Experimenting with result formatters and MapReduce

lib/Cake/ORM/MapReduce.php

@@ -0,0 +1,71 @@
+<?php
+/**
+ * PHP Version 5.4
+ *
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         CakePHP(tm) v 3.0.0
+ * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
+ */
+namespace Cake\ORM;
+
+use \IteratorAggregate;
+use \ArrayIterator;
+
+class MapReduce implements IteratorAggregate {
+
+	protected $_intermediate = [];
+
+	protected $_result = [];
+
+	protected $_executed = false;
+
+	protected $_data;
+
+	protected $_mapper;
+
+	protected $_reducer;
+
+	protected $_counter = 0;
+
+	public function __construct($data, callable $mapper, callable $reducer) {
+		$this->_data = $data;
+		$this->_mapper = $mapper;
+		$this->_reducer = $reducer;
+	}
+
+	public function getIterator() {
+		if (!$this->_executed) {
+			$this->_execute();
+		}
+		return new ArrayIterator($this->_result);
+	}
+
+	public function emitIntermediate($key, $value) {
+		$this->_intermediate[$key][] = $value;
+	}
+
+	public function emit($value, $slot = null) {
+		$this->_result[$slot === null ? $this->_counter : $slot] = $value;
+	}
+
+	protected function _execute() {
+		foreach ($this->_data as $key => $value) {
+			$this->_mapper->__invoke($key, $value, $this);
+		}
+
+		foreach ($this->_intermediate as $key => $list) {
+			$this->_reducer->__invoke($key, $list, $this);
+			$this->_counter++;
+		}
+		$this->_execute = true;
+	}
+
+}

lib/Cake/ORM/Query.php

@@ -67,6 +67,10 @@ class Query extends DatabaseQuery {
  */
 	protected $_loadEagerly = [];
 
+	protected $_mapper;
+
+	protected $_reducer;
+
 /**
  * List of options accepted by associations in contain()
  * index by key for faster access
@@ -100,6 +104,8 @@ class Query extends DatabaseQuery {
  */
 	protected $_useBufferedResults = false;
 
+	protected $_formatters = [];
+
 /**
  * @param Cake\Database\Connection $connection
  * @param Cake\ORM\Table $table
@@ -349,6 +355,11 @@ public function bufferResults() {
 		return $this;
 	}
 
+	public function formatResults($current = null, $key = null) {
+		$this->_formatters[] = compact('current', 'key');
+		return $this;
+	}
+
 /**
  * Set the result set for a query.
  *
@@ -382,9 +393,9 @@ public function execute() {
 			return $this->_results;
 		}
 		if ($this->_useBufferedResults) {
-			return new BufferedResultSet($this, parent::execute());
+			return $this->_applyFormatters(new BufferedResultSet($this, parent::execute()));
 		}
-		return new ResultSet($this, parent::execute());
+		return  $this->_applyFormatters(new ResultSet($this, parent::execute()));
 	}
 
 /**
@@ -518,6 +529,24 @@ public function applyOptions(array $options) {
 		return $this;
 	}
 
+	public function mapReduce(callable $mapper, callable $reducer) {
+		$this->_mapper = $mapper;
+		$this->_reducer = $reducer;
+		return $this;
+	}
+
+	protected function _applyFormatters($result) {
+		foreach ($this->_formatters as $formatter) {
+			$result = new ResultSetDecorator($result, $formatter);
+		}
+		if (!empty($this->_mapper) && !empty($this->_reducer)) {
+			$result = new ResultSetDecorator(
+				new MapReduce($result, $this->_mapper, $this->_reducer)
+			);
+		}
+		return $result;
+	}
+
 /**
  * Auxiliary function used to wrap the original statement from the driver with
  * any registered callbacks. This will also setup the correct statement class

lib/Cake/ORM/ResultSetDecorator.php

@@ -0,0 +1,83 @@
+<?php
+/**
+ * PHP Version 5.4
+ *
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         CakePHP(tm) v 3.0.0
+ * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
+ */
+namespace Cake\ORM;
+
+use \IteratorIterator;
+use \Iterator;
+
+class ResultSetDecorator implements Iterator {
+
+	protected $_keyCallback;
+
+	protected $_currentCallback;
+
+	protected $_results;
+
+	protected $_current;
+
+	public function __construct(\Traversable $results, $callbacks = []) {
+		if (!empty($callbacks['key'])) {
+			$this->_keyCallback = $callbacks['key'];
+		}
+		if (!empty($callbacks['current'])) {
+			$this->_currentCallback = $callbacks['current'];
+		}
+		$this->_results = $results;
+
+		if ($results instanceOf \IteratorAggregate) {
+			$this->_results = $results->getIterator();
+		}
+	}
+
+	public function key() {
+		$key = $this->_results->key();
+		if ($this->_keyCallback) {
+			$current = $this->_results->current();
+			$key = $this->_keyCallback->__invoke($current, $key);
+		}
+		return $key;
+	}
+
+	public function current() {
+		if ($this->_current) {
+			return $this->_current;
+		}
+		$current = $this->_results->current();
+		if ($current && $this->_currentCallback) {
+			$current = $this->_currentCallback->__invoke($current);
+		}
+		return $current;
+	}
+
+	public function next() {
+		$this->_current = null;
+		$this->_results->next();
+	}
+
+	public function rewind() {
+		$this->_current = null;
+		$this->_results->rewind();
+	}
+
+	public function valid() {
+		return $this->_results->valid();
+	}
+
+	public function toArray() {
+		return iterator_to_array($this);
+	}
+}

lib/Cake/ORM/Table.php

@@ -524,6 +524,32 @@ public function findAll(Query $query, array $options = []) {
 		return $query;
 	}
 
+	public function findList(Query $query, array $options = []) {
+		$mapper = function($key, $row, $mr) use ($query, &$columns) {
+			if (empty($columns)) {
+				$columns = array_slice(array_keys($row), 0, 3);
+			}
+
+			$key = isset($columns[2]) ? $row[$columns[2]] : $key;
+			list($rowKey, $rowVal) = $columns;
+			$mr->emitIntermediate($key, [$row[$rowKey] => $row[$rowVal]]);
+		};
+
+		$reducer = function($key, $values, $mr) use (&$columns) {
+			if (!isset($columns[2])) {
+				$mr->emit(current(current($values)), key(current($values)));
+				return;
+			}
+			$result = [];
+			foreach ($values as $value) {
+				$result += $value;
+			}
+			$mr->emit($result, $key);
+		};
+
+		return $query->mapReduce($mapper, $reducer);
+	}
+
 /**
  * Creates a new Query instance for this table
  *

lib/Cake/Test/TestCase/ORM/TableTest.php

@@ -506,4 +506,37 @@ public function testFindApplyOptions() {
 			->with($options);
 		$table->find('all', $options);
 	}
+
+/**
+ * Tests find('list')
+ *
+ * @return void
+ */
+	public function testFindList() {
+		$table = new Table(['table' => 'users', 'connection' => $this->connection]);
+		$query = $table->find('list', ['fields' => ['id', 'username']])->order('id');
+		$expected = [
+			1 => 'mariano',
+			2 => 'nate',
+			3 => 'larry',
+			4 => 'garrett'
+		];
+		$this->assertSame($expected, $query->toArray());
+
+		$query = $table->find('list')
+			->select(['id', 'username', 'odd' => 'id % 2 = 0'])
+			->order('id');
+		$expected = [
+			0 => [
+				1 => 'mariano',
+				3 => 'larry'
+			],
+			1 => [
+				2 => 'nate',
+				4 => 'garret'
+			]
+		];
+		$this->assertSame($expected, $query->toArray());
+	}
+
 }