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
  61                 $xi = $yi = 1;
  62                 $block = false;
  63                 $context = array();
  64
  65                 $nlead = $this->leadingContextLines;
  66                 $ntrail = $this->trailingContextLines;
  67
  68                 $this->startDiff();
  69
  70                 // Initialize $x0 and $y0 to prevent IDEs from getting confused.
  71                 $x0 = $y0 = 0;
  72                 foreach ( $diff->edits as $edit ) {
  73                         if ( $edit->type == 'copy' ) {
  74                                 if ( is_array( $block ) ) {
  75                                         if ( count( $edit->orig ) <= $nlead + $ntrail ) {
  76                                                 $block[] = $edit;
  77                                         } else {
  78                                                 if ( $ntrail ) {
  79                                                         $context = array_slice( $edit->orig, 0, $ntrail );
  80                                                         $block[] = new DiffOpCopy( $context );
  81                                                 }
  82                                                 $this->block( $x0, $ntrail + $xi - $x0,
  83                                                         $y0, $ntrail + $yi - $y0,
  84                                                         $block );
  85                                                 $block = false;
  86                                         }
  87                                 }
  88                                 $context = $edit->orig;
  89                         } else {
  90                                 if ( !is_array( $block ) ) {
  91                                         $context = array_slice( $context, count( $context ) - $nlead );
  92                                         $x0 = $xi - count( $context );
  93                                         $y0 = $yi - count( $context );
  94                                         $block = array();
  95                                         if ( $context ) {
  96                                                 $block[] = new DiffOpCopy( $context );
  97                                         }
  98                                 }
  99                                 $block[] = $edit;
 100                         }
 101
 102                         if ( $edit->orig ) {
 103                                 $xi += count( $edit->orig );
 104                         }
 105                         if ( $edit->closing ) {
 106                                 $yi += count( $edit->closing );
 107                         }
 108                 }
 109
 110                 if ( is_array( $block ) ) {
 111                         $this->block( $x0, $xi - $x0,
 112                                 $y0, $yi - $y0,
 113                                 $block );
 114                 }
 115
 116                 $end = $this->endDiff();
 117
 118                 return $end;
 119         }
 120
 121         /**
 122          * @param int $xbeg
 123          * @param int $xlen
 124          * @param int $ybeg
 125          * @param int $ylen
 126          * @param array $edits
 127          *
 128          * @throws MWException If the edit type is not known.
 129          */
 130         protected function block( $xbeg, $xlen, $ybeg, $ylen, &$edits ) {
 131                 $this->startBlock( $this->blockHeader( $xbeg, $xlen, $ybeg, $ylen ) );
 132                 foreach ( $edits as $edit ) {
 133                         if ( $edit->type == 'copy' ) {
 134                                 $this->context( $edit->orig );
 135                         } elseif ( $edit->type == 'add' ) {
 136                                 $this->added( $edit->closing );
 137                         } elseif ( $edit->type == 'delete' ) {
 138                                 $this->deleted( $edit->orig );
 139                         } elseif ( $edit->type == 'change' ) {
 140                                 $this->changed( $edit->orig, $edit->closing );
 141                         } else {
 142                                 throw new MWException( "Unknown edit type: {$edit->type}" );
 143                         }
 144                 }
 145                 $this->endBlock();
 146         }
 147
 148         protected function startDiff() {
 149                 ob_start();
 150         }
 151
 152         /**
 153          * @return string
 154          */
 155         protected function endDiff() {
 156                 $val = ob_get_contents();
 157                 ob_end_clean();
 158
 159                 return $val;
 160         }
 161
 162         /**
 163          * @param int $xbeg
 164          * @param int $xlen
 165          * @param int $ybeg
 166          * @param int $ylen
 167          *
 168          * @return string
 169          */
 170         protected function blockHeader( $xbeg, $xlen, $ybeg, $ylen ) {
 171                 if ( $xlen > 1 ) {
 172                         $xbeg .= ',' . ( $xbeg + $xlen - 1 );
 173                 }
 174                 if ( $ylen > 1 ) {
 175                         $ybeg .= ',' . ( $ybeg + $ylen - 1 );
 176                 }
 177
 178                 return $xbeg . ( $xlen ? ( $ylen ? 'c' : 'd' ) : 'a' ) . $ybeg;
 179         }
 180
 181         /**
 182          * Called at the start of a block of connected edits.
 183          * This default implementation writes the header and a newline to the output buffer.
 184          *
 185          * @param string $header
 186          */
 187         protected function startBlock( $header ) {
 188                 echo $header . "\n";
 189         }
 190
 191         /**
 192          * Called at the end of a block of connected edits.
 193          * This default implementation does nothing.
 194          */
 195         protected function endBlock() {
 196         }
 197
 198         /**
 199          * Writes all (optionally prefixed) lines to the output buffer, separated by newlines.
 200          *
 201          * @param string[] $lines
 202          * @param string $prefix
 203          */
 204         protected function lines( $lines, $prefix = ' ' ) {
 205                 foreach ( $lines as $line ) {
 206                         echo "$prefix $line\n";
 207                 }
 208         }
 209
 210         /**
 211          * @param string[] $lines
 212          */
 213         protected function context( $lines ) {
 214                 $this->lines( $lines );
 215         }
 216
 217         /**
 218          * @param string[] $lines
 219          */
 220         protected function added( $lines ) {
 221                 $this->lines( $lines, '>' );
 222         }
 223
 224         /**
 225          * @param string[] $lines
 226          */
 227         protected function deleted( $lines ) {
 228                 $this->lines( $lines, '<' );
 229         }
 230
 231         /**
 232          * Writes the two sets of lines to the output buffer, separated by "---" and a newline.
 233          *
 234          * @param string[] $orig
 235          * @param string[] $closing
 236          */
 237         protected function changed( $orig, $closing ) {
 238                 $this->deleted( $orig );
 239                 echo "---\n";
 240                 $this->added( $closing );
 241         }
 242
 243 }