import Check from './Check.js';
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/**
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* Finds an item in a sorted array.
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*
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* @exports binarySearch
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* @param {Array} array The sorted array to search.
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* @param {*} itemToFind The item to find in the array.
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* @param {binarySearch~Comparator} comparator The function to use to compare the item to
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* elements in the array.
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* @returns {Number} The index of <code>itemToFind</code> in the array, if it exists. If <code>itemToFind</code>
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* does not exist, the return value is a negative number which is the bitwise complement (~)
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* of the index before which the itemToFind should be inserted in order to maintain the
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* sorted order of the array.
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*
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* @example
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* // Create a comparator function to search through an array of numbers.
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* function comparator(a, b) {
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* return a - b;
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* };
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* var numbers = [0, 2, 4, 6, 8];
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* var index = Cesium.binarySearch(numbers, 6, comparator); // 3
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*/
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function binarySearch(array, itemToFind, comparator) {
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//>>includeStart('debug', pragmas.debug);
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Check.defined('array', array);
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Check.defined('itemToFind', itemToFind);
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Check.defined('comparator', comparator);
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//>>includeEnd('debug');
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var low = 0;
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var high = array.length - 1;
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var i;
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var comparison;
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while (low <= high) {
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i = ~~((low + high) / 2);
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comparison = comparator(array[i], itemToFind);
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if (comparison < 0) {
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low = i + 1;
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continue;
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}
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if (comparison > 0) {
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high = i - 1;
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continue;
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}
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return i;
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}
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return ~(high + 1);
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}
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/**
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* A function used to compare two items while performing a binary search.
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* @callback binarySearch~Comparator
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*
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* @param {*} a An item in the array.
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* @param {*} b The item being searched for.
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* @returns {Number} Returns a negative value if <code>a</code> is less than <code>b</code>,
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* a positive value if <code>a</code> is greater than <code>b</code>, or
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* 0 if <code>a</code> is equal to <code>b</code>.
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*
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* @example
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* function compareNumbers(a, b) {
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* return a - b;
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* }
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*/
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export default binarySearch;
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