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Text/Diff/Engine/shell.php

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+<?php
+/**
+ * Class used internally by Diff to actually compute the diffs.
+ *
+ * This class uses the Unix `diff` program via shell_exec to compute the
+ * differences between the two input arrays.
+ *
+ * $Horde: framework/Text_Diff/Diff/Engine/shell.php,v 1.6.2.4 2009/01/06 15:23:41 jan Exp $
+ *
+ * Copyright 2007-2009 The Horde Project (http://www.horde.org/)
+ *
+ * See the enclosed file COPYING for license information (LGPL). If you did
+ * not receive this file, see http://opensource.org/licenses/lgpl-license.php.
+ *
+ * @author  Milian Wolff <[email protected]>
+ * @package Text_Diff
+ * @since   0.3.0
+ */
+class Text_Diff_Engine_shell {
+
+    /**
+     * Path to the diff executable
+     *
+     * @var string
+     */
+    var $_diffCommand = 'diff';
+
+    /**
+     * Returns the array of differences.
+     *
+     * @param array $from_lines lines of text from old file
+     * @param array $to_lines   lines of text from new file
+     *
+     * @return array all changes made (array with Text_Diff_Op_* objects)
+     */
+    function diff($from_lines, $to_lines)
+    {
+        array_walk($from_lines, array('Text_Diff', 'trimNewlines'));
+        array_walk($to_lines, array('Text_Diff', 'trimNewlines'));
+
+        $temp_dir = Text_Diff::_getTempDir();
+
+        // Execute gnu diff or similar to get a standard diff file.
+        $from_file = tempnam($temp_dir, 'Text_Diff');
+        $to_file = tempnam($temp_dir, 'Text_Diff');
+        $fp = fopen($from_file, 'w');
+        fwrite($fp, implode("\n", $from_lines));
+        fclose($fp);
+        $fp = fopen($to_file, 'w');
+        fwrite($fp, implode("\n", $to_lines));
+        fclose($fp);
+        $diff = shell_exec($this->_diffCommand . ' ' . $from_file . ' ' . $to_file);
+        unlink($from_file);
+        unlink($to_file);
+
+        if (is_null($diff)) {
+            // No changes were made
+            return array(new Text_Diff_Op_copy($from_lines));
+        }
+
+        $from_line_no = 1;
+        $to_line_no = 1;
+        $edits = array();
+
+        // Get changed lines by parsing something like:
+        // 0a1,2
+        // 1,2c4,6
+        // 1,5d6
+        preg_match_all('#^(\d+)(?:,(\d+))?([adc])(\d+)(?:,(\d+))?$#m', $diff,
+            $matches, PREG_SET_ORDER);
+
+        foreach ($matches as $match) {
+            if (!isset($match[5])) {
+                // This paren is not set every time (see regex).
+                $match[5] = false;
+            }
+
+            if ($match[3] == 'a') {
+                $from_line_no--;
+            }
+
+            if ($match[3] == 'd') {
+                $to_line_no--;
+            }
+
+            if ($from_line_no < $match[1] || $to_line_no < $match[4]) {
+                // copied lines
+                assert('$match[1] - $from_line_no == $match[4] - $to_line_no');
+                array_push($edits,
+                    new Text_Diff_Op_copy(
+                        $this->_getLines($from_lines, $from_line_no, $match[1] - 1),
+                        $this->_getLines($to_lines, $to_line_no, $match[4] - 1)));
+            }
+
+            switch ($match[3]) {
+            case 'd':
+                // deleted lines
+                array_push($edits,
+                    new Text_Diff_Op_delete(
+                        $this->_getLines($from_lines, $from_line_no, $match[2])));
+                $to_line_no++;
+                break;
+
+            case 'c':
+                // changed lines
+                array_push($edits,
+                    new Text_Diff_Op_change(
+                        $this->_getLines($from_lines, $from_line_no, $match[2]),
+                        $this->_getLines($to_lines, $to_line_no, $match[5])));
+                break;
+
+            case 'a':
+                // added lines
+                array_push($edits,
+                    new Text_Diff_Op_add(
+                        $this->_getLines($to_lines, $to_line_no, $match[5])));
+                $from_line_no++;
+                break;
+            }
+        }
+
+        if (!empty($from_lines)) {
+            // Some lines might still be pending. Add them as copied
+            array_push($edits,
+                new Text_Diff_Op_copy(
+                    $this->_getLines($from_lines, $from_line_no,
+                                     $from_line_no + count($from_lines) - 1),
+                    $this->_getLines($to_lines, $to_line_no,
+                                     $to_line_no + count($to_lines) - 1)));
+        }
+
+        return $edits;
+    }
+
+    /**
+     * Get lines from either the old or new text
+     *
+     * @access private
+     *
+     * @param array &$text_lines Either $from_lines or $to_lines
+     * @param int   &$line_no    Current line number
+     * @param int   $end         Optional end line, when we want to chop more
+     *                           than one line.
+     *
+     * @return array The chopped lines
+     */
+    function _getLines(&$text_lines, &$line_no, $end = false)
+    {
+        if (!empty($end)) {
+            $lines = array();
+            // We can shift even more
+            while ($line_no <= $end) {
+                array_push($lines, array_shift($text_lines));
+                $line_no++;
+            }
+        } else {
+            $lines = array(array_shift($text_lines));
+            $line_no++;
+        }
+
+        return $lines;
+    }
+
+}