simple-squiggle

A restricted subset of Squiggle
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array-set.js (3197B)

      1 /* -*- Mode: js; js-indent-level: 2; -*- */
      2 /*
      3  * Copyright 2011 Mozilla Foundation and contributors
      4  * Licensed under the New BSD license. See LICENSE or:
      5  * http://opensource.org/licenses/BSD-3-Clause
      6  */
      7 
      8 var util = require('./util');
      9 var has = Object.prototype.hasOwnProperty;
     10 var hasNativeMap = typeof Map !== "undefined";
     11 
     12 /**
     13  * A data structure which is a combination of an array and a set. Adding a new
     14  * member is O(1), testing for membership is O(1), and finding the index of an
     15  * element is O(1). Removing elements from the set is not supported. Only
     16  * strings are supported for membership.
     17  */
     18 function ArraySet() {
     19   this._array = [];
     20   this._set = hasNativeMap ? new Map() : Object.create(null);
     21 }
     22 
     23 /**
     24  * Static method for creating ArraySet instances from an existing array.
     25  */
     26 ArraySet.fromArray = function ArraySet_fromArray(aArray, aAllowDuplicates) {
     27   var set = new ArraySet();
     28   for (var i = 0, len = aArray.length; i < len; i++) {
     29     set.add(aArray[i], aAllowDuplicates);
     30   }
     31   return set;
     32 };
     33 
     34 /**
     35  * Return how many unique items are in this ArraySet. If duplicates have been
     36  * added, than those do not count towards the size.
     37  *
     38  * @returns Number
     39  */
     40 ArraySet.prototype.size = function ArraySet_size() {
     41   return hasNativeMap ? this._set.size : Object.getOwnPropertyNames(this._set).length;
     42 };
     43 
     44 /**
     45  * Add the given string to this set.
     46  *
     47  * @param String aStr
     48  */
     49 ArraySet.prototype.add = function ArraySet_add(aStr, aAllowDuplicates) {
     50   var sStr = hasNativeMap ? aStr : util.toSetString(aStr);
     51   var isDuplicate = hasNativeMap ? this.has(aStr) : has.call(this._set, sStr);
     52   var idx = this._array.length;
     53   if (!isDuplicate || aAllowDuplicates) {
     54     this._array.push(aStr);
     55   }
     56   if (!isDuplicate) {
     57     if (hasNativeMap) {
     58       this._set.set(aStr, idx);
     59     } else {
     60       this._set[sStr] = idx;
     61     }
     62   }
     63 };
     64 
     65 /**
     66  * Is the given string a member of this set?
     67  *
     68  * @param String aStr
     69  */
     70 ArraySet.prototype.has = function ArraySet_has(aStr) {
     71   if (hasNativeMap) {
     72     return this._set.has(aStr);
     73   } else {
     74     var sStr = util.toSetString(aStr);
     75     return has.call(this._set, sStr);
     76   }
     77 };
     78 
     79 /**
     80  * What is the index of the given string in the array?
     81  *
     82  * @param String aStr
     83  */
     84 ArraySet.prototype.indexOf = function ArraySet_indexOf(aStr) {
     85   if (hasNativeMap) {
     86     var idx = this._set.get(aStr);
     87     if (idx >= 0) {
     88         return idx;
     89     }
     90   } else {
     91     var sStr = util.toSetString(aStr);
     92     if (has.call(this._set, sStr)) {
     93       return this._set[sStr];
     94     }
     95   }
     96 
     97   throw new Error('"' + aStr + '" is not in the set.');
     98 };
     99 
    100 /**
    101  * What is the element at the given index?
    102  *
    103  * @param Number aIdx
    104  */
    105 ArraySet.prototype.at = function ArraySet_at(aIdx) {
    106   if (aIdx >= 0 && aIdx < this._array.length) {
    107     return this._array[aIdx];
    108   }
    109   throw new Error('No element indexed by ' + aIdx);
    110 };
    111 
    112 /**
    113  * Returns the array representation of this set (which has the proper indices
    114  * indicated by indexOf). Note that this is a copy of the internal array used
    115  * for storing the members so that no one can mess with internal state.
    116  */
    117 ArraySet.prototype.toArray = function ArraySet_toArray() {
    118   return this._array.slice();
    119 };
    120 
    121 exports.ArraySet = ArraySet;