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feat(eslint-plugin): add extension rule `comma-dangle` (#2416)
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- +1 −0 packages/eslint-plugin/README.md
- +34 −0 packages/eslint-plugin/docs/rules/comma-dangle.md
- +2 −0 packages/eslint-plugin/src/configs/all.ts
- +179 −0 packages/eslint-plugin/src/rules/comma-dangle.ts
- +2 −0 packages/eslint-plugin/src/rules/index.ts
- +255 −0 packages/eslint-plugin/tests/rules/comma-dangle.test.ts
- +33 −0 packages/eslint-plugin/typings/eslint-rules.d.ts
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| # Require or disallow trailing comma (`comma-dangle`) | ||
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| ## Rule Details | ||
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| This rule extends the base [`eslint/comma-dangle`](https://eslint.org/docs/rules/comma-dangle) rule. | ||
| It adds support for TypeScript syntax. | ||
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| See the [ESLint documentation](https://eslint.org/docs/rules/comma-dangle) for more details on the `comma-dangle` rule. | ||
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| ## Rule Changes | ||
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| ```cjson | ||
| { | ||
| // note you must disable the base rule as it can report incorrect errors | ||
| "comma-dangle": "off", | ||
| "@typescript-eslint/comma-dangle": ["error"] | ||
| } | ||
| ``` | ||
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| In addition to the options supported by the `comma-dangle` rule in ESLint core, the rule adds the following options: | ||
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| ## Options | ||
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| This rule has a string option and an object option. | ||
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| - Object option: | ||
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| - `"enums"` is for trailing comma in enum. (e.g. `enum Foo = {Bar,}`) | ||
| - `"generics"` is for trailing comma in generic. (e.g. `function foo<T,>() {}`) | ||
| - `"tuples"` is for trailing comma in tuple. (e.g. `type Foo = [string,]`) | ||
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| - [See the other options allowed](https://github.com/eslint/eslint/blob/master/docs/rules/comma-dangle.md#options) | ||
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| <sup>Taken with ❤️ [from ESLint core](https://github.com/eslint/eslint/blob/master/docs/rules/comma-dangle.md)</sup> |
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| import * as util from '../util'; | ||
| import baseRule from 'eslint/lib/rules/comma-dangle'; | ||
| import { | ||
| TSESTree, | ||
| AST_NODE_TYPES, | ||
| } from '@typescript-eslint/experimental-utils'; | ||
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| export type Options = util.InferOptionsTypeFromRule<typeof baseRule>; | ||
| export type MessageIds = util.InferMessageIdsTypeFromRule<typeof baseRule>; | ||
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| type Option = Options[0]; | ||
| type NormalizedOptions = Required< | ||
| Pick<Exclude<Option, string>, 'enums' | 'generics' | 'tuples'> | ||
| >; | ||
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| const OPTION_VALUE_SCHEME = [ | ||
| 'always-multiline', | ||
| 'always', | ||
| 'never', | ||
| 'only-multiline', | ||
| ]; | ||
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| const DEFAULT_OPTION_VALUE = 'never'; | ||
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| function normalizeOptions(options: Option): NormalizedOptions { | ||
| if (typeof options === 'string') { | ||
| return { | ||
| enums: options, | ||
| generics: options, | ||
| tuples: options, | ||
| }; | ||
| } | ||
| return { | ||
| enums: options.enums ?? DEFAULT_OPTION_VALUE, | ||
| generics: options.generics ?? DEFAULT_OPTION_VALUE, | ||
| tuples: options.tuples ?? DEFAULT_OPTION_VALUE, | ||
| }; | ||
| } | ||
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| export default util.createRule<Options, MessageIds>({ | ||
| name: 'comma-dangle', | ||
| meta: { | ||
| type: 'layout', | ||
| docs: { | ||
| description: 'Require or disallow trailing comma', | ||
| category: 'Stylistic Issues', | ||
| recommended: false, | ||
| extendsBaseRule: true, | ||
| }, | ||
| schema: { | ||
| definitions: { | ||
| value: { | ||
| enum: OPTION_VALUE_SCHEME, | ||
| }, | ||
| valueWithIgnore: { | ||
| enum: [...OPTION_VALUE_SCHEME, 'ignore'], | ||
| }, | ||
| }, | ||
| type: 'array', | ||
| items: [ | ||
| { | ||
| oneOf: [ | ||
| { | ||
| $ref: '#/definitions/value', | ||
| }, | ||
| { | ||
| type: 'object', | ||
| properties: { | ||
| arrays: { $ref: '#/definitions/valueWithIgnore' }, | ||
| objects: { $ref: '#/definitions/valueWithIgnore' }, | ||
| imports: { $ref: '#/definitions/valueWithIgnore' }, | ||
| exports: { $ref: '#/definitions/valueWithIgnore' }, | ||
| functions: { $ref: '#/definitions/valueWithIgnore' }, | ||
| enums: { $ref: '#/definitions/valueWithIgnore' }, | ||
| generics: { $ref: '#/definitions/valueWithIgnore' }, | ||
| tuples: { $ref: '#/definitions/valueWithIgnore' }, | ||
| }, | ||
| additionalProperties: false, | ||
| }, | ||
| ], | ||
| }, | ||
| ], | ||
| }, | ||
| fixable: 'code', | ||
| messages: baseRule.meta.messages, | ||
| }, | ||
| defaultOptions: ['never'], | ||
| create(context, [options]) { | ||
| const rules = baseRule.create(context); | ||
| const sourceCode = context.getSourceCode(); | ||
| const normalizedOptions = normalizeOptions(options); | ||
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| const predicate = { | ||
| always: forceComma, | ||
| 'always-multiline': forceCommaIfMultiline, | ||
| 'only-multiline': allowCommaIfMultiline, | ||
| never: forbidComma, | ||
| ignore: (): void => {}, | ||
| }; | ||
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| function last(nodes: TSESTree.Node[]): TSESTree.Node | null { | ||
| return nodes[nodes.length - 1] ?? null; | ||
| } | ||
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| function getLastItem(node: TSESTree.Node): TSESTree.Node | null { | ||
| switch (node.type) { | ||
| case AST_NODE_TYPES.TSEnumDeclaration: | ||
| return last(node.members); | ||
| case AST_NODE_TYPES.TSTypeParameterDeclaration: | ||
| return last(node.params); | ||
| case AST_NODE_TYPES.TSTupleType: | ||
| return last(node.elementTypes); | ||
| default: | ||
| return null; | ||
| } | ||
| } | ||
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| function getTrailingToken(node: TSESTree.Node): TSESTree.Token | null { | ||
| const last = getLastItem(node); | ||
| const trailing = last && sourceCode.getTokenAfter(last); | ||
| return trailing; | ||
| } | ||
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| function isMultiline(node: TSESTree.Node): boolean { | ||
| const last = getLastItem(node); | ||
| const lastToken = sourceCode.getLastToken(node); | ||
| return last?.loc.end.line !== lastToken?.loc.end.line; | ||
| } | ||
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| function forbidComma(node: TSESTree.Node): void { | ||
| const last = getLastItem(node); | ||
| const trailing = getTrailingToken(node); | ||
| if (last && trailing && util.isCommaToken(trailing)) { | ||
| context.report({ | ||
| node, | ||
| messageId: 'unexpected', | ||
| fix(fixer) { | ||
| return fixer.remove(trailing); | ||
| }, | ||
| }); | ||
| } | ||
| } | ||
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| function forceComma(node: TSESTree.Node): void { | ||
| const last = getLastItem(node); | ||
| const trailing = getTrailingToken(node); | ||
| if (last && trailing && !util.isCommaToken(trailing)) { | ||
| context.report({ | ||
| node, | ||
| messageId: 'missing', | ||
| fix(fixer) { | ||
| return fixer.insertTextAfter(last, ','); | ||
| }, | ||
| }); | ||
| } | ||
| } | ||
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| function allowCommaIfMultiline(node: TSESTree.Node): void { | ||
| if (!isMultiline(node)) { | ||
| forbidComma(node); | ||
| } | ||
| } | ||
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| function forceCommaIfMultiline(node: TSESTree.Node): void { | ||
| if (isMultiline(node)) { | ||
| forceComma(node); | ||
| } else { | ||
| forbidComma(node); | ||
| } | ||
| } | ||
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| return { | ||
| ...rules, | ||
| TSEnumDeclaration: predicate[normalizedOptions.enums], | ||
| TSTypeParameterDeclaration: predicate[normalizedOptions.generics], | ||
| TSTupleType: predicate[normalizedOptions.tuples], | ||
| }; | ||
| }, | ||
| }); |
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