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app_vue/node_modules/eslint/lib/rules/arrow-parens.js

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+/**
+ * @fileoverview Rule to require parens in arrow function arguments.
+ * @author Jxck
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Determines if the given arrow function has block body.
+ * @param {ASTNode} node `ArrowFunctionExpression` node.
+ * @returns {boolean} `true` if the function has block body.
+ */
+function hasBlockBody(node) {
+    return node.body.type === "BlockStatement";
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "layout",
+
+        docs: {
+            description: "require parentheses around arrow function arguments",
+            category: "ECMAScript 6",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/arrow-parens"
+        },
+
+        fixable: "code",
+
+        schema: [
+            {
+                enum: ["always", "as-needed"]
+            },
+            {
+                type: "object",
+                properties: {
+                    requireForBlockBody: {
+                        type: "boolean",
+                        default: false
+                    }
+                },
+                additionalProperties: false
+            }
+        ],
+
+        messages: {
+            unexpectedParens: "Unexpected parentheses around single function argument.",
+            expectedParens: "Expected parentheses around arrow function argument.",
+
+            unexpectedParensInline: "Unexpected parentheses around single function argument having a body with no curly braces.",
+            expectedParensBlock: "Expected parentheses around arrow function argument having a body with curly braces."
+        }
+    },
+
+    create(context) {
+        const asNeeded = context.options[0] === "as-needed";
+        const requireForBlockBody = asNeeded && context.options[1] && context.options[1].requireForBlockBody === true;
+
+        const sourceCode = context.getSourceCode();
+
+        /**
+         * Finds opening paren of parameters for the given arrow function, if it exists.
+         * It is assumed that the given arrow function has exactly one parameter.
+         * @param {ASTNode} node `ArrowFunctionExpression` node.
+         * @returns {Token|null} the opening paren, or `null` if the given arrow function doesn't have parens of parameters.
+         */
+        function findOpeningParenOfParams(node) {
+            const tokenBeforeParams = sourceCode.getTokenBefore(node.params[0]);
+
+            if (
+                tokenBeforeParams &&
+                astUtils.isOpeningParenToken(tokenBeforeParams) &&
+                node.range[0] <= tokenBeforeParams.range[0]
+            ) {
+                return tokenBeforeParams;
+            }
+
+            return null;
+        }
+
+        /**
+         * Finds closing paren of parameters for the given arrow function.
+         * It is assumed that the given arrow function has parens of parameters and that it has exactly one parameter.
+         * @param {ASTNode} node `ArrowFunctionExpression` node.
+         * @returns {Token} the closing paren of parameters.
+         */
+        function getClosingParenOfParams(node) {
+            return sourceCode.getTokenAfter(node.params[0], astUtils.isClosingParenToken);
+        }
+
+        /**
+         * Determines whether the given arrow function has comments inside parens of parameters.
+         * It is assumed that the given arrow function has parens of parameters.
+         * @param {ASTNode} node `ArrowFunctionExpression` node.
+         * @param {Token} openingParen Opening paren of parameters.
+         * @returns {boolean} `true` if the function has at least one comment inside of parens of parameters.
+         */
+        function hasCommentsInParensOfParams(node, openingParen) {
+            return sourceCode.commentsExistBetween(openingParen, getClosingParenOfParams(node));
+        }
+
+        /**
+         * Determines whether the given arrow function has unexpected tokens before opening paren of parameters,
+         * in which case it will be assumed that the existing parens of parameters are necessary.
+         * Only tokens within the range of the arrow function (tokens that are part of the arrow function) are taken into account.
+         * Example: <T>(a) => b
+         * @param {ASTNode} node `ArrowFunctionExpression` node.
+         * @param {Token} openingParen Opening paren of parameters.
+         * @returns {boolean} `true` if the function has at least one unexpected token.
+         */
+        function hasUnexpectedTokensBeforeOpeningParen(node, openingParen) {
+            const expectedCount = node.async ? 1 : 0;
+
+            return sourceCode.getFirstToken(node, { skip: expectedCount }) !== openingParen;
+        }
+
+        return {
+            "ArrowFunctionExpression[params.length=1]"(node) {
+                const shouldHaveParens = !asNeeded || requireForBlockBody && hasBlockBody(node);
+                const openingParen = findOpeningParenOfParams(node);
+                const hasParens = openingParen !== null;
+                const [param] = node.params;
+
+                if (shouldHaveParens && !hasParens) {
+                    context.report({
+                        node,
+                        messageId: requireForBlockBody ? "expectedParensBlock" : "expectedParens",
+                        loc: param.loc,
+                        *fix(fixer) {
+                            yield fixer.insertTextBefore(param, "(");
+                            yield fixer.insertTextAfter(param, ")");
+                        }
+                    });
+                }
+
+                if (
+                    !shouldHaveParens &&
+                    hasParens &&
+                    param.type === "Identifier" &&
+                    !param.typeAnnotation &&
+                    !node.returnType &&
+                    !hasCommentsInParensOfParams(node, openingParen) &&
+                    !hasUnexpectedTokensBeforeOpeningParen(node, openingParen)
+                ) {
+                    context.report({
+                        node,
+                        messageId: requireForBlockBody ? "unexpectedParensInline" : "unexpectedParens",
+                        loc: param.loc,
+                        *fix(fixer) {
+                            const tokenBeforeOpeningParen = sourceCode.getTokenBefore(openingParen);
+                            const closingParen = getClosingParenOfParams(node);
+
+                            if (
+                                tokenBeforeOpeningParen &&
+                                tokenBeforeOpeningParen.range[1] === openingParen.range[0] &&
+                                !astUtils.canTokensBeAdjacent(tokenBeforeOpeningParen, sourceCode.getFirstToken(param))
+                            ) {
+                                yield fixer.insertTextBefore(openingParen, " ");
+                            }
+
+                            // remove parens, whitespace inside parens, and possible trailing comma
+                            yield fixer.removeRange([openingParen.range[0], param.range[0]]);
+                            yield fixer.removeRange([param.range[1], closingParen.range[1]]);
+                        }
+                    });
+                }
+            }
+        };
+    }
+};