map-tree

MapTree structure, allows Maps to lookup elements in its Map children in a BFS way.

• Solves Map inheritance
• Allows overrides by setting keys on parents
• Similar interface to the Map you love
• Uses Map and Set under the hood to keep lookups and changes fast
• Fundamental algorithm used is Breadth-first search (BSF)
• Does not test for cycles, thus does not support graphs
• Dependency free

Installation

npm install map-tree --save

Usage

const MapTree = require("map-tree");
 
const foodMap = new MapTree([["steak", {value: 1}]]);
 
const fruitMap = new MapTree();
fruitMap.set("banana", {value: 2});
fruitMap.set("apple", {value: 3});
 
foodMap.children.add(fruitMap);
foodMap.get("banana", true); // {value: 2}
foodMap.has("steak"); // true
foodMap.has("apple"); // false (not traversing)
 
for (let [key, value] of foodMap.entries(true)) {
    // will traverse children too!
}

Syntax

new MapTree([iterable [, children]]);

• iterable : Array or iterable object of key-value pairs.

• children : Array or iterable object of MapTree objects defining the children of the new object.

Properties

• Map.prototype.size : Returns the number of key/value pairs in the MapTree object. It does not include children.

• Map.prototype.children : Returns the MapTree children Set. The Set can be changed to add/remove/clear children. Property can be set provided an array or iterable object of MapTree objects to replace all children.

Methods

• Map.prototype.clear() : Removes all key/value pairs from the MapTree object. Does not clear the children.

• Map.prototype.delete(key) : Removes element from MapTree and returns true if the element did not exist, or false if the element did not. It will not delete from the children.

• Map.prototype.entries([traverse]) : Returns a new Iterator object that contains an array of [key, value] for each element in the MapTree object in insertion order. If traverse is true, the Iterator will include children [key, value] in a BFS order.

• Map.prototype.forEach(callbackFn [, traverse [, thisArg]]) : Calls callbackFn once for each key-value pair present in the MapTree object, in insertion order. If traverse is true, key-value pair present in children will be provided in BFS order. If a thisArg parameter is provided to forEach, it will be used as the this value for each callback.

• Map.prototype.get(key[, traverse]) : Returns the value associated to the key, or undefined if there is none. If traverse is true, the key will be matched with children in BFS order.

• Map.prototype.has(key[, traverse]) : Returns a boolean asserting whether a value has been associated to the key in the MapTree object or not. If traverse is true, the key will be matched with children in BFS order.

• Map.prototype.keys([traverse]) : Returns a new Iterator object that contains the keys for each element in the MapTree object in insertion order. If traverse is true, the Iterator will include children keys in a BFS order.

• Map.prototype.set(key, value) : Sets the value for the key in the MapTree object. Returns the MapTree object.

• Map.prototype.values([traverse]) : Returns a new Iterator object that contains the values for each element in the MapTree object in insertion order. If traverse is true, the Iterator will include children values in a BFS order.

• Map.prototype[@@iterator]() : Returns a new Iterator object that contains an array of [key, value] for each element in the MapTree object in insertion order. It does not include children.