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 begs = []; 32 left = str.length; 33 34 while (i >= 0 && !result) { 35 if (i == ai) { 36 begs.push(i); 37 ai = str.indexOf(a, i + 1); 38 } else if (begs.length == 1) { 39 result = [ begs.pop(), bi ]; 40 } else { 41 beg = begs.pop(); 42 if (beg < left) { 43 left = beg; 44 right = bi; 45 } 46 47 bi = str.indexOf(b, i + 1); 48 } 49 50 i = ai < bi && ai >= 0 ? ai : bi; 51 } 52 53 if (begs.length) { 54 result = [ left, right ]; 55 } 56 } 57 58 return result; 59} 60