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

The iterable toolbox

const {
  iterableCurry
} = require('../../internal/iterable.js');

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

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

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

exports.__windowBehind = __windowBehind;
const windowBehind = /*#__PURE__*/iterableCurry(__windowBehind, {
  minArgs: 1,
  maxArgs: 2,

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

});
exports.windowBehind = windowBehind;