each

composer.json

@@ -41,6 +41,7 @@
             "src/reduce.php",
             "src/take.php",
             "src/flatten.php",
+            "src/each.php",
             "src/until.php"
         ]
     },

src/Transducer/Each.php

@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * This file is part of the camille-hdl/lazy-lists library
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @copyright Copyright (c) Camille Hodoul <[email protected]>
+ * @license http://opensource.org/licenses/MIT MIT
+ */
+
+declare(strict_types=1);
+
+namespace LazyLists\Transducer;
+
+class Each extends PureTransducer implements TransducerInterface
+{
+    /**
+     * Applies $sideEffect to each $item, but does not change the $item itself
+     *
+     * @var callable
+     */
+    protected $sideEffect;
+
+    public function __construct(callable $sideEffect)
+    {
+        $this->sideEffect = $sideEffect;
+    }
+
+    public function computeNextResult($item)
+    {
+        $sideEffect = $this->sideEffect;
+        $sideEffect($item);
+        $this->iterator->yieldToNextTransducer($item);
+    }
+
+    public function getEmptyFinalResult()
+    {
+        return [];
+    }
+
+    public function computeFinalResult($previousResult, $lastValue)
+    {
+        if (\is_null($previousResult)) {
+            return [];
+        }
+        $previousResult[] = $lastValue;
+        return $previousResult;
+    }
+}

src/each.php

@@ -0,0 +1,38 @@
+<?php
+
+/**
+ * This file is part of the camille-hdl/lazy-lists library
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * @copyright Copyright (c) Camille Hodoul <[email protected]>
+ * @license   http://opensource.org/licenses/MIT MIT
+ */
+
+declare(strict_types=1);
+
+namespace LazyLists;
+
+use LazyLists\Exception\InvalidArgumentException;
+
+/**
+ * Calls `$sideEffect` on each element in `$list`.
+ * If $list is omitted, returns a Transducer to be used with `pipe()` instead.
+ *
+ * @param callable $sideEffect
+ * @param array|\Traversable|null $list
+ * @see \LazyLists\Transducer\Map
+ * @return mixed void or \LazyLists\Transducer\Map
+ */
+function each(callable $sideEffect, $list = null)
+{
+    if (\is_null($list)) {
+        return new \LazyLists\Transducer\Each($sideEffect);
+    }
+
+    InvalidArgumentException::assertCollection($list, __FUNCTION__, 2);
+    foreach ($list as $key => $item) {
+        $sideEffect($item, $key);
+    }
+}

tests/EachTest.php

@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LazyLists\Test;
+
+use function LazyLists\each;
+
+class EachTest extends TestCase
+{
+    public function test()
+    {
+
+        $list = ['value', 'value'];
+        $c = 0;
+        $fn = function ($v) use (&$c) {
+            $c++;
+        };
+        each($fn, $list);
+        $this->assertEquals(2, $c);
+    }
+
+    public function testPassNoCollection()
+    {
+        $this->expectException(\Exception::class);
+        each(function () {
+            return;
+        }, 'invalidCollection');
+    }
+
+    public function testPassNonCallable()
+    {
+        $this->expectException(\TypeError::class);
+        each('notACallable', []);
+    }
+}

tests/PipeTest.php

@@ -12,6 +12,8 @@
 use function LazyLists\flatten;
 use function LazyLists\reduce;
 use function LazyLists\take;
+use function LazyLists\each;
+use function LazyLists\until;
 
 /**
  * "integration" tests
@@ -195,4 +197,23 @@ public function testRealUseCase()
         $this->assertEquals(7, $sup_count);
         $this->assertEquals(3, $sum_count);
     }
+
+    public function testFlattenEachUntil()
+    {
+        $list = [
+            [1, 2],
+            [3, 4]
+        ];
+        $c = 0;
+        $pipe = pipe(
+            flatten(1),
+            each(function ($v) use (&$c) {
+                $c = $c + $v;
+            }),
+            until(function ($v) use (&$c) {
+                return $c > 6;
+            })
+        );
+        $this->assertSame([1, 2, 3], $pipe($list));
+    }
 }

tests/Transducer/EachTest.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LazyLists\Test\Transducer;
+
+use LazyLists\Test\TestCase;
+
+use function LazyLists\each;
+use function LazyLists\filter;
+use function LazyLists\pipe;
+
+class EachTest extends TestCase
+{
+    public function test()
+    {
+        $log = [];
+        $logValue = each(function ($v) use (&$log) {
+            $log[] = $v;
+        });
+        $pipe2 = pipe($logValue);
+        $this->assertSame([1, 2, 3], $pipe2([1, 2, 3]));
+    }
+}