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Merge pull request #108 from endojs/mfig-107-eslint-await
ESLint `await` rule cleanup
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| Original file line number | Diff line number | Diff line change |
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| User-visible changes in `@endo/eslint-plugin` | ||
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| # v0.4.4 (2023-04-14) | ||
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| - Separate rules into subsets (documented in README.md) |
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| { | ||
| "compilerOptions": { | ||
| "baseUrl": ".", | ||
| "moduleResolution": "node", | ||
| "target": "esnext", | ||
| "module": "CommonJS", | ||
| "noImplicitAny": true, | ||
| "noEmit": true, | ||
| "noUnusedLocals": true, | ||
| "noUnusedParameters": true, | ||
| "alwaysStrict": true, | ||
| "downlevelIteration": true | ||
| }, | ||
| "include": ["lib/**/*.js"], | ||
| "exclude": ["node_modules/**"] | ||
| } |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,60 @@ | ||
| // @ts-check | ||
| /* eslint-env node */ | ||
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| /** | ||
| * @author Michael FIG | ||
| * See LICENSE file in root directory for full license. | ||
| */ | ||
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| 'use strict'; | ||
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| const { isFunctionLike, makeAwaitAllowedVisitor } = require('../tools.js'); | ||
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| /** @type {import('eslint').Rule.RuleModule} */ | ||
| module.exports = { | ||
| meta: { | ||
| docs: { | ||
| description: `ensure the first \`await\` in an \`async\` function is non-nested so that it is clear when the synchronous portion of the function is finished`, | ||
| category: 'Possible Errors', | ||
| recommended: true, | ||
| url: | ||
| 'https://github.com/endojs/Jessie/blob/main/packages/eslint-plugin/lib/rules/safe-await-separator', | ||
| }, | ||
| type: 'problem', | ||
| fixable: null, | ||
| hasSuggestions: true, | ||
| messages: { | ||
| unsafeAwaitSeparator: | ||
| 'The first `await` appearing in an async function must not be nested', | ||
| insertAwaitNull: 'Insert `await null;` before the first `await`', | ||
| }, | ||
| schema: [], | ||
| supported: true, | ||
| }, | ||
| create(context) { | ||
| /** | ||
| * @param {import('eslint').Rule.Node} node | ||
| */ | ||
| const makeReport = node => { | ||
| context.report({ | ||
| node, | ||
| messageId: 'unsafeAwaitSeparator', | ||
| suggest: [ | ||
| { | ||
| messageId: 'insertAwaitNull', | ||
| fix: fixer => { | ||
| let cur = node; | ||
| let parent = cur.parent; | ||
| while (!isFunctionLike(parent.parent)) { | ||
| cur = parent; | ||
| parent = cur.parent; | ||
| } | ||
| return fixer.insertTextBefore(cur, 'await null;'); | ||
| }, | ||
| }, | ||
| ], | ||
| }); | ||
| }; | ||
| return makeAwaitAllowedVisitor(context, makeReport, true); | ||
| }, | ||
| }; |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,135 @@ | ||
| // @ts-check | ||
| /* eslint-env node */ | ||
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| 'use strict'; | ||
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| /** @typedef {import('eslint').Rule.Node} Node */ | ||
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| const harden = Object.freeze; | ||
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| /** @type {Node['type'][]} */ | ||
| const functionLikeNodeTypes = [ | ||
| 'ArrowFunctionExpression', | ||
| 'FunctionExpression', | ||
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| 'FunctionDeclaration', | ||
| 'MethodDefinition', | ||
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| 'Program', | ||
| 'StaticBlock', | ||
| ]; | ||
| harden(functionLikeNodeTypes); | ||
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| /** | ||
| * @param {Node} node | ||
| */ | ||
| const isFunctionLike = node => functionLikeNodeTypes.includes(node.type); | ||
| harden(isFunctionLike); | ||
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| /** | ||
| * @param {Node} node | ||
| * @param {WeakSet<Node>} already | ||
| * @returns {boolean} | ||
| */ | ||
| const isAwaitAllowedInNode = (node, already = new WeakSet()) => { | ||
| // Climb the AST until finding the nearest enclosing function or | ||
| // function-like node. | ||
| let result = true; | ||
| for (; node && !isFunctionLike(node); node = node.parent) { | ||
| if (already.has(node)) { | ||
| return true; | ||
| } | ||
| already.add(node); | ||
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| if (node.type === 'BlockStatement') { | ||
| // do nothing | ||
| } else if (node.type === 'ForOfStatement' && node.await) { | ||
| // do nothing | ||
| } else { | ||
| // Encountering anything other than an enclosing block is grounds for | ||
| // rejection. | ||
| result = false; | ||
| } | ||
| } | ||
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| if (!node) { | ||
| // Should never reach here because Program is a FunctionLike for | ||
| // top-level await. | ||
| throw new Error(`unexpected non-Program AST!`); | ||
| } | ||
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| return result; | ||
| }; | ||
| harden(isAwaitAllowedInNode); | ||
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| /** | ||
| * @param {import('eslint').Rule.RuleContext} _context | ||
| * @param {(node: Node) => void} makeReport | ||
| * @param {boolean} [addToCache] | ||
| */ | ||
| const makeAwaitAllowedVisitor = ( | ||
| _context, | ||
| makeReport, | ||
| addToCache = undefined, | ||
| ) => { | ||
| const already = addToCache ? new WeakSet() : undefined; | ||
| return harden({ | ||
| /** | ||
| * An `await` expression is treated as non-nested if it is: | ||
| * - a non-nested expression statement, | ||
| * - the right-hand side of a non-nested declarator, or | ||
| * - the right-hand side of an assignment expression. | ||
| * | ||
| * As a hint to future readers, the following ASTExplorer workspace | ||
| * reveals some of the relevant AST shapes (note that node.parent is not | ||
| * displayed in the ASTExplorer, but is available in the ESLint visitor): | ||
| * | ||
| * @see https://astexplorer.net/#/gist/4508eec25a8d5be1e0248c4cc06b9634/f6b22f2e8e3abd82a911ca6286a304ef0a3018c4 | ||
| * | ||
| * This will need different handling for do expressions if they are ever | ||
| * added to the language. | ||
| * @see https://github.com/tc39/proposal-do-expressions | ||
| * | ||
| * @param {Node} node | ||
| */ | ||
| AwaitExpression: node => { | ||
| let parent = node.parent; | ||
| if (parent.type === 'VariableDeclarator' && parent.init === node) { | ||
| // It's a declarator, so look up to the declaration statement's parent. | ||
| parent = parent.parent.parent; | ||
| } else if ( | ||
| parent.type === 'AssignmentExpression' && | ||
| parent.right === node && | ||
| parent.operator === '=' | ||
| ) { | ||
| // It's an assignment, so look up to the assigment's parent. | ||
| parent = parent.parent; | ||
| } | ||
| if (parent.type === 'ExpressionStatement') { | ||
| // Try to find the parent block. | ||
| parent = parent.parent; | ||
| } | ||
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| if (!isAwaitAllowedInNode(parent, already)) { | ||
| makeReport(node); | ||
| } | ||
| }, | ||
| /** | ||
| * A `for-await-of` loop is treated as a simple `await` statement. | ||
| * | ||
| * @param {Node} node | ||
| */ | ||
| 'ForOfStatement[await=true]': node => { | ||
| if (!isAwaitAllowedInNode(node.parent, already)) { | ||
| makeReport(node); | ||
| } | ||
| }, | ||
| }); | ||
| }; | ||
| harden(makeAwaitAllowedVisitor); | ||
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| module.exports = harden({ | ||
| isFunctionLike, | ||
| isAwaitAllowedInNode, | ||
| makeAwaitAllowedVisitor, | ||
| }); |
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