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eb39fafa DC |
1 | /** |
2 | * @fileoverview Rule to enforce a particular function style | |
3 | * @author Nicholas C. Zakas | |
4 | */ | |
5 | "use strict"; | |
6 | ||
7 | //------------------------------------------------------------------------------ | |
8 | // Rule Definition | |
9 | //------------------------------------------------------------------------------ | |
10 | ||
34eeec05 | 11 | /** @type {import('../shared/types').Rule} */ |
eb39fafa DC |
12 | module.exports = { |
13 | meta: { | |
14 | type: "suggestion", | |
15 | ||
16 | docs: { | |
17 | description: "enforce the consistent use of either `function` declarations or expressions", | |
eb39fafa DC |
18 | recommended: false, |
19 | url: "https://eslint.org/docs/rules/func-style" | |
20 | }, | |
21 | ||
22 | schema: [ | |
23 | { | |
24 | enum: ["declaration", "expression"] | |
25 | }, | |
26 | { | |
27 | type: "object", | |
28 | properties: { | |
29 | allowArrowFunctions: { | |
30 | type: "boolean", | |
31 | default: false | |
32 | } | |
33 | }, | |
34 | additionalProperties: false | |
35 | } | |
36 | ], | |
37 | ||
38 | messages: { | |
39 | expression: "Expected a function expression.", | |
40 | declaration: "Expected a function declaration." | |
41 | } | |
42 | }, | |
43 | ||
44 | create(context) { | |
45 | ||
46 | const style = context.options[0], | |
47 | allowArrowFunctions = context.options[1] && context.options[1].allowArrowFunctions, | |
48 | enforceDeclarations = (style === "declaration"), | |
49 | stack = []; | |
50 | ||
51 | const nodesToCheck = { | |
52 | FunctionDeclaration(node) { | |
53 | stack.push(false); | |
54 | ||
55 | if (!enforceDeclarations && node.parent.type !== "ExportDefaultDeclaration") { | |
56 | context.report({ node, messageId: "expression" }); | |
57 | } | |
58 | }, | |
59 | "FunctionDeclaration:exit"() { | |
60 | stack.pop(); | |
61 | }, | |
62 | ||
63 | FunctionExpression(node) { | |
64 | stack.push(false); | |
65 | ||
66 | if (enforceDeclarations && node.parent.type === "VariableDeclarator") { | |
67 | context.report({ node: node.parent, messageId: "declaration" }); | |
68 | } | |
69 | }, | |
70 | "FunctionExpression:exit"() { | |
71 | stack.pop(); | |
72 | }, | |
73 | ||
74 | ThisExpression() { | |
75 | if (stack.length > 0) { | |
76 | stack[stack.length - 1] = true; | |
77 | } | |
78 | } | |
79 | }; | |
80 | ||
81 | if (!allowArrowFunctions) { | |
82 | nodesToCheck.ArrowFunctionExpression = function() { | |
83 | stack.push(false); | |
84 | }; | |
85 | ||
86 | nodesToCheck["ArrowFunctionExpression:exit"] = function(node) { | |
87 | const hasThisExpr = stack.pop(); | |
88 | ||
89 | if (enforceDeclarations && !hasThisExpr && node.parent.type === "VariableDeclarator") { | |
90 | context.report({ node: node.parent, messageId: "declaration" }); | |
91 | } | |
92 | }; | |
93 | } | |
94 | ||
95 | return nodesToCheck; | |
96 | ||
97 | } | |
98 | }; |