mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-10-29 21:25:35 +00:00
76 lines
2.5 KiB
JavaScript
76 lines
2.5 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
|
|
* You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
"use strict";
|
|
|
|
this.EXPORTED_SYMBOLS = [
|
|
"BinarySearch",
|
|
];
|
|
|
|
this.BinarySearch = Object.freeze({
|
|
|
|
/**
|
|
* Returns the index of the given target in the given array or -1 if the
|
|
* target is not found.
|
|
*
|
|
* See search() for a description of this function's parameters.
|
|
*
|
|
* @return The index of `target` in `array` or -1 if `target` is not found.
|
|
*/
|
|
indexOf: function (comparator, array, target) {
|
|
let [found, idx] = this.search(comparator, array, target);
|
|
return found ? idx : -1;
|
|
},
|
|
|
|
/**
|
|
* Returns the index within the given array where the given target may be
|
|
* inserted to keep the array ordered.
|
|
*
|
|
* See search() for a description of this function's parameters.
|
|
*
|
|
* @return The index in `array` where `target` may be inserted to keep `array`
|
|
* ordered.
|
|
*/
|
|
insertionIndexOf: function (comparator, array, target) {
|
|
return this.search(comparator, array, target)[1];
|
|
},
|
|
|
|
/**
|
|
* Searches for the given target in the given array.
|
|
*
|
|
* @param comparator
|
|
* A function that takes two arguments and compares them, returning a
|
|
* negative number if the first should be ordered before the second,
|
|
* zero if the first and second have the same ordering, or a positive
|
|
* number if the second should be ordered before the first. The first
|
|
* argument is always `target`, and the second argument is a value
|
|
* from the array.
|
|
* @param array
|
|
* An array whose elements are ordered by `comparator`.
|
|
* @param target
|
|
* The value to search for.
|
|
* @return An array with two elements. If `target` is found, the first
|
|
* element is true, and the second element is its index in the array.
|
|
* If `target` is not found, the first element is false, and the
|
|
* second element is the index where it may be inserted to keep the
|
|
* array ordered.
|
|
*/
|
|
search: function (comparator, array, target) {
|
|
let low = 0;
|
|
let high = array.length - 1;
|
|
while (low <= high) {
|
|
// Thanks to http://jsperf.com/code-review-1480 for this tip.
|
|
let mid = (low + high) >> 1;
|
|
let cmp = comparator(target, array[mid]);
|
|
if (cmp == 0)
|
|
return [true, mid];
|
|
if (cmp < 0)
|
|
high = mid - 1;
|
|
else
|
|
low = mid + 1;
|
|
}
|
|
return [false, low];
|
|
},
|
|
});
|