import {Operator} from '../Operator';
import {Subscriber} from '../Subscriber';
import {Observable} from '../Observable';
/**
* Buffers a number of values from the source observable by `bufferSize` then
* emits the buffer and clears it, and starts a new buffer each
* `startBufferEvery` values. If `startBufferEvery` is not provided or is
* `null`, then new buffers are started immediately at the start of the source
* and when each buffer closes and is emitted.
*
* <img src="./img/bufferCount.png" width="100%">
*
* @param {number} bufferSize the maximum size of the buffer emitted.
* @param {number} [startBufferEvery] optional interval at which to start a new
* buffer. (e.g. if `startBufferEvery` is `2`, then a new buffer will be started
* on every other value from the source.) A new buffer is started at the
* beginning of the source by default.
* @returns {Observable<T[]>} an Observable of arrays of buffered values.
*/
export function bufferCount<T>(bufferSize: number, startBufferEvery: number = null): Observable<T[]> {
return this.lift(new BufferCountOperator(bufferSize, startBufferEvery));
}
class BufferCountOperator<T> implements Operator<T, T[]> {
constructor(private bufferSize: number, private startBufferEvery: number) {
}
call(subscriber: Subscriber<T[]>): Subscriber<T> {
return new BufferCountSubscriber(subscriber, this.bufferSize, this.startBufferEvery);
}
}
class BufferCountSubscriber<T> extends Subscriber<T> {
private buffers: Array<T[]> = [[]];
private count: number = 0;
constructor(destination: Subscriber<T[]>, private bufferSize: number, private startBufferEvery: number) {
super(destination);
}
protected _next(value: T) {
const count = (this.count += 1);
const destination = this.destination;
const bufferSize = this.bufferSize;
const startBufferEvery = (this.startBufferEvery == null) ? bufferSize : this.startBufferEvery;
const buffers = this.buffers;
const len = buffers.length;
let remove = -1;
if (count % startBufferEvery === 0) {
buffers.push([]);
}
for (let i = 0; i < len; i++) {
const buffer = buffers[i];
buffer.push(value);
if (buffer.length === bufferSize) {
remove = i;
destination.next(buffer);
}
}
if (remove !== -1) {
buffers.splice(remove, 1);
}
}
protected _complete() {
const destination = this.destination;
const buffers = this.buffers;
while (buffers.length > 0) {
let buffer = buffers.shift();
if (buffer.length > 0) {
destination.next(buffer);
}
}
super._complete();
}
}
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