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