * Base class for diff formatters
  29  *
  30  * This class formats the diff in classic diff format.
  31  * It is intended that this class be customized via inheritance,
  32  * to obtain fancier outputs.
  33  * @todo document
  34  * @ingroup DifferenceEngine
  35  */
  36 abstract class DiffFormatter {
  37
  38         /** @var int Number of leading context "lines" to preserve.
  39          *
  40          * This should be left at zero for this class, but subclasses
  41          * may want to set this to other values.
  42          */
  43         protected $leadingContextLines = 0;
  44
  45         /** @var int Number of trailing context "lines" to preserve.
  46          *
  47          * This should be left at zero for this class, but subclasses
  48          * may want to set this to other values.
  49          */
  50         protected $trailingContextLines = 0;
  51
  52         /**
  53          * Format a diff.
  54          *
  55          * @param Diff $diff
  56          *
  57          * @return string The formatted output.
  58          */
  59         public function format( $diff ) {
  60                 wfProfileIn( __METHOD__ );
  61
  62                 $xi = $yi = 1;
  63                 $block = false;
  64                 $context = array();
  65
  66                 $nlead = $this->leadingContextLines;
  67                 $ntrail = $this->trailingContextLines;
  68
  69                 $this->startDiff();
  70
  71                 // Initialize $x0 and $y0 to prevent IDEs from getting confused.
  72                 $x0 = $y0 = 0;
  73                 foreach ( $diff->edits as $edit ) {
  74                         if ( $edit->type == 'copy' ) {
  75                                 if ( is_array( $block ) ) {
  76                                         if ( count( $edit->orig ) <= $nlead + $ntrail ) {
  77                                                 $block[] = $edit;
  78                                         } else {
  79                                                 if ( $ntrail ) {
  80                                                         $context = array_slice( $edit->orig, 0, $ntrail );
  81                                                         $block[] = new DiffOpCopy( $context );
  82                                                 }
  83                                                 $this->block( $x0, $ntrail + $xi - $x0,
  84                                                         $y0, $ntrail + $yi - $y0,
  85                                                         $block );
  86                                                 $block = false;
  87                                         }
  88                                 }
  89                                 $context = $edit->orig;
  90                         } else {
  91                                 if ( !is_array( $block ) ) {
  92                                         $context = array_slice( $context, count( $context ) - $nlead );
  93                                         $x0 = $xi - count( $context );
  94                                         $y0 = $yi - count( $context );
  95                                         $block = array();
  96                                         if ( $context ) {
  97                                                 $block[] = new DiffOpCopy( $context );
  98                                         }
  99                                 }
 100                                 $block[] = $edit;
 101                         }
 102
 103                         if ( $edit->orig ) {
 104                                 $xi += count( $edit->orig );
 105                         }
 106                         if ( $edit->closing ) {
 107                                 $yi += count( $edit->closing );
 108                         }
 109                 }
 110
 111                 if ( is_array( $block ) ) {
 112                         $this->block( $x0, $xi - $x0,
 113                                 $y0, $yi - $y0,
 114                                 $block );
 115                 }
 116
 117                 $end = $this->endDiff();
 118                 wfProfileOut( __METHOD__ );
 119
 120                 return $end;
 121         }
 122
 123         /**
 124          * @param int $xbeg
 125          * @param int $xlen
 126          * @param int $ybeg
 127          * @param int $ylen
 128          * @param array $edits
 129          *
 130          * @throws MWException If the edit type is not known.
 131          */
 132         protected function block( $xbeg, $xlen, $ybeg, $ylen, &$edits ) {
 133                 wfProfileIn( __METHOD__ );
 134                 $this->startBlock( $this->blockHeader( $xbeg, $xlen, $ybeg, $ylen ) );
 135                 foreach ( $edits as $edit ) {
 136                         if ( $edit->type == 'copy' ) {
 137                                 $this->context( $edit->orig );
 138                         } elseif ( $edit->type == 'add' ) {
 139                                 $this->added( $edit->closing );
 140                         } elseif ( $edit->type == 'delete' ) {
 141                                 $this->deleted( $edit->orig );
 142                         } elseif ( $edit->type == 'change' ) {
 143                                 $this->changed( $edit->orig, $edit->closing );
 144                         } else {
 145                                 throw new MWException( "Unknown edit type: {$edit->type}" );
 146                         }
 147                 }
 148                 $this->endBlock();
 149                 wfProfileOut( __METHOD__ );
 150         }
 151
 152         protected function startDiff() {
 153                 ob_start();
 154         }
 155
 156         /**
 157          * @return string
 158          */
 159         protected function endDiff() {
 160                 $val = ob_get_contents();
 161                 ob_end_clean();
 162
 163                 return $val;
 164         }
 165
 166         /**
 167          * @param int $xbeg
 168          * @param int $xlen
 169          * @param int $ybeg
 170          * @param int $ylen
 171          *
 172          * @return string
 173          */
 174         protected function blockHeader( $xbeg, $xlen, $ybeg, $ylen ) {
 175                 if ( $xlen > 1 ) {
 176                         $xbeg .= ',' . ( $xbeg + $xlen - 1 );
 177                 }
 178                 if ( $ylen > 1 ) {
 179                         $ybeg .= ',' . ( $ybeg + $ylen - 1 );
 180                 }
 181
 182                 return $xbeg . ( $xlen ? ( $ylen ? 'c' : 'd' ) : 'a' ) . $ybeg;
 183         }
 184
 185         /**
 186          * Called at the start of a block of connected edits.
 187          * This default implementation writes the header and a newline to the output buffer.
 188          *
 189          * @param string $header
 190          */
 191         protected function startBlock( $header ) {
 192                 echo $header . "\n";
 193         }
 194
 195         /**
 196          * Called at the end of a block of connected edits.
 197          * This default implementation does nothing.
 198          */
 199         protected function endBlock() {
 200         }
 201
 202         /**
 203          * Writes all (optionally prefixed) lines to the output buffer, separated by newlines.
 204          *
 205          * @param string[] $lines
 206          * @param string $prefix
 207          */
 208         protected function lines( $lines, $prefix = ' ' ) {
 209                 foreach ( $lines as $line ) {
 210                         echo "$prefix $line\n";
 211                 }
 212         }
 213
 214         /**
 215          * @param string[] $lines
 216          */
 217         protected function context( $lines ) {
 218                 $this->lines( $lines );
 219         }
 220
 221         /**
 222          * @param string[] $lines
 223          */
 224         protected function added( $lines ) {
 225                 $this->lines( $lines, '>' );
 226         }
 227
 228         /**
 229          * @param string[] $lines
 230          */
 231         protected function deleted( $lines ) {
 232                 $this->lines( $lines, '<' );
 233         }
 234
 235         /**
 236          * Writes the two sets of lines to the output buffer, separated by "---" and a newline.
 237          *
 238          * @param string[] $orig
 239          * @param string[] $closing
 240          */
 241         protected function changed( $orig, $closing ) {
 242                 $this->deleted( $orig );
 243                 echo "---\n";
 244                 $this->added( $closing );
 245         }
 246
 247 }