Good insight. I wasn't aware that using an empty object in the Map.set implementation would yield unique keys, but it makes sense... You mention sub-linear time, but not constant? Is Map expected to have a lot of collisions? It seems as if it would be fine, based on the spec, but I'll run a benchmark to see where V8's map ops stand in comparison to the external queue / deque libraries.
Is there any way to extend that to a deque with similar operation times? I don't see anything out-of-box, but it looks like the map iterator keeps a numerical index of the keys. Could this be used to allow an iterator in the reverse direction? https://tc39.github.io/ecma262/#sec-createmapiterator , the MapNextIndex. Or is this index just meant to be a counter to check for exhaustion of the iterator? Assuming this Map approach is performant, I still think syntactic sugar would be nice. Although, wrapping up a Map implementation in an alleged Queue might be misleading. Are there any discussions around including linked structures? Or maybe a reversed Iterable for each iterable? Best, Zach Boldyga Scalabull | Founder 1 (866) 846-8771 x 101 On Sat, Feb 25, 2017 at 3:27 PM, Oriol _ <[email protected]> wrote: > Hello, > > you can try using a Map with unique keys. Map operations are guaranteed to > be sublinear on average, and new entries are added to the end. > > Then you only need a trivial wrapper for better abstraction: > > ```js > class Queue { > constructor() { > this._map = new Map(); > } > push(value) { > this._map.set({}, value); > } > pop() { > var first = this._map.entries().next(); > if (first.done) return; > this._map.delete(first.value[0]); > return first.value[1]; > } > get size() { > return this._map.size; > } > } > var q = new Queue(); > q.push(1); > q.push(2); > q.pop(); // 1 > q.push(3); > q.pop(); // 2 > q.pop(); // 3 > q.pop(); // undefined > ``` > > -- Oriol > >
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