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         /** @var string The output buffer; holds the output while it is built. */
  53         private $result = '';
  54
  55         /**
  56          * Format a diff.
  57          *
  58          * @param Diff $diff
  59          *
  60          * @return string The formatted output.
  61          */
  62         public function format( $diff ) {
  63                 $xi = $yi = 1;
  64                 $block = false;
  65                 $context = [];
  66
  67                 $nlead = $this->leadingContextLines;
  68                 $ntrail = $this->trailingContextLines;
  69
  70                 $this->startDiff();
  71
  72                 // Initialize $x0 and $y0 to prevent IDEs from getting confused.
  73                 $x0 = $y0 = 0;
  74                 foreach ( $diff->edits as $edit ) {
  75                         if ( $edit->type == 'copy' ) {
  76                                 if ( is_array( $block ) ) {
  77                                         if ( count( $edit->orig ) <= $nlead + $ntrail ) {
  78                                                 $block[] = $edit;
  79                                         } else {
  80                                                 if ( $ntrail ) {
  81                                                         $context = array_slice( $edit->orig, 0, $ntrail );
  82                                                         $block[] = new DiffOpCopy( $context );
  83                                                 }
  84                                                 $this->block( $x0, $ntrail + $xi - $x0,
  85                                                         $y0, $ntrail + $yi - $y0,
  86                                                         $block );
  87                                                 $block = false;
  88                                         }
  89                                 }
  90                                 $context = $edit->orig;
  91                         } else {
  92                                 if ( !is_array( $block ) ) {
  93                                         $context = array_slice( $context, count( $context ) - $nlead );
  94                                         $x0 = $xi - count( $context );
  95                                         $y0 = $yi - count( $context );
  96                                         $block = [];
  97                                         if ( $context ) {
  98                                                 $block[] = new DiffOpCopy( $context );
  99                                         }
 100                                 }
 101                                 $block[] = $edit;
 102                         }
 103
 104                         if ( $edit->orig ) {
 105                                 $xi += count( $edit->orig );
 106                         }
 107                         if ( $edit->closing ) {
 108                                 $yi += count( $edit->closing );
 109                         }
 110                 }
 111
 112                 if ( is_array( $block ) ) {
 113                         $this->block( $x0, $xi - $x0,
 114                                 $y0, $yi - $y0,
 115                                 $block );
 116                 }
 117
 118                 $end = $this->endDiff();
 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                 $this->startBlock( $this->blockHeader( $xbeg, $xlen, $ybeg, $ylen ) );
 134                 foreach ( $edits as $edit ) {
 135                         if ( $edit->type == 'copy' ) {
 136                                 $this->context( $edit->orig );
 137                         } elseif ( $edit->type == 'add' ) {
 138                                 $this->added( $edit->closing );
 139                         } elseif ( $edit->type == 'delete' ) {
 140                                 $this->deleted( $edit->orig );
 141                         } elseif ( $edit->type == 'change' ) {
 142                                 $this->changed( $edit->orig, $edit->closing );
 143                         } else {
 144                                 throw new MWException( "Unknown edit type: {$edit->type}" );
 145                         }
 146                 }
 147                 $this->endBlock();
 148         }
 149
 150         protected function startDiff() {
 151                 $this->result = '';
 152         }
 153
 154         /**
 155          * Writes a string to the output buffer.
 156          *
 157          * @param string $text
 158          */
 159         protected function writeOutput( $text ) {
 160                 $this->result .= $text;
 161         }
 162
 163         /**
 164          * @return string
 165          */
 166         protected function endDiff() {
 167                 $val = $this->result;
 168                 $this->result = '';
 169
 170                 return $val;
 171         }
 172
 173         /**
 174          * @param int $xbeg
 175          * @param int $xlen
 176          * @param int $ybeg
 177          * @param int $ylen
 178          *
 179          * @return string
 180          */
 181         protected function blockHeader( $xbeg, $xlen, $ybeg, $ylen ) {
 182                 if ( $xlen > 1 ) {
 183                         $xbeg .= ',' . ( $xbeg + $xlen - 1 );
 184                 }
 185                 if ( $ylen > 1 ) {
 186                         $ybeg .= ',' . ( $ybeg + $ylen - 1 );
 187                 }
 188
 189                 return $xbeg . ( $xlen ? ( $ylen ? 'c' : 'd' ) : 'a' ) . $ybeg;
 190         }
 191
 192         /**
 193          * Called at the start of a block of connected edits.
 194          * This default implementation writes the header and a newline to the output buffer.
 195          *
 196          * @param string $header
 197          */
 198         protected function startBlock( $header ) {
 199                 $this->writeOutput( $header . "\n" );
 200         }
 201
 202         /**
 203          * Called at the end of a block of connected edits.
 204          * This default implementation does nothing.
 205          */
 206         protected function endBlock() {
 207         }
 208
 209         /**
 210          * Writes all (optionally prefixed) lines to the output buffer, separated by newlines.
 211          *
 212          * @param string[] $lines
 213          * @param string $prefix
 214          */
 215         protected function lines( $lines, $prefix = ' ' ) {
 216                 foreach ( $lines as $line ) {
 217                         $this->writeOutput( "$prefix $line\n" );
 218                 }
 219         }
 220
 221         /**
 222          * @param string[] $lines
 223          */
 224         protected function context( $lines ) {
 225                 $this->lines( $lines );
 226         }
 227
 228         /**
 229          * @param string[] $lines
 230          */
 231         protected function added( $lines ) {
 232                 $this->lines( $lines, '>' );
 233         }
 234
 235         /**
 236          * @param string[] $lines
 237          */
 238         protected function deleted( $lines ) {
 239                 $this->lines( $lines, '<' );
 240         }
 241
 242         /**
 243          * Writes the two sets of lines to the output buffer, separated by "---" and a newline.
 244          *
 245          * @param string[] $orig
 246          * @param string[] $closing
 247          */
 248         protected function changed( $orig, $closing ) {
 249                 $this->deleted( $orig );
 250                 $this->writeOutput( "---\n" );
 251                 $this->added( $closing );
 252         }
 253
 254 }