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Diffstat (limited to 'tools/node_modules/eslint/lib/rules/no-use-before-define.js')
| -rw-r--r-- | tools/node_modules/eslint/lib/rules/no-use-before-define.js | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-use-before-define.js b/tools/node_modules/eslint/lib/rules/no-use-before-define.js new file mode 100644 index 0000000000..ada01815d9 --- /dev/null +++ b/tools/node_modules/eslint/lib/rules/no-use-before-define.js @@ -0,0 +1,266 @@ +/** + * @fileoverview Rule to flag use of variables before they are defined + * @author Ilya Volodin + */ + +"use strict"; + +//------------------------------------------------------------------------------ +// Helpers +//------------------------------------------------------------------------------ + +const SENTINEL_TYPE = /^(?:(?:Function|Class)(?:Declaration|Expression)|ArrowFunctionExpression|CatchClause|ImportDeclaration|ExportNamedDeclaration)$/; +const FOR_IN_OF_TYPE = /^For(?:In|Of)Statement$/; + +/** + * Parses a given value as options. + * + * @param {any} options - A value to parse. + * @returns {Object} The parsed options. + */ +function parseOptions(options) { + let functions = true; + let classes = true; + let variables = true; + + if (typeof options === "string") { + functions = (options !== "nofunc"); + } else if (typeof options === "object" && options !== null) { + functions = options.functions !== false; + classes = options.classes !== false; + variables = options.variables !== false; + } + + return { functions, classes, variables }; +} + +/** + * Checks whether or not a given variable is a function declaration. + * + * @param {eslint-scope.Variable} variable - A variable to check. + * @returns {boolean} `true` if the variable is a function declaration. + */ +function isFunction(variable) { + return variable.defs[0].type === "FunctionName"; +} + +/** + * Checks whether or not a given variable is a class declaration in an upper function scope. + * + * @param {eslint-scope.Variable} variable - A variable to check. + * @param {eslint-scope.Reference} reference - A reference to check. + * @returns {boolean} `true` if the variable is a class declaration. + */ +function isOuterClass(variable, reference) { + return ( + variable.defs[0].type === "ClassName" && + variable.scope.variableScope !== reference.from.variableScope + ); +} + +/** + * Checks whether or not a given variable is a variable declaration in an upper function scope. + * @param {eslint-scope.Variable} variable - A variable to check. + * @param {eslint-scope.Reference} reference - A reference to check. + * @returns {boolean} `true` if the variable is a variable declaration. + */ +function isOuterVariable(variable, reference) { + return ( + variable.defs[0].type === "Variable" && + variable.scope.variableScope !== reference.from.variableScope + ); +} + +/** + * Checks whether or not a given location is inside of the range of a given node. + * + * @param {ASTNode} node - An node to check. + * @param {number} location - A location to check. + * @returns {boolean} `true` if the location is inside of the range of the node. + */ +function isInRange(node, location) { + return node && node.range[0] <= location && location <= node.range[1]; +} + +/** + * Checks whether or not a given reference is inside of the initializers of a given variable. + * + * This returns `true` in the following cases: + * + * var a = a + * var [a = a] = list + * var {a = a} = obj + * for (var a in a) {} + * for (var a of a) {} + * + * @param {Variable} variable - A variable to check. + * @param {Reference} reference - A reference to check. + * @returns {boolean} `true` if the reference is inside of the initializers. + */ +function isInInitializer(variable, reference) { + if (variable.scope !== reference.from) { + return false; + } + + let node = variable.identifiers[0].parent; + const location = reference.identifier.range[1]; + + while (node) { + if (node.type === "VariableDeclarator") { + if (isInRange(node.init, location)) { + return true; + } + if (FOR_IN_OF_TYPE.test(node.parent.parent.type) && + isInRange(node.parent.parent.right, location) + ) { + return true; + } + break; + } else if (node.type === "AssignmentPattern") { + if (isInRange(node.right, location)) { + return true; + } + } else if (SENTINEL_TYPE.test(node.type)) { + break; + } + + node = node.parent; + } + + return false; +} + +//------------------------------------------------------------------------------ +// Rule Definition +//------------------------------------------------------------------------------ + +module.exports = { + meta: { + docs: { + description: "disallow the use of variables before they are defined", + category: "Variables", + recommended: false + }, + + schema: [ + { + oneOf: [ + { + enum: ["nofunc"] + }, + { + type: "object", + properties: { + functions: { type: "boolean" }, + classes: { type: "boolean" }, + variables: { type: "boolean" } + }, + additionalProperties: false + } + ] + } + ] + }, + + create(context) { + const options = parseOptions(context.options[0]); + + /** + * Determines whether a given use-before-define case should be reported according to the options. + * @param {eslint-scope.Variable} variable The variable that gets used before being defined + * @param {eslint-scope.Reference} reference The reference to the variable + * @returns {boolean} `true` if the usage should be reported + */ + function isForbidden(variable, reference) { + if (isFunction(variable)) { + return options.functions; + } + if (isOuterClass(variable, reference)) { + return options.classes; + } + if (isOuterVariable(variable, reference)) { + return options.variables; + } + return true; + } + + /** + * Finds and validates all variables in a given scope. + * @param {Scope} scope The scope object. + * @returns {void} + * @private + */ + function findVariablesInScope(scope) { + scope.references.forEach(reference => { + const variable = reference.resolved; + + /* + * Skips when the reference is: + * - initialization's. + * - referring to an undefined variable. + * - referring to a global environment variable (there're no identifiers). + * - located preceded by the variable (except in initializers). + * - allowed by options. + */ + if (reference.init || + !variable || + variable.identifiers.length === 0 || + (variable.identifiers[0].range[1] < reference.identifier.range[1] && !isInInitializer(variable, reference)) || + !isForbidden(variable, reference) + ) { + return; + } + + // Reports. + context.report({ + node: reference.identifier, + message: "'{{name}}' was used before it was defined.", + data: reference.identifier + }); + }); + } + + /** + * Validates variables inside of a node's scope. + * @param {ASTNode} node The node to check. + * @returns {void} + * @private + */ + function findVariables() { + const scope = context.getScope(); + + findVariablesInScope(scope); + } + + const ruleDefinition = { + "Program:exit"(node) { + const scope = context.getScope(), + ecmaFeatures = context.parserOptions.ecmaFeatures || {}; + + findVariablesInScope(scope); + + // both Node.js and Modules have an extra scope + if (ecmaFeatures.globalReturn || node.sourceType === "module") { + findVariablesInScope(scope.childScopes[0]); + } + } + }; + + if (context.parserOptions.ecmaVersion >= 6) { + ruleDefinition["BlockStatement:exit"] = + ruleDefinition["SwitchStatement:exit"] = findVariables; + + ruleDefinition["ArrowFunctionExpression:exit"] = function(node) { + if (node.body.type !== "BlockStatement") { + findVariables(); + } + }; + } else { + ruleDefinition["FunctionExpression:exit"] = + ruleDefinition["FunctionDeclaration:exit"] = + ruleDefinition["ArrowFunctionExpression:exit"] = findVariables; + } + + return ruleDefinition; + } +}; |