intraxia / jaxion

src/Axolotl/Collection.php

Indentation +741 added lines, -741 removed lines

@@ -15,745 +15,745 @@
  */
 class Collection implements CollectionContract {
 
-	/**
-	 * Collection elements.
-	 *
-	 * @var array
-	 */
-	protected $elements = array();
-
-	/**
-	 * Collection type to enforce.
-	 *
-	 * @var Type
-	 */
-	private $type;
-
-	/**
-	 * Where Collection is in loop.
-	 *
-	 * @var int
-	 */
-	protected $position = 0;
-
-	/**
-	 * Collection constructor.
-	 *
-	 * @param string $type
-	 * @param array  $elements
-	 */
-	public function __construct( $type, array $elements = array() ) {
-		$this->type = new Type( $type );
-
-		if ( $this->type->is_model() ) {
-			foreach ( $elements as $idx => $element ) {
-				if ( is_array( $element ) ) {
-					$elements[ $idx ] = $this->type->create_model( $element );
-				}
-			}
-		}
-
-		if ( $elements ) {
-			$this->type->validate_elements( $elements );
-		}
-
-		$this->elements = $elements;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return string
-	 */
-	public function get_type() {
-		return $this->type->get_type();
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param mixed $element
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function add( $element ) {
-		if ( $this->type->is_model() && is_array( $element ) ) {
-			$element = $this->type->create_model( $element );
-		}
-
-		$this->type->validate_element( $element );
-
-		$elements   = $this->elements;
-		$elements[] = $element;
-
-		$collection = new static( $this->get_type() );
-		$collection->set_from_trusted( $elements );
-
-		return $collection;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return Collection
-	 */
-	public function clear() {
-		return new static( $this->get_type() );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  callable $condition Condition to satisfy.
-	 *
-	 * @return bool
-	 */
-	public function contains( $condition ) {
-		return (bool) $this->find( $condition );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  callable $condition Condition to satisfy.
-	 *
-	 * @return mixed
-	 */
-	public function find( $condition ) {
-		$index = $this->find_index( $condition );
-
-		return -1 === $index ? false : $this->elements[ $index ];
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  callable $condition Condition to satisfy.
-	 *
-	 * @return int
-	 */
-	public function find_index( $condition ) {
-		$index = -1;
-
-		for ( $i = 0, $count = count( $this->elements ); $i < $count; $i++ ) {
-			if ( call_user_func( $condition, ($this->at( $i ) ) ) ) {
-				$index = $i;
-				break;
-			}
-		}
-
-		return $index;
-	}
-
-	/**
-	 * Fetches the element at the provided index.
-	 *
-	 * @param int $index Index to get element from.
-	 *
-	 * @return mixed
-	 *
-	 * @throws OutOfRangeException
-	 */
-	public function at( $index ) {
-		$this->validate_index( $index );
-
-		return $this->elements[ $index ];
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  int $index Index to check for existence.
-	 *
-	 * @return bool
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function index_exists( $index ) {
-		if ( ! is_int( $index ) ) {
-			throw new InvalidArgumentException( 'Index must be an integer' );
-		}
-
-		if ( $index < 0 ) {
-			throw new InvalidArgumentException( 'Index must be a non-negative integer' );
-		}
-
-		return $index < $this->count();
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  callable $condition Condition to satisfy.
-	 *
-	 * @return mixed
-	 */
-	public function filter( $condition ) {
-		$elements = array();
-
-		foreach ( $this->elements as $element ) {
-			if ( call_user_func( $condition, $element ) ) {
-				$elements[] = $element;
-			}
-		}
-
-		return $this->new_from_trusted( $elements );
-	}
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  callable $condition Condition to satisfy.
-	 *
-	 * @return mixed
-	 */
-	public function find_last( $condition ) {
-		$index = $this->find_last_index( $condition );
-
-		return -1 === $index ? null : $this->elements[ $index ];
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  callable $condition
-	 * @return int
-	 */
-	public function find_last_index( $condition ) {
-		$index = -1;
-
-		for ( $i = count( $this->elements ) - 1; $i >= 0; $i-- ) {
-			if ( call_user_func( $condition, $this->elements[ $i ] ) ) {
-				$index = $i;
-				break;
-			}
-		}
-
-		return $index;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  int $start Begining index to slice from.
-	 * @param  int $end   End index to slice to.
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function slice( $start, $end ) {
-		if ( $start < 0 || ! is_int( $start ) ) {
-			throw new InvalidArgumentException( 'Start must be a non-negative integer' );
-		}
-
-		if ( $end < 0 || ! is_int( $end ) ) {
-			throw new InvalidArgumentException( 'End must be a positive integer' );
-		}
-
-		if ( $start > $end ) {
-			throw new InvalidArgumentException( 'End must be greater than start' );
-		}
-
-		if ( $end > $this->count() + 1 ) {
-			throw new InvalidArgumentException( 'End must be less than the count of the items in the Collection' );
-		}
-
-		$length = $end - $start + 1;
-
-		return $this->new_from_trusted( array_slice( $this->elements, $start, $length ) );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param int   $index     Index to start at.
-	 * @param mixed $element Element to insert.
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 * @throws OutOfRangeException
-	 */
-	public function insert( $index, $element ) {
-		$this->validate_index( $index );
-		$this->type->validate_element( $element );
-
-		$a = array_slice( $this->elements, 0, $index );
-		$b = array_slice( $this->elements, $index, count( $this->elements ) );
-
-		$a[] = $element;
-
-		return $this->new_from_trusted( array_merge( $a, $b ) );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param int   $index    Index to start insertion at.
-	 * @param array $elements Elements in insert.
-	 *
-	 * @return Collection
-	 *
-	 * @throws OutOfRangeException
-	 */
-	public function insert_range( $index, array $elements ) {
-		$this->validate_index( $index );
-		$this->type->validate_elements( $elements );
-
-		if ( $index < 0 ) {
-			$index = $this->count() + $index + 1;
-		}
-
-		return $this->new_from_trusted(
-			array_merge(
-				array_slice( $this->elements, 0, $index ),
-				$elements,
-				array_slice( $this->elements, $index, count( $this->elements ) )
-			)
-		);
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  callable $condition Condition to satisfy.
-	 *
-	 * @return Collection
-	 */
-	public function without( $condition ) {
-		$inverse = function ( $element ) use ( $condition ) {
-			return ! call_user_func( $condition, $element );
-		};
-
-		return $this->filter( $inverse );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  int $index Index to remove.
-	 *
-	 * @return Collection
-	 *
-	 * @throws OutOfRangeException
-	 */
-	public function remove_at( $index ) {
-		$this->validate_index( $index );
-
-		$elements = $this->elements;
-
-		return $this->new_from_trusted(
-			array_merge(
-				array_slice( $elements, 0, $index ),
-				array_slice( $elements, $index + 1, count( $elements ) )
-			)
-		);
-	}
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return Collection
-	 */
-	public function reverse() {
-		return $this->new_from_trusted(
-			array_reverse( $this->elements )
-		);
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $callback Sort callback.
-	 *
-	 * @return Collection
-	 */
-	public function sort( $callback ) {
-		$elements = $this->elements;
-		usort( $elements, $callback );
-		return $this->new_from_trusted( $elements );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return array
-	 */
-	public function to_array() {
-		return $this->elements;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $callable Reducer function.
-	 *
-	 * @param null     $initial  Initial reducer value.
-	 *
-	 * @return mixed
-	 */
-	public function reduce( $callable, $initial = null ) {
-		return array_reduce( $this->elements, $callable, $initial );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $condition Condition callback.
-	 *
-	 * @return bool
-	 */
-	public function every( $condition ) {
-		$response = true;
-
-		foreach ( $this->elements as $element ) {
-			$result = call_user_func( $condition, $element );
-
-			if ( false === $result ) {
-				$response = false;
-				break;
-			}
-		}
-
-		return $response;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  int $num Number of elements to drop.
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function drop( $num ) {
-		if ( $num > $this->count() ) {
-			$num = $this->count();
-		}
-
-		return $this->slice( $num, $this->count() );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param int $num Number of elements to drop.
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function drop_right( $num ) {
-		return $num !== $this->count()
-			? $this->slice( 0, $this->count() - $num - 1 )
-			: $this->clear();
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $condition Condition callback.
-	 *
-	 * @return Collection
-	 */
-	public function drop_while( $condition ) {
-		$count = $this->count_while_true( $condition );
-		return $count ? $this->drop( $count ) : $this;
-	}
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function tail() {
-		return $this->slice( 1, $this->count() );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param  int $num Number of elements to take.
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function take( $num ) {
-		return $this->slice( 0, $num - 1 );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param int $num Number of elements to take.
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function take_right( $num ) {
-		return $this->slice( $this->count() - $num, $this->count() );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $condition Callback function.
-	 *
-	 * @return Collection
-	 */
-	public function take_while( $condition ) {
-		$count = $this->count_while_true( $condition );
-
-		return $count ? $this->take( $count ) : $this->clear();
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $callable Callback function.
-	 */
-	public function each( $callable ) {
-		foreach ( $this->elements as $element ) {
-			call_user_func( $callable, $element );
-		}
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $callable Callback function.
-	 *
-	 * @return Collection
-	 */
-	public function map( $callable ) {
-		$elements = array();
-		$type = null;
-		foreach ( $this->elements as $element ) {
-			$result = call_user_func( $callable, $element );
-
-			if ( null === $type ) {
-				$type = gettype( $result );
-
-				if ( 'object' === $type ) {
-					$type = get_class( $result );
-				}
-			}
-
-			$elements[] = $result;
-		}
-
-		return $this->new_from_trusted( $elements, $type ? : $this->get_type() );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param callable $callable Reducer function.
-	 * @param null     $initial  Initial value.
-	 *
-	 * @return mixed
-	 */
-	public function reduce_right( $callable, $initial = null ) {
-		return array_reduce(
-			array_reverse( $this->elements ),
-			$callable,
-			$initial
-		);
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return Collection
-	 */
-	public function shuffle() {
-		$elements = $this->elements;
-		shuffle( $elements );
-
-		return $this->new_from_trusted( $elements );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @param array|Collection $elements Array of elements to merge.
-	 *
-	 * @return Collection
-	 *
-	 * @throws InvalidArgumentException
-	 */
-	public function merge( $elements ) {
-		if ( $elements instanceof static ) {
-			$elements = $elements->to_array();
-		}
-
-		if ( ! is_array( $elements ) ) {
-			throw new InvalidArgumentException( 'Merge must be given array or Collection' );
-		}
-
-		$this->type->validate_elements( $elements );
-
-		return $this->new_from_trusted(
-			array_merge( $this->elements, $elements )
-		);
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return mixed
-	 *
-	 * @throws OutOfBoundsException
-	 */
-	public function first() {
-		if ( empty( $this->elements ) ) {
-			throw new OutOfBoundsException( 'Cannot get first element of empty Collection' );
-		}
-
-		return reset( $this->elements );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return mixed
-	 *
-	 * @throws OutOfBoundsException
-	 */
-	public function last() {
-		if ( empty( $this->elements ) ) {
-			throw new OutOfBoundsException( 'Cannot get last element of empty Collection' );
-		}
-
-		return end( $this->elements );
-	}
-
-	/**
-	 * {@inheritdoc}
-	 *
-	 * @return int
-	 */
-	public function count() {
-		return count( $this->elements );
-	}
-
-	/**
-	 * {@inheritDoc}
-	 *
-	 * @return array
-	 */
-	public function serialize() {
-		return $this->map(function( $element ) {
-			if ( $element instanceof Serializes ) {
-				return $element->serialize();
-			}
-
-			return $element;
-		} )->to_array();
-	}
-
-	/**
-	 * Return the current element.
-	 *
-	 * @return mixed
-	 */
-	public function current() {
-		return $this->at( $this->position );
-	}
-
-	/**
-	 * Move forward to next element.
-	 */
-	public function next() {
-		$this->position ++;
-	}
-
-	/**
-	 * Return the key of the current element.
-	 *
-	 * @return mixed
-	 */
-	public function key() {
-		return $this->position;
-	}
-
-	/**
-	 * Checks if current position is valid.
-	 *
-	 * @return bool
-	 */
-	public function valid() {
-		return isset( $this->elements[ $this->position ] );
-	}
-
-	/**
-	 * Rewind the Iterator to the first element.
-	 */
-	public function rewind() {
-		$this->position = 0;
-	}
-
-	/**
-	 * Creates a new instance of the Collection
-	 * from a trusted set of elements.
-	 *
-	 * @param array      $elements Array of elements to pass into new collection.
-	 * @param null|mixed $type
-	 *
-	 * @return static
-	 */
-	protected function new_from_trusted( array $elements, $type = null ) {
-		$collection = new static( null !== $type ? $type : $this->get_type() );
-		$collection->set_from_trusted( $elements );
-
-		return $collection;
-	}
-
-	/**
-	 * Sets the elements without validating them.
-	 *
-	 * @param array $elements Pre-validated elements to set.
-	 */
-	protected function set_from_trusted( array $elements ) {
-		$this->elements = $elements;
-	}
-
-	/**
-	 * Number of elements true for the condition.
-	 *
-	 * @param callable $condition Condition to check.
-	 * @return int
-	 */
-	protected function count_while_true( $condition ) {
-		$count = 0;
-
-		foreach ( $this->elements as $element ) {
-			if ( ! $condition($element) ) {
-				break;
-			}
-			$count++;
-		}
-
-		return $count;
-	}
-
-	/**
-	 * Validates a number to be used as an index.
-	 *
-	 * @param  integer $index The number to be validated as an index.
-	 *
-	 * @throws OutOfRangeException
-	 */
-	protected function validate_index( $index ) {
-		$exists = $this->index_exists( $index );
-
-		if ( ! $exists ) {
-			throw new OutOfRangeException( 'Index out of bounds of collection' );
-		}
-	}
+    /**
+     * Collection elements.
+     *
+     * @var array
+     */
+    protected $elements = array();
+
+    /**
+     * Collection type to enforce.
+     *
+     * @var Type
+     */
+    private $type;
+
+    /**
+     * Where Collection is in loop.
+     *
+     * @var int
+     */
+    protected $position = 0;
+
+    /**
+     * Collection constructor.
+     *
+     * @param string $type
+     * @param array  $elements
+     */
+    public function __construct( $type, array $elements = array() ) {
+        $this->type = new Type( $type );
+
+        if ( $this->type->is_model() ) {
+            foreach ( $elements as $idx => $element ) {
+                if ( is_array( $element ) ) {
+                    $elements[ $idx ] = $this->type->create_model( $element );
+                }
+            }
+        }
+
+        if ( $elements ) {
+            $this->type->validate_elements( $elements );
+        }
+
+        $this->elements = $elements;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return string
+     */
+    public function get_type() {
+        return $this->type->get_type();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param mixed $element
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function add( $element ) {
+        if ( $this->type->is_model() && is_array( $element ) ) {
+            $element = $this->type->create_model( $element );
+        }
+
+        $this->type->validate_element( $element );
+
+        $elements   = $this->elements;
+        $elements[] = $element;
+
+        $collection = new static( $this->get_type() );
+        $collection->set_from_trusted( $elements );
+
+        return $collection;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return Collection
+     */
+    public function clear() {
+        return new static( $this->get_type() );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  callable $condition Condition to satisfy.
+     *
+     * @return bool
+     */
+    public function contains( $condition ) {
+        return (bool) $this->find( $condition );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  callable $condition Condition to satisfy.
+     *
+     * @return mixed
+     */
+    public function find( $condition ) {
+        $index = $this->find_index( $condition );
+
+        return -1 === $index ? false : $this->elements[ $index ];
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  callable $condition Condition to satisfy.
+     *
+     * @return int
+     */
+    public function find_index( $condition ) {
+        $index = -1;
+
+        for ( $i = 0, $count = count( $this->elements ); $i < $count; $i++ ) {
+            if ( call_user_func( $condition, ($this->at( $i ) ) ) ) {
+                $index = $i;
+                break;
+            }
+        }
+
+        return $index;
+    }
+
+    /**
+     * Fetches the element at the provided index.
+     *
+     * @param int $index Index to get element from.
+     *
+     * @return mixed
+     *
+     * @throws OutOfRangeException
+     */
+    public function at( $index ) {
+        $this->validate_index( $index );
+
+        return $this->elements[ $index ];
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  int $index Index to check for existence.
+     *
+     * @return bool
+     *
+     * @throws InvalidArgumentException
+     */
+    public function index_exists( $index ) {
+        if ( ! is_int( $index ) ) {
+            throw new InvalidArgumentException( 'Index must be an integer' );
+        }
+
+        if ( $index < 0 ) {
+            throw new InvalidArgumentException( 'Index must be a non-negative integer' );
+        }
+
+        return $index < $this->count();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  callable $condition Condition to satisfy.
+     *
+     * @return mixed
+     */
+    public function filter( $condition ) {
+        $elements = array();
+
+        foreach ( $this->elements as $element ) {
+            if ( call_user_func( $condition, $element ) ) {
+                $elements[] = $element;
+            }
+        }
+
+        return $this->new_from_trusted( $elements );
+    }
+    /**
+     * {@inheritdoc}
+     *
+     * @param  callable $condition Condition to satisfy.
+     *
+     * @return mixed
+     */
+    public function find_last( $condition ) {
+        $index = $this->find_last_index( $condition );
+
+        return -1 === $index ? null : $this->elements[ $index ];
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  callable $condition
+     * @return int
+     */
+    public function find_last_index( $condition ) {
+        $index = -1;
+
+        for ( $i = count( $this->elements ) - 1; $i >= 0; $i-- ) {
+            if ( call_user_func( $condition, $this->elements[ $i ] ) ) {
+                $index = $i;
+                break;
+            }
+        }
+
+        return $index;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  int $start Begining index to slice from.
+     * @param  int $end   End index to slice to.
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function slice( $start, $end ) {
+        if ( $start < 0 || ! is_int( $start ) ) {
+            throw new InvalidArgumentException( 'Start must be a non-negative integer' );
+        }
+
+        if ( $end < 0 || ! is_int( $end ) ) {
+            throw new InvalidArgumentException( 'End must be a positive integer' );
+        }
+
+        if ( $start > $end ) {
+            throw new InvalidArgumentException( 'End must be greater than start' );
+        }
+
+        if ( $end > $this->count() + 1 ) {
+            throw new InvalidArgumentException( 'End must be less than the count of the items in the Collection' );
+        }
+
+        $length = $end - $start + 1;
+
+        return $this->new_from_trusted( array_slice( $this->elements, $start, $length ) );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param int   $index     Index to start at.
+     * @param mixed $element Element to insert.
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     * @throws OutOfRangeException
+     */
+    public function insert( $index, $element ) {
+        $this->validate_index( $index );
+        $this->type->validate_element( $element );
+
+        $a = array_slice( $this->elements, 0, $index );
+        $b = array_slice( $this->elements, $index, count( $this->elements ) );
+
+        $a[] = $element;
+
+        return $this->new_from_trusted( array_merge( $a, $b ) );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param int   $index    Index to start insertion at.
+     * @param array $elements Elements in insert.
+     *
+     * @return Collection
+     *
+     * @throws OutOfRangeException
+     */
+    public function insert_range( $index, array $elements ) {
+        $this->validate_index( $index );
+        $this->type->validate_elements( $elements );
+
+        if ( $index < 0 ) {
+            $index = $this->count() + $index + 1;
+        }
+
+        return $this->new_from_trusted(
+            array_merge(
+                array_slice( $this->elements, 0, $index ),
+                $elements,
+                array_slice( $this->elements, $index, count( $this->elements ) )
+            )
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  callable $condition Condition to satisfy.
+     *
+     * @return Collection
+     */
+    public function without( $condition ) {
+        $inverse = function ( $element ) use ( $condition ) {
+            return ! call_user_func( $condition, $element );
+        };
+
+        return $this->filter( $inverse );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  int $index Index to remove.
+     *
+     * @return Collection
+     *
+     * @throws OutOfRangeException
+     */
+    public function remove_at( $index ) {
+        $this->validate_index( $index );
+
+        $elements = $this->elements;
+
+        return $this->new_from_trusted(
+            array_merge(
+                array_slice( $elements, 0, $index ),
+                array_slice( $elements, $index + 1, count( $elements ) )
+            )
+        );
+    }
+    /**
+     * {@inheritdoc}
+     *
+     * @return Collection
+     */
+    public function reverse() {
+        return $this->new_from_trusted(
+            array_reverse( $this->elements )
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $callback Sort callback.
+     *
+     * @return Collection
+     */
+    public function sort( $callback ) {
+        $elements = $this->elements;
+        usort( $elements, $callback );
+        return $this->new_from_trusted( $elements );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return array
+     */
+    public function to_array() {
+        return $this->elements;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $callable Reducer function.
+     *
+     * @param null     $initial  Initial reducer value.
+     *
+     * @return mixed
+     */
+    public function reduce( $callable, $initial = null ) {
+        return array_reduce( $this->elements, $callable, $initial );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $condition Condition callback.
+     *
+     * @return bool
+     */
+    public function every( $condition ) {
+        $response = true;
+
+        foreach ( $this->elements as $element ) {
+            $result = call_user_func( $condition, $element );
+
+            if ( false === $result ) {
+                $response = false;
+                break;
+            }
+        }
+
+        return $response;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  int $num Number of elements to drop.
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function drop( $num ) {
+        if ( $num > $this->count() ) {
+            $num = $this->count();
+        }
+
+        return $this->slice( $num, $this->count() );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param int $num Number of elements to drop.
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function drop_right( $num ) {
+        return $num !== $this->count()
+            ? $this->slice( 0, $this->count() - $num - 1 )
+            : $this->clear();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $condition Condition callback.
+     *
+     * @return Collection
+     */
+    public function drop_while( $condition ) {
+        $count = $this->count_while_true( $condition );
+        return $count ? $this->drop( $count ) : $this;
+    }
+    /**
+     * {@inheritdoc}
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function tail() {
+        return $this->slice( 1, $this->count() );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param  int $num Number of elements to take.
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function take( $num ) {
+        return $this->slice( 0, $num - 1 );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param int $num Number of elements to take.
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function take_right( $num ) {
+        return $this->slice( $this->count() - $num, $this->count() );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $condition Callback function.
+     *
+     * @return Collection
+     */
+    public function take_while( $condition ) {
+        $count = $this->count_while_true( $condition );
+
+        return $count ? $this->take( $count ) : $this->clear();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $callable Callback function.
+     */
+    public function each( $callable ) {
+        foreach ( $this->elements as $element ) {
+            call_user_func( $callable, $element );
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $callable Callback function.
+     *
+     * @return Collection
+     */
+    public function map( $callable ) {
+        $elements = array();
+        $type = null;
+        foreach ( $this->elements as $element ) {
+            $result = call_user_func( $callable, $element );
+
+            if ( null === $type ) {
+                $type = gettype( $result );
+
+                if ( 'object' === $type ) {
+                    $type = get_class( $result );
+                }
+            }
+
+            $elements[] = $result;
+        }
+
+        return $this->new_from_trusted( $elements, $type ? : $this->get_type() );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param callable $callable Reducer function.
+     * @param null     $initial  Initial value.
+     *
+     * @return mixed
+     */
+    public function reduce_right( $callable, $initial = null ) {
+        return array_reduce(
+            array_reverse( $this->elements ),
+            $callable,
+            $initial
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return Collection
+     */
+    public function shuffle() {
+        $elements = $this->elements;
+        shuffle( $elements );
+
+        return $this->new_from_trusted( $elements );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @param array|Collection $elements Array of elements to merge.
+     *
+     * @return Collection
+     *
+     * @throws InvalidArgumentException
+     */
+    public function merge( $elements ) {
+        if ( $elements instanceof static ) {
+            $elements = $elements->to_array();
+        }
+
+        if ( ! is_array( $elements ) ) {
+            throw new InvalidArgumentException( 'Merge must be given array or Collection' );
+        }
+
+        $this->type->validate_elements( $elements );
+
+        return $this->new_from_trusted(
+            array_merge( $this->elements, $elements )
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return mixed
+     *
+     * @throws OutOfBoundsException
+     */
+    public function first() {
+        if ( empty( $this->elements ) ) {
+            throw new OutOfBoundsException( 'Cannot get first element of empty Collection' );
+        }
+
+        return reset( $this->elements );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return mixed
+     *
+     * @throws OutOfBoundsException
+     */
+    public function last() {
+        if ( empty( $this->elements ) ) {
+            throw new OutOfBoundsException( 'Cannot get last element of empty Collection' );
+        }
+
+        return end( $this->elements );
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @return int
+     */
+    public function count() {
+        return count( $this->elements );
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @return array
+     */
+    public function serialize() {
+        return $this->map(function( $element ) {
+            if ( $element instanceof Serializes ) {
+                return $element->serialize();
+            }
+
+            return $element;
+        } )->to_array();
+    }
+
+    /**
+     * Return the current element.
+     *
+     * @return mixed
+     */
+    public function current() {
+        return $this->at( $this->position );
+    }
+
+    /**
+     * Move forward to next element.
+     */
+    public function next() {
+        $this->position ++;
+    }
+
+    /**
+     * Return the key of the current element.
+     *
+     * @return mixed
+     */
+    public function key() {
+        return $this->position;
+    }
+
+    /**
+     * Checks if current position is valid.
+     *
+     * @return bool
+     */
+    public function valid() {
+        return isset( $this->elements[ $this->position ] );
+    }
+
+    /**
+     * Rewind the Iterator to the first element.
+     */
+    public function rewind() {
+        $this->position = 0;
+    }
+
+    /**
+     * Creates a new instance of the Collection
+     * from a trusted set of elements.
+     *
+     * @param array      $elements Array of elements to pass into new collection.
+     * @param null|mixed $type
+     *
+     * @return static
+     */
+    protected function new_from_trusted( array $elements, $type = null ) {
+        $collection = new static( null !== $type ? $type : $this->get_type() );
+        $collection->set_from_trusted( $elements );
+
+        return $collection;
+    }
+
+    /**
+     * Sets the elements without validating them.
+     *
+     * @param array $elements Pre-validated elements to set.
+     */
+    protected function set_from_trusted( array $elements ) {
+        $this->elements = $elements;
+    }
+
+    /**
+     * Number of elements true for the condition.
+     *
+     * @param callable $condition Condition to check.
+     * @return int
+     */
+    protected function count_while_true( $condition ) {
+        $count = 0;
+
+        foreach ( $this->elements as $element ) {
+            if ( ! $condition($element) ) {
+                break;
+            }
+            $count++;
+        }
+
+        return $count;
+    }
+
+    /**
+     * Validates a number to be used as an index.
+     *
+     * @param  integer $index The number to be validated as an index.
+     *
+     * @throws OutOfRangeException
+     */
+    protected function validate_index( $index ) {
+        $exists = $this->index_exists( $index );
+
+        if ( ! $exists ) {
+            throw new OutOfRangeException( 'Index out of bounds of collection' );
+        }
+    }
 }