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