1 | 'use strict';
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2 |
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3 |
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4 | module.exports = visit;
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5 |
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6 |
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7 | function visit(tree, type, visitor, reverse) {
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8 | if (typeof type === 'function') {
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9 | reverse = visitor;
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10 | visitor = type;
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11 | type = null;
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12 | }
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13 |
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14 | one(tree);
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15 |
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16 |
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17 | function one(node, index, parent) {
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18 | var result;
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19 |
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20 | index = index || (parent ? 0 : null);
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21 |
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22 | if (!type || node.type === type) {
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23 | result = visitor(node, index, parent || null);
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24 | }
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25 |
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26 | if (node.children && result !== false) {
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27 | return all(node.children, node);
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28 | }
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29 |
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30 | return result;
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31 | }
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32 |
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33 |
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34 | function all(children, parent) {
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35 | var step = reverse ? -1 : 1;
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36 | var max = children.length;
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37 | var min = -1;
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38 | var index = (reverse ? max : min) + step;
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39 | var child;
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40 |
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41 | while (index > min && index < max) {
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42 | child = children[index];
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43 |
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44 | if (child && one(child, index, parent) === false) {
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45 | return false;
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46 | }
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47 |
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48 | index += step;
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49 | }
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50 |
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51 | return true;
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52 | }
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53 | }
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