Merge pull request #5 from lstrojny/feature/partial_right

Implement bind_right()

README.md

@@ -111,10 +111,27 @@ $add = function ($a, $b) {
 
 $addOne = Partial\bind($add, 1);
 
-echo sprintf("%s\n", $addOne(5));
+echo sprintf("%d\n", $addOne(5));
 // outputs 6
 ```
 
+### bind_right
+
+```php
+<?php
+
+use React\Partial;
+
+$div = function ($a, $b, $c) {
+    return $a / $b / $c;
+};
+
+$addOne = Partial\bind_right($add, 20, 10);
+
+echo sprintf("%F\n", $addOne(100)); // 100 / 20 / 10
+// outputs 0.5
+```
+
 ### placeholder
 
 It is possible to use the `…` function (there is an alias called

src/React/Partial/Util.php

@@ -6,9 +6,11 @@ final class Util
 {
     public static function bind(/*$fn, $args...*/)
     {
-        $args = func_get_args();
-        $fn = array_shift($args);
-
         return call_user_func_array('React\Partial\bind', func_get_args());
     }
+
+    public static function bindRight(/*$fn, $args...*/)
+    {
+        return call_user_func_array('React\Partial\bind_right', func_get_args());
+    }
 }

src/React/Partial/functions.php

@@ -2,42 +2,58 @@
 
 namespace React\Partial;
 
-use React\Partial\Placeholder;
-
 function bind(/*$fn, $args...*/)
 {
     $args = func_get_args();
     $fn = array_shift($args);
 
     return function () use ($fn, $args) {
-        return call_user_func_array($fn, mergeParameters($args, func_get_args()));
+        return call_user_func_array($fn, mergeLeft($args, func_get_args()));
+    };
+}
+
+function bind_right(/*$fn, $args...*/)
+{
+    $args = func_get_args();
+    $fn = array_shift($args);
+
+    return function () use ($fn, $args) {
+        return call_user_func_array($fn, mergeRight($args, func_get_args()));
     };
 }
 
-/**
- * @return Partial
- */
+/** @return Placeholder */
 function …()
 {
     return Placeholder::create();
 }
 
-/**
- * @return Partial
- */
+/** @return Placeholder */
 function placeholder()
 {
     return …();
 }
 
 /** @internal */
-function mergeParameters(array $left, array $right)
+function mergeLeft(array $left, array $right)
+{
+    resolvePlaceholder($left, $right);
+    return array_merge($left, $right);
+}
+
+/** @internal */
+function mergeRight(array $left, array $right)
+{
+    resolvePlaceholder($left, $right);
+    return array_merge($right, $left);
+}
+
+/** @internal */
+function resolvePlaceholder(array &$parameters, array &$source)
 {
-    foreach ($left as $position => &$param) {
+    foreach ($parameters as $position => &$param) {
         if ($param instanceof Placeholder) {
-            $param = $param->resolve($right, $position);
+            $param = $param->resolve($source, $position);
         }
     }
-
-    return array_merge($left, $right);
 }

tests/React/Partial/BindRightTest.php

@@ -0,0 +1,81 @@
+<?php
+
+namespace React\Partial;
+
+class BindRightTest extends \PHPUnit_Framework_TestCase
+{
+    public function testBindWithNoArgs()
+    {
+        $div = $this->createDivFunction();
+        $newDiv = bind_right($div);
+        $this->assertSame(2, $newDiv(4, 2));
+    }
+
+    public function testBindWithOneArg()
+    {
+        $div = $this->createDivFunction();
+        $divOne = bind_right($div, 4);
+        $this->assertSame(0.5, $divOne(2));
+    }
+
+    public function testBindWithTwoArgs()
+    {
+        $div = $this->createDivFunction();
+        $divTwo = bind_right($div, 2, 4);
+        $this->assertSame(0.5, $divTwo());
+    }
+
+    public function testBindWithPlaceholder()
+    {
+        $div = $this->createDivFunction();
+        $divFun = bind_right($div, …(), 4);
+        $this->assertSame(5, $divFun(20));
+        $this->assertSame(10, $divFun(40));
+    }
+
+    public function testBindWithMultiplePlaceholders()
+    {
+        $div = $this->createDivFunction();
+        $divTwo = bind_right($div, …(), 2, …());
+        $this->assertSame(1, $divTwo(4, 2));
+        $this->assertSame(1, $divTwo(10, 5));
+        $this->assertSame(25, $divTwo(100, 2));
+    }
+
+    public function testPlaceholderParameterPosition()
+    {
+        $substr = bind_right('substr', …(), 0, …());
+        $this->assertSame('foo', $substr('foo', 3));
+        $this->assertSame('fo', $substr('foo', 2));
+        $this->assertSame('f', $substr('foo', 1));
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     * @expectedExceptionMessage Cannot resolve parameter placeholder at position 0. Parameter stack is empty
+     */
+    public function testStringConversion()
+    {
+        $div = $this->createDivFunction();
+        $divTwo = bind_right($div, …(), 2);
+
+        $divTwo();
+    }
+
+    public function testAliasForUnicodePlaceholderFunction()
+    {
+        $this->assertSame(…(), placeholder());
+    }
+
+    private function createDivFunction()
+    {
+        return function () {
+            $args = func_get_args();
+            $value = array_shift($args);
+            foreach ($args as $arg) {
+                $value /= $arg;
+            }
+            return $value;
+        };
+    }
+}

tests/React/Partial/BindTest.php

@@ -25,7 +25,6 @@ public function testBindWithTwoArgs()
         $this->assertSame(6, $addOneAndFive());
     }
 
-
     public function testBindWithPlaceholder()
     {
         $add = $this->createAddFunction();

tests/React/Partial/UtilTest.php

@@ -6,17 +6,24 @@
 
 class UtilTest extends \PHPUnit_Framework_TestCase
 {
-    public function testBindWithTwoArgs()
+    public function testBind()
     {
-        $add = $this->createAddFunction();
-        $addOneAndFive = Partial::bind($add, 1, 5);
-        $this->assertSame(6, $addOneAndFive());
+        $div = $this->createDivFunction();
+        $divFun = Partial::bind($div, 10, 5);
+        $this->assertSame(0.02, $divFun(100));
     }
 
-    private function createAddFunction()
+    public function testBindRight()
     {
-        return function ($a, $b) {
-            return $a + $b;
+        $div = $this->createDivFunction();
+        $divFun = Partial::bindRight($div, 10, 5);
+        $this->assertSame(2, $divFun(100));
+    }
+
+    private function createDivFunction()
+    {
+        return function ($a, $b, $c) {
+            return $a / $b / $c;
         };
     }
 }