iter-tools-es/impls/$starts-with-any-seq/starts-with-any-seq.js

The iterable toolbox

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

const {
  __zipAll
} = require('../$zip-all/zip-all.js');

const {
  __peekerate
} = require('../$peekerate/peekerate.js');

const none = Symbol('none');

function _startsWithAnySeq(peekr, subseqPeekr, same) {
  if (subseqPeekr.done || subseqPeekr.value.includes(none)) return true;
  const matches = subseqPeekr.value.map(() => true);

  while (!peekr.done && !subseqPeekr.done) {
    const {
      value
    } = peekr;
    const {
      value: seqValue
    } = subseqPeekr;

    for (let i = 0; i < seqValue.length; i++) {
      if (!matches[i]) continue;

      if (seqValue[i] === none) {
        return true;
      } else {
        matches[i] = same(seqValue[i], value);
      }
    }

    subseqPeekr.advance();
    peekr.advance();
  }

  return subseqPeekr.done && matches.includes(true);
}

exports._startsWithAnySeq = _startsWithAnySeq;

function __startsWithAnySeq(iterable, seqs, same = Object.is) {
  if (!seqs.length) return false;

  const peekr = __peekerate(iterable);

  const subseqPeekr = __peekerate(__zipAll(seqs, {
    filler: none
  }));

  const seqFound = _startsWithAnySeq(peekr, subseqPeekr, same);

  subseqPeekr.return();
  peekr.return();
  return seqFound;
}

exports.__startsWithAnySeq = __startsWithAnySeq;
const startsWithAnySeq = /*#__PURE__*/iterableCurry(__startsWithAnySeq, {
  minArgs: 1,
  maxArgs: 2,
  reduces: true,

  validateArgs(args) {
    args[1] = args[1].map(arg => ensureIterable(arg));
  }

});
exports.startsWithAnySeq = startsWithAnySeq;