src/public/tree-multiset.js
/** An implementation of red-black tree */
const {Tree} = require('../internal/tree');
/** Classes that regulate whether tree nodes hold keys only, or key-value pairs */
const {KeyOnlyPolicy} = require('../internal/policies');
/** Node for a red-black tree */
const {TreeNode} = require('../internal/tree-node');
/**
* TreeMultiSet is a container that stores elements following a specific order,
* and where multiple elements can have equivalent values.
*
* In a TreeMultiSet, the value of an element also identifies it
* (the value is itself the key). The value of the elements in a multiset
* cannot be modified once in the container (the elements are always immutable),
* but they can be inserted or removed from the container.
*
* ## Container properties
* * **Associative** - Elements in associative containers are referenced
* by their key and not by their absolute position in the container.
* * **Ordered** - The elements in the container follow a strict order
* at all times. All inserted elements are given a position in this order.
* * **Set** - The value of an element is also the key used to identify it.
* * **Multiple equivalent keys** - Multiple elements in the container
* can have equivalent keys.
*
* @example
* let set = new TreeMultiSet();
* // add few values
* set.add(1);
* set.add(2);
* set.add(2);
* // check whether key exists
* let flag = set.has(1); // << true
* // print all keys
* for (let key of set) {
* console.log(`key: ${key}`); // 1, 2, 2
* }
*/
class TreeMultiSet {
/*======================================================
* Methods of ES6 Set
*======================================================*/
/**
* Creates an empty, or a pre-initialized set.
* @param {*} [iterable] Another iterable object whose values are added into the newly created set.
* @example
* // Create an empty set
* let set = new TreeMultiSet();
* // Create and initialize set
* let set2 = new TreeMultiSet([1, 2, 3]);
*/
constructor(iterable) {
/** Internal tree */
this.__t = new Tree();
this.__t.valuePolicy = new KeyOnlyPolicy();
if ((iterable !== undefined)
&& (iterable !== null)) {
if (iterable[Symbol.iterator] !== undefined) {
// copy contents
for (let k of iterable) {
this.add(k);
}
}
else {
throw new Error('TreeMultiSet constructor accepts only iterable objects');
}
}
}
/**
* String tag of this class
* @returns {String}
* @example
* Object.prototype.toString.call(new TreeMultiSet()); // "[object TreeMultiSet]"
*/
get [Symbol.toStringTag]() {
return 'TreeMultiSet';
}
/**
* Allows to create programmatically an instance of the same class
* @returns constructor object for this class.
* @example
* let set = new TreeMultiSet();
* let constrFunc = Object.getPrototypeOf(set).constructor[Symbol.species];
* let set2 = new constrFunc();
*/
static get [Symbol.species]() {
return TreeMultiSet;
}
/**
* Removes all key-value pairs.
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* set.clear();
* console.log(set.size); // 0
*/
clear() {
this.__t.clear();
}
/**
* Removes key-value pair with the specified key if such entry exists. Does nothing otherwise.
* @example
* let set = new TreeMultiSet([1, 2, 2, 3]);
* set.delete(2);
* console.log(set.toString()); // {1,2,3}
* set.delete(2); / remove the second copy of the key
* console.log(set.toString()); // {1,3}
*/
delete(key) {
let it = this.__t.find(key);
if (!it.equals(this.__t.end())) {
this.__t.erase(it.node);
}
}
/**
* Forward ES6 iterator for all values in ascending order.
* @returns {JsIterator}
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* for (let key of set.entries()) {
* console.log(`key: ${key}`);
* }
*/
entries() {
return this.__t.entries();
}
/**
* Iterates all values using a callback in ascending order.
* Note that ES6 specifies the order of key parameters in the callback differently from for-of loop.
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* set.forEach(function(value, key, container) {
* // value is the same as key
* console.log(`key: ${key}, value: ${value}`);
* });
*/
forEach(callback) {
for (let k of this.__t) {
callback(k, k, this);
}
}
/**
* A boolean indicator whether set contains the specified key.
* @returns {Boolean}
* @param {*} key a value of any type that can be compared with a key
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* let b = set.get(3); // true
* b = set.get(4); // false
*/
has(key) {
let it = this.__t.find(key);
if (!it.equals(this.__t.end())) {
return true;
}
else {
return false;
}
}
/**
* Forward ES6 iterator for all keys in ascending order.
* @returns {JsIterator}
* @example
* // iterate all keys
* let set = new TreeMultiSet([1, 2, 3]);
* for (let k of set.keys()) {
* console.log(k); // 1, 2, 3
* }
* // iterate all keys in reverse order
* let set = new TreeMultiSet([1, 2, 3]);
* for (let k of set.keys().backward()) {
* console.log(k); // 3, 2, 1
* }
*/
keys() {
return this.__t.keys();
}
/**
* Adds a key to the set. If the key already exists then another entry with the same value is added.
* @param {*} key
* @example
* let set = new TreeMultiSet();
* set.add(1);
* set.add(1);
* set.add(2);
* // print all keys
* for (let key of set) {
* console.log(`key: ${key}`); // 1, 1, 2
* }
*/
add(key) {
let n = new TreeNode();
n.key = key;
this.__t.insertMulti(n);
}
/**
* Number of keys in the set.
* @returns {Number}
*/
get size() {
return this.__t.size();
}
/**
* Forward ES6 iterator for all keys in ascending order. It is the same as keys() method
* @returns {JsITerator}
* @example
* // iterate all values
* let set = new TreeMultiSet([1, 2, 3]);
* for (let v of set.values()) {
* console.log(v); // '1', '2', '3'
* }
* // iterate all values in reverse order
* let set = new TreeMultiSet([1, 2, 3]);
* for (let v of set.values().backward()) {
* console.log(v); // '3', '2', '1'
* }
*/
values() {
return this.__t.keys();
}
/**
* Forward ES6 iterator for all keys in ascending order. The same as entries() method
* @returns {JsIterator}
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* for (let key of set) {
* console.log(`key: ${key}, value: ${value}`);
* }
*/
[Symbol.iterator]() {
return this.__t[Symbol.iterator]();
}
/*======================================================
* More methods
*======================================================*/
/**
* ES6 reverse iterator for all keys in descending order.
* @returns {JsReverseIterator}
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* for (let key of set.backwards()) {
* console.log(`key: ${key}`);
* }
*/
backward() {
return this.__t.backward();
}
/**
* Sets custom comparison function if key values are not of primitive types.
* Callback is a 3-way comparison function accepts two key values (lhs, rhs). It is expected to return
* +1 if the value of rhs is greater than lhs
* -1 if the value of rhs is less than lhs
* 0 if values are the same
*/
set compareFunc(func) {
this.clear();
this.__t.compare = func;
}
/*======================================================
* STL-like methods
*======================================================*/
/**
* Forward iterator to the first element
* @returns {Iterator}
* @example
* let set = new TreeMultiSet();
* ...
* for (let it = set.begin(); !it.equals(set.end()); it.next()) {
* console.log(`key: ${it.key}`);
* }
*/
begin() {
return this.__t.begin();
}
/**
* Forward iterator to the element following the last element
* @returns {Iterator}
* @example
* let set = new TreeMultiSet();
* ...
* for (let it = set.begin(); !it.equals(set.end()); it.next()) {
* console.log(`key: ${it.key}`);
* }
*/
end() {
return this.__t.end();
}
/**
* Finds an element with key equivalent to the specified one. If such key does not exist end() iterator is returned.
* @param {*} key
* @returns {Iterator}
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* ...
* let it = set.find(1);
* if (!it.equals(set.end())) {
* console.log(`Found key: ${it.key}`); // 1
* }
*/
find(key) {
return this.__t.find(key);
}
/**
* Adds key if such key does not exist in the set.
* @param {*} key
* @returns {InsertionResult} - indicates whether a node was added and provides iterator to it.
* @example
* let set = new TreeMultiSet();
* set.insertUnique(1);
* set.insertUnique(1); // this step has no effect on the set
* let flag = set.has(1); // true
* let size = set.size; // 1
*/
insertUnique(key) {
let n = new TreeNode();
n.key = key;
return this.__t.insertUnique(n);
}
/**
* Adds key if such key does not exist in the set. Same as insertUnique()
* @param {*} key
* @returns {InsertionResult} - indicates whether a node was added and provides iterator to it.
* @example
* let set = new TreeMultiSet();
* set.insertOrReplace(1);
* set.insertOrReplace(1); // this step has no effect on the set
* let flag = set.has(1); // true
* let size = set.size; // 1
*/
insertOrReplace(key) {
let n = new TreeNode();
n.key = key;
return this.__t.insertOrReplace(n);
}
/**
* Adds key whether it exists or not in the set.
* @param {*} key
* @returns {InsertionResult} - indicates whether a node was added and provides iterator to it.
* @example
* let set = new TreeMultiSet();
* set.insertMulti(1);
* set.insertMulti(1); // this step has no effect on the map
* let flag = set.has(1); // true
* let size = set.size; // 2
*/
insertMulti(key) {
let n = new TreeNode();
n.key = key;
return this.__t.insertMulti(n);
}
/**
* Removes value for the specified iterator.
* @param {Iterator} iterator
* @example
* let set = new TreeMultiSet([1,2,3]);
* let it = set.find(2);
* it.prev();
* set.erase(it); // removes a node with key 1
* console.log(set.toString()); // {2,3}
*/
erase(iterator) {
this.__t.erase(iterator.node);
}
/**
* Iterator pointing to the first element that is not less than specified key. If no such element is found, see end() iterator is returned.
* @param {*} key
* @returns {Iterator}
* @example
* let set = new TreeMultiSet();
* ... // add key-value pairs., using numbers as keys
* // iterate through all key-value pairs with keys between 0 and 50 inclusive
* let from = set.lowerBound(0);
* let to = set.upperBound(50);
* let it = from;
* while (!it.equals(to)) {
* console.log(it.key);
* it.next();
* }
*
* let set = new TreeMultiSet();
* ... // add key-value pairs., using numbers as keys
* // iterate through all key-value pairs with keys between 0 and 50 inclusive in reverse order
* let from = new ReverseIterator(set.upperBound(50));
* let to = new ReverseIterator(set.lowerBound(0));
* let it = from;
* while (!it.equals(to)) {
* console.log(it.key);
* it.next();
* }
*/
lowerBound(key) {
return this.__t.lowerBound(key);
}
/**
* Reverse iterator to the last element.
* @returns {ReverseIterator}
* @example
* let set = new TreeMultiSet();
* ...
* for (let it = set.rbegin(); !it.equals(set.rend()); it.next()) {
* console.log(`key: ${it.key}`);
* }
*/
rbegin() {
return this.__t.rbegin();
}
/**
* Reverse iterator pointing to before the first element.
* @returns {ReverseIterator}
* @example
* let set = new TreeMultiSet();
* ...
* for (let it = set.rbegin(); !it.equals(set.rend()); it.next()) {
* console.log(`key: ${it.key}`);
* }
*/
rend() {
return this.__t.rend();
}
/**
* Iterator pointing to the first element that is greater than key. If no such element is found end() iterator is returned.
* @param {*} key
* @returns {Iterator}
* @example
* let set = new TreeMultiSet();
* ... // add key-value pairs., using numbers as keys
* // iterate through all key-value pairs with keys between 0 and 50 inclusive
* let from = set.lowerBound(0);
* let to = set.upperBound(50);
* let it = from;
* while (!it.equals(to)) {
* console.log(it.key);
* it.next();
* }
*
* let set = new TreeMultiSet();
* ... // add key-value pairs., using numbers as keys
* // iterate through all key-value pairs with keys between 0 and 50 inclusive in reverse order
* let from = new ReverseIterator(set.upperBound(50));
* let to = new ReverseIterator(set.lowerBound(0));
* let it = from;
* while (!it.equals(to)) {
* console.log(it.key);
* it.next();
* }
*/
upperBound(key) {
return this.__t.upperBound(key);
}
/**
* @returns first element of the container, or undefined if container is empty
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* let first = set.first(); // 1
*/
first() {
return this.__t.first();
}
/**
* @returns last element of the container, or undefined if container is empty
* @example
* let set = new TreeMultiSet([1, 2, 3]);
* let last = set.last(); // 3
*/
last() {
return this.__t.last();
}
/**
* Serializes contents of the set in the form {key1,key2,...}
* @returns {String}
*/
toString() {
return this.__t.toString();
}
}
module.exports = {
TreeMultiSet: TreeMultiSet,
};
