1 var uncurryThis = require('../internals/function-uncurry-this');
2 var toObject = require('../internals/to-object');
4 var floor = Math.floor;
5 var charAt = uncurryThis(''.charAt);
6 var replace = uncurryThis(''.replace);
7 var stringSlice = uncurryThis(''.slice);
8 var SUBSTITUTION_SYMBOLS = /\$([$&'`]|\d{1,2}|<[^>]*>)/g;
9 var SUBSTITUTION_SYMBOLS_NO_NAMED = /\$([$&'`]|\d{1,2})/g;
11 // `GetSubstitution` abstract operation
12 // https://tc39.es/ecma262/#sec-getsubstitution
13 module.exports = function (matched, str, position, captures, namedCaptures, replacement) {
14 var tailPos = position + matched.length;
15 var m = captures.length;
16 var symbols = SUBSTITUTION_SYMBOLS_NO_NAMED;
17 if (namedCaptures !== undefined) {
18 namedCaptures = toObject(namedCaptures);
19 symbols = SUBSTITUTION_SYMBOLS;
21 return replace(replacement, symbols, function (match, ch) {
23 switch (charAt(ch, 0)) {
25 case '&': return matched;
26 case '`': return stringSlice(str, 0, position);
27 case "'": return stringSlice(str, tailPos);
29 capture = namedCaptures[stringSlice(ch, 1, -1)];
33 if (n === 0) return match;
35 var f = floor(n / 10);
36 if (f === 0) return match;
37 if (f <= m) return captures[f - 1] === undefined ? charAt(ch, 1) : captures[f - 1] + charAt(ch, 1);
40 capture = captures[n - 1];
42 return capture === undefined ? '' : capture;