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<?php

/**

 * 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

 * @package       Cake.Utility

 * @since         CakePHP(tm) v 2.2.0

 * @license       http://www.opensource.org/licenses/mit-license.php MIT License

 */

App::uses('String', 'Utility');

/**

 * Library of array functions for manipulating and extracting data

 * from arrays or 'sets' of data.

 *

 * `Hash` provides an improved interface, more consistent and

 * predictable set of features over `Set`. While it lacks the spotty

 * support for pseudo Xpath, its more fully featured dot notation provides

 * similar features in a more consistent implementation.

 *

 * @package       Cake.Utility

 */

class Hash {

/**

 * Get a single value specified by $path out of $data.

 * Does not support the full dot notation feature set,

 * but is faster for simple read operations.

 *

 * @param array $data Array of data to operate on.

 * @param string|array $path The path being searched for. Either a dot

 *   separated string, or an array of path segments.

 * @return mixed The value fetched from the array, or null.

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::get

 */

	public static function get(array $data, $path) {

		if (empty($data)) {

			return null;

		}

		if (is_string($path) || is_numeric($path)) {

			$parts = explode('.', $path);

		} else {

			$parts = $path;

		}

		foreach ($parts as $key) {

			if (is_array($data) && isset($data[$key])) {

				$data =& $data[$key];

			} else {

				return null;

			}

		}

		return $data;

	}

/**

 * Gets the values from an array matching the $path expression.

 * The path expression is a dot separated expression, that can contain a set

 * of patterns and expressions:

 *

 * - `{n}` Matches any numeric key, or integer.

 * - `{s}` Matches any string key.

 * - `Foo` Matches any key with the exact same value.

 *

 * There are a number of attribute operators:

 *

 *  - `=`, `!=` Equality.

 *  - `>`, `<`, `>=`, `<=` Value comparison.

 *  - `=/.../` Regular expression pattern match.

 *

 * Given a set of User array data, from a `$User->find('all')` call:

 *

 * - `1.User.name` Get the name of the user at index 1.

 * - `{n}.User.name` Get the name of every user in the set of users.

 * - `{n}.User[id]` Get the name of every user with an id key.

 * - `{n}.User[id>=2]` Get the name of every user with an id key greater than or equal to 2.

 * - `{n}.User[username=/^paul/]` Get User elements with username matching `^paul`.

 *

 * @param array $data The data to extract from.

 * @param string $path The path to extract.

 * @return array An array of the extracted values. Returns an empty array

 *   if there are no matches.

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::extract

 */

	public static function extract(array $data, $path) {

		if (empty($path)) {

			return $data;

		}

		// Simple paths.

		if (!preg_match('/[{\[]/', $path)) {

			return (array)self::get($data, $path);

		}

		if (strpos($path, '[') === false) {

			$tokens = explode('.', $path);

		} else {

			$tokens = String::tokenize($path, '.', '[', ']');

		}

		$_key = '__set_item__';

		$context = array($_key => array($data));

		foreach ($tokens as $token) {

			$next = array();

			$conditions = false;

			$position = strpos($token, '[');

			if ($position !== false) {

				$conditions = substr($token, $position);

				$token = substr($token, 0, $position);

			}

			foreach ($context[$_key] as $item) {

				foreach ((array)$item as $k => $v) {

					if (self::_matchToken($k, $token)) {

						$next[] = $v;

					}

				}

			}

			// Filter for attributes.

			if ($conditions) {

				$filter = array();

				foreach ($next as $item) {

					if (is_array($item) && self::_matches($item, $conditions)) {

						$filter[] = $item;

					}

				}

				$next = $filter;

			}

			$context = array($_key => $next);

		}

		return $context[$_key];

	}

/**

 * Check a key against a token.

 *

 * @param string $key The key in the array being searched.

 * @param string $token The token being matched.

 * @return boolean

 */

	protected static function _matchToken($key, $token) {

		if ($token === '{n}') {

			return is_numeric($key);

		}

		if ($token === '{s}') {

			return is_string($key);

		}

		if (is_numeric($token)) {

			return ($key == $token);

		}

		return ($key === $token);

	}

/**

 * Checks whether or not $data matches the attribute patterns

 *

 * @param array $data Array of data to match.

 * @param string $selector The patterns to match.

 * @return boolean Fitness of expression.

 */

	protected static function _matches(array $data, $selector) {

		preg_match_all(

			'/(\[ (?P<attr>[^=><!]+?) (\s* (?P<op>[><!]?[=]|[><]) \s* (?P<val>(?:\/.*?\/ | [^\]]+)) )? \])/x',

			$selector,

			$conditions,

			PREG_SET_ORDER

		);

		foreach ($conditions as $cond) {

			$attr = $cond['attr'];

			$op = isset($cond['op']) ? $cond['op'] : null;

			$val = isset($cond['val']) ? $cond['val'] : null;

			// Presence test.

			if (empty($op) && empty($val) && !isset($data[$attr])) {

				return false;

			}

			// Empty attribute = fail.

			if (!(isset($data[$attr]) || array_key_exists($attr, $data))) {

				return false;

			}

			$prop = isset($data[$attr]) ? $data[$attr] : null;

			// Pattern matches and other operators.

			if ($op === '=' && $val && $val[0] === '/') {

				if (!preg_match($val, $prop)) {

					return false;

				}

			} elseif (

				($op === '=' && $prop != $val) ||

				($op === '!=' && $prop == $val) ||

				($op === '>' && $prop <= $val) ||

				($op === '<' && $prop >= $val) ||

				($op === '>=' && $prop < $val) ||

				($op === '<=' && $prop > $val)

			) {

				return false;

			}

		}

		return true;

	}

/**

 * Insert $values into an array with the given $path. You can use

 * `{n}` and `{s}` elements to insert $data multiple times.

 *

 * @param array $data The data to insert into.

 * @param string $path The path to insert at.

 * @param array $values The values to insert.

 * @return array The data with $values inserted.

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::insert

 */

	public static function insert(array $data, $path, $values = null) {

		$tokens = explode('.', $path);

		if (strpos($path, '{') === false) {

			return self::_simpleOp('insert', $data, $tokens, $values);

		}

		$token = array_shift($tokens);

		$nextPath = implode('.', $tokens);

		foreach ($data as $k => $v) {

			if (self::_matchToken($k, $token)) {

				$data[$k] = self::insert($v, $nextPath, $values);

			}

		}

		return $data;

	}

/**

 * Perform a simple insert/remove operation.

 *

 * @param string $op The operation to do.

 * @param array $data The data to operate on.

 * @param array $path The path to work on.

 * @param mixed $values The values to insert when doing inserts.

 * @return array $data.

 */

	protected static function _simpleOp($op, $data, $path, $values = null) {

		$_list =& $data;

		$count = count($path);

		$last = $count - 1;

		foreach ($path as $i => $key) {

			if (is_numeric($key) && intval($key) > 0 || $key === '0') {

				$key = intval($key);

			}

			if ($op === 'insert') {

				if ($i === $last) {

					$_list[$key] = $values;

					return $data;

				}

				if (!isset($_list[$key])) {

					$_list[$key] = array();

				}

				$_list =& $_list[$key];

				if (!is_array($_list)) {

					$_list = array();

				}

			} elseif ($op === 'remove') {

				if ($i === $last) {

					unset($_list[$key]);

					return $data;

				}

				if (!isset($_list[$key])) {

					return $data;

				}

				$_list =& $_list[$key];

			}

		}

	}

/**

 * Remove data matching $path from the $data array.

 * You can use `{n}` and `{s}` to remove multiple elements

 * from $data.

 *

 * @param array $data The data to operate on

 * @param string $path A path expression to use to remove.

 * @return array The modified array.

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::remove

 */

	public static function remove(array $data, $path) {

		$tokens = explode('.', $path);

		if (strpos($path, '{') === false) {

			return self::_simpleOp('remove', $data, $tokens);

		}

		$token = array_shift($tokens);

		$nextPath = implode('.', $tokens);

		foreach ($data as $k => $v) {

			$match = self::_matchToken($k, $token);

			if ($match && is_array($v)) {

				$data[$k] = self::remove($v, $nextPath);

			} elseif ($match) {

				unset($data[$k]);

			}

		}

		return $data;

	}

/**

 * Creates an associative array using `$keyPath` as the path to build its keys, and optionally

 * `$valuePath` as path to get the values. If `$valuePath` is not specified, all values will be initialized

 * to null (useful for Hash::merge). You can optionally group the values by what is obtained when

 * following the path specified in `$groupPath`.

 *

 * @param array $data Array from where to extract keys and values

 * @param string $keyPath A dot-separated string.

 * @param string $valuePath A dot-separated string.

 * @param string $groupPath A dot-separated string.

 * @return array Combined array

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::combine

 */

	public static function combine(array $data, $keyPath, $valuePath = null, $groupPath = null) {

		if (empty($data)) {

			return array();

		}

		if (is_array($keyPath)) {

			$format = array_shift($keyPath);

			$keys = self::format($data, $keyPath, $format);

		} else {

			$keys = self::extract($data, $keyPath);

		}

		if (empty($keys)) {

			return array();

		}

		if (!empty($valuePath) && is_array($valuePath)) {

			$format = array_shift($valuePath);

			$vals = self::format($data, $valuePath, $format);

		} elseif (!empty($valuePath)) {

			$vals = self::extract($data, $valuePath);

		}

		$count = count($keys);

		for ($i = 0; $i < $count; $i++) {

			$vals[$i] = isset($vals[$i]) ? $vals[$i] : null;

		}

		if ($groupPath !== null) {

			$group = self::extract($data, $groupPath);

			if (!empty($group)) {

				$c = count($keys);

				for ($i = 0; $i < $c; $i++) {

					if (!isset($group[$i])) {

						$group[$i] = 0;

					}

					if (!isset($out[$group[$i]])) {

						$out[$group[$i]] = array();

					}

					$out[$group[$i]][$keys[$i]] = $vals[$i];

				}

				return $out;

			}

		}

		if (empty($vals)) {

			return array();

		}

		return array_combine($keys, $vals);

	}

/**

 * Returns a formatted series of values extracted from `$data`, using

 * `$format` as the format and `$paths` as the values to extract.

 *

 * Usage:

 *

 * {{{

 * $result = Hash::format($users, array('{n}.User.id', '{n}.User.name'), '%s : %s');

 * }}}

 *

 * The `$format` string can use any format options that `vsprintf()` and `sprintf()` do.

 *

 * @param array $data Source array from which to extract the data

 * @param string $paths An array containing one or more Hash::extract()-style key paths

 * @param string $format Format string into which values will be inserted, see sprintf()

 * @return array An array of strings extracted from `$path` and formatted with `$format`

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::format

 * @see sprintf()

 * @see Hash::extract()

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::format

 */

	public static function format(array $data, array $paths, $format) {

		$extracted = array();

		$count = count($paths);

		if (!$count) {

			return;

		}

		for ($i = 0; $i < $count; $i++) {

			$extracted[] = self::extract($data, $paths[$i]);

		}

		$out = array();

		$data = $extracted;

		$count = count($data[0]);

		$countTwo = count($data);

		for ($j = 0; $j < $count; $j++) {

			$args = array();

			for ($i = 0; $i < $countTwo; $i++) {

				if (array_key_exists($j, $data[$i])) {

					$args[] = $data[$i][$j];

				}

			}

			$out[] = vsprintf($format, $args);

		}

		return $out;

	}

/**

 * Determines if one array contains the exact keys and values of another.

 *

 * @param array $data The data to search through.

 * @param array $needle The values to file in $data

 * @return boolean true if $data contains $needle, false otherwise

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::contains

 */

	public static function contains(array $data, array $needle) {

		if (empty($data) || empty($needle)) {

			return false;

		}

		$stack = array();

		while (!empty($needle)) {

			$key = key($needle);

			$val = $needle[$key];

			unset($needle[$key]);

			if (array_key_exists($key, $data) && is_array($val)) {

				$next = $data[$key];

				unset($data[$key]);

				if (!empty($val)) {

					$stack[] = array($val, $next);

				}

			} elseif (!array_key_exists($key, $data) || $data[$key] != $val) {

				return false;

			}

			if (empty($needle) && !empty($stack)) {

				list($needle, $data) = array_pop($stack);

			}

		}

		return true;

	}

/**

 * Test whether or not a given path exists in $data.

 * This method uses the same path syntax as Hash::extract()

 *

 * Checking for paths that could target more than one element will

 * make sure that at least one matching element exists.

 *

 * @param array $data The data to check.

 * @param string $path The path to check for.

 * @return boolean Existence of path.

 * @see Hash::extract()

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::check

 */

	public static function check(array $data, $path) {

		$results = self::extract($data, $path);

		if (!is_array($results)) {

			return false;

		}

		return count($results) > 0;

	}

/**

 * Recursively filters a data set.

 *

 * @param array $data Either an array to filter, or value when in callback

 * @param callable $callback A function to filter the data with. Defaults to

 *   `self::_filter()` Which strips out all non-zero empty values.

 * @return array Filtered array

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::filter

 */

	public static function filter(array $data, $callback = array('self', '_filter')) {

		foreach ($data as $k => $v) {

			if (is_array($v)) {

				$data[$k] = self::filter($v, $callback);

			}

		}

		return array_filter($data, $callback);

	}

/**

 * Callback function for filtering.

 *

 * @param array $var Array to filter.

 * @return boolean

 */

	protected static function _filter($var) {

		if ($var === 0 || $var === '0' || !empty($var)) {

			return true;

		}

		return false;

	}

/**

 * Collapses a multi-dimensional array into a single dimension, using a delimited array path for

 * each array element's key, i.e. array(array('Foo' => array('Bar' => 'Far'))) becomes

 * array('0.Foo.Bar' => 'Far').)

 *

 * @param array $data Array to flatten

 * @param string $separator String used to separate array key elements in a path, defaults to '.'

 * @return array

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::flatten

 */

	public static function flatten(array $data, $separator = '.') {

		$result = array();

		$stack = array();

		$path = null;

		reset($data);

		while (!empty($data)) {

			$key = key($data);

			$element = $data[$key];

			unset($data[$key]);

			if (is_array($element) && !empty($element)) {

				if (!empty($data)) {

					$stack[] = array($data, $path);

				}

				$data = $element;

				reset($data);

				$path .= $key . $separator;

			} else {

				$result[$path . $key] = $element;

			}

			if (empty($data) && !empty($stack)) {

				list($data, $path) = array_pop($stack);

				reset($data);

			}

		}

		return $result;

	}

/**

 * Expands a flat array to a nested array.

 *

 * For example, unflattens an array that was collapsed with `Hash::flatten()`

 * into a multi-dimensional array. So, `array('0.Foo.Bar' => 'Far')` becomes

 * `array(array('Foo' => array('Bar' => 'Far')))`.

 *

 * @param array $data Flattened array

 * @param string $separator The delimiter used

 * @return array

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::expand

 */

	public static function expand($data, $separator = '.') {

		$result = array();

		foreach ($data as $flat => $value) {

			$keys = explode($separator, $flat);

			$keys = array_reverse($keys);

			$child = array(

				$keys[0] => $value

			);

			array_shift($keys);

			foreach ($keys as $k) {

				$child = array(

					$k => $child

				);

			}

			$result = self::merge($result, $child);

		}

		return $result;

	}

/**

 * This function can be thought of as a hybrid between PHP's `array_merge` and `array_merge_recursive`.

 *

 * The difference between this method and the built-in ones, is that if an array key contains another array, then

 * Hash::merge() will behave in a recursive fashion (unlike `array_merge`). But it will not act recursively for

 * keys that contain scalar values (unlike `array_merge_recursive`).

 *

 * Note: This function will work with an unlimited amount of arguments and typecasts non-array parameters into arrays.

 *

 * @param array $data Array to be merged

 * @param mixed $merge Array to merge with. The argument and all trailing arguments will be array cast when merged

 * @return array Merged array

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::merge

 */

	public static function merge(array $data, $merge) {

		$args = func_get_args();

		$return = current($args);

		while (($arg = next($args)) !== false) {

			foreach ((array)$arg as $key => $val) {

				if (!empty($return[$key]) && is_array($return[$key]) && is_array($val)) {

					$return[$key] = self::merge($return[$key], $val);

				} elseif (is_int($key) && isset($return[$key])) {

					$return[] = $val;

				} else {

					$return[$key] = $val;

				}

			}

		}

		return $return;

	}

/**

 * Checks to see if all the values in the array are numeric

 *

 * @param array $array The array to check.

 * @return boolean true if values are numeric, false otherwise

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::numeric

 */

	public static function numeric(array $data) {

		if (empty($data)) {

			return false;

		}

		return $data === array_filter($data, 'is_numeric');

	}

/**

 * Counts the dimensions of an array.

 * Only considers the dimension of the first element in the array.

 *

 * If you have an un-even or heterogenous array, consider using Hash::maxDimensions()

 * to get the dimensions of the array.

 *

 * @param array $array Array to count dimensions on

 * @return integer The number of dimensions in $data

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::dimensions

 */

	public static function dimensions(array $data) {

		if (empty($data)) {

			return 0;

		}

		reset($data);

		$depth = 1;

		while ($elem = array_shift($data)) {

			if (is_array($elem)) {

				$depth += 1;

				$data =& $elem;

			} else {

				break;

			}

		}

		return $depth;

	}

/**

 * Counts the dimensions of *all* array elements. Useful for finding the maximum

 * number of dimensions in a mixed array.

 *

 * @param array $data Array to count dimensions on

 * @return integer The maximum number of dimensions in $data

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::maxDimensions

 */

	public static function maxDimensions(array $data) {

		$depth = array();

		if (is_array($data) && reset($data) !== false) {

			foreach ($data as $value) {

				$depth[] = self::dimensions((array)$value) + 1;

			}

		}

		return max($depth);

	}

/**

 * Map a callback across all elements in a set.

 * Can be provided a path to only modify slices of the set.

 *

 * @param array $data The data to map over, and extract data out of.

 * @param string $path The path to extract for mapping over.

 * @param callable $function The function to call on each extracted value.

 * @return array An array of the modified values.

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::map

 */

	public static function map(array $data, $path, $function) {

		$values = (array)self::extract($data, $path);

		return array_map($function, $values);

	}

/**

 * Reduce a set of extracted values using `$function`.

 *

 * @param array $data The data to reduce.

 * @param string $path The path to extract from $data.

 * @param callable $function The function to call on each extracted value.

 * @return mixed The reduced value.

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::reduce

 */

	public static function reduce(array $data, $path, $function) {

		$values = (array)self::extract($data, $path);

		return array_reduce($values, $function);

	}

/**

 * Apply a callback to a set of extracted values using `$function`.

 * The function will get the extracted values as the first argument.

 *

 * ### Example

 *

 * You can easily count the results of an extract using apply().

 * For example to count the comments on an Article:

 *

 * `$count = Hash::apply($data, 'Article.Comment.{n}', 'count');`

 *

 * You could also use a function like `array_sum` to sum the results.

 *

 * `$total = Hash::apply($data, '{n}.Item.price', 'array_sum');`

 *

 * @param array $data The data to reduce.

 * @param string $path The path to extract from $data.

 * @param callable $function The function to call on each extracted value.

 * @return mixed The results of the applied method.

 */

	public static function apply(array $data, $path, $function) {

		$values = (array)self::extract($data, $path);

		return call_user_func($function, $values);

	}

/**

 * Sorts an array by any value, determined by a Set-compatible path

 *

 * ### Sort directions

 *

 * - `asc` Sort ascending.

 * - `desc` Sort descending.

 *

 * ## Sort types

 *

 * - `regular` For regular sorting (don't change types)

 * - `numeric` Compare values numerically

 * - `string` Compare values as strings

 * - `natural` Compare items as strings using "natural ordering" in a human friendly way.

 *   Will sort foo10 below foo2 as an example. Requires PHP 5.4 or greater or it will fallback to 'regular'

 *

 * @param array $data An array of data to sort

 * @param string $path A Set-compatible path to the array value

 * @param string $dir See directions above.

 * @param string $type See direction types above. Defaults to 'regular'.

 * @return array Sorted array of data

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::sort

 */

	public static function sort(array $data, $path, $dir, $type = 'regular') {

		if (empty($data)) {

			return array();

		}

		$originalKeys = array_keys($data);

		$numeric = is_numeric(implode('', $originalKeys));

		if ($numeric) {

			$data = array_values($data);

		}

		$sortValues = self::extract($data, $path);

		$sortCount = count($sortValues);

		$dataCount = count($data);

		// Make sortValues match the data length, as some keys could be missing

		// the sorted value path.

		if ($sortCount < $dataCount) {

			$sortValues = array_pad($sortValues, $dataCount, null);

		}

		$result = self::_squash($sortValues);

		$keys = self::extract($result, '{n}.id');

		$values = self::extract($result, '{n}.value');

		$dir = strtolower($dir);

		$type = strtolower($type);

		if ($type === 'natural' && version_compare(PHP_VERSION, '5.4.0', '<')) {

			$type = 'regular';

		}

		if ($dir === 'asc') {

			$dir = SORT_ASC;

		} else {

			$dir = SORT_DESC;

		}

		if ($type === 'numeric') {

			$type = SORT_NUMERIC;

		} elseif ($type === 'string') {

			$type = SORT_STRING;

		} elseif ($type === 'natural') {

			$type = SORT_NATURAL;

		} else {

			$type = SORT_REGULAR;

		}

		array_multisort($values, $dir, $type, $keys, $dir, $type);

		$sorted = array();

		$keys = array_unique($keys);

		foreach ($keys as $k) {

			if ($numeric) {

				$sorted[] = $data[$k];

				continue;

			}

			if (isset($originalKeys[$k])) {

				$sorted[$originalKeys[$k]] = $data[$originalKeys[$k]];

			} else {

				$sorted[$k] = $data[$k];

			}

		}

		return $sorted;

	}

/**

 * Helper method for sort()

 * Squashes an array to a single hash so it can be sorted.

 *

 * @param array $data The data to squash.

 * @param string $key The key for the data.

 * @return array

 */

	protected static function _squash($data, $key = null) {

		$stack = array();

		foreach ($data as $k => $r) {

			$id = $k;

			if ($key !== null) {

				$id = $key;

			}

			if (is_array($r) && !empty($r)) {

				$stack = array_merge($stack, self::_squash($r, $id));

			} else {

				$stack[] = array('id' => $id, 'value' => $r);

			}

		}

		return $stack;

	}

/**

 * Computes the difference between two complex arrays.

 * This method differs from the built-in array_diff() in that it will preserve keys

 * and work on multi-dimensional arrays.

 *

 * @param array $data First value

 * @param array $compare Second value

 * @return array Returns the key => value pairs that are not common in $data and $compare

 *    The expression for this function is ($data - $compare) + ($compare - ($data - $compare))

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::diff

 */

	public static function diff(array $data, $compare) {

		if (empty($data)) {

			return (array)$compare;

		}

		if (empty($compare)) {

			return (array)$data;

		}

		$intersection = array_intersect_key($data, $compare);

		while (($key = key($intersection)) !== null) {

			if ($data[$key] == $compare[$key]) {

				unset($data[$key]);

				unset($compare[$key]);

			}

			next($intersection);

		}

		return $data + $compare;

	}

/**

 * Merges the difference between $data and $compare onto $data.

 *

 * @param array $data The data to append onto.

 * @param array $compare The data to compare and append onto.

 * @return array The merged array.

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::mergeDiff

 */

	public static function mergeDiff(array $data, $compare) {

		if (empty($data) && !empty($compare)) {

			return $compare;

		}

		if (empty($compare)) {

			return $data;

		}

		foreach ($compare as $key => $value) {

			if (!array_key_exists($key, $data)) {

				$data[$key] = $value;

			} elseif (is_array($value)) {

				$data[$key] = self::mergeDiff($data[$key], $compare[$key]);

			}

		}

		return $data;

	}

/**

 * Normalizes an array, and converts it to a standard format.

 *

 * @param array $data List to normalize

 * @param boolean $assoc If true, $data will be converted to an associative array.

 * @return array

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::normalize

 */

	public static function normalize(array $data, $assoc = true) {

		$keys = array_keys($data);

		$count = count($keys);

		$numeric = true;

		if (!$assoc) {

			for ($i = 0; $i < $count; $i++) {

				if (!is_int($keys[$i])) {

					$numeric = false;

					break;

				}

			}

		}

		if (!$numeric || $assoc) {

			$newList = array();

			for ($i = 0; $i < $count; $i++) {

				if (is_int($keys[$i])) {

					$newList[$data[$keys[$i]]] = null;

				} else {

					$newList[$keys[$i]] = $data[$keys[$i]];

				}

			}

			$data = $newList;

		}

		return $data;

	}

/**

 * Takes in a flat array and returns a nested array

 *

 * ### Options:

 *

 * - `children` The key name to use in the resultset for children.

 * - `idPath` The path to a key that identifies each entry. Should be

 *   compatible with Hash::extract(). Defaults to `{n}.$alias.id`

 * - `parentPath` The path to a key that identifies the parent of each entry.

 *   Should be compatible with Hash::extract(). Defaults to `{n}.$alias.parent_id`

 * - `root` The id of the desired top-most result.

 *

 * @param array $data The data to nest.

 * @param array $options Options are:

 * @return array of results, nested

 * @see Hash::extract()

 * @link http://book.cakephp.org/2.0/en/core-utility-libraries/hash.html#Hash::nest

 */

	public static function nest(array $data, $options = array()) {

		if (!$data) {

			return $data;

		}

		$alias = key(current($data));

		$options += array(

			'idPath' => "{n}.$alias.id",

			'parentPath' => "{n}.$alias.parent_id",

			'children' => 'children',

			'root' => null

		);

		$return = $idMap = array();

		$ids = self::extract($data, $options['idPath']);

		$idKeys = explode('.', $options['idPath']);

		array_shift($idKeys);

		$parentKeys = explode('.', $options['parentPath']);

		array_shift($parentKeys);

		foreach ($data as $result) {

			$result[$options['children']] = array();

			$id = self::get($result, $idKeys);

			$parentId = self::get($result, $parentKeys);

			if (isset($idMap[$id][$options['children']])) {

				$idMap[$id] = array_merge($result, (array)$idMap[$id]);

			} else {

				$idMap[$id] = array_merge($result, array($options['children'] => array()));

			}

			if (!$parentId || !in_array($parentId, $ids)) {

				$return[] =& $idMap[$id];

			} else {

				$idMap[$parentId][$options['children']][] =& $idMap[$id];

			}

		}

		if ($options['root']) {

			$root = $options['root'];

		} else {

			$root = self::get($return[0], $parentKeys);

		}

		foreach ($return as $i => $result) {

			$id = self::get($result, $idKeys);

			$parentId = self::get($result, $parentKeys);

			if ($id !== $root && $parentId != $root) {

				unset($return[$i]);

			}

		}

		return array_values($return);