Providing Pipe Function see #141

composer.json

@@ -87,6 +87,7 @@
             "src/Functional/PartialRight.php",
             "src/Functional/Partition.php",
             "src/Functional/Pick.php",
+            "src/Functional/Pipe.php",
             "src/Functional/Pluck.php",
             "src/Functional/Poll.php",
             "src/Functional/Product.php",

src/Functional/Functional.php

@@ -14,7 +14,7 @@ final class Functional
 {
 
     /**
-     * @see \Function\ary
+     * @see \Functional\ary
      */
     const ary = '\Functional\ary';
 
@@ -333,6 +333,11 @@ final class Functional
      */
     const pick = '\Functional\pick';
 
+    /**
+     * @see \Functional\pipe
+     */
+    const pipe = '\Functional\pipe';
+
     /**
      * @see \Functional\pluck
      */

src/Functional/Pipe.php

@@ -0,0 +1,80 @@
+<?php
+
+/**
+ * Copyright (C) 2019, 2020 by Jesus Franco Martinez <tezcatl@fedoraproject.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+namespace Functional;
+
+use Functional\Exceptions\InvalidArgumentException;
+
+/**
+ * Provides a functor that applies the functions passed at construction
+ * from left to right, first function is able to admit several arguments
+ * at once.
+ *
+ * @link https://github.com/lstrojny/functional-php/issues/141
+ * @param callable[] ...$functions functions to be composed
+ * @return callable
+ */
+function pipe(...$functions): callable
+{
+    return new Pipe($functions);
+}
+
+class Pipe
+{
+    /** @var callable[] */
+    protected $callables;
+
+    protected $carry;
+
+    protected $pipeLength = 0;
+
+    public function __construct(array $functions)
+    {
+        $this->pipeLength = \count($functions);
+        if ($this->pipeLength < 2) {
+            throw new InvalidArgumentException(
+                'You should pass at least 2 functions or functors to build a pipe'
+            );
+        }
+        foreach ($functions as $index => $callable) {
+            InvalidArgumentException::assertCallback($callable, 'pipe', $index + 1);
+            $this->callables[] = $callable;
+        }
+    }
+
+    public function __invoke()
+    {
+        $funArgs = \func_get_args();
+        $this->carry = \call_user_func_array($this->callables[0], $funArgs);
+
+        for ($index = 1; $index < $this->pipeLength; $index++) {
+            $this->carry = \call_user_func(
+                $this->callables[$index],
+                $this->carry
+            );
+        }
+
+        return $this->carry;
+    }
+}

tests/Functional/FunctionalTest.php

@@ -24,7 +24,7 @@ public function testAllDefinedConstantsAreValidCallables()
         $functions = $functionalClass->getConstants();
 
         foreach ($functions as $function) {
-            $this->assertInternalType('callable', $function);
+            $this->assertIsCallable($function);
         }
     }
 

tests/Functional/PipeTest.php

@@ -0,0 +1,107 @@
+<?php
+
+/**
+ * Copyright (C) 2019, 2020 by Jesus Franco Martinez <tezcatl@fedoraproject.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+namespace Functional\Tests;
+
+use Functional\Exceptions\InvalidArgumentException;
+
+use function Functional\pipe;
+
+class PipeTest extends AbstractTestCase
+{
+    public function testPipeFunction()
+    {
+        $mockFirst = $this->getClosureMock(1, ['o', 'n', 'e'], 'one');
+        $mockSecond = $this->getClosureMock(1, ['one'], 'one, two');
+        $mockThird = $this->getClosureMock(1, ['one, two'], 'one, two, three');
+
+        $result = pipe(
+            $mockFirst,
+            $mockSecond,
+            $mockThird
+        )('o', 'n', 'e');
+
+        $this->assertEquals('one, two, three', $result);
+    }
+
+    public function testShouldNotAcceptSingleFunction()
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('You should pass at least 2 functions or functors to build a pipe');
+        pipe('strval')();
+    }
+
+    /** @dataProvider notQuiteFunctionsProvider */
+    public function testExceptionNotCallable($maybeFun1, $maybeFun2, $expectedException)
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage($expectedException);
+        pipe($maybeFun1, $maybeFun2)();
+    }
+
+    public function notQuiteFunctionsProvider()
+    {
+        return [
+          [
+            'strval',
+            '__not',
+            'pipe() expects parameter 2 to be a valid callback, ' .
+            'function \'__not\' not found or invalid function name'
+          ],
+          [
+            'runabout',
+            'intval',
+            'pipe() expects parameter 1 to be a valid callback, ' .
+            'function \'runabout\' not found or invalid function name'
+          ]
+        ];
+    }
+
+    private function getClosureMock(
+        int $invocations,
+        array $expectedArguments,
+        $mustReturnValue
+    ) {
+        $mock = $this->getMockBuilder(CustomTestClosure::class)
+          ->getMock();
+
+        $argsArray = [];
+        for ($index = 0; $index < count($expectedArguments); $index++) {
+            $argsArray[] = $this->equalTo($expectedArguments[$index]);
+        }
+
+        $mock->expects($this->exactly($invocations))
+            ->method('__invoke')
+            ->withConsecutive($argsArray)
+            ->willReturn($mustReturnValue);
+        return $mock;
+    }
+}
+
+class CustomTestClosure
+{
+    public function __invoke()
+    {
+    }
+}