lazy-widgets
Version:
Typescript retained mode GUI for the HTML canvas API
57 lines • 1.6 kB
JavaScript
/**
* A special collection type that can be modified while being iterated. Useful
* for implementing event listener lists.
*
* Can only add at the end of the collection, but can remove from anywhere in
* the collection (while iterating). Preserves insertion order.
*/
export class ConcurrentCollection {
constructor() {
this.iterators = new Set();
this.values = [];
}
indexOf(value) {
return this.values.indexOf(value);
}
forEach(callback) {
const iterator = { nextIndex: 0 };
this.iterators.add(iterator);
try {
while (iterator.nextIndex < this.size) {
callback(this.values[iterator.nextIndex++]);
}
}
finally {
this.iterators.delete(iterator);
}
}
add(value) {
return this.values.push(value) - 1;
}
remove(index) {
const removed = this.values.splice(index, 1).length > 0;
for (const iterator of this.iterators) {
if (iterator.nextIndex < index) {
iterator.nextIndex--;
}
}
return removed;
}
removeByValue(value) {
const index = this.indexOf(value);
if (index < 0) {
return false;
}
this.values.splice(index, 1);
for (const iterator of this.iterators) {
if (iterator.nextIndex < index) {
iterator.nextIndex--;
}
}
return true;
}
get size() {
return this.values.length;
}
}
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