1'use strict';
2module.exports = balanced;
3function balanced(a, b, str) {
4  if (a instanceof RegExp) a = maybeMatch(a, str);
5  if (b instanceof RegExp) b = maybeMatch(b, str);
6
7  var r = range(a, b, str);
8
9  return r && {
10    start: r[0],
11    end: r[1],
12    pre: str.slice(0, r[0]),
13    body: str.slice(r[0] + a.length, r[1]),
14    post: str.slice(r[1] + b.length)
15  };
16}
17
18function maybeMatch(reg, str) {
19  var m = str.match(reg);
20  return m ? m[0] : null;
21}
22
23balanced.range = range;
24function range(a, b, str) {
25  var begs, beg, left, right, result;
26  var ai = str.indexOf(a);
27  var bi = str.indexOf(b, ai + 1);
28  var i = ai;
29
30  if (ai >= 0 && bi > 0) {
31    if(a===b) {
32      return [ai, bi];
33    }
34    begs = [];
35    left = str.length;
36
37    while (i >= 0 && !result) {
38      if (i == ai) {
39        begs.push(i);
40        ai = str.indexOf(a, i + 1);
41      } else if (begs.length == 1) {
42        result = [ begs.pop(), bi ];
43      } else {
44        beg = begs.pop();
45        if (beg < left) {
46          left = beg;
47          right = bi;
48        }
49
50        bi = str.indexOf(b, i + 1);
51      }
52
53      i = ai < bi && ai >= 0 ? ai : bi;
54    }
55
56    if (begs.length) {
57      result = [ left, right ];
58    }
59  }
60
61  return result;
62}
63