[5.4] Faster implementation for Arr::crossJoin() (#19864)

* Faster implementation for Arr::crossJoin() * Stricter tests, for the internal ordering of the resulting arrays * Update Arr.php
laravel · Jul 2, 2017 · 73f8da3 · 73f8da3
1 parent d29f5eb
commit 73f8da3
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Showing 2 changed files with 32 additions and 12 deletions.
diff --git a/src/Illuminate/Support/Arr.php b/src/Illuminate/Support/Arr.php
@@ -69,13 +69,23 @@ public static function collapse($array)
      */
     public static function crossJoin(...$arrays)
     {
-        return array_reduce($arrays, function ($results, $array) {
-            return static::collapse(array_map(function ($parent) use ($array) {
-                return array_map(function ($item) use ($parent) {
-                    return array_merge($parent, [$item]);
-                }, $array);
-            }, $results));
-        }, [[]]);
+        $results = [[]];
+
+        foreach ($arrays as $index => $array) {
+            $append = [];
+
+            foreach ($results as $product) {
+                foreach ($array as $item) {
+                    $product[$index] = $item;
+
+                    $append[] = $product;
+                }
+            }
+
+            $results = $append;
+        }
+
+        return $results;
     }
 
     /**

diff --git a/tests/Support/SupportArrTest.php b/tests/Support/SupportArrTest.php
@@ -39,25 +39,25 @@ public function testCollapse()
     public function testCrossJoin()
     {
         // Single dimension
-        $this->assertEquals(
+        $this->assertSame(
             [[1, 'a'], [1, 'b'], [1, 'c']],
             Arr::crossJoin([1], ['a', 'b', 'c'])
         );
 
         // Square matrix
-        $this->assertEquals(
+        $this->assertSame(
             [[1, 'a'], [1, 'b'], [2, 'a'], [2, 'b']],
             Arr::crossJoin([1, 2], ['a', 'b'])
         );
 
         // Rectangular matrix
-        $this->assertEquals(
+        $this->assertSame(
             [[1, 'a'], [1, 'b'], [1, 'c'], [2, 'a'], [2, 'b'], [2, 'c']],
             Arr::crossJoin([1, 2], ['a', 'b', 'c'])
         );
 
         // 3D matrix
-        $this->assertEquals(
+        $this->assertSame(
             [
                 [1, 'a', 'I'], [1, 'a', 'II'], [1, 'a', 'III'],
                 [1, 'b', 'I'], [1, 'b', 'II'], [1, 'b', 'III'],
@@ -68,7 +68,17 @@ public function testCrossJoin()
         );
 
         // With 1 empty dimension
-        $this->assertEquals([], Arr::crossJoin([1, 2], [], ['I', 'II', 'III']));
+        $this->assertSame([], Arr::crossJoin([], ['a', 'b'], ['I', 'II', 'III']));
+        $this->assertSame([], Arr::crossJoin([1, 2], [], ['I', 'II', 'III']));
+        $this->assertSame([], Arr::crossJoin([1, 2], ['a', 'b'], []));
+
+        // With empty arrays
+        $this->assertSame([], Arr::crossJoin([], [], []));
+        $this->assertSame([], Arr::crossJoin([], []));
+        $this->assertSame([], Arr::crossJoin([]));
+
+        // Not really a proper usage, still, test for preserving BC
+        $this->assertSame([[]], Arr::crossJoin());
     }
 
     public function testDivide()