fake-indexeddb/build/cjs/lib/binarySearch.js

Fake IndexedDB: a pure JS in-memory implementation of the IndexedDB API

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.getByKey = getByKey;
exports.getByKeyRange = getByKeyRange;
exports.getIndexByKey = getIndexByKey;
exports.getIndexByKeyGTE = getIndexByKeyGTE;
exports.getIndexByKeyRange = getIndexByKeyRange;
var _cmp = _interopRequireDefault(require("./cmp.js"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
/**
 * Classic binary search implementation. Returns the index where the key
 * should be inserted, assuming the records list is ordered.
 */
function binarySearch(records, key) {
  let low = 0;
  let high = records.length;
  let mid;
  while (low < high) {
    mid = low + high >>> 1; // like Math.floor((low + high) / 2) but fast
    if ((0, _cmp.default)(records[mid].key, key) < 0) {
      low = mid + 1;
    } else {
      high = mid;
    }
  }
  return low;
}

/**
 * Equivalent to `records.findIndex(record => cmp(record.key, key) === 0)`
 */
function getIndexByKey(records, key) {
  const idx = binarySearch(records, key);
  const record = records[idx];
  if (record && (0, _cmp.default)(record.key, key) === 0) {
    return idx;
  }
  return -1;
}

/**
 * Equivalent to `records.find(record => cmp(record.key, key) === 0)`
 */
function getByKey(records, key) {
  const idx = getIndexByKey(records, key);
  return records[idx];
}

/**
 * Equivalent to `records.findIndex(record => key.includes(record.key))`
 */
function getIndexByKeyRange(records, keyRange) {
  const lowerIdx = typeof keyRange.lower === "undefined" ? 0 : binarySearch(records, keyRange.lower);
  const upperIdx = typeof keyRange.upper === "undefined" ? records.length - 1 : binarySearch(records, keyRange.upper);
  for (let i = lowerIdx; i <= upperIdx; i++) {
    const record = records[i];
    if (record && keyRange.includes(record.key)) {
      return i;
    }
  }
  return -1;
}

/**
 * Equivalent to `records.find(record => key.includes(record.key))`
 */
function getByKeyRange(records, keyRange) {
  const idx = getIndexByKeyRange(records, keyRange);
  return records[idx];
}

/**
 * Equivalent to `records.findIndex(record => cmp(record.key, key) >= 0)`
 */
function getIndexByKeyGTE(records, key) {
  const idx = binarySearch(records, key);
  const record = records[idx];
  if (record && (0, _cmp.default)(record.key, key) >= 0) {
    return idx;
  }
  return -1;
}