es.string.replace.js

'use strict';

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 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
require('../internals/fix-regexp-well-known-symbol-logic')(
  'replace',
  2,
  function (defined, REPLACE, nativeReplace, maybeCallNative) {
    return [
      // `String.prototype.replace` method
      // https://tc39.github.io/ecma262/#sec-string.prototype.replace
      function replace(searchValue, replaceValue) {
        var O = defined(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) {
        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;
      });
    }
  }
);