some diff engine updates (only minor, but will hopefully not break anything)

git-svn-id: file:///svn/phpbb/branches/phpBB-3_0_0@8692 89ea8834-ac86-4346-8a33-228a782c2dd0

phpBB/includes/diff/diff.php

@@ -17,7 +17,7 @@ if (!defined('IN_PHPBB'))
 }
 
 /**
-* Code from pear.php.net, Text_Diff-0.2.1 (beta) package
+* Code from pear.php.net, Text_Diff-1.0.0 package
 * http://pear.php.net/package/Text_Diff/
 *
 * Modified by phpBB Group to meet our coding standards
@@ -26,6 +26,9 @@ if (!defined('IN_PHPBB'))
 * General API for generating and formatting diffs - the differences between
 * two sequences of strings.
 *
+* Copyright 2004 Geoffrey T. Dairiki <dairiki@dairiki.org>
+* Copyright 2004-2008 The Horde Project (http://www.horde.org/)
+*
 * @package diff
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 */
@@ -45,7 +48,7 @@ class diff
 	*/
 	function diff(&$from_content, &$to_content, $preserve_cr = true)
 	{
-		$diff_engine = &new diff_engine();
+		$diff_engine = new diff_engine();
 		$this->_edits = $diff_engine->diff($from_content, $to_content, $preserve_cr);
 	}
 
@@ -62,7 +65,7 @@ class diff
 	*
 	* Example:
 	* <code>
-	* $diff = &new diff($lines1, $lines2);
+	* $diff = new diff($lines1, $lines2);
 	* $rev = $diff->reverse();
 	* </code>
 	*
@@ -285,7 +288,7 @@ class diff_op
 	var $orig;
 	var $final;
 
-	function reverse()
+	function &reverse()
 	{
 		trigger_error('[diff] Abstract method', E_USER_ERROR);
 	}
@@ -413,7 +416,7 @@ class diff3 extends diff
 	*/
 	function diff3(&$orig, &$final1, &$final2)
 	{
-		$diff_engine = &new diff_engine();
+		$diff_engine = new diff_engine();
 
 		$diff_1 = $diff_engine->diff($orig, $final1);
 		$diff_2 = $diff_engine->diff($orig, $final2);
@@ -548,7 +551,7 @@ class diff3 extends diff
 	function _diff3(&$edits1, &$edits2)
 	{
 		$edits = array();
-		$bb = &new diff3_block_builder();
+		$bb = new diff3_block_builder();
 
 		$e1 = current($edits1);
 		$e2 = current($edits2);
@@ -565,7 +568,7 @@ class diff3 extends diff
 				}
 
 				$ncopy = min($e1->norig(), $e2->norig());
-				$edits[] = &new diff3_op_copy(array_slice($e1->orig, 0, $ncopy));
+				$edits[] = new diff3_op_copy(array_slice($e1->orig, 0, $ncopy));
 
 				if ($e1->norig() > $ncopy)
 				{
@@ -759,7 +762,7 @@ class diff3_block_builder
 		}
 		else
 		{
-			$edit = &new diff3_op($this->orig, $this->final1, $this->final2);
+			$edit = new diff3_op($this->orig, $this->final1, $this->final2);
 			$this->_init();
 			return $edit;
 		}

phpBB/includes/diff/engine.php

@@ -17,21 +17,20 @@ if (!defined('IN_PHPBB'))
 }
 
 /**
-* Code from pear.php.net, Text_Diff-0.2.1 (beta) package
+* Code from pear.php.net, Text_Diff-1.0.0 package
-* http://pear.php.net/package/Text_Diff/
+* http://pear.php.net/package/Text_Diff/ (native engine)
 *
 * Modified by phpBB Group to meet our coding standards
 * and being able to integrate into phpBB
 *
-* Class used internally by Diff to actually compute the diffs.  This class is
+* Class used internally by Text_Diff to actually compute the diffs. This
-* implemented using native PHP code.
+* class is implemented using native PHP code.
 *
 * The algorithm used here is mostly lifted from the perl module
 * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 * http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 *
-* More ideas are taken from:
+* More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html
-* http://www.ics.uci.edu/~eppstein/161/960229.html
 *
 * Some ideas (and a bit of code) are taken from analyze.c, of GNU
 * diffutils-2.7, which can be found at:
@@ -41,6 +40,8 @@ if (!defined('IN_PHPBB'))
 * Geoffrey T. Dairiki <dairiki@dairiki.org>. The original PHP version of this
 * code was written by him, and is used/adapted with his permission.
 *
+* Copyright 2004-2008 The Horde Project (http://www.horde.org/)
+*
 * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
 * @package diff
 *
@@ -251,7 +252,7 @@ class diff_engine
 				}
 			}
 
-			$x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
+			$x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $chunk) / $nchunks);
 
 			for (; $x < $x1; $x++)
 			{
@@ -262,7 +263,8 @@ class diff_engine
 				}
 				$matches = $ymatches[$line];
 
-				foreach ($matches as $y)
+				reset($matches);
+				while (list(, $y) = each($matches))
 				{
 					if (empty($this->in_seq[$y]))
 					{
@@ -273,7 +275,7 @@ class diff_engine
 				}
 
 				// no reset() here
-				while (list($junk, $y) = each($matches))
+				while (list(, $y) = each($matches))
 				{
 					if ($y > $this->seq[$k - 1])
 					{

phpBB/includes/diff/renderer.php

@@ -17,7 +17,7 @@ if (!defined('IN_PHPBB'))
 }
 
 /**
-* Code from pear.php.net, Text_Diff-0.2.1 (beta) package
+* Code from pear.php.net, Text_Diff-1.0.0 package
 * http://pear.php.net/package/Text_Diff/
 *
 * Modified by phpBB Group to meet our coding standards
@@ -28,6 +28,8 @@ if (!defined('IN_PHPBB'))
 * This class renders the diff in classic diff format. It is intended that
 * this class be customized via inheritance, to obtain fancier outputs.
 *
+* Copyright 2004-2008 The Horde Project (http://www.horde.org/)
+*
 * @package diff
 */
 class diff_renderer
@@ -105,7 +107,7 @@ class diff_renderer
 
 			unset($diff3);
 
-			$diff = &new diff($diff_1, $diff_2);
+			$diff = new diff($diff_1, $diff_2);
 		}
 
 		$nlead = $this->_leading_context_lines;
@@ -116,19 +118,24 @@ class diff_renderer
 
 		foreach ($diffs as $i => $edit)
 		{
+			// If these are unchanged (copied) lines, and we want to keep leading or trailing context lines, extract them from the copy block.
 			if (is_a($edit, 'diff_op_copy'))
 			{
+				// Do we have any diff blocks yet?
 				if (is_array($block))
 				{
+					// How many lines to keep as context from the copy block.
 					$keep = ($i == sizeof($diffs) - 1) ? $ntrail : $nlead + $ntrail;
 					if (sizeof($edit->orig) <= $keep)
 					{
+						// We have less lines in the block than we want for context => keep the whole block.
 						$block[] = $edit;
 					}
 					else
 					{
 						if ($ntrail)
 						{
+							// Create a new block with as many lines as we need for the trailing context.
 							$context = array_slice($edit->orig, 0, $ntrail);
 							$block[] = &new diff_op_copy($context);
 						}
@@ -137,12 +144,15 @@ class diff_renderer
 						$block = false;
 					}
 				}
+				// Keep the copy block as the context for the next block.
 				$context = $edit->orig;
 			}
 			else
 			{
+				// Don't we have any diff blocks yet?
 				if (!is_array($block))
 				{
+					// Extract context lines from the preceding copy block.
 					$context = array_slice($context, sizeof($context) - $nlead);
 					$x0 = $xi - sizeof($context);
 					$y0 = $yi - sizeof($context);
@@ -219,6 +229,16 @@ class diff_renderer
 			$ybeg .= ',' . ($ybeg + $ylen - 1);
 		}
 
+		// this matches the GNU Diff behaviour
+		if ($xlen && !$ylen)
+		{
+			$ybeg--;
+		}
+		else if (!$xlen)
+		{
+			$xbeg--;
+		}
+
 		return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
 	}
 
@@ -449,11 +469,11 @@ class diff_renderer_inline extends diff_renderer
 		$splitted_text_1 = $this->_split_on_words($text1, $nl);
 		$splitted_text_2 = $this->_split_on_words($text2, $nl);
 
-		$diff = &new diff($splitted_text_1, $splitted_text_2);
+		$diff = new diff($splitted_text_1, $splitted_text_2);
 		unset($splitted_text_1, $splitted_text_2);
 
 		// Get the diff in inline format.
-		$renderer = &new diff_renderer_inline(array_merge($this->get_params(), array('split_level' => 'words')));
+		$renderer = new diff_renderer_inline(array_merge($this->get_params(), array('split_level' => 'words')));
 
 		// Run the diff and get the output.
 		return str_replace($nl, "\n", $renderer->render($diff)) . "\n";