CRM/Utils/Array.php

   1 <?php
   2 /*
   3  +--------------------------------------------------------------------+
   4  | CiviCRM version 4.6                                                |
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   6  | Copyright CiviCRM LLC (c) 2004-2014                                |
   7  +--------------------------------------------------------------------+
   8  | This file is a part of CiviCRM.                                    |
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  10  | CiviCRM is free software; you can copy, modify, and distribute it  |
  11  | under the terms of the GNU Affero General Public License           |
  12  | Version 3, 19 November 2007 and the CiviCRM Licensing Exception.   |
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  25  +--------------------------------------------------------------------+
  26  */
  27
  28 /**
  29  * Provides a collection of static methods for array manipulation.
  30  *
  31  * @package CRM
  32  * @copyright CiviCRM LLC (c) 2004-2014
  33  */
  34 class CRM_Utils_Array {
  35
  36   /**
  37    * Returns $list[$key] if such element exists, or a default value otherwise.
  38    *
  39    * If $list is not actually an array at all, then the default value is
  40    * returned.
  41    *
  42    *
  43    * @param string $key
  44    *   Key value to look up in the array.
  45    * @param array $list
  46    *   Array from which to look up a value.
  47    * @param mixed $default
  48    *   (optional) Value to return $list[$key] does not exist.
  49    *
  50    * @return mixed
  51    *   Can return any type, since $list might contain anything.
  52    */
  53   public static function value($key, $list, $default = NULL) {
  54     if (is_array($list)) {
  55       return array_key_exists($key, $list) ? $list[$key] : $default;
  56     }
  57     return $default;
  58   }
  59
  60   /**
  61    * Recursively searches an array for a key, returning the first value found.
  62    *
  63    * If $params[$key] does not exist and $params contains arrays, descend into
  64    * each array in a depth-first manner, in array iteration order.
  65    *
  66    * @param array $params
  67    *   The array to be searched.
  68    * @param string $key
  69    *   The key to search for.
  70    *
  71    * @return mixed
  72    *   The value of the key, or null if the key is not found.
  73    */
  74   public static function retrieveValueRecursive(&$params, $key) {
  75     if (!is_array($params)) {
  76       return NULL;
  77     }
  78     elseif ($value = CRM_Utils_Array::value($key, $params)) {
  79       return $value;
  80     }
  81     else {
  82       foreach ($params as $subParam) {
  83         if (is_array($subParam) &&
  84           $value = self::retrieveValueRecursive($subParam, $key)
  85         ) {
  86           return $value;
  87         }
  88       }
  89     }
  90     return NULL;
  91   }
  92
  93   /**
  94    * Wraps and slightly changes the behavior of PHP's array_search().
  95    *
  96    * This function reproduces the behavior of array_search() from PHP prior to
  97    * version 4.2.0, which was to return NULL on failure. This function also
  98    * checks that $list is an array before attempting to search it.
  99    *
 100    *
 101    * @param mixed $value
 102    *   The value to search for.
 103    * @param array $list
 104    *   The array to be searched.
 105    *
 106    * @return int|string|null
 107    *   Returns the key, which could be an int or a string, or NULL on failure.
 108    */
 109   public static function key($value, &$list) {
 110     if (is_array($list)) {
 111       $key = array_search($value, $list);
 112
 113       // array_search returns key if found, false otherwise
 114       // it may return values like 0 or empty string which
 115       // evaluates to false
 116       // hence we must use identical comparison operator
 117       return ($key === FALSE) ? NULL : $key;
 118     }
 119     return NULL;
 120   }
 121
 122   /**
 123    * Builds an XML fragment representing an array.
 124    *
 125    * Depending on the nature of the keys of the array (and its sub-arrays,
 126    * if any) the XML fragment may not be valid.
 127    *
 128    * @param array $list
 129    *   The array to be serialized.
 130    * @param int $depth
 131    *   (optional) Indentation depth counter.
 132    * @param string $seperator
 133    *   (optional) String to be appended after open/close tags.
 134    *
 135    *
 136    * @return string
 137    *   XML fragment representing $list.
 138    */
 139   public static function &xml(&$list, $depth = 1, $seperator = "\n") {
 140     $xml = '';
 141     foreach ($list as $name => $value) {
 142       $xml .= str_repeat(' ', $depth * 4);
 143       if (is_array($value)) {
 144         $xml .= "<{$name}>{$seperator}";
 145         $xml .= self::xml($value, $depth + 1, $seperator);
 146         $xml .= str_repeat(' ', $depth * 4);
 147         $xml .= "</{$name}>{$seperator}";
 148       }
 149       else {
 150         // make sure we escape value
 151         $value = self::escapeXML($value);
 152         $xml .= "<{$name}>$value</{$name}>{$seperator}";
 153       }
 154     }
 155     return $xml;
 156   }
 157
 158   /**
 159    * Sanitizes a string for serialization in CRM_Utils_Array::xml().
 160    *
 161    * Replaces '&', '<', and '>' with their XML escape sequences. Replaces '^A'
 162    * with a comma.
 163    *
 164    * @param string $value
 165    *   String to be sanitized.
 166    *
 167    * @return string
 168    *   Sanitized version of $value.
 169    */
 170   public static function escapeXML($value) {
 171     static $src = NULL;
 172     static $dst = NULL;
 173
 174     if (!$src) {
 175       $src = array('&', '<', '>', '\ 1');
 176       $dst = array('&amp;', '&lt;', '&gt;', ',');
 177     }
 178
 179     return str_replace($src, $dst, $value);
 180   }
 181
 182   /**
 183    * Converts a nested array to a flat array.
 184    *
 185    * The nested structure is preserved in the string values of the keys of the
 186    * flat array.
 187    *
 188    * Example nested array:
 189    * Array
 190    * (
 191    *     [foo] => Array
 192    *         (
 193    *             [0] => bar
 194    *             [1] => baz
 195    *             [2] => 42
 196    *         )
 197    *
 198    *     [asdf] => Array
 199    *         (
 200    *             [merp] => bleep
 201    *             [quack] => Array
 202    *                 (
 203    *                     [0] => 1
 204    *                     [1] => 2
 205    *                     [2] => 3
 206    *                 )
 207    *
 208    *         )
 209    *
 210    *     [quux] => 999
 211    * )
 212    *
 213    * Corresponding flattened array:
 214    * Array
 215    * (
 216    *     [foo.0] => bar
 217    *     [foo.1] => baz
 218    *     [foo.2] => 42
 219    *     [asdf.merp] => bleep
 220    *     [asdf.quack.0] => 1
 221    *     [asdf.quack.1] => 2
 222    *     [asdf.quack.2] => 3
 223    *     [quux] => 999
 224    * )
 225    *
 226    * @param array $list
 227    *   Array to be flattened.
 228    * @param array $flat
 229    *   Destination array.
 230    * @param string $prefix
 231    *   (optional) String to prepend to keys.
 232    * @param string $seperator
 233    *   (optional) String that separates the concatenated keys.
 234    */
 235   public static function flatten(&$list, &$flat, $prefix = '', $seperator = ".") {
 236     foreach ($list as $name => $value) {
 237       $newPrefix = ($prefix) ? $prefix . $seperator . $name : $name;
 238       if (is_array($value)) {
 239         self::flatten($value, $flat, $newPrefix, $seperator);
 240       }
 241       else {
 242         if (!empty($value)) {
 243           $flat[$newPrefix] = $value;
 244         }
 245       }
 246     }
 247   }
 248
 249   /**
 250    * Converts an array with path-like keys into a tree of arrays.
 251    *
 252    * This function is the inverse of CRM_Utils_Array::flatten().
 253    *
 254    * @param string $delim
 255    *   A path delimiter
 256    * @param array $arr
 257    *   A one-dimensional array indexed by string keys
 258    *
 259    * @return array
 260    *   Array-encoded tree
 261    */
 262   public function unflatten($delim, &$arr) {
 263     $result = array();
 264     foreach ($arr as $key => $value) {
 265       $path = explode($delim, $key);
 266       $node = &$result;
 267       while (count($path) > 1) {
 268         $key = array_shift($path);
 269         if (!isset($node[$key])) {
 270           $node[$key] = array();
 271         }
 272         $node = &$node[$key];
 273       }
 274       // last part of path
 275       $key = array_shift($path);
 276       $node[$key] = $value;
 277     }
 278     return $result;
 279   }
 280
 281   /**
 282    * Merges two arrays.
 283    *
 284    * If $a1[foo] and $a2[foo] both exist and are both arrays, the merge
 285    * process recurses into those sub-arrays. If $a1[foo] and $a2[foo] both
 286    * exist but they are not both arrays, the value from $a1 overrides the
 287    * value from $a2 and the value from $a2 is discarded.
 288    *
 289    * @param array $a1
 290    *   First array to be merged.
 291    * @param array $a2
 292    *   Second array to be merged.
 293    *
 294    * @return array
 295    *   The merged array.
 296    */
 297   public static function crmArrayMerge($a1, $a2) {
 298     if (empty($a1)) {
 299       return $a2;
 300     }
 301
 302     if (empty($a2)) {
 303       return $a1;
 304     }
 305
 306     $a3 = array();
 307     foreach ($a1 as $key => $value) {
 308       if (array_key_exists($key, $a2) &&
 309         is_array($a2[$key]) && is_array($a1[$key])
 310       ) {
 311         $a3[$key] = array_merge($a1[$key], $a2[$key]);
 312       }
 313       else {
 314         $a3[$key] = $a1[$key];
 315       }
 316     }
 317
 318     foreach ($a2 as $key => $value) {
 319       if (array_key_exists($key, $a1)) {
 320         // already handled in above loop
 321         continue;
 322       }
 323       $a3[$key] = $a2[$key];
 324     }
 325
 326     return $a3;
 327   }
 328
 329   /**
 330    * Determines whether an array contains any sub-arrays.
 331    *
 332    * @param array $list
 333    *   The array to inspect.
 334    *
 335    * @return bool
 336    *   True if $list contains at least one sub-array, false otherwise.
 337    */
 338   public static function isHierarchical(&$list) {
 339     foreach ($list as $n => $v) {
 340       if (is_array($v)) {
 341         return TRUE;
 342       }
 343     }
 344     return FALSE;
 345   }
 346
 347   /**
 348    * @param $subset
 349    * @param $superset
 350    * @return bool
 351    *   TRUE if $subset is a subset of $superset
 352    */
 353   public static function isSubset($subset, $superset) {
 354     foreach ($subset as $expected) {
 355       if (!in_array($expected, $superset)) {
 356         return FALSE;
 357       }
 358     }
 359     return TRUE;
 360   }
 361
 362   /**
 363    * Searches an array recursively in an optionally case-insensitive manner.
 364    *
 365    * @param string $value
 366    *   Value to search for.
 367    * @param array $params
 368    *   Array to search within.
 369    * @param bool $caseInsensitive
 370    *   (optional) Whether to search in a case-insensitive manner.
 371    *
 372    * @return bool
 373    *   True if $value was found, false otherwise.
 374    */
 375   public static function crmInArray($value, $params, $caseInsensitive = TRUE) {
 376     foreach ($params as $item) {
 377       if (is_array($item)) {
 378         $ret = crmInArray($value, $item, $caseInsensitive);
 379       }
 380       else {
 381         $ret = ($caseInsensitive) ? strtolower($item) == strtolower($value) : $item == $value;
 382         if ($ret) {
 383           return $ret;
 384         }
 385       }
 386     }
 387     return FALSE;
 388   }
 389
 390   /**
 391    * convert associative array names to values.
 392    * and vice-versa.
 393    *
 394    * This function is used by both the web form layer and the api. Note that
 395    * the api needs the name => value conversion, also the view layer typically
 396    * requires value => name conversion
 397    */
 398   public static function lookupValue(&$defaults, $property, $lookup, $reverse) {
 399     $id = $property . '_id';
 400
 401     $src = $reverse ? $property : $id;
 402     $dst = $reverse ? $id : $property;
 403
 404     if (!array_key_exists(strtolower($src), array_change_key_case($defaults, CASE_LOWER))) {
 405       return FALSE;
 406     }
 407
 408     $look = $reverse ? array_flip($lookup) : $lookup;
 409
 410     //trim lookup array, ignore . ( fix for CRM-1514 ), eg for prefix/suffix make sure Dr. and Dr both are valid
 411     $newLook = array();
 412     foreach ($look as $k => $v) {
 413       $newLook[trim($k, ".")] = $v;
 414     }
 415
 416     $look = $newLook;
 417
 418     if (is_array($look)) {
 419       if (!array_key_exists(trim(strtolower($defaults[strtolower($src)]), '.'), array_change_key_case($look, CASE_LOWER))) {
 420         return FALSE;
 421       }
 422     }
 423
 424     $tempLook = array_change_key_case($look, CASE_LOWER);
 425
 426     $defaults[$dst] = $tempLook[trim(strtolower($defaults[strtolower($src)]), '.')];
 427     return TRUE;
 428   }
 429
 430   /**
 431    * Checks whether an array is empty.
 432    *
 433    * An array is empty if its values consist only of NULL and empty sub-arrays.
 434    * Containing a non-NULL value or non-empty array makes an array non-empty.
 435    *
 436    * If something other than an array is passed, it is considered to be empty.
 437    *
 438    * If nothing is passed at all, the default value provided is empty.
 439    *
 440    * @param array $array
 441    *   (optional) Array to be checked for emptiness.
 442    *
 443    * @return bool
 444    *   True if the array is empty.
 445    */
 446   public static function crmIsEmptyArray($array = array()) {
 447     if (!is_array($array)) {
 448       return TRUE;
 449     }
 450     foreach ($array as $element) {
 451       if (is_array($element)) {
 452         if (!self::crmIsEmptyArray($element)) {
 453           return FALSE;
 454         }
 455       }
 456       elseif (isset($element)) {
 457         return FALSE;
 458       }
 459     }
 460     return TRUE;
 461   }
 462
 463   /**
 464    * Sorts an associative array of arrays by an attribute using strnatcmp().
 465    *
 466    * @param array $array
 467    *   Array to be sorted.
 468    * @param string $field
 469    *   Name of the attribute used for sorting.
 470    *
 471    * @return array
 472    *   Sorted array
 473    */
 474   public static function crmArraySortByField($array, $field) {
 475     $code = "return strnatcmp(\$a['$field'], \$b['$field']);";
 476     uasort($array, create_function('$a,$b', $code));
 477     return $array;
 478   }
 479
 480   /**
 481    * Recursively removes duplicate values from a multi-dimensional array.
 482    *
 483    * @param array $array
 484    *   The input array possibly containing duplicate values.
 485    *
 486    * @return array
 487    *   The input array with duplicate values removed.
 488    */
 489   public static function crmArrayUnique($array) {
 490     $result = array_map("unserialize", array_unique(array_map("serialize", $array)));
 491     foreach ($result as $key => $value) {
 492       if (is_array($value)) {
 493         $result[$key] = self::crmArrayUnique($value);
 494       }
 495     }
 496     return $result;
 497   }
 498
 499   /**
 500    * Sorts an array and maintains index association (with localization).
 501    *
 502    * Uses Collate from the PECL "intl" package, if available, for UTF-8
 503    * sorting (e.g. list of countries). Otherwise calls PHP's asort().
 504    *
 505    * On Debian/Ubuntu: apt-get install php5-intl
 506    *
 507    * @param array $array
 508    *   (optional) Array to be sorted.
 509    *
 510    * @return array
 511    *   Sorted array.
 512    */
 513   public static function asort($array = array()) {
 514     $lcMessages = CRM_Utils_System::getUFLocale();
 515
 516     if ($lcMessages && $lcMessages != 'en_US' && class_exists('Collator')) {
 517       $collator = new Collator($lcMessages . '.utf8');
 518       $collator->asort($array);
 519     }
 520     else {
 521       // This calls PHP's built-in asort().
 522       asort($array);
 523     }
 524
 525     return $array;
 526   }
 527
 528   /**
 529    * Unsets an arbitrary list of array elements from an associative array.
 530    *
 531    * @param array $items
 532    *   The array from which to remove items.
 533    *
 534    * Additional params:
 535    *   When passed a string, unsets $items[$key].
 536    *   When passed an array of strings, unsets $items[$k] for each string $k in the array.
 537    */
 538   public static function remove(&$items) {
 539     foreach (func_get_args() as $n => $key) {
 540       // Skip argument 0 ($items) by testing $n for truth.
 541       if ($n && is_array($key)) {
 542         foreach ($key as $k) {
 543           unset($items[$k]);
 544         }
 545       }
 546       elseif ($n) {
 547         unset($items[$key]);
 548       }
 549     }
 550   }
 551
 552   /**
 553    * Builds an array-tree which indexes the records in an array.
 554    *
 555    * @param string[] $keys
 556    *   Properties by which to index.
 557    * @param object|array $records
 558    *
 559    * @return array
 560    *   Multi-dimensional array, with one layer for each key.
 561    */
 562   public static function index($keys, $records) {
 563     $final_key = array_pop($keys);
 564
 565     $result = array();
 566     foreach ($records as $record) {
 567       $node = &$result;
 568       foreach ($keys as $key) {
 569         if (is_array($record)) {
 570           $keyvalue = isset($record[$key]) ? $record[$key] : NULL;
 571         }
 572         else {
 573           $keyvalue = isset($record->{$key}) ? $record->{$key} : NULL;
 574         }
 575         if (isset($node[$keyvalue]) && !is_array($node[$keyvalue])) {
 576           $node[$keyvalue] = array();
 577         }
 578         $node = &$node[$keyvalue];
 579       }
 580       if (is_array($record)) {
 581         $node[$record[$final_key]] = $record;
 582       }
 583       else {
 584         $node[$record->{$final_key}] = $record;
 585       }
 586     }
 587     return $result;
 588   }
 589
 590   /**
 591    * Iterates over a list of records and returns the value of some property.
 592    *
 593    * @param string $prop
 594    *   Property to retrieve.
 595    * @param array|object $records
 596    *   A list of records.
 597    *
 598    * @return array
 599    *   Keys are the original keys of $records; values are the $prop values.
 600    */
 601   public static function collect($prop, $records) {
 602     $result = array();
 603     if (is_array($records)) {
 604       foreach ($records as $key => $record) {
 605         if (is_object($record)) {
 606           $result[$key] = $record->{$prop};
 607         }
 608         else {
 609           $result[$key] = $record[$prop];
 610         }
 611       }
 612     }
 613     return $result;
 614   }
 615
 616   /**
 617    * Trims delimiters from a string and then splits it using explode().
 618    *
 619    * This method works mostly like PHP's built-in explode(), except that
 620    * surrounding delimiters are trimmed before explode() is called.
 621    *
 622    * Also, if an array or NULL is passed as the $values parameter, the value is
 623    * returned unmodified rather than being passed to explode().
 624    *
 625    * @param array|null|string $values
 626    *   The input string (or an array, or NULL).
 627    * @param string $delim
 628    *   (optional) The boundary string.
 629    *
 630    * @return array|null
 631    *   An array of strings produced by explode(), or the unmodified input
 632    *   array, or NULL.
 633    */
 634   public static function explodePadded($values, $delim = CRM_Core_DAO::VALUE_SEPARATOR) {
 635     if ($values === NULL) {
 636       return NULL;
 637     }
 638     // If we already have an array, no need to continue
 639     if (is_array($values)) {
 640       return $values;
 641     }
 642     return explode($delim, trim((string) $values, $delim));
 643   }
 644
 645   /**
 646    * Joins array elements with a string, adding surrounding delimiters.
 647    *
 648    * This method works mostly like PHP's built-in implode(), but the generated
 649    * string is surrounded by delimiter characters. Also, if NULL is passed as
 650    * the $values parameter, NULL is returned.
 651    *
 652    * @param mixed $values
 653    *   Array to be imploded. If a non-array is passed, it will be cast to an
 654    *   array.
 655    * @param string $delim
 656    *   Delimiter to be used for implode() and which will surround the output
 657    *   string.
 658    *
 659    * @return string|NULL
 660    *   The generated string, or NULL if NULL was passed as $values parameter.
 661    */
 662   public static function implodePadded($values, $delim = CRM_Core_DAO::VALUE_SEPARATOR) {
 663     if ($values === NULL) {
 664       return NULL;
 665     }
 666     // If we already have a string, strip $delim off the ends so it doesn't get added twice
 667     if (is_string($values)) {
 668       $values = trim($values, $delim);
 669     }
 670     return $delim . implode($delim, (array) $values) . $delim;
 671   }
 672
 673   /**
 674    * Modifies a key in an array while preserving the key order.
 675    *
 676    * By default when an element is added to an array, it is added to the end.
 677    * This method allows for changing an existing key while preserving its
 678    * position in the array.
 679    *
 680    * The array is both modified in-place and returned.
 681    *
 682    * @param array $elementArray
 683    *   Array to manipulate.
 684    * @param string $oldKey
 685    *   Old key to be replaced.
 686    * @param string $newKey
 687    *   Replacement key string.
 688    *
 689    * @throws Exception
 690    *   Throws a generic Exception if $oldKey is not found in $elementArray.
 691    *
 692    * @return array
 693    *   The manipulated array.
 694    */
 695   public static function crmReplaceKey(&$elementArray, $oldKey, $newKey) {
 696     $keys = array_keys($elementArray);
 697     if (FALSE === $index = array_search($oldKey, $keys)) {
 698       throw new Exception(sprintf('key "%s" does not exit', $oldKey));
 699     }
 700     $keys[$index] = $newKey;
 701     $elementArray = array_combine($keys, array_values($elementArray));
 702     return $elementArray;
 703   }
 704
 705   /**
 706    * Searches array keys by regex, returning the value of the first match.
 707    *
 708    * Given a regular expression and an array, this method searches the keys
 709    * of the array using the regular expression. The first match is then used
 710    * to index into the array, and the associated value is retrieved and
 711    * returned. If no matches are found, or if something other than an array
 712    * is passed, then a default value is returned. Unless otherwise specified,
 713    * the default value is NULL.
 714    *
 715    * @param string $regexKey
 716    *   The regular expression to use when searching for matching keys.
 717    * @param array $list
 718    *   The array whose keys will be searched.
 719    * @param mixed $default
 720    *   (optional) The default value to return if the regex does not match an
 721    *   array key, or if something other than an array is passed.
 722    *
 723    * @return mixed
 724    *   The value found.
 725    */
 726   public static function valueByRegexKey($regexKey, $list, $default = NULL) {
 727     if (is_array($list) && $regexKey) {
 728       $matches = preg_grep($regexKey, array_keys($list));
 729       $key = reset($matches);
 730       return ($key && array_key_exists($key, $list)) ? $list[$key] : $default;
 731     }
 732     return $default;
 733   }
 734
 735   /**
 736    * Generates the Cartesian product of zero or more vectors.
 737    *
 738    * @param array $dimensions
 739    *   List of dimensions to multiply.
 740    *   Each key is a dimension name; each value is a vector.
 741    * @param array $template
 742    *   (optional) A base set of values included in every output.
 743    *
 744    * @return array
 745    *   Each item is a distinct combination of values from $dimensions.
 746    *
 747    *   For example, the product of
 748    *   {
 749    *   fg => {red, blue},
 750    *   bg => {white, black}
 751    *   }
 752    *   would be
 753    *   {
 754    *   {fg => red, bg => white},
 755    *   {fg => red, bg => black},
 756    *   {fg => blue, bg => white},
 757    *   {fg => blue, bg => black}
 758    *   }
 759    */
 760   public static function product($dimensions, $template = array()) {
 761     if (empty($dimensions)) {
 762       return array($template);
 763     }
 764
 765     foreach ($dimensions as $key => $value) {
 766       $firstKey = $key;
 767       $firstValues = $value;
 768       break;
 769     }
 770     unset($dimensions[$key]);
 771
 772     $results = array();
 773     foreach ($firstValues as $firstValue) {
 774       foreach (self::product($dimensions, $template) as $result) {
 775         $result[$firstKey] = $firstValue;
 776         $results[] = $result;
 777       }
 778     }
 779
 780     return $results;
 781   }
 782
 783   /**
 784    * Get the first element of an array.
 785    *
 786    * @param array $array
 787    * @return mixed|NULL
 788    */
 789   public static function first($array) {
 790     foreach ($array as $value) {
 791       return $value;
 792     }
 793     return NULL;
 794   }
 795
 796   /**
 797    * Extract any $keys from $array and copy to a new array.
 798    *
 799    * Note: If a $key does not appear in $array, then it will
 800    * not appear in the result.
 801    *
 802    * @param array $array
 803    * @param array $keys
 804    *   List of keys to copy.
 805    * @return array
 806    */
 807   public static function subset($array, $keys) {
 808     $result = array();
 809     foreach ($keys as $key) {
 810       if (isset($array[$key])) {
 811         $result[$key] = $array[$key];
 812       }
 813     }
 814     return $result;
 815   }
 816
 817   /**
 818    * Transform an associative array of key=>value pairs into a non-associative array of arrays.
 819    * This is necessary to preserve sort order when sending an array through json_encode.
 820    *
 821    * @param array $associative
 822    * @param string $keyName
 823    * @param string $valueName
 824    * @return array
 825    */
 826   public static function makeNonAssociative($associative, $keyName = 'key', $valueName = 'value') {
 827     $output = array();
 828     foreach ($associative as $key => $val) {
 829       $output[] = array($keyName => $key, $valueName => $val);
 830     }
 831     return $output;
 832   }
 833
 834 }