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eb39fafa DC |
1 | /** |
2 | * @fileoverview Rule to flag missing semicolons. | |
3 | * @author Nicholas C. Zakas | |
4 | */ | |
5 | "use strict"; | |
6 | ||
7 | //------------------------------------------------------------------------------ | |
8 | // Requirements | |
9 | //------------------------------------------------------------------------------ | |
10 | ||
11 | const FixTracker = require("./utils/fix-tracker"); | |
12 | const astUtils = require("./utils/ast-utils"); | |
13 | ||
14 | //------------------------------------------------------------------------------ | |
15 | // Rule Definition | |
16 | //------------------------------------------------------------------------------ | |
17 | ||
34eeec05 | 18 | /** @type {import('../shared/types').Rule} */ |
eb39fafa DC |
19 | module.exports = { |
20 | meta: { | |
21 | type: "layout", | |
22 | ||
23 | docs: { | |
24 | description: "require or disallow semicolons instead of ASI", | |
eb39fafa DC |
25 | recommended: false, |
26 | url: "https://eslint.org/docs/rules/semi" | |
27 | }, | |
28 | ||
29 | fixable: "code", | |
30 | ||
31 | schema: { | |
32 | anyOf: [ | |
33 | { | |
34 | type: "array", | |
35 | items: [ | |
36 | { | |
37 | enum: ["never"] | |
38 | }, | |
39 | { | |
40 | type: "object", | |
41 | properties: { | |
42 | beforeStatementContinuationChars: { | |
43 | enum: ["always", "any", "never"] | |
44 | } | |
45 | }, | |
46 | additionalProperties: false | |
47 | } | |
48 | ], | |
49 | minItems: 0, | |
50 | maxItems: 2 | |
51 | }, | |
52 | { | |
53 | type: "array", | |
54 | items: [ | |
55 | { | |
56 | enum: ["always"] | |
57 | }, | |
58 | { | |
59 | type: "object", | |
60 | properties: { | |
61 | omitLastInOneLineBlock: { type: "boolean" } | |
62 | }, | |
63 | additionalProperties: false | |
64 | } | |
65 | ], | |
66 | minItems: 0, | |
67 | maxItems: 2 | |
68 | } | |
69 | ] | |
70 | }, | |
71 | ||
72 | messages: { | |
73 | missingSemi: "Missing semicolon.", | |
74 | extraSemi: "Extra semicolon." | |
75 | } | |
76 | }, | |
77 | ||
78 | create(context) { | |
79 | ||
80 | const OPT_OUT_PATTERN = /^[-[(/+`]/u; // One of [(/+-` | |
609c276f TL |
81 | const unsafeClassFieldNames = new Set(["get", "set", "static"]); |
82 | const unsafeClassFieldFollowers = new Set(["*", "in", "instanceof"]); | |
eb39fafa DC |
83 | const options = context.options[1]; |
84 | const never = context.options[0] === "never"; | |
85 | const exceptOneLine = Boolean(options && options.omitLastInOneLineBlock); | |
86 | const beforeStatementContinuationChars = options && options.beforeStatementContinuationChars || "any"; | |
87 | const sourceCode = context.getSourceCode(); | |
88 | ||
89 | //-------------------------------------------------------------------------- | |
90 | // Helpers | |
91 | //-------------------------------------------------------------------------- | |
92 | ||
93 | /** | |
94 | * Reports a semicolon error with appropriate location and message. | |
95 | * @param {ASTNode} node The node with an extra or missing semicolon. | |
96 | * @param {boolean} missing True if the semicolon is missing. | |
97 | * @returns {void} | |
98 | */ | |
99 | function report(node, missing) { | |
100 | const lastToken = sourceCode.getLastToken(node); | |
101 | let messageId, | |
102 | fix, | |
103 | loc; | |
104 | ||
105 | if (!missing) { | |
106 | messageId = "missingSemi"; | |
107 | loc = { | |
108 | start: lastToken.loc.end, | |
109 | end: astUtils.getNextLocation(sourceCode, lastToken.loc.end) | |
110 | }; | |
111 | fix = function(fixer) { | |
112 | return fixer.insertTextAfter(lastToken, ";"); | |
113 | }; | |
114 | } else { | |
115 | messageId = "extraSemi"; | |
116 | loc = lastToken.loc; | |
117 | fix = function(fixer) { | |
118 | ||
119 | /* | |
120 | * Expand the replacement range to include the surrounding | |
121 | * tokens to avoid conflicting with no-extra-semi. | |
122 | * https://github.com/eslint/eslint/issues/7928 | |
123 | */ | |
124 | return new FixTracker(fixer, sourceCode) | |
125 | .retainSurroundingTokens(lastToken) | |
126 | .remove(lastToken); | |
127 | }; | |
128 | } | |
129 | ||
130 | context.report({ | |
131 | node, | |
132 | loc, | |
133 | messageId, | |
134 | fix | |
135 | }); | |
136 | ||
137 | } | |
138 | ||
139 | /** | |
140 | * Check whether a given semicolon token is redundant. | |
141 | * @param {Token} semiToken A semicolon token to check. | |
142 | * @returns {boolean} `true` if the next token is `;` or `}`. | |
143 | */ | |
144 | function isRedundantSemi(semiToken) { | |
145 | const nextToken = sourceCode.getTokenAfter(semiToken); | |
146 | ||
147 | return ( | |
148 | !nextToken || | |
149 | astUtils.isClosingBraceToken(nextToken) || | |
150 | astUtils.isSemicolonToken(nextToken) | |
151 | ); | |
152 | } | |
153 | ||
154 | /** | |
155 | * Check whether a given token is the closing brace of an arrow function. | |
156 | * @param {Token} lastToken A token to check. | |
157 | * @returns {boolean} `true` if the token is the closing brace of an arrow function. | |
158 | */ | |
159 | function isEndOfArrowBlock(lastToken) { | |
160 | if (!astUtils.isClosingBraceToken(lastToken)) { | |
161 | return false; | |
162 | } | |
163 | const node = sourceCode.getNodeByRangeIndex(lastToken.range[0]); | |
164 | ||
165 | return ( | |
166 | node.type === "BlockStatement" && | |
167 | node.parent.type === "ArrowFunctionExpression" | |
168 | ); | |
169 | } | |
170 | ||
609c276f TL |
171 | /** |
172 | * Checks if a given PropertyDefinition node followed by a semicolon | |
173 | * can safely remove that semicolon. It is not to safe to remove if | |
174 | * the class field name is "get", "set", or "static", or if | |
175 | * followed by a generator method. | |
176 | * @param {ASTNode} node The node to check. | |
177 | * @returns {boolean} `true` if the node cannot have the semicolon | |
178 | * removed. | |
179 | */ | |
180 | function maybeClassFieldAsiHazard(node) { | |
181 | ||
182 | if (node.type !== "PropertyDefinition") { | |
183 | return false; | |
184 | } | |
185 | ||
186 | /* | |
187 | * Computed property names and non-identifiers are always safe | |
188 | * as they can be distinguished from keywords easily. | |
189 | */ | |
190 | const needsNameCheck = !node.computed && node.key.type === "Identifier"; | |
191 | ||
192 | /* | |
193 | * Certain names are problematic unless they also have a | |
194 | * a way to distinguish between keywords and property | |
195 | * names. | |
196 | */ | |
197 | if (needsNameCheck && unsafeClassFieldNames.has(node.key.name)) { | |
198 | ||
199 | /* | |
200 | * Special case: If the field name is `static`, | |
201 | * it is only valid if the field is marked as static, | |
202 | * so "static static" is okay but "static" is not. | |
203 | */ | |
204 | const isStaticStatic = node.static && node.key.name === "static"; | |
205 | ||
206 | /* | |
207 | * For other unsafe names, we only care if there is no | |
208 | * initializer. No initializer = hazard. | |
209 | */ | |
210 | if (!isStaticStatic && !node.value) { | |
211 | return true; | |
212 | } | |
213 | } | |
214 | ||
215 | const followingToken = sourceCode.getTokenAfter(node); | |
216 | ||
217 | return unsafeClassFieldFollowers.has(followingToken.value); | |
218 | } | |
219 | ||
eb39fafa DC |
220 | /** |
221 | * Check whether a given node is on the same line with the next token. | |
222 | * @param {Node} node A statement node to check. | |
223 | * @returns {boolean} `true` if the node is on the same line with the next token. | |
224 | */ | |
225 | function isOnSameLineWithNextToken(node) { | |
226 | const prevToken = sourceCode.getLastToken(node, 1); | |
227 | const nextToken = sourceCode.getTokenAfter(node); | |
228 | ||
229 | return !!nextToken && astUtils.isTokenOnSameLine(prevToken, nextToken); | |
230 | } | |
231 | ||
232 | /** | |
233 | * Check whether a given node can connect the next line if the next line is unreliable. | |
234 | * @param {Node} node A statement node to check. | |
235 | * @returns {boolean} `true` if the node can connect the next line. | |
236 | */ | |
237 | function maybeAsiHazardAfter(node) { | |
238 | const t = node.type; | |
239 | ||
240 | if (t === "DoWhileStatement" || | |
241 | t === "BreakStatement" || | |
242 | t === "ContinueStatement" || | |
243 | t === "DebuggerStatement" || | |
244 | t === "ImportDeclaration" || | |
245 | t === "ExportAllDeclaration" | |
246 | ) { | |
247 | return false; | |
248 | } | |
249 | if (t === "ReturnStatement") { | |
250 | return Boolean(node.argument); | |
251 | } | |
252 | if (t === "ExportNamedDeclaration") { | |
253 | return Boolean(node.declaration); | |
254 | } | |
255 | if (isEndOfArrowBlock(sourceCode.getLastToken(node, 1))) { | |
256 | return false; | |
257 | } | |
258 | ||
259 | return true; | |
260 | } | |
261 | ||
262 | /** | |
263 | * Check whether a given token can connect the previous statement. | |
264 | * @param {Token} token A token to check. | |
265 | * @returns {boolean} `true` if the token is one of `[`, `(`, `/`, `+`, `-`, ```, `++`, and `--`. | |
266 | */ | |
267 | function maybeAsiHazardBefore(token) { | |
268 | return ( | |
269 | Boolean(token) && | |
270 | OPT_OUT_PATTERN.test(token.value) && | |
271 | token.value !== "++" && | |
272 | token.value !== "--" | |
273 | ); | |
274 | } | |
275 | ||
276 | /** | |
277 | * Check if the semicolon of a given node is unnecessary, only true if: | |
278 | * - next token is a valid statement divider (`;` or `}`). | |
279 | * - next token is on a new line and the node is not connectable to the new line. | |
280 | * @param {Node} node A statement node to check. | |
281 | * @returns {boolean} whether the semicolon is unnecessary. | |
282 | */ | |
283 | function canRemoveSemicolon(node) { | |
284 | if (isRedundantSemi(sourceCode.getLastToken(node))) { | |
285 | return true; // `;;` or `;}` | |
286 | } | |
609c276f TL |
287 | if (maybeClassFieldAsiHazard(node)) { |
288 | return false; | |
289 | } | |
eb39fafa DC |
290 | if (isOnSameLineWithNextToken(node)) { |
291 | return false; // One liner. | |
292 | } | |
609c276f TL |
293 | |
294 | // continuation characters should not apply to class fields | |
295 | if ( | |
296 | node.type !== "PropertyDefinition" && | |
297 | beforeStatementContinuationChars === "never" && | |
298 | !maybeAsiHazardAfter(node) | |
299 | ) { | |
eb39fafa DC |
300 | return true; // ASI works. This statement doesn't connect to the next. |
301 | } | |
302 | if (!maybeAsiHazardBefore(sourceCode.getTokenAfter(node))) { | |
303 | return true; // ASI works. The next token doesn't connect to this statement. | |
304 | } | |
305 | ||
306 | return false; | |
307 | } | |
308 | ||
309 | /** | |
609c276f TL |
310 | * Checks a node to see if it's the last item in a one-liner block. |
311 | * Block is any `BlockStatement` or `StaticBlock` node. Block is a one-liner if its | |
312 | * braces (and consequently everything between them) are on the same line. | |
eb39fafa | 313 | * @param {ASTNode} node The node to check. |
609c276f | 314 | * @returns {boolean} whether the node is the last item in a one-liner block. |
eb39fafa | 315 | */ |
609c276f | 316 | function isLastInOneLinerBlock(node) { |
eb39fafa DC |
317 | const parent = node.parent; |
318 | const nextToken = sourceCode.getTokenAfter(node); | |
319 | ||
320 | if (!nextToken || nextToken.value !== "}") { | |
321 | return false; | |
322 | } | |
609c276f TL |
323 | |
324 | if (parent.type === "BlockStatement") { | |
325 | return parent.loc.start.line === parent.loc.end.line; | |
326 | } | |
327 | ||
328 | if (parent.type === "StaticBlock") { | |
329 | const openingBrace = sourceCode.getFirstToken(parent, { skip: 1 }); // skip the `static` token | |
330 | ||
331 | return openingBrace.loc.start.line === parent.loc.end.line; | |
332 | } | |
333 | ||
334 | return false; | |
eb39fafa DC |
335 | } |
336 | ||
337 | /** | |
338 | * Checks a node to see if it's followed by a semicolon. | |
339 | * @param {ASTNode} node The node to check. | |
340 | * @returns {void} | |
341 | */ | |
342 | function checkForSemicolon(node) { | |
343 | const isSemi = astUtils.isSemicolonToken(sourceCode.getLastToken(node)); | |
344 | ||
345 | if (never) { | |
346 | if (isSemi && canRemoveSemicolon(node)) { | |
347 | report(node, true); | |
609c276f TL |
348 | } else if ( |
349 | !isSemi && beforeStatementContinuationChars === "always" && | |
350 | node.type !== "PropertyDefinition" && | |
351 | maybeAsiHazardBefore(sourceCode.getTokenAfter(node)) | |
352 | ) { | |
eb39fafa DC |
353 | report(node); |
354 | } | |
355 | } else { | |
609c276f | 356 | const oneLinerBlock = (exceptOneLine && isLastInOneLinerBlock(node)); |
eb39fafa DC |
357 | |
358 | if (isSemi && oneLinerBlock) { | |
359 | report(node, true); | |
360 | } else if (!isSemi && !oneLinerBlock) { | |
361 | report(node); | |
362 | } | |
363 | } | |
364 | } | |
365 | ||
366 | /** | |
367 | * Checks to see if there's a semicolon after a variable declaration. | |
368 | * @param {ASTNode} node The node to check. | |
369 | * @returns {void} | |
370 | */ | |
371 | function checkForSemicolonForVariableDeclaration(node) { | |
372 | const parent = node.parent; | |
373 | ||
374 | if ((parent.type !== "ForStatement" || parent.init !== node) && | |
375 | (!/^For(?:In|Of)Statement/u.test(parent.type) || parent.left !== node) | |
376 | ) { | |
377 | checkForSemicolon(node); | |
378 | } | |
379 | } | |
380 | ||
381 | //-------------------------------------------------------------------------- | |
382 | // Public API | |
383 | //-------------------------------------------------------------------------- | |
384 | ||
385 | return { | |
386 | VariableDeclaration: checkForSemicolonForVariableDeclaration, | |
387 | ExpressionStatement: checkForSemicolon, | |
388 | ReturnStatement: checkForSemicolon, | |
389 | ThrowStatement: checkForSemicolon, | |
390 | DoWhileStatement: checkForSemicolon, | |
391 | DebuggerStatement: checkForSemicolon, | |
392 | BreakStatement: checkForSemicolon, | |
393 | ContinueStatement: checkForSemicolon, | |
394 | ImportDeclaration: checkForSemicolon, | |
395 | ExportAllDeclaration: checkForSemicolon, | |
396 | ExportNamedDeclaration(node) { | |
397 | if (!node.declaration) { | |
398 | checkForSemicolon(node); | |
399 | } | |
400 | }, | |
401 | ExportDefaultDeclaration(node) { | |
402 | if (!/(?:Class|Function)Declaration/u.test(node.declaration.type)) { | |
403 | checkForSemicolon(node); | |
404 | } | |
609c276f TL |
405 | }, |
406 | PropertyDefinition: checkForSemicolon | |
eb39fafa DC |
407 | }; |
408 | ||
409 | } | |
410 | }; |