Myers diff algorithm

CHANGELOG.md

@@ -1,6 +1,9 @@
 CHANGE LOG
 ==========
 
+## 1.1.0 (2015-10-20)
+ - Myers’ diff
+
 ## 1.0.1 (2015-05-15)
  - Exclude test scripts in export.
 

README.md

@@ -8,6 +8,9 @@
 
 General purpose algorithms in PHP
 
+* Dijkstra
+* Myers’ diff
+
 ## Installation
 
 Use [composer](https://getcomposer.org), and add `"fisharebest/algorithm": "*"` to the dependencies in your `composer.json`.
@@ -67,7 +70,34 @@ $path = $dijkstra->shortestPaths('A', 'E'); // array(array('A', 'B', 'D', 'E'))
 $path = $dijkstra->shortestPaths('A', 'E', array('B')); // array(array('A', 'B', 'D', 'E'))
 $path = $dijkstra->shortestPaths('A', 'E', array('D')); // array(array('A', 'B', 'C', 'E'))
 $path = $dijkstra->shortestPaths('A', 'E', array('B', 'D')); // array(array('A', 'F', 'C', 'E'))
+```
 
+## Myers’ diff
 
-```
+Find the difference between two sequences of tokens (characters, words, lines, etc.) using
+“[An O(ND) Difference Algorithm and Its Variations](http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.4.6927)”
+by Eugene W. Myers.
+
+The output can be interpreted as either:
 
+* A series of instructions to transform the first sequence into the second sequence.
+* A list of matches (tokens that appear in both sequences) and mismatches (tokens that appear in
+just one sequence).
+
+``` php
+		$x = array('a', 'b', 'c', 'a', 'b', 'b', 'a');
+		$y = array('c', 'b', 'a', 'b', 'a', 'c');
+		$algorithm = new MyersDiff;
+		$diff = $algorithm->calculate($x, $y);
+		// array(
+		//  array('a', MyersDiff::DELETE),   i.e. 'a' occurs only in $x
+		//  array('b', MyersDiff::DELETE),   i.e. 'b' occurs only in $x
+		//  array('c', MyersDiff::KEEP),     i.e. 'c' occurs both $x and $y
+		//  array('b', MyersDiff::INSERT),   i.e. 'b' occurs only in $y
+		//  array('a', MyersDiff::KEEP),     i.e. 'a' occurs in both $x and $y
+		//  array('b', MyersDiff::KEEP),     i.e. 'b' occurs in both $x and $y
+		//  array('b', MyersDiff::DELETE),   i.e. 'b' occurs only in $x
+		//  array('a', MyersDiff::KEEP),     i.e. 'a' occurs in both $x and $y
+		//  array('c', MyersDiff::INSERT),   i.e. 'c' occurs only in $y
+		// );
+```

composer.json

@@ -3,7 +3,7 @@
 	"description": "Implementation of standard algorithms in PHP.",
 	"type": "library",
 	"keywords": [
-		"algorithm", "dijkstra"
+		"algorithm", "dijkstra", "myers", "diff"
 	],
 	"homepage": "https://github.com/fisharebest/algorithm",
 	"license": "GPL-3.0+",