Added support for stategies and mappings in Copy path.

Also affects CopyContext and Walk paths in the same way.
Updated readme and tests.
Deprecated Translate because it can now be achieved with just Walk.

Author: Paul

README.md

@@ -317,17 +317,17 @@ The following strategies ship with Mapper and provide a suite of commonly used f
 
 ### Copy
 
-Copy copies a portion of the input data with support for nested structures.
+Copies a portion of the input data according to the specified path. Supports traversing nested arrays.
 
-Copy is probably the most common strategy whether used by itself or injected into other strategies.
+`Copy` is probably the most common strategy whether used by itself or injected into other strategies.
 
 #### Signature
 
 ```php
-Copy(array|string $path)
+Copy(Strategy|Mapping|array|mixed $path)
 ```
 
- 1. `$path` – Array of path components or string of  `->`-delimited components.
+ 1. `$path` – Array of path components, string of `->`-delimited path components or a strategy or mapping resolving to such an expression.
 
 #### Example
 
@@ -351,17 +351,35 @@ $data = [
 
 > 123
 
+#### Path resolver example
+
+Since the path can be derived from other strategies we could nest `Copy` instances to look up values referenced by other keys.
+
+```php
+(new Mapper)->map(
+    [
+        'foo' => 'bar',
+        'bar' => 'baz',
+        'baz' => 'qux',
+    ],
+    new Copy(new Copy(new Copy('foo')))
+);
+```
+
+> 'qux'
+
 ### CopyContext
 
 Copies a portion of context data; works exactly the same way as `Copy` in all other respects.
 
 #### Signature
 
 ```php
-CopyContext(array|string $path)
+CopyContext(Strategy|Mapping|array|mixed $path)
 ```
 
- 1. `$path` – Array of path components or string of  `->`-delimited components.
+ 1. `$path` – Array of path components, string of `->`-delimited path components or a strategy or mapping resolving to such an expression.
+
 
 #### Example
 
@@ -871,11 +889,11 @@ Walks a nested structure to the specified element in the same manner as [`Copy`]
 #### Signature
 
 ```php
-Walk(Strategy|Mapping|array|mixed $expression, array|string $path)
+Walk(Strategy|Mapping|array|mixed $expression, Strategy|Mapping|array|mixed $path)
 ```
 
- 1. `$expression` – Expression.
- 2. `$path` Array of path components or string of  `->`-delimited components.
+ 1. `$expression` – Expression to walk.
+ 2. `$path` – Array of path components, string of `->`-delimited path components or a strategy or mapping resolving to such an expression.
 
 #### Example
 

src/Mapper.php

@@ -25,18 +25,24 @@ class Mapper
      */
     public function map(array $record, $expression, $context = null, $key = null)
     {
-        /* Strategy. */
+        // Null or scalar values.
+        if (null === $expression || is_scalar($expression)) {
+            return $expression;
+        }
+
+        // Strategy.
         if ($expression instanceof Strategy) {
             return $this->mapStrategy($record, $expression, $context, $key);
-        } /* Mapping. */
-        elseif ($expression instanceof Mapping) {
+        }
+
+        // Mapping.
+        if ($expression instanceof Mapping) {
             return $this->mapMapping($record, $expression, $context, $key);
-        } /* Mapping fragment. */
-        elseif (is_array($expression)) {
+        }
+
+        // Mapping fragment.
+        if (is_array($expression)) {
             return $this->mapFragment($record, $expression, $context, $key);
-        } /* Null or scalar values. */
-        elseif (null === $expression || is_scalar($expression)) {
-            return $expression;
         }
 
         throw new InvalidExpressionException('Invalid strategy or mapping: "' . get_class($expression) . '".');

src/Strategy/Copy.php

@@ -6,22 +6,10 @@
 /**
  * Copies a portion of input data.
  */
-class Copy implements Strategy
+class Copy extends Delegate
 {
     const PATH_SEPARATOR = '->';
 
-    private $path;
-
-    /**
-     * Initializes this instance with the specified path.
-     *
-     * @param array|string $path Array of path components or string of `->`-delimited components.
-     */
-    public function __construct($path)
-    {
-        $this->path = is_array($path) ? $path : explode(self::PATH_SEPARATOR, $path);
-    }
-
     /**
      * @param mixed $data
      * @param mixed $context
@@ -30,8 +18,14 @@ public function __construct($path)
      */
     public function __invoke($data, $context = null)
     {
-        if ($this->path && is_array($data)) {
-            return ArrayWalker::walk($data, $this->path);
+        if (!is_array($data)) {
+            return null;
         }
+
+        if (!is_array($path = parent::__invoke($data, $context))) {
+            $path = explode(self::PATH_SEPARATOR, $path);
+        }
+
+        return $path ? ArrayWalker::walk($data, $path) : null;
     }
 }

src/Strategy/CopyContext.php

@@ -1,6 +1,8 @@
 <?php
 namespace ScriptFUSION\Mapper\Strategy;
 
+use ScriptFUSION\Mapper\Mapping;
+
 /**
  * Copies a portion of context data.
  */
@@ -11,7 +13,8 @@ class CopyContext extends Copy
     /**
      * {@inheritdoc}
      *
-     * @param array|string $path Array of path components or string of `->`-delimited components.
+     * @param Strategy|Mapping|array|mixed $path Array of path components, string of `->`-delimited path components or
+     *     a strategy or mapping resolving to such an expression.
      */
     public function __construct($path = null)
     {

src/Strategy/Translate.php

@@ -5,6 +5,8 @@
 
 /**
  * Translates a value using a mapping.
+ *
+ * @deprecated Use Walk instead.
  */
 class Translate extends Decorator
 {

src/Strategy/Walk.php

@@ -1,6 +1,7 @@
 <?php
 namespace ScriptFUSION\Mapper\Strategy;
 
+use ScriptFUSION\Mapper\Mapper;
 use ScriptFUSION\Mapper\Mapping;
 
 /**
@@ -14,8 +15,9 @@ class Walk extends Delegate
     private $copy;
 
     /**
-     * @param Strategy|Mapping|array|mixed $expression Expression.
-     * @param array|string $path Array of path components or string of `->`-delimited components.
+     * @param Strategy|Mapping|array|mixed $expression Expression to walk.
+     * @param Strategy|Mapping|array|mixed $path Array of path components, string of `->`-delimited path components or
+     *     a strategy or mapping resolving to such an expression.
      */
     public function __construct($expression, $path)
     {
@@ -28,4 +30,11 @@ public function __invoke($data, $context = null)
     {
         return call_user_func($this->copy, parent::__invoke($data, $context), $context);
     }
+
+    public function setMapper(Mapper $mapper)
+    {
+        $this->copy->setMapper($mapper);
+
+        return parent::setMapper($mapper);
+    }
 }

test/Functional/DocumentationTest.php

@@ -100,6 +100,21 @@ public function testCopy()
         self::assertSame($bar, (new Mapper)->map($data, new Copy(['foo', 'bar'])));
     }
 
+    public function testNestedCopy()
+    {
+        self::assertSame(
+            'qux',
+            (new Mapper)->map(
+                [
+                    'foo' => 'bar',
+                    'bar' => 'baz',
+                    'baz' => 'qux',
+                ],
+                new Copy(new Copy(new Copy('foo')))
+            )
+        );
+    }
+
     public function testCopyContext()
     {
         $data = ['foo' => 123];

test/Integration/Mapper/Strategy/DebugTest.php

@@ -14,6 +14,14 @@ protected function setUp()
             self::$debugged = false;
         }
 
+        /**
+         * Tests that the strategy can be created with no arguments.
+         */
+        public function testNoArguments()
+        {
+            new Debug;
+        }
+
         /**
          * Tests that expressions are delegated to Mapper.
          */

test/Integration/Mapper/Strategy/WalkTest.php

@@ -0,0 +1,18 @@
+<?php
+namespace ScriptFUSIONTest\Integration\Mapper\Strategy;
+
+use ScriptFUSION\Mapper\Mapper;
+use ScriptFUSION\Mapper\Strategy\Walk;
+
+final class WalkTest extends \PHPUnit_Framework_TestCase
+{
+    public function testWalk()
+    {
+        /** @var Walk $walk */
+        $walk = (new Walk(['foo' => ['bar' => 'baz']], 'foo->bar'))
+            ->setMapper(new Mapper)
+        ;
+
+        self::assertSame('baz', $walk([]));
+    }
+}

test/Unit/Mapper/Strategy/CopyContextTest.php

@@ -2,20 +2,26 @@
 namespace ScriptFUSIONTest\Unit\Mapper\Strategy;
 
 use ScriptFUSION\Mapper\Strategy\CopyContext;
+use ScriptFUSIONTest\MockFactory;
 
 final class CopyContextTest extends \PHPUnit_Framework_TestCase
 {
     public function testNoPath()
     {
-        $copyContext = new CopyContext;
+        $copyContext = self::createStrategy(null);
 
         self::assertSame('foo', $copyContext(null, 'foo'));
     }
 
     public function testPath()
     {
-        $copyContext = new CopyContext('foo->bar');
+        $copyContext = self::createStrategy('foo->bar');
 
         self::assertSame('baz', $copyContext(null, ['foo' => ['bar' => 'baz']]));
     }
+
+    private static function createStrategy($path)
+    {
+        return (new CopyContext($path))->setMapper(MockFactory::mockMapper($path));
+    }
 }