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ES6 collections polyfill for Espruino
//shared pointer
var i;
//shortcuts
var defineProperty = Object.defineProperty, is = function(a,b) { return (a === b) || (a !== a && b !== b) };
/**
* ES6 collection constructor
* @return {Function} a collection class
*/
function createCollection(proto, objectOnly){
function Collection(a){
if (!this || this.constructor !== Collection) return new Collection(a);
this._keys = [];
this._values = [];
this._itp = []; // iteration pointers
this.objectOnly = objectOnly;
//parse initial iterable argument passed
if (a) init.call(this, a);
}
//define size for non object-only collections
if (!objectOnly) {
defineProperty(proto, 'size', {
get: sharedSize
});
}
//set prototype
proto.constructor = Collection;
Collection.prototype = proto;
return Collection;
}
/** parse initial iterable argument passed */
function init(a){
var i;
//init Set argument, like `[1,2,3,{}]`
if (this.add)
a.forEach(this.add, this);
//init Map argument like `[[1,2], [{}, 4]]`
else
a.forEach(function(a){this.set(a[0],a[1])}, this);
}
/** delete */
function sharedDelete(key) {
if (this.has(key)) {
this._keys.splice(i, 1);
this._values.splice(i, 1);
// update iteration pointers
this._itp.forEach(function(p) { if (i < p[0]) p[0]--; });
}
// Aurora here does it while Canary doesn't
return -1 < i;
};
function sharedGet(key) {
return this.has(key) ? this._values[i] : undefined;
}
function has(list, key) {
if (this.objectOnly && key !== Object(key))
throw new TypeError("Invalid value used as weak collection key");
//NaN or 0 passed
if (key != key || key === 0) for (i = list.length; i-- && !is(list[i], key);){}
else i = list.indexOf(key);
return -1 < i;
}
function setHas(value) {
return has.call(this, this._values, value);
}
function mapHas(value) {
return has.call(this, this._keys, value);
}
/** @chainable */
function sharedSet(key, value) {
this.has(key) ?
this._values[i] = value
:
this._values[this._keys.push(key) - 1] = value
;
return this;
}
/** @chainable */
function sharedAdd(value) {
if (!this.has(value)) this._values.push(value);
return this;
}
function sharedClear() {
(this._keys || 0).length =
this._values.length = 0;
}
/** keys, values, and iterate related methods */
function sharedKeys() {
return sharedIterator(this._itp, this._keys);
}
function sharedValues() {
return sharedIterator(this._itp, this._values);
}
function mapEntries() {
return sharedIterator(this._itp, this._keys, this._values);
}
function setEntries() {
return sharedIterator(this._itp, this._values, this._values);
}
function sharedIterator(itp, array, array2) {
var p = [0], done = false;
itp.push(p);
return {
next: function() {
var v, k = p[0];
if (!done && k < array.length) {
v = array2 ? [array[k], array2[k]]: array[k];
p[0]++;
} else {
done = true;
itp.splice(itp.indexOf(p), 1);
}
return { done: done, value: v };
}
};
}
function sharedSize() {
return this._values.length;
}
function sharedForEach(callback, context) {
var it = this.entries();
for (;;) {
var r = it.next();
if (r.done) break;
callback.call(context, r.value[1], r.value[0], this);
}
}
//Polyfill global objects
if (typeof WeakMap == 'undefined') {
exports.WeakMap = createCollection({
// WeakMap#delete(key:void*):boolean
'delete': sharedDelete,
// WeakMap#clear():
clear: sharedClear,
// WeakMap#get(key:void*):void*
get: sharedGet,
// WeakMap#has(key:void*):boolean
has: mapHas,
// WeakMap#set(key:void*, value:void*):void
set: sharedSet
}, true);
}
if (typeof Map == 'undefined' || typeof ((new Map).values) !== 'function' || !(new Map).values().next) {
exports.Map = createCollection({
// WeakMap#delete(key:void*):boolean
'delete': sharedDelete,
//:was Map#get(key:void*[, d3fault:void*]):void*
// Map#has(key:void*):boolean
has: mapHas,
// Map#get(key:void*):boolean
get: sharedGet,
// Map#set(key:void*, value:void*):void
set: sharedSet,
// Map#keys(void):Iterator
keys: sharedKeys,
// Map#values(void):Iterator
values: sharedValues,
// Map#entries(void):Iterator
entries: mapEntries,
// Map#forEach(callback:Function, context:void*):void ==> callback.call(context, key, value, mapObject) === not in specs`
forEach: sharedForEach,
// Map#clear():
clear: sharedClear
});
}
if (typeof Set == 'undefined' || typeof ((new Set).values) !== 'function' || !(new Set).values().next) {
exports.Set = createCollection({
// Set#has(value:void*):boolean
has: setHas,
// Set#add(value:void*):boolean
add: sharedAdd,
// Set#delete(key:void*):boolean
'delete': sharedDelete,
// Set#clear():
clear: sharedClear,
// Set#keys(void):Iterator
keys: sharedValues, // specs actually say "the same function object as the initial value of the values property"
// Set#values(void):Iterator
values: sharedValues,
// Set#entries(void):Iterator
entries: setEntries,
// Set#forEach(callback:Function, context:void*):void ==> callback.call(context, value, index) === not in specs
forEach: sharedForEach
});
}
if (typeof WeakSet == 'undefined') {
exports.WeakSet = createCollection({
// WeakSet#delete(key:void*):boolean
'delete': sharedDelete,
// WeakSet#add(value:void*):boolean
add: sharedAdd,
// WeakSet#clear():
clear: sharedClear,
// WeakSet#has(value:void*):boolean
has: setHas
}, true);
}
@joakim

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Owner Author

joakim commented May 22, 2018

Basically copy+paste from https://github.com/WebReflection/es6-collections, with two issues when running on Espruino:

  • Although it shims the iterator protocol, Espruino doesn't support iterators or for…of
  • The .size property is missing (requires support for getters in Object.defineProperty)

And WeakSet isn't really weak, like the readme says.

Apart from that, it seems to work as expected.

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