From d1f796bf255ea92aad1070293cf41a892a8245bf Mon Sep 17 00:00:00 2001
From: Meik Sievertsen <acydburn@phpbb.com>
Date: Thu, 17 Sep 2009 14:18:57 +0000
Subject: [PATCH] phpBB updater now solves common conflicts on it's own. This
 further reduces the chance of conflicts. (tested with some heavily modified
 files who previously generated a lot of conflicts)

git-svn-id: file:///svn/phpbb/branches/phpBB-3_0_0@10160 89ea8834-ac86-4346-8a33-228a782c2dd0
---
 phpBB/docs/CHANGELOG.html    |  1 +
 phpBB/includes/diff/diff.php | 95 ++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index f79c7c7a9b..32b3548227 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -244,6 +244,7 @@
 		<li>[Change] Resize oversized Topic icons (Bug #44415)</li>
 		<li>[Change] Banned IPs are now sorted (Bug #43045 - Patch by DavidIQ)</li>
 		<li>[Change] phpBB updater now skips sole whitespace/tab changes while computing differences. This reduces the chance of conflicts tremendously.</li>
+		<li>[Change] phpBB updater now solves common conflicts on it's own. This further reduces the chance of conflicts.</li>
 		<li>[Feature] Add language selection on the registration terms page (Bug #15085 - Patch by leviatan21)</li>
 		<li>[Feature] Backported 3.2 captcha plugins.
 			<ul>
diff --git a/phpBB/includes/diff/diff.php b/phpBB/includes/diff/diff.php
index 2adc3a3e6e..d8ee43feec 100644
--- a/phpBB/includes/diff/diff.php
+++ b/phpBB/includes/diff/diff.php
@@ -727,7 +727,9 @@ class diff3_op
 			}
 			else
 			{
+				// The following tries to aggressively solve conflicts...
 				$this->_merged = false;
+				$this->solve_conflict();
 			}
 		}
 
@@ -738,6 +740,99 @@ class diff3_op
 	{
 		return ($this->merged() === false) ? true : false;
 	}
+
+	/**
+	* Tries to solve conflicts aggressively based on typical "assumptions"
+	* @author acydburn
+	*/
+	function solve_conflict()
+	{
+		$this->_merged = false;
+
+		// CASE ONE: orig changed into final2, but modified/unknown code in final1.
+		// IF orig is found "as is" in final1 we replace the code directly in final1 and populate this as final2/merge
+		if (sizeof($this->orig) && sizeof($this->final2))
+		{
+			// Ok, we basically search for $this->orig in $this->final1 and replace it with $this->final2
+			$compare_seq = sizeof($this->orig);
+
+			// Search for matching code block
+			$merge = array();
+			$merge_found = false;
+
+			// Go through the conflict code
+			for ($i = 0, $j = 0, $size = sizeof($this->final1); $i < $size; $i++, $j = $i)
+			{
+				$line = $this->final1[$i];
+				$skip = 0;
+
+				for ($x = 0; $x < $compare_seq; $x++)
+				{
+					// Try to skip all matching lines
+					if (trim($line) === trim($this->orig[$x]))
+					{
+						$line = (++$j < $size) ? $this->final1[$j] : $line;
+						$skip++;
+					}
+				}
+
+				if ($skip === $compare_seq)
+				{
+					$merge_found = true;
+					$merge = array_merge($merge, $this->final2);
+					$i += ($skip - 1);
+				}
+				else
+				{
+					$merge[] = $line;
+				}
+			}
+
+			if ($merge_found)
+			{
+				$this->final2 = $merge;
+				$this->_merged = &$this->final2;
+			}
+
+			return;
+		}
+
+		// CASE TWO: Added lines from orig to final2 but final1 had added lines too. Just merge them.
+		if (!sizeof($this->orig) && $this->final1 !== $this->final2 && sizeof($this->final1) && sizeof($this->final2))
+		{
+			$this->final2 = array_merge($this->final1, $this->final2);
+			$this->_merged = &$this->final2;
+
+			return;
+		}
+
+		// CASE THREE: Removed lines (orig has the to-remove line(s), but final1 has additional lines which does not need to be removed). Just remove orig from final1 and then use final1 as final2/merge
+		if (!sizeof($this->final2) && sizeof($this->orig) && sizeof($this->final1) && $this->orig !== $this->final1)
+		{
+			$merged = $this->final1;
+
+			foreach ($this->final1 as $i => $line)
+			{
+				foreach ($this->orig as $j => $old_line)
+				{
+					if (trim($line) === trim($old_line))
+					{
+						unset($merged[$i]);
+					}
+				}
+			}
+
+			if (sizeof($merged))
+			{
+				$this->final2 = array_values($merged);
+				$this->_merged = &$this->final2;
+			}
+
+			return;
+		}
+
+		return;
+	}
 }
 
 /**