1 | /**
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2 | * @fileoverview Rule to enforce declarations in program or function body root.
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3 | * @author Brandon Mills
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4 | */
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5 |
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6 | ;
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7 |
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8 | //------------------------------------------------------------------------------
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9 | // Rule Definition
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10 | //------------------------------------------------------------------------------
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11 |
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12 | module.exports = {
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13 | meta: {
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14 | docs: {
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15 | description: "disallow variable or `function` declarations in nested blocks",
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16 | category: "Possible Errors",
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17 | recommended: true,
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18 | url: "https://eslint.org/docs/rules/no-inner-declarations"
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19 | },
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20 |
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21 | schema: [
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22 | {
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23 | enum: ["functions", "both"]
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24 | }
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25 | ]
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26 | },
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27 |
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28 | create(context) {
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29 |
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30 | /**
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31 | * Find the nearest Program or Function ancestor node.
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32 | * @returns {Object} Ancestor's type and distance from node.
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33 | */
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34 | function nearestBody() {
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35 | const ancestors = context.getAncestors();
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36 | let ancestor = ancestors.pop(),
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37 | generation = 1;
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38 |
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39 | while (ancestor && ["Program", "FunctionDeclaration",
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40 | "FunctionExpression", "ArrowFunctionExpression"
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41 | ].indexOf(ancestor.type) < 0) {
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42 | generation += 1;
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43 | ancestor = ancestors.pop();
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44 | }
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45 |
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46 | return {
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47 |
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48 | // Type of containing ancestor
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49 | type: ancestor.type,
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50 |
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51 | // Separation between ancestor and node
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52 | distance: generation
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53 | };
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54 | }
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55 |
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56 | /**
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57 | * Ensure that a given node is at a program or function body's root.
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58 | * @param {ASTNode} node Declaration node to check.
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59 | * @returns {void}
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60 | */
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61 | function check(node) {
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62 | const body = nearestBody(),
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63 | valid = ((body.type === "Program" && body.distance === 1) ||
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64 | body.distance === 2);
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65 |
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66 | if (!valid) {
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67 | context.report({
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68 | node,
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69 | message: "Move {{type}} declaration to {{body}} root.",
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70 | data: {
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71 | type: (node.type === "FunctionDeclaration" ? "function" : "variable"),
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72 | body: (body.type === "Program" ? "program" : "function body")
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73 | }
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74 | });
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75 | }
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76 | }
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77 |
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78 | return {
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79 |
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80 | FunctionDeclaration: check,
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81 | VariableDeclaration(node) {
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82 | if (context.options[0] === "both" && node.kind === "var") {
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83 | check(node);
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84 | }
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85 | }
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86 |
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87 | };
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88 |
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89 | }
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90 | };
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