Acme.BookStore.HttpApi.Host/node_modules/source-map/lib/binary-search.js

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/* -*- Mode: js; js-indent-level: 2; -*- */
/*
 * Copyright 2011 Mozilla Foundation and contributors
 * Licensed under the New BSD license. See LICENSE or:
 * http://opensource.org/licenses/BSD-3-Clause
 */

exports.GREATEST_LOWER_BOUND = 1;
exports.LEAST_UPPER_BOUND = 2;

/**
 * Recursive implementation of binary search.
 *
 * @param aLow Indices here and lower do not contain the needle.
 * @param aHigh Indices here and higher do not contain the needle.
 * @param aNeedle The element being searched for.
 * @param aHaystack The non-empty array being searched.
 * @param aCompare Function which takes two elements and returns -1, 0, or 1.
 * @param aBias Either 'binarySearch.GREATEST_LOWER_BOUND' or
 *     'binarySearch.LEAST_UPPER_BOUND'. Specifies whether to return the
 *     closest element that is smaller than or greater than the one we are
 *     searching for, respectively, if the exact element cannot be found.
 */
function recursiveSearch(aLow, aHigh, aNeedle, aHaystack, aCompare, aBias) {
  // This function terminates when one of the following is true:
  //
  //   1. We find the exact element we are looking for.
  //
  //   2. We did not find the exact element, but we can return the index of
  //      the next-closest element.
  //
  //   3. We did not find the exact element, and there is no next-closest
  //      element than the one we are searching for, so we return -1.
  var mid = Math.floor((aHigh - aLow) / 2) + aLow;
  var cmp = aCompare(aNeedle, aHaystack[mid], true);
  if (cmp === 0) {
    // Found the element we are looking for.
    return mid;
  }
  else if (cmp > 0) {
    // Our needle is greater than aHaystack[mid].
    if (aHigh - mid > 1) {
      // The element is in the upper half.
      return recursiveSearch(mid, aHigh, aNeedle, aHaystack, aCompare, aBias);
    }

    // The exact needle element was not found in this haystack. Determine if
    // we are in termination case (3) or (2) and return the appropriate thing.
    if (aBias == exports.LEAST_UPPER_BOUND) {
      return aHigh < aHaystack.length ? aHigh : -1;
    } else {
      return mid;
    }
  }
  else {
    // Our needle is less than aHaystack[mid].
    if (mid - aLow > 1) {
      // The element is in the lower half.
      return recursiveSearch(aLow, mid, aNeedle, aHaystack, aCompare, aBias);
    }