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