iter-tools-es/impls/$window-behind/async-window-behind.js

The iterable toolbox

const {
  asyncIterableCurry
} = require('../../internal/async-iterable.js');

const {
  CircularBuffer,
  ReadOnlyCircularBuffer
} = require('../../internal/circular-buffer.js');

async function* __asyncWindowBehind(source, size, {
  filler
} = {}) {
  const buffer = new CircularBuffer(size);
  const bufferReadProxy = new ReadOnlyCircularBuffer(buffer);
  buffer.fill(filler);

  for await (const value of source) {
    buffer.push(value);
    yield bufferReadProxy;
  }
}

exports.__asyncWindowBehind = __asyncWindowBehind;
const asyncWindowBehind = /*#__PURE__*/asyncIterableCurry(__asyncWindowBehind, {
  minArgs: 1,
  maxArgs: 2,

  validateArgs(args) {
    if (typeof args[1] !== 'number') {
      throw new Error(`${'asyncWindowBehind'} must be passed a numeric size`);
    }
  }

});
exports.asyncWindowBehind = asyncWindowBehind;