diff options
Diffstat (limited to 'tools/node_modules/eslint/lib/rules/no-unused-vars.js')
-rw-r--r-- | tools/node_modules/eslint/lib/rules/no-unused-vars.js | 647 |
1 files changed, 647 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-unused-vars.js b/tools/node_modules/eslint/lib/rules/no-unused-vars.js new file mode 100644 index 0000000000..05940d5932 --- /dev/null +++ b/tools/node_modules/eslint/lib/rules/no-unused-vars.js @@ -0,0 +1,647 @@ +/** + * @fileoverview Rule to flag declared but unused variables + * @author Ilya Volodin + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Requirements +//------------------------------------------------------------------------------ + +const lodash = require("lodash"); +const astUtils = require("../ast-utils"); + +//------------------------------------------------------------------------------ +// Rule Definition +//------------------------------------------------------------------------------ + +module.exports = { + meta: { + docs: { + description: "disallow unused variables", + category: "Variables", + recommended: true + }, + + schema: [ + { + oneOf: [ + { + enum: ["all", "local"] + }, + { + type: "object", + properties: { + vars: { + enum: ["all", "local"] + }, + varsIgnorePattern: { + type: "string" + }, + args: { + enum: ["all", "after-used", "none"] + }, + ignoreRestSiblings: { + type: "boolean" + }, + argsIgnorePattern: { + type: "string" + }, + caughtErrors: { + enum: ["all", "none"] + }, + caughtErrorsIgnorePattern: { + type: "string" + } + } + } + ] + } + ] + }, + + create(context) { + const sourceCode = context.getSourceCode(); + + const REST_PROPERTY_TYPE = /^(?:Experimental)?RestProperty$/; + + const config = { + vars: "all", + args: "after-used", + ignoreRestSiblings: false, + caughtErrors: "none" + }; + + const firstOption = context.options[0]; + + if (firstOption) { + if (typeof firstOption === "string") { + config.vars = firstOption; + } else { + config.vars = firstOption.vars || config.vars; + config.args = firstOption.args || config.args; + config.ignoreRestSiblings = firstOption.ignoreRestSiblings || config.ignoreRestSiblings; + config.caughtErrors = firstOption.caughtErrors || config.caughtErrors; + + if (firstOption.varsIgnorePattern) { + config.varsIgnorePattern = new RegExp(firstOption.varsIgnorePattern); + } + + if (firstOption.argsIgnorePattern) { + config.argsIgnorePattern = new RegExp(firstOption.argsIgnorePattern); + } + + if (firstOption.caughtErrorsIgnorePattern) { + config.caughtErrorsIgnorePattern = new RegExp(firstOption.caughtErrorsIgnorePattern); + } + } + } + + /** + * Generate the warning message about the variable being + * defined and unused, including the ignore pattern if configured. + * @param {Variable} unusedVar - eslint-scope variable object. + * @returns {string} The warning message to be used with this unused variable. + */ + function getDefinedMessage(unusedVar) { + let type; + let pattern; + + if (config.varsIgnorePattern) { + type = "vars"; + pattern = config.varsIgnorePattern.toString(); + } + + if (unusedVar.defs && unusedVar.defs[0] && unusedVar.defs[0].type) { + const defType = unusedVar.defs[0].type; + + if (defType === "CatchClause" && config.caughtErrorsIgnorePattern) { + type = "args"; + pattern = config.caughtErrorsIgnorePattern.toString(); + } else if (defType === "Parameter" && config.argsIgnorePattern) { + type = "args"; + pattern = config.argsIgnorePattern.toString(); + } + } + + const additional = type ? ` Allowed unused ${type} must match ${pattern}.` : ""; + + return `'{{name}}' is defined but never used.${additional}`; + } + + /** + * Generate the warning message about the variable being + * assigned and unused, including the ignore pattern if configured. + * @returns {string} The warning message to be used with this unused variable. + */ + function getAssignedMessage() { + const additional = config.varsIgnorePattern ? ` Allowed unused vars must match ${config.varsIgnorePattern.toString()}.` : ""; + + return `'{{name}}' is assigned a value but never used.${additional}`; + } + + //-------------------------------------------------------------------------- + // Helpers + //-------------------------------------------------------------------------- + + const STATEMENT_TYPE = /(?:Statement|Declaration)$/; + + /** + * Determines if a given variable is being exported from a module. + * @param {Variable} variable - eslint-scope variable object. + * @returns {boolean} True if the variable is exported, false if not. + * @private + */ + function isExported(variable) { + + const definition = variable.defs[0]; + + if (definition) { + + let node = definition.node; + + if (node.type === "VariableDeclarator") { + node = node.parent; + } else if (definition.type === "Parameter") { + return false; + } + + return node.parent.type.indexOf("Export") === 0; + } + return false; + + } + + /** + * Determines if a variable has a sibling rest property + * @param {Variable} variable - eslint-scope variable object. + * @returns {boolean} True if the variable is exported, false if not. + * @private + */ + function hasRestSpreadSibling(variable) { + if (config.ignoreRestSiblings) { + return variable.defs.some(def => { + const propertyNode = def.name.parent; + const patternNode = propertyNode.parent; + + return ( + propertyNode.type === "Property" && + patternNode.type === "ObjectPattern" && + REST_PROPERTY_TYPE.test(patternNode.properties[patternNode.properties.length - 1].type) + ); + }); + } + + return false; + } + + /** + * Determines if a reference is a read operation. + * @param {Reference} ref - An eslint-scope Reference + * @returns {boolean} whether the given reference represents a read operation + * @private + */ + function isReadRef(ref) { + return ref.isRead(); + } + + /** + * Determine if an identifier is referencing an enclosing function name. + * @param {Reference} ref - The reference to check. + * @param {ASTNode[]} nodes - The candidate function nodes. + * @returns {boolean} True if it's a self-reference, false if not. + * @private + */ + function isSelfReference(ref, nodes) { + let scope = ref.from; + + while (scope) { + if (nodes.indexOf(scope.block) >= 0) { + return true; + } + + scope = scope.upper; + } + + return false; + } + + /** + * Checks the position of given nodes. + * + * @param {ASTNode} inner - A node which is expected as inside. + * @param {ASTNode} outer - A node which is expected as outside. + * @returns {boolean} `true` if the `inner` node exists in the `outer` node. + * @private + */ + function isInside(inner, outer) { + return ( + inner.range[0] >= outer.range[0] && + inner.range[1] <= outer.range[1] + ); + } + + /** + * If a given reference is left-hand side of an assignment, this gets + * the right-hand side node of the assignment. + * + * In the following cases, this returns null. + * + * - The reference is not the LHS of an assignment expression. + * - The reference is inside of a loop. + * - The reference is inside of a function scope which is different from + * the declaration. + * + * @param {eslint-scope.Reference} ref - A reference to check. + * @param {ASTNode} prevRhsNode - The previous RHS node. + * @returns {ASTNode|null} The RHS node or null. + * @private + */ + function getRhsNode(ref, prevRhsNode) { + const id = ref.identifier; + const parent = id.parent; + const granpa = parent.parent; + const refScope = ref.from.variableScope; + const varScope = ref.resolved.scope.variableScope; + const canBeUsedLater = refScope !== varScope || astUtils.isInLoop(id); + + /* + * Inherits the previous node if this reference is in the node. + * This is for `a = a + a`-like code. + */ + if (prevRhsNode && isInside(id, prevRhsNode)) { + return prevRhsNode; + } + + if (parent.type === "AssignmentExpression" && + granpa.type === "ExpressionStatement" && + id === parent.left && + !canBeUsedLater + ) { + return parent.right; + } + return null; + } + + /** + * Checks whether a given function node is stored to somewhere or not. + * If the function node is stored, the function can be used later. + * + * @param {ASTNode} funcNode - A function node to check. + * @param {ASTNode} rhsNode - The RHS node of the previous assignment. + * @returns {boolean} `true` if under the following conditions: + * - the funcNode is assigned to a variable. + * - the funcNode is bound as an argument of a function call. + * - the function is bound to a property and the object satisfies above conditions. + * @private + */ + function isStorableFunction(funcNode, rhsNode) { + let node = funcNode; + let parent = funcNode.parent; + + while (parent && isInside(parent, rhsNode)) { + switch (parent.type) { + case "SequenceExpression": + if (parent.expressions[parent.expressions.length - 1] !== node) { + return false; + } + break; + + case "CallExpression": + case "NewExpression": + return parent.callee !== node; + + case "AssignmentExpression": + case "TaggedTemplateExpression": + case "YieldExpression": + return true; + + default: + if (STATEMENT_TYPE.test(parent.type)) { + + /* + * If it encountered statements, this is a complex pattern. + * Since analyzeing complex patterns is hard, this returns `true` to avoid false positive. + */ + return true; + } + } + + node = parent; + parent = parent.parent; + } + + return false; + } + + /** + * Checks whether a given Identifier node exists inside of a function node which can be used later. + * + * "can be used later" means: + * - the function is assigned to a variable. + * - the function is bound to a property and the object can be used later. + * - the function is bound as an argument of a function call. + * + * If a reference exists in a function which can be used later, the reference is read when the function is called. + * + * @param {ASTNode} id - An Identifier node to check. + * @param {ASTNode} rhsNode - The RHS node of the previous assignment. + * @returns {boolean} `true` if the `id` node exists inside of a function node which can be used later. + * @private + */ + function isInsideOfStorableFunction(id, rhsNode) { + const funcNode = astUtils.getUpperFunction(id); + + return ( + funcNode && + isInside(funcNode, rhsNode) && + isStorableFunction(funcNode, rhsNode) + ); + } + + /** + * Checks whether a given reference is a read to update itself or not. + * + * @param {eslint-scope.Reference} ref - A reference to check. + * @param {ASTNode} rhsNode - The RHS node of the previous assignment. + * @returns {boolean} The reference is a read to update itself. + * @private + */ + function isReadForItself(ref, rhsNode) { + const id = ref.identifier; + const parent = id.parent; + const granpa = parent.parent; + + return ref.isRead() && ( + + // self update. e.g. `a += 1`, `a++` + ( + parent.type === "AssignmentExpression" && + granpa.type === "ExpressionStatement" && + parent.left === id + ) || + ( + parent.type === "UpdateExpression" && + granpa.type === "ExpressionStatement" + ) || + + // in RHS of an assignment for itself. e.g. `a = a + 1` + ( + rhsNode && + isInside(id, rhsNode) && + !isInsideOfStorableFunction(id, rhsNode) + ) + ); + } + + /** + * Determine if an identifier is used either in for-in loops. + * + * @param {Reference} ref - The reference to check. + * @returns {boolean} whether reference is used in the for-in loops + * @private + */ + function isForInRef(ref) { + let target = ref.identifier.parent; + + + // "for (var ...) { return; }" + if (target.type === "VariableDeclarator") { + target = target.parent.parent; + } + + if (target.type !== "ForInStatement") { + return false; + } + + // "for (...) { return; }" + if (target.body.type === "BlockStatement") { + target = target.body.body[0]; + + // "for (...) return;" + } else { + target = target.body; + } + + // For empty loop body + if (!target) { + return false; + } + + return target.type === "ReturnStatement"; + } + + /** + * Determines if the variable is used. + * @param {Variable} variable - The variable to check. + * @returns {boolean} True if the variable is used + * @private + */ + function isUsedVariable(variable) { + const functionNodes = variable.defs.filter(def => def.type === "FunctionName").map(def => def.node), + isFunctionDefinition = functionNodes.length > 0; + let rhsNode = null; + + return variable.references.some(ref => { + if (isForInRef(ref)) { + return true; + } + + const forItself = isReadForItself(ref, rhsNode); + + rhsNode = getRhsNode(ref, rhsNode); + + return ( + isReadRef(ref) && + !forItself && + !(isFunctionDefinition && isSelfReference(ref, functionNodes)) + ); + }); + } + + /** + * Checks whether the given variable is the last parameter in the non-ignored parameters. + * + * @param {eslint-scope.Variable} variable - The variable to check. + * @returns {boolean} `true` if the variable is the last. + */ + function isLastInNonIgnoredParameters(variable) { + const def = variable.defs[0]; + + // This is the last. + if (def.index === def.node.params.length - 1) { + return true; + } + + // if all parameters preceded by this variable are ignored and unused, this is the last. + if (config.argsIgnorePattern) { + const params = context.getDeclaredVariables(def.node); + const posteriorParams = params.slice(params.indexOf(variable) + 1); + + if (posteriorParams.every(v => v.references.length === 0 && config.argsIgnorePattern.test(v.name))) { + return true; + } + } + + return false; + } + + /** + * Gets an array of variables without read references. + * @param {Scope} scope - an eslint-scope Scope object. + * @param {Variable[]} unusedVars - an array that saving result. + * @returns {Variable[]} unused variables of the scope and descendant scopes. + * @private + */ + function collectUnusedVariables(scope, unusedVars) { + const variables = scope.variables; + const childScopes = scope.childScopes; + let i, l; + + if (scope.type !== "TDZ" && (scope.type !== "global" || config.vars === "all")) { + for (i = 0, l = variables.length; i < l; ++i) { + const variable = variables[i]; + + // skip a variable of class itself name in the class scope + if (scope.type === "class" && scope.block.id === variable.identifiers[0]) { + continue; + } + + // skip function expression names and variables marked with markVariableAsUsed() + if (scope.functionExpressionScope || variable.eslintUsed) { + continue; + } + + // skip implicit "arguments" variable + if (scope.type === "function" && variable.name === "arguments" && variable.identifiers.length === 0) { + continue; + } + + // explicit global variables don't have definitions. + const def = variable.defs[0]; + + if (def) { + const type = def.type; + + // skip catch variables + if (type === "CatchClause") { + if (config.caughtErrors === "none") { + continue; + } + + // skip ignored parameters + if (config.caughtErrorsIgnorePattern && config.caughtErrorsIgnorePattern.test(def.name.name)) { + continue; + } + } + + if (type === "Parameter") { + + // skip any setter argument + if ((def.node.parent.type === "Property" || def.node.parent.type === "MethodDefinition") && def.node.parent.kind === "set") { + continue; + } + + // if "args" option is "none", skip any parameter + if (config.args === "none") { + continue; + } + + // skip ignored parameters + if (config.argsIgnorePattern && config.argsIgnorePattern.test(def.name.name)) { + continue; + } + + // if "args" option is "after-used", skip all but the last parameter + if (config.args === "after-used" && astUtils.isFunction(def.name.parent) && !isLastInNonIgnoredParameters(variable)) { + continue; + } + } else { + + // skip ignored variables + if (config.varsIgnorePattern && config.varsIgnorePattern.test(def.name.name)) { + continue; + } + } + } + + if (!isUsedVariable(variable) && !isExported(variable) && !hasRestSpreadSibling(variable)) { + unusedVars.push(variable); + } + } + } + + for (i = 0, l = childScopes.length; i < l; ++i) { + collectUnusedVariables(childScopes[i], unusedVars); + } + + return unusedVars; + } + + /** + * Gets the index of a given variable name in a given comment. + * @param {eslint-scope.Variable} variable - A variable to get. + * @param {ASTNode} comment - A comment node which includes the variable name. + * @returns {number} The index of the variable name's location. + * @private + */ + function getColumnInComment(variable, comment) { + const namePattern = new RegExp(`[\\s,]${lodash.escapeRegExp(variable.name)}(?:$|[\\s,:])`, "g"); + + // To ignore the first text "global". + namePattern.lastIndex = comment.value.indexOf("global") + 6; + + // Search a given variable name. + const match = namePattern.exec(comment.value); + + return match ? match.index + 1 : 0; + } + + /** + * Creates the correct location of a given variables. + * The location is at its name string in a `/*global` comment. + * + * @param {eslint-scope.Variable} variable - A variable to get its location. + * @returns {{line: number, column: number}} The location object for the variable. + * @private + */ + function getLocation(variable) { + const comment = variable.eslintExplicitGlobalComment; + + return sourceCode.getLocFromIndex(comment.range[0] + 2 + getColumnInComment(variable, comment)); + } + + //-------------------------------------------------------------------------- + // Public + //-------------------------------------------------------------------------- + + return { + "Program:exit"(programNode) { + const unusedVars = collectUnusedVariables(context.getScope(), []); + + for (let i = 0, l = unusedVars.length; i < l; ++i) { + const unusedVar = unusedVars[i]; + + if (unusedVar.eslintExplicitGlobal) { + context.report({ + node: programNode, + loc: getLocation(unusedVar), + message: getDefinedMessage(unusedVar), + data: unusedVar + }); + } else if (unusedVar.defs.length > 0) { + context.report({ + node: unusedVar.identifiers[0], + message: unusedVar.references.some(ref => ref.isWrite()) + ? getAssignedMessage() + : getDefinedMessage(unusedVar), + data: unusedVar + }); + } + } + } + }; + + } +}; |