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eb39fafa DC |
1 | /** |
2 | * @fileoverview Rule to check for "block scoped" variables by binding context | |
3 | * @author Matt DuVall <http://www.mattduvall.com> | |
4 | */ | |
5 | "use strict"; | |
6 | ||
7 | //------------------------------------------------------------------------------ | |
8 | // Rule Definition | |
9 | //------------------------------------------------------------------------------ | |
10 | ||
11 | module.exports = { | |
12 | meta: { | |
13 | type: "suggestion", | |
14 | ||
15 | docs: { | |
16 | description: "enforce the use of variables within the scope they are defined", | |
17 | category: "Best Practices", | |
18 | recommended: false, | |
19 | url: "https://eslint.org/docs/rules/block-scoped-var" | |
20 | }, | |
21 | ||
22 | schema: [], | |
23 | ||
24 | messages: { | |
25 | outOfScope: "'{{name}}' used outside of binding context." | |
26 | } | |
27 | }, | |
28 | ||
29 | create(context) { | |
30 | let stack = []; | |
31 | ||
32 | /** | |
33 | * Makes a block scope. | |
34 | * @param {ASTNode} node A node of a scope. | |
35 | * @returns {void} | |
36 | */ | |
37 | function enterScope(node) { | |
38 | stack.push(node.range); | |
39 | } | |
40 | ||
41 | /** | |
42 | * Pops the last block scope. | |
43 | * @returns {void} | |
44 | */ | |
45 | function exitScope() { | |
46 | stack.pop(); | |
47 | } | |
48 | ||
49 | /** | |
50 | * Reports a given reference. | |
51 | * @param {eslint-scope.Reference} reference A reference to report. | |
52 | * @returns {void} | |
53 | */ | |
54 | function report(reference) { | |
55 | const identifier = reference.identifier; | |
56 | ||
57 | context.report({ node: identifier, messageId: "outOfScope", data: { name: identifier.name } }); | |
58 | } | |
59 | ||
60 | /** | |
61 | * Finds and reports references which are outside of valid scopes. | |
62 | * @param {ASTNode} node A node to get variables. | |
63 | * @returns {void} | |
64 | */ | |
65 | function checkForVariables(node) { | |
66 | if (node.kind !== "var") { | |
67 | return; | |
68 | } | |
69 | ||
70 | // Defines a predicate to check whether or not a given reference is outside of valid scope. | |
71 | const scopeRange = stack[stack.length - 1]; | |
72 | ||
73 | /** | |
74 | * Check if a reference is out of scope | |
75 | * @param {ASTNode} reference node to examine | |
76 | * @returns {boolean} True is its outside the scope | |
77 | * @private | |
78 | */ | |
79 | function isOutsideOfScope(reference) { | |
80 | const idRange = reference.identifier.range; | |
81 | ||
82 | return idRange[0] < scopeRange[0] || idRange[1] > scopeRange[1]; | |
83 | } | |
84 | ||
85 | // Gets declared variables, and checks its references. | |
86 | const variables = context.getDeclaredVariables(node); | |
87 | ||
88 | for (let i = 0; i < variables.length; ++i) { | |
89 | ||
90 | // Reports. | |
91 | variables[i] | |
92 | .references | |
93 | .filter(isOutsideOfScope) | |
94 | .forEach(report); | |
95 | } | |
96 | } | |
97 | ||
98 | return { | |
99 | Program(node) { | |
100 | stack = [node.range]; | |
101 | }, | |
102 | ||
103 | // Manages scopes. | |
104 | BlockStatement: enterScope, | |
105 | "BlockStatement:exit": exitScope, | |
106 | ForStatement: enterScope, | |
107 | "ForStatement:exit": exitScope, | |
108 | ForInStatement: enterScope, | |
109 | "ForInStatement:exit": exitScope, | |
110 | ForOfStatement: enterScope, | |
111 | "ForOfStatement:exit": exitScope, | |
112 | SwitchStatement: enterScope, | |
113 | "SwitchStatement:exit": exitScope, | |
114 | CatchClause: enterScope, | |
115 | "CatchClause:exit": exitScope, | |
116 | ||
117 | // Finds and reports references which are outside of valid scope. | |
118 | VariableDeclaration: checkForVariables | |
119 | }; | |
120 | ||
121 | } | |
122 | }; |