es.string.replace.js

'use strict';
var fixRegExpWellKnownSymbolLogic = require('../internals/fix-regexp-well-known-symbol-logic');
var anObject = require('../internals/an-object');
var toObject = require('../internals/to-object');
var toLength = require('../internals/to-length');
var toInteger = require('../internals/to-integer');
var requireObjectCoercible = require('../internals/require-object-coercible');
var advanceStringIndex = require('../internals/advance-string-index');
var regExpExec = require('../internals/regexp-exec-abstract');

var max = Math.max;
var min = Math.min;
var floor = Math.floor;
var SUBSTITUTION_SYMBOLS = /\$([$&'`]|\d\d?|<[^>]*>)/g;
var SUBSTITUTION_SYMBOLS_NO_NAMED = /\$([$&'`]|\d\d?)/g;

var maybeToString = function (it) {
  return it === undefined ? it : String(it);
};

// @@replace logic
fixRegExpWellKnownSymbolLogic('replace', 2, function (REPLACE, nativeReplace, maybeCallNative, reason) {
  var REGEXP_REPLACE_SUBSTITUTES_UNDEFINED_CAPTURE = reason.REGEXP_REPLACE_SUBSTITUTES_UNDEFINED_CAPTURE;
  var REPLACE_KEEPS_$0 = reason.REPLACE_KEEPS_$0;
  var UNSAFE_SUBSTITUTE = REGEXP_REPLACE_SUBSTITUTES_UNDEFINED_CAPTURE ? '$' : '$0';

  return [
    // `String.prototype.replace` method
    // https://tc39.github.io/ecma262/#sec-string.prototype.replace
    function replace(searchValue, replaceValue) {
      var O = requireObjectCoercible(this);
      var replacer = searchValue == undefined ? undefined : searchValue[REPLACE];
      return replacer !== undefined
        ? replacer.call(searchValue, O, replaceValue)
        : nativeReplace.call(String(O), searchValue, replaceValue);
    },
    // `RegExp.prototype[@@replace]` method
    // https://tc39.github.io/ecma262/#sec-regexp.prototype-@@replace
    function (regexp, replaceValue) {
      if (
        (!REGEXP_REPLACE_SUBSTITUTES_UNDEFINED_CAPTURE && REPLACE_KEEPS_$0) ||
        (typeof replaceValue === 'string' && replaceValue.indexOf(UNSAFE_SUBSTITUTE) === -1)
      ) {
        var res = maybeCallNative(nativeReplace, regexp, this, replaceValue);
        if (res.done) return res.value;
      }

      var rx = anObject(regexp);
      var S = String(this);

      var functionalReplace = typeof replaceValue === 'function';
      if (!functionalReplace) replaceValue = String(replaceValue);

      var global = rx.global;
      if (global) {
        var fullUnicode = rx.unicode;
        rx.lastIndex = 0;
      }
      var results = [];
      while (true) {
        var result = regExpExec(rx, S);
        if (result === null) break;

        results.push(result);
        if (!global) break;

        var matchStr = String(result[0]);
        if (matchStr === '') rx.lastIndex = advanceStringIndex(S, toLength(rx.lastIndex), fullUnicode);
      }

      var accumulatedResult = '';
      var nextSourcePosition = 0;
      for (var i = 0; i < results.length; i++) {
        result = results[i];

        var matched = String(result[0]);
        var position = max(min(toInteger(result.index), S.length), 0);
        var captures = [];
        // NOTE: This is equivalent to
        //   captures = result.slice(1).map(maybeToString)
        // but for some reason `nativeSlice.call(result, 1, result.length)` (called in
        // the slice polyfill when slicing native arrays) "doesn't work" in safari 9 and
        // causes a crash (https://pastebin.com/N21QzeQA) when trying to debug it.
        for (var j = 1; j < result.length; j++) captures.push(maybeToString(result[j]));
        var namedCaptures = result.groups;
        if (functionalReplace) {
          var replacerArgs = [matched].concat(captures, position, S);
          if (namedCaptures !== undefined) replacerArgs.push(namedCaptures);
          var replacement = String(replaceValue.apply(undefined, replacerArgs));
        } else {
          replacement = getSubstitution(matched, S, position, captures, namedCaptures, replaceValue);
        }
        if (position >= nextSourcePosition) {
          accumulatedResult += S.slice(nextSourcePosition, position) + replacement;
          nextSourcePosition = position + matched.length;
        }
      }
      return accumulatedResult + S.slice(nextSourcePosition);
    }
  ];

  // https://tc39.github.io/ecma262/#sec-getsubstitution
  function getSubstitution(matched, str, position, captures, namedCaptures, replacement) {
    var tailPos = position + matched.length;
    var m = captures.length;
    var symbols = SUBSTITUTION_SYMBOLS_NO_NAMED;
    if (namedCaptures !== undefined) {
      namedCaptures = toObject(namedCaptures);
      symbols = SUBSTITUTION_SYMBOLS;
    }
    return nativeReplace.call(replacement, symbols, function (match, ch) {
      var capture;
      switch (ch.charAt(0)) {
        case '$': return '$';
        case '&': return matched;
        case '`': return str.slice(0, position);
        case "'": return str.slice(tailPos);
        case '<':
          capture = namedCaptures[ch.slice(1, -1)];
          break;
        default: // \d\d?
          var n = +ch;
          if (n === 0) return match;
          if (n > m) {
            var f = floor(n / 10);
            if (f === 0) return match;
            if (f <= m) return captures[f - 1] === undefined ? ch.charAt(1) : captures[f - 1] + ch.charAt(1);
            return match;
          }
          capture = captures[n - 1];
      }
      return capture === undefined ? '' : capture;
    });
  }
});