Added Join strategy and accompanying tests and documentation.

Removed support for PHP 5.6.

.travis.yml

@@ -6,7 +6,6 @@ sudo: false
 language: php
 
 php:
-  - 5.5
   - 5.6
   - 7.0
   - 7.1

README.md

@@ -32,6 +32,7 @@ Contents
     1. [Filter](#filter)
     1. [Flatten](#flatten)
     1. [IfExists](#ifexists)
+    1. [Join](#join)
     1. [Merge](#merge)
     1. [TakeFirst](#takefirst)
     1. [ToList](#tolist)
@@ -294,6 +295,7 @@ The following strategies ship with Mapper and provide a suite of commonly used f
  - [Filter](#filter) – Filters null values or values rejected by the specified callback.
  - [Flatten](#flatten) – Moves all nested values to the top level.
  - [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.
  - [ToList](#tolist) – Converts data to a single-element list unless it is already a list.
@@ -605,6 +607,30 @@ $data = ['foo' => 'foo'];
 
 > false
 
+### Join
+
+Joins sub-string expressions together with a glue string.
+
+#### Signature
+
+```php
+Join(string $glue, array ...$expressions)
+```
+
+ 1. `$glue` – Glue.
+ 2. `$expressions` – Sub-string expressions.
+
+#### Example
+
+```php
+(new Mapper)->map(
+    ['foo' => 'foo'],
+    new Join('-', new Copy('foo'), 'bar')
+);
+```
+
+> 'foo-bar'
+
 ### Merge
 
 Merges two data sets together giving precedence to the latter if string keys collide; integer keys never collide. For more information see [array_merge](http://php.net/manual/en/function.array-merge.php).
@@ -828,7 +854,7 @@ Walk(Strategy|Mapping|array|mixed $expression, array|string $path)
 Requirements
 ------------
 
- - [PHP 5.5](http://php.net/)
+ - [PHP 5.6](http://php.net/)
  - [Composer](https://getcomposer.org/)
 
 Limitations

composer.json

@@ -9,7 +9,7 @@
   ],
   "license": "LGPL-3.0",
   "require": {
-    "php": ">=5.5",
+    "php": "^5.6|^7",
     "scriptfusion/array-walker": "^1",
     "eloquent/enumeration": "^5"
   },

src/Strategy/Join.php

@@ -0,0 +1,28 @@
+<?php
+namespace ScriptFUSION\Mapper\Strategy;
+
+/**
+ * Joins sub-string expressions together with a glue string.
+ */
+class Join extends Delegate
+{
+    private $glue;
+
+    /**
+     * Initializes this instance with the specified glue to join the specified sub-strings together.
+     *
+     * @param string $glue Glue.
+     * @param array ...$expressions Sub-string expressions.
+     */
+    public function __construct($glue, ...$expressions)
+    {
+        parent::__construct($expressions);
+
+        $this->glue = "$glue";
+    }
+
+    public function __invoke($data, $context = null)
+    {
+        return implode($this->glue, parent::__invoke($data, $context));
+    }
+}

test/Functional/DocumentationTest.php

@@ -13,6 +13,7 @@
 use ScriptFUSION\Mapper\Strategy\Filter;
 use ScriptFUSION\Mapper\Strategy\Flatten;
 use ScriptFUSION\Mapper\Strategy\IfExists;
+use ScriptFUSION\Mapper\Strategy\Join;
 use ScriptFUSION\Mapper\Strategy\Merge;
 use ScriptFUSION\Mapper\Strategy\TakeFirst;
 use ScriptFUSION\Mapper\Strategy\ToList;
@@ -228,6 +229,17 @@ public function testIfExists()
         self::assertFalse((new Mapper)->map($data, new IfExists(new Copy('bar'), true, false)));
     }
 
+    public function testJoin()
+    {
+        self::assertSame(
+            'foo-bar',
+            (new Mapper)->map(
+                ['foo' => 'foo'],
+                new Join('-', new Copy('foo'), 'bar')
+            )
+        );
+    }
+
     public function testMerge()
     {
         self::assertSame(

test/Integration/Mapper/Strategy/JoinTest.php

@@ -0,0 +1,20 @@
+<?php
+namespace ScriptFUSIONTest\Integration\Mapper\Strategy;
+
+use ScriptFUSION\Mapper\Mapper;
+use ScriptFUSION\Mapper\Strategy\Join;
+use ScriptFUSION\Mapper\Strategy\Strategy;
+
+final class JoinTest extends \PHPUnit_Framework_TestCase
+{
+    public function testJoin()
+    {
+        $join = (new Join(
+            '-',
+            'foo',
+            \Mockery::mock(Strategy::class)->shouldReceive('__invoke')->andReturn('bar')->once()->getMock()
+        ))->setMapper(new Mapper);
+
+        self::assertSame('foo-bar', $join([]));
+    }
+}