source: imaps-frontend/node_modules/eslint/lib/rules/arrow-body-style.js@ d565449

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Last change on this file since d565449 was d565449, checked in by stefan toskovski <stefantoska84@…>, 4 weeks ago

Update repo after prototype presentation
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1/**
2 * @fileoverview Rule to require braces in arrow function body.
3 * @author Alberto Rodríguez
4 */
5"use strict";
6
7//------------------------------------------------------------------------------
8// Requirements
9//------------------------------------------------------------------------------
10
11const astUtils = require("./utils/ast-utils");
12
13//------------------------------------------------------------------------------
14// Rule Definition
15//------------------------------------------------------------------------------
16
17/** @type {import('../shared/types').Rule} */
18module.exports = {
19 meta: {
20 type: "suggestion",
21
22 docs: {
23 description: "Require braces around arrow function bodies",
24 recommended: false,
25 url: "https://eslint.org/docs/latest/rules/arrow-body-style"
26 },
27
28 schema: {
29 anyOf: [
30 {
31 type: "array",
32 items: [
33 {
34 enum: ["always", "never"]
35 }
36 ],
37 minItems: 0,
38 maxItems: 1
39 },
40 {
41 type: "array",
42 items: [
43 {
44 enum: ["as-needed"]
45 },
46 {
47 type: "object",
48 properties: {
49 requireReturnForObjectLiteral: { type: "boolean" }
50 },
51 additionalProperties: false
52 }
53 ],
54 minItems: 0,
55 maxItems: 2
56 }
57 ]
58 },
59
60 fixable: "code",
61
62 messages: {
63 unexpectedOtherBlock: "Unexpected block statement surrounding arrow body.",
64 unexpectedEmptyBlock: "Unexpected block statement surrounding arrow body; put a value of `undefined` immediately after the `=>`.",
65 unexpectedObjectBlock: "Unexpected block statement surrounding arrow body; parenthesize the returned value and move it immediately after the `=>`.",
66 unexpectedSingleBlock: "Unexpected block statement surrounding arrow body; move the returned value immediately after the `=>`.",
67 expectedBlock: "Expected block statement surrounding arrow body."
68 }
69 },
70
71 create(context) {
72 const options = context.options;
73 const always = options[0] === "always";
74 const asNeeded = !options[0] || options[0] === "as-needed";
75 const never = options[0] === "never";
76 const requireReturnForObjectLiteral = options[1] && options[1].requireReturnForObjectLiteral;
77 const sourceCode = context.sourceCode;
78 let funcInfo = null;
79
80 /**
81 * Checks whether the given node has ASI problem or not.
82 * @param {Token} token The token to check.
83 * @returns {boolean} `true` if it changes semantics if `;` or `}` followed by the token are removed.
84 */
85 function hasASIProblem(token) {
86 return token && token.type === "Punctuator" && /^[([/`+-]/u.test(token.value);
87 }
88
89 /**
90 * Gets the closing parenthesis by the given node.
91 * @param {ASTNode} node first node after an opening parenthesis.
92 * @returns {Token} The found closing parenthesis token.
93 */
94 function findClosingParen(node) {
95 let nodeToCheck = node;
96
97 while (!astUtils.isParenthesised(sourceCode, nodeToCheck)) {
98 nodeToCheck = nodeToCheck.parent;
99 }
100 return sourceCode.getTokenAfter(nodeToCheck);
101 }
102
103 /**
104 * Check whether the node is inside of a for loop's init
105 * @param {ASTNode} node node is inside for loop
106 * @returns {boolean} `true` if the node is inside of a for loop, else `false`
107 */
108 function isInsideForLoopInitializer(node) {
109 if (node && node.parent) {
110 if (node.parent.type === "ForStatement" && node.parent.init === node) {
111 return true;
112 }
113 return isInsideForLoopInitializer(node.parent);
114 }
115 return false;
116 }
117
118 /**
119 * Determines whether a arrow function body needs braces
120 * @param {ASTNode} node The arrow function node.
121 * @returns {void}
122 */
123 function validate(node) {
124 const arrowBody = node.body;
125
126 if (arrowBody.type === "BlockStatement") {
127 const blockBody = arrowBody.body;
128
129 if (blockBody.length !== 1 && !never) {
130 return;
131 }
132
133 if (asNeeded && requireReturnForObjectLiteral && blockBody[0].type === "ReturnStatement" &&
134 blockBody[0].argument && blockBody[0].argument.type === "ObjectExpression") {
135 return;
136 }
137
138 if (never || asNeeded && blockBody[0].type === "ReturnStatement") {
139 let messageId;
140
141 if (blockBody.length === 0) {
142 messageId = "unexpectedEmptyBlock";
143 } else if (blockBody.length > 1) {
144 messageId = "unexpectedOtherBlock";
145 } else if (blockBody[0].argument === null) {
146 messageId = "unexpectedSingleBlock";
147 } else if (astUtils.isOpeningBraceToken(sourceCode.getFirstToken(blockBody[0], { skip: 1 }))) {
148 messageId = "unexpectedObjectBlock";
149 } else {
150 messageId = "unexpectedSingleBlock";
151 }
152
153 context.report({
154 node,
155 loc: arrowBody.loc,
156 messageId,
157 fix(fixer) {
158 const fixes = [];
159
160 if (blockBody.length !== 1 ||
161 blockBody[0].type !== "ReturnStatement" ||
162 !blockBody[0].argument ||
163 hasASIProblem(sourceCode.getTokenAfter(arrowBody))
164 ) {
165 return fixes;
166 }
167
168 const openingBrace = sourceCode.getFirstToken(arrowBody);
169 const closingBrace = sourceCode.getLastToken(arrowBody);
170 const firstValueToken = sourceCode.getFirstToken(blockBody[0], 1);
171 const lastValueToken = sourceCode.getLastToken(blockBody[0]);
172 const commentsExist =
173 sourceCode.commentsExistBetween(openingBrace, firstValueToken) ||
174 sourceCode.commentsExistBetween(lastValueToken, closingBrace);
175
176 /*
177 * Remove tokens around the return value.
178 * If comments don't exist, remove extra spaces as well.
179 */
180 if (commentsExist) {
181 fixes.push(
182 fixer.remove(openingBrace),
183 fixer.remove(closingBrace),
184 fixer.remove(sourceCode.getTokenAfter(openingBrace)) // return keyword
185 );
186 } else {
187 fixes.push(
188 fixer.removeRange([openingBrace.range[0], firstValueToken.range[0]]),
189 fixer.removeRange([lastValueToken.range[1], closingBrace.range[1]])
190 );
191 }
192
193 /*
194 * If the first token of the return value is `{` or the return value is a sequence expression,
195 * enclose the return value by parentheses to avoid syntax error.
196 */
197 if (astUtils.isOpeningBraceToken(firstValueToken) || blockBody[0].argument.type === "SequenceExpression" || (funcInfo.hasInOperator && isInsideForLoopInitializer(node))) {
198 if (!astUtils.isParenthesised(sourceCode, blockBody[0].argument)) {
199 fixes.push(
200 fixer.insertTextBefore(firstValueToken, "("),
201 fixer.insertTextAfter(lastValueToken, ")")
202 );
203 }
204 }
205
206 /*
207 * If the last token of the return statement is semicolon, remove it.
208 * Non-block arrow body is an expression, not a statement.
209 */
210 if (astUtils.isSemicolonToken(lastValueToken)) {
211 fixes.push(fixer.remove(lastValueToken));
212 }
213
214 return fixes;
215 }
216 });
217 }
218 } else {
219 if (always || (asNeeded && requireReturnForObjectLiteral && arrowBody.type === "ObjectExpression")) {
220 context.report({
221 node,
222 loc: arrowBody.loc,
223 messageId: "expectedBlock",
224 fix(fixer) {
225 const fixes = [];
226 const arrowToken = sourceCode.getTokenBefore(arrowBody, astUtils.isArrowToken);
227 const [firstTokenAfterArrow, secondTokenAfterArrow] = sourceCode.getTokensAfter(arrowToken, { count: 2 });
228 const lastToken = sourceCode.getLastToken(node);
229
230 let parenthesisedObjectLiteral = null;
231
232 if (
233 astUtils.isOpeningParenToken(firstTokenAfterArrow) &&
234 astUtils.isOpeningBraceToken(secondTokenAfterArrow)
235 ) {
236 const braceNode = sourceCode.getNodeByRangeIndex(secondTokenAfterArrow.range[0]);
237
238 if (braceNode.type === "ObjectExpression") {
239 parenthesisedObjectLiteral = braceNode;
240 }
241 }
242
243 // If the value is object literal, remove parentheses which were forced by syntax.
244 if (parenthesisedObjectLiteral) {
245 const openingParenToken = firstTokenAfterArrow;
246 const openingBraceToken = secondTokenAfterArrow;
247
248 if (astUtils.isTokenOnSameLine(openingParenToken, openingBraceToken)) {
249 fixes.push(fixer.replaceText(openingParenToken, "{return "));
250 } else {
251
252 // Avoid ASI
253 fixes.push(
254 fixer.replaceText(openingParenToken, "{"),
255 fixer.insertTextBefore(openingBraceToken, "return ")
256 );
257 }
258
259 // Closing paren for the object doesn't have to be lastToken, e.g.: () => ({}).foo()
260 fixes.push(fixer.remove(findClosingParen(parenthesisedObjectLiteral)));
261 fixes.push(fixer.insertTextAfter(lastToken, "}"));
262
263 } else {
264 fixes.push(fixer.insertTextBefore(firstTokenAfterArrow, "{return "));
265 fixes.push(fixer.insertTextAfter(lastToken, "}"));
266 }
267
268 return fixes;
269 }
270 });
271 }
272 }
273 }
274
275 return {
276 "BinaryExpression[operator='in']"() {
277 let info = funcInfo;
278
279 while (info) {
280 info.hasInOperator = true;
281 info = info.upper;
282 }
283 },
284 ArrowFunctionExpression() {
285 funcInfo = {
286 upper: funcInfo,
287 hasInOperator: false
288 };
289 },
290 "ArrowFunctionExpression:exit"(node) {
291 validate(node);
292 funcInfo = funcInfo.upper;
293 }
294 };
295 }
296};
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