Add JArrayHelper::invert

libraries/joomla/utilities/arrayhelper.php

@@ -330,6 +330,55 @@ public static function getValue(&$array, $name, $default = null, $type = '')
 		return $result;
 	}
 
+	/**
+	 * Takes an associative array of arrays and inverts the array keys to values using the array values as keys.
+	 *
+	 * Example:
+	 * $input = array(
+	 *     'New' => array('1000', '1500', '1750'),
+	 *     'Used' => array('3000', '4000', '5000', '6000')
+	 * );
+	 * $output = JArrayHelper::invert($input);
+	 *
+	 * Output would be equal to:
+	 * $output = array(
+	 *     '1000' => 'New',
+	 *     '1500' => 'New',
+	 *     '1750' => 'New',
+	 *     '3000' => 'Used',
+	 *     '4000' => 'Used',
+	 *     '5000' => 'Used',
+	 *     '6000' => 'Used'
+	 * );
+	 *
+	 * @param   array  $array  The source array.
+	 *
+	 * @return  array  The inverted array.
+	 *
+	 * @since   12.3
+	 */
+	public static function invert($array)
+	{
+		$return = array();
+		foreach ($array as $base => $values)
+		{
+			if (!is_array($values))
+			{
+				continue;
+			}
+
+			foreach ($values as $key)
+			{
+				// If the key isn't scalar then ignore it.
+				if (is_scalar($key))
+				{
+					$return[$key] = $base;
+				}
+			}
+		}
+		return $return;
+	}
+
 	/**
 	 * Method to determine if an array is an associative array.
 	 *

tests/suites/unit/joomla/utilities/JArrayHelperTest.php

@@ -372,6 +372,59 @@ function getTestGetValueData()
 		);
 	}
 
+	/**
+	 * Data provider for invert
+	 *
+	 * @return  array
+	 *
+	 * @since   12.3
+	 */
+	function getTestInvertData()
+	{
+
+		return array(
+			'Case 1' => array(
+				// Input
+				array(
+					'New' => array('1000', '1500', '1750'),
+		 			'Used' => array('3000', '4000', '5000', '6000')
+				),
+				// Expected
+				array(
+					'1000' => 'New',
+					'1500' => 'New',
+					'1750' => 'New',
+					'3000' => 'Used',
+					'4000' => 'Used',
+					'5000' => 'Used',
+					'6000' => 'Used'
+				)
+			),
+			'Case 2' => array(
+				// Input
+				array(
+					'New' => array(1000, 1500, 1750),
+					'Used' => array(2750, 3000, 4000, 5000, 6000),
+					'Refurbished' => array(2000, 2500),
+					'Unspecified' => array()
+				),
+				// Expected
+				array(
+					'1000' => 'New',
+					'1500' => 'New',
+					'1750' => 'New',
+					'2750' => 'Used',
+					'3000' => 'Used',
+					'4000' => 'Used',
+					'5000' => 'Used',
+					'6000' => 'Used',
+					'2000' => 'Refurbished',
+					'2500' => 'Refurbished'
+				)
+			)
+		);
+	}
+
 	/**
 	 * Data provider for testPivot
 	 *
@@ -1329,6 +1382,7 @@ public function testArrayUnique($input, $expected)
 			$this->equalTo($expected)
 		);
 	}
+
 	/**
 	 * Tests conversion of object to string.
 	 *
@@ -1409,6 +1463,25 @@ public function testGetValue($input, $index, $default, $type, $expect, $message,
 		$this->assertEquals($expect, $output, $message);
 	}
 
+	/**
+	 * Tests the JArrayHelper::invert method.
+	 *
+	 * @param   array   $input     The array being input.
+	 * @param   string  $expected  The expected return value.
+	 *
+	 * @return  void
+	 *
+	 * @dataProvider  getTestInvertData
+	 * @since   12.3
+	 */
+	public function testInvert($input, $expected)
+	{
+		$this->assertThat(
+			JArrayHelper::invert($input),
+			$this->equalTo($expected)
+		);
+	}
+
 	/**
 	 * Test the JArrayHelper::isAssociate method.
 	 *