MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / includes / 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
 */

/**
 * 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
         *
         * @throws MWException If the edit type is not known.
         */
        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, $edit->closing );
                        } else {
                                throw new MWException( "Unknown edit type: {$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 );
        }

}