Remove Exists strategy. Make IfElse condition a callable. Address CR requests.

Author: Mark Challoner

README.md

@@ -29,11 +29,10 @@ Contents
     1. [Collection](#collection)
     1. [Context](#context)
     1. [Either](#either)
-    1. [Exists](#exists)
     1. [Filter](#filter)
     1. [Flatten](#flatten)
     1. [IfElse](#ifelse)
-    1. [IfExists](#ifexists) (deprecated)
+    1. [IfExists](#ifexists)
     1. [Join](#join)
     1. [Merge](#merge)
     1. [TakeFirst](#takefirst)
@@ -293,12 +292,11 @@ The following strategies ship with Mapper and provide a suite of commonly used f
  - [Callback](#callback) – Augments data using the specified callback.
  - [Collection](#collection) – Maps a collection of data by applying a transformation to each datum.
  - [Context](#context) – Replaces the context for the specified expression.
- - [Exists](#exists) – Returns true or false if the resolved value of the strategy or the path exists.
  - [Either](#either) – Either uses the primary strategy, if it returns non-null, otherwise delegates to a fallback expression.
  - [Filter](#filter) – Filters null values or values rejected by the specified callback.
  - [Flatten](#flatten) – Moves all nested values to the top level.
- - [IfElse](#ifelse) – Delegates to one expression or another depending on whether the specified condition loosely evaluates to true.
- - [IfExists](#ifexists) (deprecated) – Delegates to one expression or another depending on whether the specified condition maps to null.
+ - [IfElse](#ifelse) – Delegates to one expression or another depending on whether the specified condition strictly evaluates to true.
+ - [IfExists](#ifexists) – Delegates to one expression or another depending on whether the specified condition maps to null.
  - [Join](#join) – Joins sub-string expressions together with a glue string.
  - [Merge](#merge) – Merges two data sets together giving precedence to the latter if keys collide.
  - [TakeFirst](#takefirst) – Takes the first value from a collection one or more times.
@@ -515,34 +513,6 @@ Either(Strategy $strategy, Strategy|Mapping|array|mixed $expression)
 
 > 'bar'
 
-### Exists
-
-Returns true or false if the resolved value of the strategy or the path exists.
-
-#### Signature
-
-```php
-Exists(Strategy|array|mixed $strategyOrPath)
-```
-
- 1. `$strategyOrPath` –  Strategy, array of path components or string of `->`-delimited components.
-
-#### Example
-
-```php
-$data = ['foo' => 'bar']
-
-(new Mapper)->map($data, new Exists('foo'));
-```
-
-> true
-
-```php
-(new Mapper)->map($data, new Exists('bar'));
-```
-
-> false
-
 ### Filter
 
 Filters null values or values rejected by the specified callback.
@@ -611,12 +581,12 @@ $data = [
 
 ### IfElse
 
-Delegates to one expression or another depending on whether the specified condition loosely evaluates to true.
+Delegates to one expression or another depending on whether the specified condition strictly evaluates to true.
 
 #### Signature
 
 ```php
-IfElse(Strategy $condition, Strategy|Mapping|array|mixed $if, Strategy|Mapping|array|mixed $else = null)
+IfElse(callable $condition, Strategy|Mapping|array|mixed $if, Strategy|Mapping|array|mixed $else = null)
 ```
 
  1. `$condition` – Condition.
@@ -625,16 +595,48 @@ IfElse(Strategy $condition, Strategy|Mapping|array|mixed $if, Strategy|Mapping|a
 
 #### Example
 
+Test if all items in $data are positive.
+
 ```php
-$data = ['foo' => 'bar'];
+$data = [1, 3, 5, 6];
 
-(new Mapper)->map($data, new IfElse(new Exists('foo'), true, false));
+(new Mapper)->map(
+    $data,
+    new IfElse(
+        function ($data) {
+            foreach ($data as $datum) {
+                if ($datum <= 0) {
+                    return false;
+                }
+            }
+            return true;
+        },
+        true,
+        false
+    )
+);
 ```
 
 > true
 
+Test if all items in $data are even.
+
 ```php
-(new Mapper)->map($data, new IfElse(new Exists('bar'), true, false));
+(new Mapper)->map(
+    $data,
+    new IfElse(
+        function ($data) {
+            foreach ($data as $datum) {
+                if ($datum % 2 === 0) {
+                    return false;
+                }
+            }
+            return true;
+        },
+        true,
+        false
+    )
+);
 ```
 
 > false

src/Strategy/Either.php

@@ -6,14 +6,14 @@
 /**
  * Either uses the primary strategy, if it returns non-null, otherwise delegates to a fallback expression.
  */
-class Either extends IfElse
+class Either extends IfExists
 {
     /**
      * @param Strategy $strategy
      * @param Strategy|Mapping|array|mixed $expression
      */
     public function __construct(Strategy $strategy, $expression)
     {
-        parent::__construct(new Exists($strategy), $strategy, $expression);
+        parent::__construct($strategy, $strategy, $expression);
     }
 }

src/Strategy/Exists.php

@@ -4,38 +4,35 @@
 use ScriptFUSION\Mapper\Mapping;
 
 /**
- * Delegates to one expression or another depending on whether the specified condition loosely evaluates to true.
+ * Delegates to one expression or another depending on whether the specified condition strictly evaluates to true.
  */
 class IfElse extends Delegate
 {
-    /** @var Strategy|Mapping|array|mixed */
-    private $if;
+    /** @var callable */
+    private $condition;
 
     /** @var Strategy|Mapping|array|mixed */
     private $else;
 
     /**
      * Initializes this instance with the specified condition, the specified
-     * strategy or mapping to be resolved when condition is non-null and,
-     * optionally, the specified strategy or mapping to be resolved when
-     * condition is null.
+     * expression to be resolved when condition is true and, optionally, the
+     * specified expression to be resolved when condition is false.
      *
-     * @param Strategy|Mapping|array|mixed $condition Condition.
+     * @param callable $condition Condition.
      * @param Strategy|Mapping|array|mixed $if Primary expression.
      * @param Strategy|Mapping|array|mixed|null $else Optional. Fallback expression.
      */
-    public function __construct($condition, $if, $else = null)
+    public function __construct(callable $condition, $if, $else = null)
     {
-        parent::__construct($condition);
-
-        $this->if = $if;
+        $this->condition = $condition;
+        parent::__construct($if);
         $this->else = $else;
     }
 
     /**
-     * Resolves the stored strategy or mapping when the stored condition
-     * resolves to a non-null value, otherwise returns the stored default
-     * value.
+     * Resolves the stored expression when the stored condition strictly
+     * evaluates to true, otherwise resolve the stored fallback expression.
      *
      * @param mixed $data
      * @param mixed $context
@@ -44,12 +41,10 @@ public function __construct($condition, $if, $else = null)
      */
     public function __invoke($data, $context = null)
     {
-        if (parent::__invoke($data, $context)) {
-            return $this->delegate($this->if, $data, $context);
+        if (call_user_func($this->condition, $data, $context) === true) {
+            return parent::__invoke($data, $context);
         }
 
-        if ($this->else !== null) {
-            return $this->delegate($this->else, $data, $context);
-        }
+        return $this->delegate($this->else, $data, $context);
     }
 }

src/Strategy/IfElse.php

@@ -5,17 +5,9 @@
 
 /**
  * Delegates to one expression or another depending on whether the specified condition maps to null.
- *
- * @deprecated Use IfElse and Exists strategies instead.
  */
-class IfExists extends Decorator
+class IfExists extends IfElse
 {
-    /** @var Strategy|Mapping|array|mixed */
-    private $if;
-
-    /** @var Strategy|Mapping|array|mixed */
-    private $else;
-
     /**
      * Initializes this instance with the specified condition, the specified
      * strategy or mapping to be resolved when condition is non-null and,
@@ -28,30 +20,8 @@ class IfExists extends Decorator
      */
     public function __construct(Strategy $condition, $if, $else = null)
     {
-        parent::__construct($condition);
-
-        $this->if = $if;
-        $this->else = $else;
-    }
-
-    /**
-     * Resolves the stored strategy or mapping when the stored condition
-     * resolves to a non-null value, otherwise returns the stored default
-     * value.
-     *
-     * @param mixed $data
-     * @param mixed $context
-     *
-     * @return mixed
-     */
-    public function __invoke($data, $context = null)
-    {
-        if (parent::__invoke($data, $context) !== null) {
-            return $this->delegate($this->if, $data, $context);
-        }
-
-        if ($this->else !== null) {
-            return $this->delegate($this->else, $data, $context);
-        }
+        parent::__construct(function ($data, $context = null) use ($condition) {
+            return $this->delegate($condition, $data, $context) !== null;
+        }, $if, $else);
     }
 }

src/Strategy/IfExists.php

@@ -12,6 +12,7 @@
 use ScriptFUSION\Mapper\Strategy\Either;
 use ScriptFUSION\Mapper\Strategy\Filter;
 use ScriptFUSION\Mapper\Strategy\Flatten;
+use ScriptFUSION\Mapper\Strategy\IfElse;
 use ScriptFUSION\Mapper\Strategy\IfExists;
 use ScriptFUSION\Mapper\Strategy\Join;
 use ScriptFUSION\Mapper\Strategy\Merge;
@@ -221,6 +222,47 @@ public function testFlatten()
         self::assertSame([1, 2, 3, 3, 4, 5], (new Mapper)->map($data, (new Flatten(new Copy('foo')))->ignoreKeys()));
     }
 
+    public function testIfElse()
+    {
+        $data = [1, 3, 5, 6];
+
+        self::assertTrue(
+            (new Mapper)->map(
+                $data,
+                new IfElse(
+                    function ($data) {
+                        foreach ($data as $datum) {
+                            if ($datum <= 0) {
+                                return false;
+                            }
+                        }
+                        return true;
+                    },
+                    true,
+                    false
+                )
+            )
+        );
+
+        self::assertFalse(
+            (new Mapper)->map(
+                $data,
+                new IfElse(
+                    function ($data) {
+                        foreach ($data as $datum) {
+                            if ($datum % 2) {
+                                return false;
+                            }
+                        }
+                        return true;
+                    },
+                    true,
+                    false
+                )
+            )
+        );
+    }
+
     public function testIfExists()
     {
         $data = ['foo' => 'foo'];