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qwen/nodejs/node_modules/eslint/lib/rules/one-var.js

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+/**
+ * @fileoverview A rule to control the use of single variable declarations.
+ * @author Ian Christian Myers
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Determines whether the given node is in a statement list.
+ * @param {ASTNode} node node to check
+ * @returns {boolean} `true` if the given node is in a statement list
+ */
+function isInStatementList(node) {
+    return astUtils.STATEMENT_LIST_PARENTS.has(node.parent.type);
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "Enforce variables to be declared either together or separately in functions",
+            recommended: false,
+            url: "https://eslint.org/docs/latest/rules/one-var"
+        },
+
+        fixable: "code",
+
+        schema: [
+            {
+                oneOf: [
+                    {
+                        enum: ["always", "never", "consecutive"]
+                    },
+                    {
+                        type: "object",
+                        properties: {
+                            separateRequires: {
+                                type: "boolean"
+                            },
+                            var: {
+                                enum: ["always", "never", "consecutive"]
+                            },
+                            let: {
+                                enum: ["always", "never", "consecutive"]
+                            },
+                            const: {
+                                enum: ["always", "never", "consecutive"]
+                            }
+                        },
+                        additionalProperties: false
+                    },
+                    {
+                        type: "object",
+                        properties: {
+                            initialized: {
+                                enum: ["always", "never", "consecutive"]
+                            },
+                            uninitialized: {
+                                enum: ["always", "never", "consecutive"]
+                            }
+                        },
+                        additionalProperties: false
+                    }
+                ]
+            }
+        ],
+
+        messages: {
+            combineUninitialized: "Combine this with the previous '{{type}}' statement with uninitialized variables.",
+            combineInitialized: "Combine this with the previous '{{type}}' statement with initialized variables.",
+            splitUninitialized: "Split uninitialized '{{type}}' declarations into multiple statements.",
+            splitInitialized: "Split initialized '{{type}}' declarations into multiple statements.",
+            splitRequires: "Split requires to be separated into a single block.",
+            combine: "Combine this with the previous '{{type}}' statement.",
+            split: "Split '{{type}}' declarations into multiple statements."
+        }
+    },
+
+    create(context) {
+        const MODE_ALWAYS = "always";
+        const MODE_NEVER = "never";
+        const MODE_CONSECUTIVE = "consecutive";
+        const mode = context.options[0] || MODE_ALWAYS;
+
+        const options = {};
+
+        if (typeof mode === "string") { // simple options configuration with just a string
+            options.var = { uninitialized: mode, initialized: mode };
+            options.let = { uninitialized: mode, initialized: mode };
+            options.const = { uninitialized: mode, initialized: mode };
+        } else if (typeof mode === "object") { // options configuration is an object
+            options.separateRequires = !!mode.separateRequires;
+            options.var = { uninitialized: mode.var, initialized: mode.var };
+            options.let = { uninitialized: mode.let, initialized: mode.let };
+            options.const = { uninitialized: mode.const, initialized: mode.const };
+            if (Object.prototype.hasOwnProperty.call(mode, "uninitialized")) {
+                options.var.uninitialized = mode.uninitialized;
+                options.let.uninitialized = mode.uninitialized;
+                options.const.uninitialized = mode.uninitialized;
+            }
+            if (Object.prototype.hasOwnProperty.call(mode, "initialized")) {
+                options.var.initialized = mode.initialized;
+                options.let.initialized = mode.initialized;
+                options.const.initialized = mode.initialized;
+            }
+        }
+
+        const sourceCode = context.sourceCode;
+
+        //--------------------------------------------------------------------------
+        // Helpers
+        //--------------------------------------------------------------------------
+
+        const functionStack = [];
+        const blockStack = [];
+
+        /**
+         * Increments the blockStack counter.
+         * @returns {void}
+         * @private
+         */
+        function startBlock() {
+            blockStack.push({
+                let: { initialized: false, uninitialized: false },
+                const: { initialized: false, uninitialized: false }
+            });
+        }
+
+        /**
+         * Increments the functionStack counter.
+         * @returns {void}
+         * @private
+         */
+        function startFunction() {
+            functionStack.push({ initialized: false, uninitialized: false });
+            startBlock();
+        }
+
+        /**
+         * Decrements the blockStack counter.
+         * @returns {void}
+         * @private
+         */
+        function endBlock() {
+            blockStack.pop();
+        }
+
+        /**
+         * Decrements the functionStack counter.
+         * @returns {void}
+         * @private
+         */
+        function endFunction() {
+            functionStack.pop();
+            endBlock();
+        }
+
+        /**
+         * Check if a variable declaration is a require.
+         * @param {ASTNode} decl variable declaration Node
+         * @returns {bool} if decl is a require, return true; else return false.
+         * @private
+         */
+        function isRequire(decl) {
+            return decl.init && decl.init.type === "CallExpression" && decl.init.callee.name === "require";
+        }
+
+        /**
+         * Records whether initialized/uninitialized/required variables are defined in current scope.
+         * @param {string} statementType node.kind, one of: "var", "let", or "const"
+         * @param {ASTNode[]} declarations List of declarations
+         * @param {Object} currentScope The scope being investigated
+         * @returns {void}
+         * @private
+         */
+        function recordTypes(statementType, declarations, currentScope) {
+            for (let i = 0; i < declarations.length; i++) {
+                if (declarations[i].init === null) {
+                    if (options[statementType] && options[statementType].uninitialized === MODE_ALWAYS) {
+                        currentScope.uninitialized = true;
+                    }
+                } else {
+                    if (options[statementType] && options[statementType].initialized === MODE_ALWAYS) {
+                        if (options.separateRequires && isRequire(declarations[i])) {
+                            currentScope.required = true;
+                        } else {
+                            currentScope.initialized = true;
+                        }
+                    }
+                }
+            }
+        }
+
+        /**
+         * Determines the current scope (function or block)
+         * @param {string} statementType node.kind, one of: "var", "let", or "const"
+         * @returns {Object} The scope associated with statementType
+         */
+        function getCurrentScope(statementType) {
+            let currentScope;
+
+            if (statementType === "var") {
+                currentScope = functionStack[functionStack.length - 1];
+            } else if (statementType === "let") {
+                currentScope = blockStack[blockStack.length - 1].let;
+            } else if (statementType === "const") {
+                currentScope = blockStack[blockStack.length - 1].const;
+            }
+            return currentScope;
+        }
+
+        /**
+         * Counts the number of initialized and uninitialized declarations in a list of declarations
+         * @param {ASTNode[]} declarations List of declarations
+         * @returns {Object} Counts of 'uninitialized' and 'initialized' declarations
+         * @private
+         */
+        function countDeclarations(declarations) {
+            const counts = { uninitialized: 0, initialized: 0 };
+
+            for (let i = 0; i < declarations.length; i++) {
+                if (declarations[i].init === null) {
+                    counts.uninitialized++;
+                } else {
+                    counts.initialized++;
+                }
+            }
+            return counts;
+        }
+
+        /**
+         * Determines if there is more than one var statement in the current scope.
+         * @param {string} statementType node.kind, one of: "var", "let", or "const"
+         * @param {ASTNode[]} declarations List of declarations
+         * @returns {boolean} Returns true if it is the first var declaration, false if not.
+         * @private
+         */
+        function hasOnlyOneStatement(statementType, declarations) {
+
+            const declarationCounts = countDeclarations(declarations);
+            const currentOptions = options[statementType] || {};
+            const currentScope = getCurrentScope(statementType);
+            const hasRequires = declarations.some(isRequire);
+
+            if (currentOptions.uninitialized === MODE_ALWAYS && currentOptions.initialized === MODE_ALWAYS) {
+                if (currentScope.uninitialized || currentScope.initialized) {
+                    if (!hasRequires) {
+                        return false;
+                    }
+                }
+            }
+
+            if (declarationCounts.uninitialized > 0) {
+                if (currentOptions.uninitialized === MODE_ALWAYS && currentScope.uninitialized) {
+                    return false;
+                }
+            }
+            if (declarationCounts.initialized > 0) {
+                if (currentOptions.initialized === MODE_ALWAYS && currentScope.initialized) {
+                    if (!hasRequires) {
+                        return false;
+                    }
+                }
+            }
+            if (currentScope.required && hasRequires) {
+                return false;
+            }
+            recordTypes(statementType, declarations, currentScope);
+            return true;
+        }
+
+        /**
+         * Fixer to join VariableDeclaration's into a single declaration
+         * @param {VariableDeclarator[]} declarations The `VariableDeclaration` to join
+         * @returns {Function} The fixer function
+         */
+        function joinDeclarations(declarations) {
+            const declaration = declarations[0];
+            const body = Array.isArray(declaration.parent.parent.body) ? declaration.parent.parent.body : [];
+            const currentIndex = body.findIndex(node => node.range[0] === declaration.parent.range[0]);
+            const previousNode = body[currentIndex - 1];
+
+            return fixer => {
+                const type = sourceCode.getTokenBefore(declaration);
+                const prevSemi = sourceCode.getTokenBefore(type);
+                const res = [];
+
+                if (previousNode && previousNode.kind === sourceCode.getText(type)) {
+                    if (prevSemi.value === ";") {
+                        res.push(fixer.replaceText(prevSemi, ","));
+                    } else {
+                        res.push(fixer.insertTextAfter(prevSemi, ","));
+                    }
+                    res.push(fixer.replaceText(type, ""));
+                }
+
+                return res;
+            };
+        }
+
+        /**
+         * Fixer to split a VariableDeclaration into individual declarations
+         * @param {VariableDeclaration} declaration The `VariableDeclaration` to split
+         * @returns {Function|null} The fixer function
+         */
+        function splitDeclarations(declaration) {
+            const { parent } = declaration;
+
+            // don't autofix code such as: if (foo) var x, y;
+            if (!isInStatementList(parent.type === "ExportNamedDeclaration" ? parent : declaration)) {
+                return null;
+            }
+
+            return fixer => declaration.declarations.map(declarator => {
+                const tokenAfterDeclarator = sourceCode.getTokenAfter(declarator);
+
+                if (tokenAfterDeclarator === null) {
+                    return null;
+                }
+
+                const afterComma = sourceCode.getTokenAfter(tokenAfterDeclarator, { includeComments: true });
+
+                if (tokenAfterDeclarator.value !== ",") {
+                    return null;
+                }
+
+                const exportPlacement = declaration.parent.type === "ExportNamedDeclaration" ? "export " : "";
+
+                /*
+                 * `var x,y`
+                 * tokenAfterDeclarator ^^ afterComma
+                 */
+                if (afterComma.range[0] === tokenAfterDeclarator.range[1]) {
+                    return fixer.replaceText(tokenAfterDeclarator, `; ${exportPlacement}${declaration.kind} `);
+                }
+
+                /*
+                 * `var x,
+                 * tokenAfterDeclarator ^
+                 *      y`
+                 *      ^ afterComma
+                 */
+                if (
+                    afterComma.loc.start.line > tokenAfterDeclarator.loc.end.line ||
+                    afterComma.type === "Line" ||
+                    afterComma.type === "Block"
+                ) {
+                    let lastComment = afterComma;
+
+                    while (lastComment.type === "Line" || lastComment.type === "Block") {
+                        lastComment = sourceCode.getTokenAfter(lastComment, { includeComments: true });
+                    }
+
+                    return fixer.replaceTextRange(
+                        [tokenAfterDeclarator.range[0], lastComment.range[0]],
+                        `;${sourceCode.text.slice(tokenAfterDeclarator.range[1], lastComment.range[0])}${exportPlacement}${declaration.kind} `
+                    );
+                }
+
+                return fixer.replaceText(tokenAfterDeclarator, `; ${exportPlacement}${declaration.kind}`);
+            }).filter(x => x);
+        }
+
+        /**
+         * Checks a given VariableDeclaration node for errors.
+         * @param {ASTNode} node The VariableDeclaration node to check
+         * @returns {void}
+         * @private
+         */
+        function checkVariableDeclaration(node) {
+            const parent = node.parent;
+            const type = node.kind;
+
+            if (!options[type]) {
+                return;
+            }
+
+            const declarations = node.declarations;
+            const declarationCounts = countDeclarations(declarations);
+            const mixedRequires = declarations.some(isRequire) && !declarations.every(isRequire);
+
+            if (options[type].initialized === MODE_ALWAYS) {
+                if (options.separateRequires && mixedRequires) {
+                    context.report({
+                        node,
+                        messageId: "splitRequires"
+                    });
+                }
+            }
+
+            // consecutive
+            const nodeIndex = (parent.body && parent.body.length > 0 && parent.body.indexOf(node)) || 0;
+
+            if (nodeIndex > 0) {
+                const previousNode = parent.body[nodeIndex - 1];
+                const isPreviousNodeDeclaration = previousNode.type === "VariableDeclaration";
+                const declarationsWithPrevious = declarations.concat(previousNode.declarations || []);
+
+                if (
+                    isPreviousNodeDeclaration &&
+                    previousNode.kind === type &&
+                    !(declarationsWithPrevious.some(isRequire) && !declarationsWithPrevious.every(isRequire))
+                ) {
+                    const previousDeclCounts = countDeclarations(previousNode.declarations);
+
+                    if (options[type].initialized === MODE_CONSECUTIVE && options[type].uninitialized === MODE_CONSECUTIVE) {
+                        context.report({
+                            node,
+                            messageId: "combine",
+                            data: {
+                                type
+                            },
+                            fix: joinDeclarations(declarations)
+                        });
+                    } else if (options[type].initialized === MODE_CONSECUTIVE && declarationCounts.initialized > 0 && previousDeclCounts.initialized > 0) {
+                        context.report({
+                            node,
+                            messageId: "combineInitialized",
+                            data: {
+                                type
+                            },
+                            fix: joinDeclarations(declarations)
+                        });
+                    } else if (options[type].uninitialized === MODE_CONSECUTIVE &&
+                            declarationCounts.uninitialized > 0 &&
+                            previousDeclCounts.uninitialized > 0) {
+                        context.report({
+                            node,
+                            messageId: "combineUninitialized",
+                            data: {
+                                type
+                            },
+                            fix: joinDeclarations(declarations)
+                        });
+                    }
+                }
+            }
+
+            // always
+            if (!hasOnlyOneStatement(type, declarations)) {
+                if (options[type].initialized === MODE_ALWAYS && options[type].uninitialized === MODE_ALWAYS) {
+                    context.report({
+                        node,
+                        messageId: "combine",
+                        data: {
+                            type
+                        },
+                        fix: joinDeclarations(declarations)
+                    });
+                } else {
+                    if (options[type].initialized === MODE_ALWAYS && declarationCounts.initialized > 0) {
+                        context.report({
+                            node,
+                            messageId: "combineInitialized",
+                            data: {
+                                type
+                            },
+                            fix: joinDeclarations(declarations)
+                        });
+                    }
+                    if (options[type].uninitialized === MODE_ALWAYS && declarationCounts.uninitialized > 0) {
+                        if (node.parent.left === node && (node.parent.type === "ForInStatement" || node.parent.type === "ForOfStatement")) {
+                            return;
+                        }
+                        context.report({
+                            node,
+                            messageId: "combineUninitialized",
+                            data: {
+                                type
+                            },
+                            fix: joinDeclarations(declarations)
+                        });
+                    }
+                }
+            }
+
+            // never
+            if (parent.type !== "ForStatement" || parent.init !== node) {
+                const totalDeclarations = declarationCounts.uninitialized + declarationCounts.initialized;
+
+                if (totalDeclarations > 1) {
+                    if (options[type].initialized === MODE_NEVER && options[type].uninitialized === MODE_NEVER) {
+
+                        // both initialized and uninitialized
+                        context.report({
+                            node,
+                            messageId: "split",
+                            data: {
+                                type
+                            },
+                            fix: splitDeclarations(node)
+                        });
+                    } else if (options[type].initialized === MODE_NEVER && declarationCounts.initialized > 0) {
+
+                        // initialized
+                        context.report({
+                            node,
+                            messageId: "splitInitialized",
+                            data: {
+                                type
+                            },
+                            fix: splitDeclarations(node)
+                        });
+                    } else if (options[type].uninitialized === MODE_NEVER && declarationCounts.uninitialized > 0) {
+
+                        // uninitialized
+                        context.report({
+                            node,
+                            messageId: "splitUninitialized",
+                            data: {
+                                type
+                            },
+                            fix: splitDeclarations(node)
+                        });
+                    }
+                }
+            }
+        }
+
+        //--------------------------------------------------------------------------
+        // Public API
+        //--------------------------------------------------------------------------
+
+        return {
+            Program: startFunction,
+            FunctionDeclaration: startFunction,
+            FunctionExpression: startFunction,
+            ArrowFunctionExpression: startFunction,
+            StaticBlock: startFunction, // StaticBlock creates a new scope for `var` variables
+
+            BlockStatement: startBlock,
+            ForStatement: startBlock,
+            ForInStatement: startBlock,
+            ForOfStatement: startBlock,
+            SwitchStatement: startBlock,
+            VariableDeclaration: checkVariableDeclaration,
+            "ForStatement:exit": endBlock,
+            "ForOfStatement:exit": endBlock,
+            "ForInStatement:exit": endBlock,
+            "SwitchStatement:exit": endBlock,
+            "BlockStatement:exit": endBlock,
+
+            "Program:exit": endFunction,
+            "FunctionDeclaration:exit": endFunction,
+            "FunctionExpression:exit": endFunction,
+            "ArrowFunctionExpression:exit": endFunction,
+            "StaticBlock:exit": endFunction
+        };
+
+    }
+};