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eb39fafa DC |
1 | /** |
2 | * @fileoverview Rule to flag the generator functions that does not have yield. | |
3 | * @author Toru Nagashima | |
4 | */ | |
5 | ||
6 | "use strict"; | |
7 | ||
8 | //------------------------------------------------------------------------------ | |
9 | // Rule Definition | |
10 | //------------------------------------------------------------------------------ | |
11 | ||
34eeec05 | 12 | /** @type {import('../shared/types').Rule} */ |
eb39fafa DC |
13 | module.exports = { |
14 | meta: { | |
15 | type: "suggestion", | |
16 | ||
17 | docs: { | |
18 | description: "require generator functions to contain `yield`", | |
eb39fafa DC |
19 | recommended: true, |
20 | url: "https://eslint.org/docs/rules/require-yield" | |
21 | }, | |
22 | ||
23 | schema: [], | |
24 | ||
25 | messages: { | |
26 | missingYield: "This generator function does not have 'yield'." | |
27 | } | |
28 | }, | |
29 | ||
30 | create(context) { | |
31 | const stack = []; | |
32 | ||
33 | /** | |
34 | * If the node is a generator function, start counting `yield` keywords. | |
35 | * @param {Node} node A function node to check. | |
36 | * @returns {void} | |
37 | */ | |
38 | function beginChecking(node) { | |
39 | if (node.generator) { | |
40 | stack.push(0); | |
41 | } | |
42 | } | |
43 | ||
44 | /** | |
45 | * If the node is a generator function, end counting `yield` keywords, then | |
46 | * reports result. | |
47 | * @param {Node} node A function node to check. | |
48 | * @returns {void} | |
49 | */ | |
50 | function endChecking(node) { | |
51 | if (!node.generator) { | |
52 | return; | |
53 | } | |
54 | ||
55 | const countYield = stack.pop(); | |
56 | ||
57 | if (countYield === 0 && node.body.body.length > 0) { | |
58 | context.report({ node, messageId: "missingYield" }); | |
59 | } | |
60 | } | |
61 | ||
62 | return { | |
63 | FunctionDeclaration: beginChecking, | |
64 | "FunctionDeclaration:exit": endChecking, | |
65 | FunctionExpression: beginChecking, | |
66 | "FunctionExpression:exit": endChecking, | |
67 | ||
68 | // Increases the count of `yield` keyword. | |
69 | YieldExpression() { | |
70 | ||
71 | /* istanbul ignore else */ | |
72 | if (stack.length > 0) { | |
73 | stack[stack.length - 1] += 1; | |
74 | } | |
75 | } | |
76 | }; | |
77 | } | |
78 | }; |