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app_vue/node_modules/eslint/lib/rules/prefer-destructuring.js

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+/**
+ * @fileoverview Prefer destructuring from arrays and objects
+ * @author Alex LaFroscia
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const PRECEDENCE_OF_ASSIGNMENT_EXPR = astUtils.getPrecedence({ type: "AssignmentExpression" });
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "require destructuring from arrays and/or objects",
+            category: "ECMAScript 6",
+            recommended: false,
+            url: "https://eslint.org/docs/rules/prefer-destructuring"
+        },
+
+        fixable: "code",
+
+        schema: [
+            {
+
+                /*
+                 * old support {array: Boolean, object: Boolean}
+                 * new support {VariableDeclarator: {}, AssignmentExpression: {}}
+                 */
+                oneOf: [
+                    {
+                        type: "object",
+                        properties: {
+                            VariableDeclarator: {
+                                type: "object",
+                                properties: {
+                                    array: {
+                                        type: "boolean"
+                                    },
+                                    object: {
+                                        type: "boolean"
+                                    }
+                                },
+                                additionalProperties: false
+                            },
+                            AssignmentExpression: {
+                                type: "object",
+                                properties: {
+                                    array: {
+                                        type: "boolean"
+                                    },
+                                    object: {
+                                        type: "boolean"
+                                    }
+                                },
+                                additionalProperties: false
+                            }
+                        },
+                        additionalProperties: false
+                    },
+                    {
+                        type: "object",
+                        properties: {
+                            array: {
+                                type: "boolean"
+                            },
+                            object: {
+                                type: "boolean"
+                            }
+                        },
+                        additionalProperties: false
+                    }
+                ]
+            },
+            {
+                type: "object",
+                properties: {
+                    enforceForRenamedProperties: {
+                        type: "boolean"
+                    }
+                },
+                additionalProperties: false
+            }
+        ],
+
+        messages: {
+            preferDestructuring: "Use {{type}} destructuring."
+        }
+    },
+    create(context) {
+
+        const enabledTypes = context.options[0];
+        const enforceForRenamedProperties = context.options[1] && context.options[1].enforceForRenamedProperties;
+        let normalizedOptions = {
+            VariableDeclarator: { array: true, object: true },
+            AssignmentExpression: { array: true, object: true }
+        };
+
+        if (enabledTypes) {
+            normalizedOptions = typeof enabledTypes.array !== "undefined" || typeof enabledTypes.object !== "undefined"
+                ? { VariableDeclarator: enabledTypes, AssignmentExpression: enabledTypes }
+                : enabledTypes;
+        }
+
+        //--------------------------------------------------------------------------
+        // Helpers
+        //--------------------------------------------------------------------------
+
+        // eslint-disable-next-line jsdoc/require-description
+        /**
+         * @param {string} nodeType "AssignmentExpression" or "VariableDeclarator"
+         * @param {string} destructuringType "array" or "object"
+         * @returns {boolean} `true` if the destructuring type should be checked for the given node
+         */
+        function shouldCheck(nodeType, destructuringType) {
+            return normalizedOptions &&
+                normalizedOptions[nodeType] &&
+                normalizedOptions[nodeType][destructuringType];
+        }
+
+        /**
+         * Determines if the given node is accessing an array index
+         *
+         * This is used to differentiate array index access from object property
+         * access.
+         * @param {ASTNode} node the node to evaluate
+         * @returns {boolean} whether or not the node is an integer
+         */
+        function isArrayIndexAccess(node) {
+            return Number.isInteger(node.property.value);
+        }
+
+        /**
+         * Report that the given node should use destructuring
+         * @param {ASTNode} reportNode the node to report
+         * @param {string} type the type of destructuring that should have been done
+         * @param {Function|null} fix the fix function or null to pass to context.report
+         * @returns {void}
+         */
+        function report(reportNode, type, fix) {
+            context.report({
+                node: reportNode,
+                messageId: "preferDestructuring",
+                data: { type },
+                fix
+            });
+        }
+
+        /**
+         * Determines if a node should be fixed into object destructuring
+         *
+         * The fixer only fixes the simplest case of object destructuring,
+         * like: `let x = a.x`;
+         *
+         * Assignment expression is not fixed.
+         * Array destructuring is not fixed.
+         * Renamed property is not fixed.
+         * @param {ASTNode} node the node to evaluate
+         * @returns {boolean} whether or not the node should be fixed
+         */
+        function shouldFix(node) {
+            return node.type === "VariableDeclarator" &&
+                node.id.type === "Identifier" &&
+                node.init.type === "MemberExpression" &&
+                !node.init.computed &&
+                node.init.property.type === "Identifier" &&
+                node.id.name === node.init.property.name;
+        }
+
+        /**
+         * Fix a node into object destructuring.
+         * This function only handles the simplest case of object destructuring,
+         * see {@link shouldFix}.
+         * @param {SourceCodeFixer} fixer the fixer object
+         * @param {ASTNode} node the node to be fixed.
+         * @returns {Object} a fix for the node
+         */
+        function fixIntoObjectDestructuring(fixer, node) {
+            const rightNode = node.init;
+            const sourceCode = context.getSourceCode();
+
+            // Don't fix if that would remove any comments. Only comments inside `rightNode.object` can be preserved.
+            if (sourceCode.getCommentsInside(node).length > sourceCode.getCommentsInside(rightNode.object).length) {
+                return null;
+            }
+
+            let objectText = sourceCode.getText(rightNode.object);
+
+            if (astUtils.getPrecedence(rightNode.object) < PRECEDENCE_OF_ASSIGNMENT_EXPR) {
+                objectText = `(${objectText})`;
+            }
+
+            return fixer.replaceText(
+                node,
+                `{${rightNode.property.name}} = ${objectText}`
+            );
+        }
+
+        /**
+         * Check that the `prefer-destructuring` rules are followed based on the
+         * given left- and right-hand side of the assignment.
+         *
+         * Pulled out into a separate method so that VariableDeclarators and
+         * AssignmentExpressions can share the same verification logic.
+         * @param {ASTNode} leftNode the left-hand side of the assignment
+         * @param {ASTNode} rightNode the right-hand side of the assignment
+         * @param {ASTNode} reportNode the node to report the error on
+         * @returns {void}
+         */
+        function performCheck(leftNode, rightNode, reportNode) {
+            if (rightNode.type !== "MemberExpression" || rightNode.object.type === "Super") {
+                return;
+            }
+
+            if (isArrayIndexAccess(rightNode)) {
+                if (shouldCheck(reportNode.type, "array")) {
+                    report(reportNode, "array", null);
+                }
+                return;
+            }
+
+            const fix = shouldFix(reportNode)
+                ? fixer => fixIntoObjectDestructuring(fixer, reportNode)
+                : null;
+
+            if (shouldCheck(reportNode.type, "object") && enforceForRenamedProperties) {
+                report(reportNode, "object", fix);
+                return;
+            }
+
+            if (shouldCheck(reportNode.type, "object")) {
+                const property = rightNode.property;
+
+                if (
+                    (property.type === "Literal" && leftNode.name === property.value) ||
+                    (property.type === "Identifier" && leftNode.name === property.name && !rightNode.computed)
+                ) {
+                    report(reportNode, "object", fix);
+                }
+            }
+        }
+
+        /**
+         * Check if a given variable declarator is coming from an property access
+         * that should be using destructuring instead
+         * @param {ASTNode} node the variable declarator to check
+         * @returns {void}
+         */
+        function checkVariableDeclarator(node) {
+
+            // Skip if variable is declared without assignment
+            if (!node.init) {
+                return;
+            }
+
+            // We only care about member expressions past this point
+            if (node.init.type !== "MemberExpression") {
+                return;
+            }
+
+            performCheck(node.id, node.init, node);
+        }
+
+        /**
+         * Run the `prefer-destructuring` check on an AssignmentExpression
+         * @param {ASTNode} node the AssignmentExpression node
+         * @returns {void}
+         */
+        function checkAssignmentExpression(node) {
+            if (node.operator === "=") {
+                performCheck(node.left, node.right, node);
+            }
+        }
+
+        //--------------------------------------------------------------------------
+        // Public
+        //--------------------------------------------------------------------------
+
+        return {
+            VariableDeclarator: checkVariableDeclarator,
+            AssignmentExpression: checkAssignmentExpression
+        };
+    }
+};