hphp/hsl/src/vec/combine.php

   1 <?hh
   2 /*
   3  *  Copyright (c) 2004-present, Facebook, Inc.
   4  *  All rights reserved.
   5  *
   6  *  This source code is licensed under the MIT license found in the
   7  *  LICENSE file in the root directory of this source tree.
   8  *
   9  */
  10
  11 namespace HH\Lib\Vec;
  12
  13 use namespace HH\Lib\{C, Math};
  14
  15 /**
  16  * Returns a new vec formed by concatenating the given Traversables together.
  17  *
  18  * For a variable number of Traversables, see `Vec\flatten()`.
  19  *
  20  * Time complexity: O(n + m), where n is the size of `$first` and m is the
  21  * combined size of all the `...$rest`
  22  * Space complexity: O(n + m), where n is the size of `$first` and m is the
  23  * combined size of all the `...$rest`
  24  */
  25 function concat<Tv>(
  26   Traversable<Tv> $first,
  27   Container<Tv> ...$rest
  28 )[]: vec<Tv> {
  29   $result = cast_clear_legacy_array_mark($first);
  30   foreach ($rest as $traversable) {
  31     foreach ($traversable as $value) {
  32       $result[] = $value;
  33     }
  34   }
  35   return $result;
  36 }
  37
  38 /**
  39  * Returns a vec where each element is a tuple (pair) that combines, pairwise,
  40  * the elements of the two given Traversables.
  41  *
  42  * If the Traversables are not of equal length, the result will have
  43  * the same number of elements as the shortest Traversable.
  44  * Elements of the longer Traversable after the length of the shorter one
  45  * will be ignored.
  46  *
  47  * Time complexity: O(min(m, n)), where m is the size of `$first` and n is the
  48  * size of `$second`
  49  * Space complexity: O(min(m, n)), where m is the size of `$first` and n is the
  50  * size of `$second`
  51  */
  52 <<__ProvenanceSkipFrame>>
  53 function zip<Tv, Tu>(
  54   Traversable<Tv> $first,
  55   Traversable<Tu> $second,
  56 )[]: vec<(Tv, Tu)> {
  57   $one = cast_clear_legacy_array_mark($first);
  58   $two = cast_clear_legacy_array_mark($second);
  59   $result = vec[];
  60   $lesser_count = Math\minva(C\count($one), C\count($two));
  61   for ($i = 0; $i < $lesser_count; ++$i) {
  62     $result[] = tuple($one[$i], $two[$i]);
  63   }
  64   return $result;
  65 }