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app_vue/node_modules/eslint/lib/rules/comma-dangle.js

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+/**
+ * @fileoverview Rule to forbid or enforce dangling commas.
+ * @author Ian Christian Myers
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const DEFAULT_OPTIONS = Object.freeze({
+    arrays: "never",
+    objects: "never",
+    imports: "never",
+    exports: "never",
+    functions: "never"
+});
+
+/**
+ * Checks whether or not a trailing comma is allowed in a given node.
+ * If the `lastItem` is `RestElement` or `RestProperty`, it disallows trailing commas.
+ * @param {ASTNode} lastItem The node of the last element in the given node.
+ * @returns {boolean} `true` if a trailing comma is allowed.
+ */
+function isTrailingCommaAllowed(lastItem) {
+    return !(
+        lastItem.type === "RestElement" ||
+        lastItem.type === "RestProperty" ||
+        lastItem.type === "ExperimentalRestProperty"
+    );
+}
+
+/**
+ * Normalize option value.
+ * @param {string|Object|undefined} optionValue The 1st option value to normalize.
+ * @param {number} ecmaVersion The normalized ECMAScript version.
+ * @returns {Object} The normalized option value.
+ */
+function normalizeOptions(optionValue, ecmaVersion) {
+    if (typeof optionValue === "string") {
+        return {
+            arrays: optionValue,
+            objects: optionValue,
+            imports: optionValue,
+            exports: optionValue,
+            functions: (!ecmaVersion || ecmaVersion < 8) ? "ignore" : optionValue
+        };
+    }
+    if (typeof optionValue === "object" && optionValue !== null) {
+        return {
+            arrays: optionValue.arrays || DEFAULT_OPTIONS.arrays,
+            objects: optionValue.objects || DEFAULT_OPTIONS.objects,
+            imports: optionValue.imports || DEFAULT_OPTIONS.imports,
+            exports: optionValue.exports || DEFAULT_OPTIONS.exports,
+            functions: optionValue.functions || DEFAULT_OPTIONS.functions
+        };
+    }
+
+    return DEFAULT_OPTIONS;
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "layout",
+
+        docs: {
+            description: "require or disallow trailing commas",
+            category: "Stylistic Issues",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/comma-dangle"
+        },
+
+        fixable: "code",
+
+        schema: {
+            definitions: {
+                value: {
+                    enum: [
+                        "always-multiline",
+                        "always",
+                        "never",
+                        "only-multiline"
+                    ]
+                },
+                valueWithIgnore: {
+                    enum: [
+                        "always-multiline",
+                        "always",
+                        "ignore",
+                        "never",
+                        "only-multiline"
+                    ]
+                }
+            },
+            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" }
+                            },
+                            additionalProperties: false
+                        }
+                    ]
+                }
+            ]
+        },
+
+        messages: {
+            unexpected: "Unexpected trailing comma.",
+            missing: "Missing trailing comma."
+        }
+    },
+
+    create(context) {
+        const options = normalizeOptions(context.options[0], context.parserOptions.ecmaVersion);
+
+        const sourceCode = context.getSourceCode();
+
+        /**
+         * Gets the last item of the given node.
+         * @param {ASTNode} node The node to get.
+         * @returns {ASTNode|null} The last node or null.
+         */
+        function getLastItem(node) {
+
+            /**
+             * Returns the last element of an array
+             * @param {any[]} array The input array
+             * @returns {any} The last element
+             */
+            function last(array) {
+                return array[array.length - 1];
+            }
+
+            switch (node.type) {
+                case "ObjectExpression":
+                case "ObjectPattern":
+                    return last(node.properties);
+                case "ArrayExpression":
+                case "ArrayPattern":
+                    return last(node.elements);
+                case "ImportDeclaration":
+                case "ExportNamedDeclaration":
+                    return last(node.specifiers);
+                case "FunctionDeclaration":
+                case "FunctionExpression":
+                case "ArrowFunctionExpression":
+                    return last(node.params);
+                case "CallExpression":
+                case "NewExpression":
+                    return last(node.arguments);
+                default:
+                    return null;
+            }
+        }
+
+        /**
+         * Gets the trailing comma token of the given node.
+         * If the trailing comma does not exist, this returns the token which is
+         * the insertion point of the trailing comma token.
+         * @param {ASTNode} node The node to get.
+         * @param {ASTNode} lastItem The last item of the node.
+         * @returns {Token} The trailing comma token or the insertion point.
+         */
+        function getTrailingToken(node, lastItem) {
+            switch (node.type) {
+                case "ObjectExpression":
+                case "ArrayExpression":
+                case "CallExpression":
+                case "NewExpression":
+                    return sourceCode.getLastToken(node, 1);
+                default: {
+                    const nextToken = sourceCode.getTokenAfter(lastItem);
+
+                    if (astUtils.isCommaToken(nextToken)) {
+                        return nextToken;
+                    }
+                    return sourceCode.getLastToken(lastItem);
+                }
+            }
+        }
+
+        /**
+         * Checks whether or not a given node is multiline.
+         * This rule handles a given node as multiline when the closing parenthesis
+         * and the last element are not on the same line.
+         * @param {ASTNode} node A node to check.
+         * @returns {boolean} `true` if the node is multiline.
+         */
+        function isMultiline(node) {
+            const lastItem = getLastItem(node);
+
+            if (!lastItem) {
+                return false;
+            }
+
+            const penultimateToken = getTrailingToken(node, lastItem);
+            const lastToken = sourceCode.getTokenAfter(penultimateToken);
+
+            return lastToken.loc.end.line !== penultimateToken.loc.end.line;
+        }
+
+        /**
+         * Reports a trailing comma if it exists.
+         * @param {ASTNode} node A node to check. Its type is one of
+         *   ObjectExpression, ObjectPattern, ArrayExpression, ArrayPattern,
+         *   ImportDeclaration, and ExportNamedDeclaration.
+         * @returns {void}
+         */
+        function forbidTrailingComma(node) {
+            const lastItem = getLastItem(node);
+
+            if (!lastItem || (node.type === "ImportDeclaration" && lastItem.type !== "ImportSpecifier")) {
+                return;
+            }
+
+            const trailingToken = getTrailingToken(node, lastItem);
+
+            if (astUtils.isCommaToken(trailingToken)) {
+                context.report({
+                    node: lastItem,
+                    loc: trailingToken.loc,
+                    messageId: "unexpected",
+                    fix(fixer) {
+                        return fixer.remove(trailingToken);
+                    }
+                });
+            }
+        }
+
+        /**
+         * Reports the last element of a given node if it does not have a trailing
+         * comma.
+         *
+         * If a given node is `ArrayPattern` which has `RestElement`, the trailing
+         * comma is disallowed, so report if it exists.
+         * @param {ASTNode} node A node to check. Its type is one of
+         *   ObjectExpression, ObjectPattern, ArrayExpression, ArrayPattern,
+         *   ImportDeclaration, and ExportNamedDeclaration.
+         * @returns {void}
+         */
+        function forceTrailingComma(node) {
+            const lastItem = getLastItem(node);
+
+            if (!lastItem || (node.type === "ImportDeclaration" && lastItem.type !== "ImportSpecifier")) {
+                return;
+            }
+            if (!isTrailingCommaAllowed(lastItem)) {
+                forbidTrailingComma(node);
+                return;
+            }
+
+            const trailingToken = getTrailingToken(node, lastItem);
+
+            if (trailingToken.value !== ",") {
+                context.report({
+                    node: lastItem,
+                    loc: {
+                        start: trailingToken.loc.end,
+                        end: astUtils.getNextLocation(sourceCode, trailingToken.loc.end)
+                    },
+                    messageId: "missing",
+                    fix(fixer) {
+                        return fixer.insertTextAfter(trailingToken, ",");
+                    }
+                });
+            }
+        }
+
+        /**
+         * If a given node is multiline, reports the last element of a given node
+         * when it does not have a trailing comma.
+         * Otherwise, reports a trailing comma if it exists.
+         * @param {ASTNode} node A node to check. Its type is one of
+         *   ObjectExpression, ObjectPattern, ArrayExpression, ArrayPattern,
+         *   ImportDeclaration, and ExportNamedDeclaration.
+         * @returns {void}
+         */
+        function forceTrailingCommaIfMultiline(node) {
+            if (isMultiline(node)) {
+                forceTrailingComma(node);
+            } else {
+                forbidTrailingComma(node);
+            }
+        }
+
+        /**
+         * Only if a given node is not multiline, reports the last element of a given node
+         * when it does not have a trailing comma.
+         * Otherwise, reports a trailing comma if it exists.
+         * @param {ASTNode} node A node to check. Its type is one of
+         *   ObjectExpression, ObjectPattern, ArrayExpression, ArrayPattern,
+         *   ImportDeclaration, and ExportNamedDeclaration.
+         * @returns {void}
+         */
+        function allowTrailingCommaIfMultiline(node) {
+            if (!isMultiline(node)) {
+                forbidTrailingComma(node);
+            }
+        }
+
+        const predicate = {
+            always: forceTrailingComma,
+            "always-multiline": forceTrailingCommaIfMultiline,
+            "only-multiline": allowTrailingCommaIfMultiline,
+            never: forbidTrailingComma,
+            ignore: () => {}
+        };
+
+        return {
+            ObjectExpression: predicate[options.objects],
+            ObjectPattern: predicate[options.objects],
+
+            ArrayExpression: predicate[options.arrays],
+            ArrayPattern: predicate[options.arrays],
+
+            ImportDeclaration: predicate[options.imports],
+
+            ExportNamedDeclaration: predicate[options.exports],
+
+            FunctionDeclaration: predicate[options.functions],
+            FunctionExpression: predicate[options.functions],
+            ArrowFunctionExpression: predicate[options.functions],
+            CallExpression: predicate[options.functions],
+            NewExpression: predicate[options.functions]
+        };
+    }
+};