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module.exports = balanced; | |
function balanced(a, b, str) { | |
if (a instanceof RegExp) a = maybeMatch(a, str); | |
if (b instanceof RegExp) b = maybeMatch(b, str); | |
var r = range(a, b, str); | |
return r && { | |
start: r[0], | |
end: r[1], | |
pre: str.slice(0, r[0]), | |
body: str.slice(r[0] + a.length, r[1]), | |
post: str.slice(r[1] + b.length) | |
}; | |
} | |
function maybeMatch(reg, str) { | |
var m = str.match(reg); | |
return m ? m[0] : null; | |
} | |
balanced.range = range; | |
function range(a, b, str) { | |
var begs, beg, left, right, result; | |
var ai = str.indexOf(a); | |
var bi = str.indexOf(b, ai + 1); | |
var i = ai; | |
if (ai >= 0 && bi > 0) { | |
if(a===b) { | |
return [ai, bi]; | |
} | |
begs = []; | |
left = str.length; | |
while (i >= 0 && !result) { | |
if (i == ai) { | |
begs.push(i); | |
ai = str.indexOf(a, i + 1); | |
} else if (begs.length == 1) { | |
result = [ begs.pop(), bi ]; | |
} else { | |
beg = begs.pop(); | |
if (beg < left) { | |
left = beg; | |
right = bi; | |
} | |
bi = str.indexOf(b, i + 1); | |
} | |
i = ai < bi && ai >= 0 ? ai : bi; | |
} | |
if (begs.length) { | |
result = [ left, right ]; | |
} | |
} | |
return result; | |
} | |