148 lines
5.1 KiB
JavaScript
148 lines
5.1 KiB
JavaScript
/**
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* @fileoverview Rule to disallow async functions which have no `await` expression.
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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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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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/**
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* Capitalize the 1st letter of the given text.
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* @param {string} text The text to capitalize.
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* @returns {string} The text that the 1st letter was capitalized.
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*/
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function capitalizeFirstLetter(text) {
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return text[0].toUpperCase() + text.slice(1);
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../shared/types').Rule} */
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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: "Disallow async functions which have no `await` expression",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/require-await"
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},
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schema: [],
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messages: {
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missingAwait: "{{name}} has no 'await' expression.",
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removeAsync: "Remove 'async'."
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},
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hasSuggestions: true
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},
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create(context) {
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const sourceCode = context.sourceCode;
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let scopeInfo = null;
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/**
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* Push the scope info object to the stack.
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* @returns {void}
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*/
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function enterFunction() {
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scopeInfo = {
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upper: scopeInfo,
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hasAwait: false
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};
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}
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/**
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* Pop the top scope info object from the stack.
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* Also, it reports the function if needed.
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* @param {ASTNode} node The node to report.
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* @returns {void}
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*/
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function exitFunction(node) {
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if (!node.generator && node.async && !scopeInfo.hasAwait && !astUtils.isEmptyFunction(node)) {
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/*
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* If the function belongs to a method definition or
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* property, then the function's range may not include the
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* `async` keyword and we should look at the parent instead.
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*/
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const nodeWithAsyncKeyword =
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(node.parent.type === "MethodDefinition" && node.parent.value === node) ||
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(node.parent.type === "Property" && node.parent.method && node.parent.value === node)
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? node.parent
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: node;
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const asyncToken = sourceCode.getFirstToken(nodeWithAsyncKeyword, token => token.value === "async");
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const asyncRange = [asyncToken.range[0], sourceCode.getTokenAfter(asyncToken, { includeComments: true }).range[0]];
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/*
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* Removing the `async` keyword can cause parsing errors if the current
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* statement is relying on automatic semicolon insertion. If ASI is currently
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* being used, then we should replace the `async` keyword with a semicolon.
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*/
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const nextToken = sourceCode.getTokenAfter(asyncToken);
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const addSemiColon =
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nextToken.type === "Punctuator" &&
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(nextToken.value === "[" || nextToken.value === "(") &&
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(nodeWithAsyncKeyword.type === "MethodDefinition" || astUtils.isStartOfExpressionStatement(nodeWithAsyncKeyword)) &&
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astUtils.needsPrecedingSemicolon(sourceCode, nodeWithAsyncKeyword);
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context.report({
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node,
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loc: astUtils.getFunctionHeadLoc(node, sourceCode),
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messageId: "missingAwait",
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data: {
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name: capitalizeFirstLetter(
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astUtils.getFunctionNameWithKind(node)
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)
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},
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suggest: [{
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messageId: "removeAsync",
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fix: fixer => fixer.replaceTextRange(asyncRange, addSemiColon ? ";" : "")
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}]
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});
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}
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scopeInfo = scopeInfo.upper;
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}
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return {
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FunctionDeclaration: enterFunction,
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FunctionExpression: enterFunction,
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ArrowFunctionExpression: enterFunction,
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"FunctionDeclaration:exit": exitFunction,
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"FunctionExpression:exit": exitFunction,
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"ArrowFunctionExpression:exit": exitFunction,
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AwaitExpression() {
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if (!scopeInfo) {
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return;
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}
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scopeInfo.hasAwait = true;
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},
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ForOfStatement(node) {
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if (!scopeInfo) {
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return;
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}
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if (node.await) {
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scopeInfo.hasAwait = true;
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}
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}
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};
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}
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};
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