79 lines
2.1 KiB
JavaScript
79 lines
2.1 KiB
JavaScript
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/**
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* @fileoverview Rule to flag the generator functions that does not have yield.
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* @author Toru Nagashima
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = {
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meta: {
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type: "suggestion",
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docs: {
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description: "require generator functions to contain `yield`",
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category: "ECMAScript 6",
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recommended: true,
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url: "https://eslint.org/docs/rules/require-yield"
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},
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schema: [],
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messages: {
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missingYield: "This generator function does not have 'yield'."
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}
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},
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create(context) {
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const stack = [];
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/**
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* If the node is a generator function, start counting `yield` keywords.
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* @param {Node} node A function node to check.
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* @returns {void}
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*/
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function beginChecking(node) {
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if (node.generator) {
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stack.push(0);
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}
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}
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/**
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* If the node is a generator function, end counting `yield` keywords, then
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* reports result.
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* @param {Node} node A function node to check.
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* @returns {void}
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*/
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function endChecking(node) {
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if (!node.generator) {
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return;
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}
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const countYield = stack.pop();
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if (countYield === 0 && node.body.body.length > 0) {
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context.report({ node, messageId: "missingYield" });
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}
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}
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return {
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FunctionDeclaration: beginChecking,
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"FunctionDeclaration:exit": endChecking,
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FunctionExpression: beginChecking,
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"FunctionExpression:exit": endChecking,
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// Increases the count of `yield` keyword.
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YieldExpression() {
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/* istanbul ignore else */
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if (stack.length > 0) {
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stack[stack.length - 1] += 1;
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}
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}
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};
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}
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};
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