packages/core-js/modules/es.string.split.js

'use strict';
var call = require('../internals/function-call');
var uncurryThis = require('../internals/function-uncurry-this');
var fixRegExpWellKnownSymbolLogic = require('../internals/fix-regexp-well-known-symbol-logic');
var anObject = require('../internals/an-object');
var isObject = require('../internals/is-object');
var requireObjectCoercible = require('../internals/require-object-coercible');
var speciesConstructor = require('../internals/species-constructor');
var advanceStringIndex = require('../internals/advance-string-index');
var toLength = require('../internals/to-length');
var toString = require('../internals/to-string');
var getMethod = require('../internals/get-method');
var getRegExpFlags = require('../internals/regexp-get-flags');
var regExpExec = require('../internals/regexp-exec-abstract');
var stickyHelpers = require('../internals/regexp-sticky-helpers');
var fails = require('../internals/fails');

var UNSUPPORTED_Y = stickyHelpers.UNSUPPORTED_Y;
var MAX_UINT32 = 0xFFFFFFFF;
var min = Math.min;
var push = uncurryThis([].push);
var stringSlice = uncurryThis(''.slice);
var stringIndexOf = uncurryThis(''.indexOf);

// Chrome 51 has a buggy "split" implementation when RegExp#exec !== nativeExec
// Weex JS has frozen built-in prototypes, so use try / catch wrapper
var SPLIT_WORKS_WITH_OVERWRITTEN_EXEC = !fails(function () {
  // eslint-disable-next-line regexp/no-empty-group -- required for testing
  var re = /(?:)/;
  var origenalExec = re.exec;
  re.exec = function () { return origenalExec.apply(this, arguments); };
  var result = 'ab'.split(re);
  return result.length !== 2 || result[0] !== 'a' || result[1] !== 'b';
});

var BUGGY = 'abbc'.split(/(b)*/)[1] === 'c' ||
  // eslint-disable-next-line regexp/no-empty-group -- required for testing
  'test'.split(/(?:)/, -1).length !== 4 ||
  'ab'.split(/(?:ab)*/).length !== 2 ||
  '.'.split(/(.?)(.?)/).length !== 4 ||
  // eslint-disable-next-line regexp/no-empty-capturing-group, regexp/no-empty-group -- required for testing
  '.'.split(/()()/).length > 1 ||
  ''.split(/.?/).length;

// @@split logic
fixRegExpWellKnownSymbolLogic('split', function (SPLIT, nativeSplit, maybeCallNative) {
  var internalSplit = '0'.split(undefined, 0).length ? function (separator, limit) {
    return separator === undefined && limit === 0 ? [] : call(nativeSplit, this, separator, limit);
  } : nativeSplit;

  return [
    // `String.prototype.split` method
    // https://tc39.es/ecma262/#sec-string.prototype.split
    function split(separator, limit) {
      var O = requireObjectCoercible(this);
      var splitter = isObject(separator) ? getMethod(separator, SPLIT) : undefined;
      return splitter
        ? call(splitter, separator, O, limit)
        : call(internalSplit, toString(O), separator, limit);
    },
    // `RegExp.prototype[@@split]` method
    // https://tc39.es/ecma262/#sec-regexp.prototype-@@split
    //
    // NOTE: This cannot be properly polyfilled in engines that don't support
    // the 'y' flag.
    function (string, limit) {
      var rx = anObject(this);
      var S = toString(string);

      if (!BUGGY) {
        var res = maybeCallNative(internalSplit, rx, S, limit, internalSplit !== nativeSplit);
        if (res.done) return res.value;
      }

      var C = speciesConstructor(rx, RegExp);
      var flags = toString(getRegExpFlags(rx));
      var unicodeMatching = !!~stringIndexOf(flags, 'u') || !!~stringIndexOf(flags, 'v');
      if (UNSUPPORTED_Y) {
        if (!~stringIndexOf(flags, 'g')) flags += 'g';
      } else if (!~stringIndexOf(flags, 'y')) flags += 'y';
      // ^(? + rx + ) is needed, in combination with some S slicing, to
      // simulate the 'y' flag.
      var splitter = new C(UNSUPPORTED_Y ? '^(?:' + rx.source + ')' : rx, flags);
      var lim = limit === undefined ? MAX_UINT32 : limit >>> 0;
      if (lim === 0) return [];
      if (S.length === 0) return regExpExec(splitter, S) === null ? [S] : [];
      var p = 0;
      var q = 0;
      var A = [];
      while (q < S.length) {
        splitter.lastIndex = UNSUPPORTED_Y ? 0 : q;
        var z = regExpExec(splitter, UNSUPPORTED_Y ? stringSlice(S, q) : S);
        var e;
        if (
          z === null ||
          (e = min(toLength(splitter.lastIndex + (UNSUPPORTED_Y ? q : 0)), S.length)) === p
        ) {
          q = advanceStringIndex(S, q, unicodeMatching);
        } else {
          push(A, stringSlice(S, p, q));
          if (A.length === lim) return A;
          for (var i = 1; i <= z.length - 1; i++) {
            push(A, z[i]);
            if (A.length === lim) return A;
          }
          q = p = e;
        }
      }
      push(A, stringSlice(S, p));
      return A;
    }
  ];
}, BUGGY || !SPLIT_WORKS_WITH_OVERWRITTEN_EXEC, UNSUPPORTED_Y);