Add statistics function for #97

Author: JBlond

example/example.php

@@ -72,8 +72,13 @@ function changeCSS(cssFile, cssLinkIndex) {
     <h2>Informational</h2>
     Between the two versions, there's a
     <?php
+    $stats = $diff->getStatistics();
     echo round($diff->getSimilarity(), 2) * 100;
-    ?>% match.
+    ?>% match.<br>
+    Inserted lines: <?php echo $stats['inserted']; ?><br>
+    Deleted lines: <?php echo $stats['deleted']; ?><br>
+    Not modified lines: <?php echo $stats['notModified']; ?><br>
+    Lines with replacement: <?php echo $stats['replaced']; ?><br>
 </aside>
 <hr>
 

lib/jblond/Diff.php

@@ -287,4 +287,15 @@ public function getSimilarity(int $method = Similarity::CALC_DEFAULT): float
 
         return $this->similarity;
     }
+
+    /**
+     * Get diff statistics
+     *
+     * @return array
+     */
+    public function getStatistics(): array
+    {
+        $similarity = new Similarity($this->version1, $this->version2, $this->options);
+        return $similarity->getDifference();
+    }
 }

lib/jblond/Diff/Similarity.php

@@ -223,4 +223,39 @@ private function ratioReduce(int $sum, array $triple): int
     {
         return $sum + ($triple[count($triple) - 1]);
     }
+
+    /**
+     * Get diff statistics
+     *
+     * @return array
+     */
+    public function getDifference(): array
+    {
+        $return = [
+            'inserted'     => 0,
+            'deleted'      => 0,
+            'notModified'  => 0,
+            'replaced'     => 0,
+        ];
+
+        foreach ($this->getGroupedOpCodes() as $chunk) {
+            foreach ($chunk as [$string, $one, $two, $three, $four]) {
+                switch ($string) {
+                    case 'delete':
+                        $return['deleted'] += $two - $one;
+                        break;
+                    case 'insert':
+                        $return['inserted'] += $four - $three;
+                        break;
+                    case 'replace':
+                        $return['replaced'] += $two - $one;
+                        break;
+                }
+            }
+        }
+
+        $return['notModified'] = count($this->old) - $return['replaced'] - $return['deleted'];
+
+        return $return;
+    }
 }

tests/Diff/SequenceMatcherTest.php

@@ -2,7 +2,6 @@
 
 namespace Tests\Diff;
 
-use jblond\Diff\ConstantsInterface;
 use jblond\Diff\SequenceMatcher;
 use PHPUnit\Framework\TestCase;
 

tests/Diff/SimilarityTest.php

@@ -31,4 +31,21 @@ public function testGetSimilarity(): void
         $this->assertEquals(2 / 3, $similarity->getSimilarity(Similarity::CALC_FAST));
         $this->assertEquals(2 / 3, $similarity->getSimilarity(Similarity::CALC_FASTEST));
     }
+
+    /**
+     * Test the statistics function
+     */
+    public function testGetDifference(): void
+    {
+        $similarity = new Similarity(range(0, 10), range(1, 23));
+        $this->assertEquals(
+            [
+                'inserted'    => 13,
+                'deleted'     => 1,
+                'notModified' => 10,
+                'replaced'    => 0,
+            ],
+            $similarity->getDifference()
+        );
+    }
 }