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/**
* @fileoverview Rule to check for "block scoped" variables by binding context
* @author Matt DuVall <http://www.mattduvall.com>
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = function(context) {
var scopeStack = [];
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
/**
* Determines whether an identifier is in declaration position or is a non-declaration reference.
* @param {ASTNode} id The identifier.
* @param {ASTNode} parent The identifier's parent AST node.
* @returns {Boolean} true when the identifier is in declaration position.
*/
function isDeclaration(id, parent) {
switch (parent.type) {
case "FunctionDeclaration":
case "FunctionExpression":
return parent.params.indexOf(id) > -1 || id === parent.id;
case "VariableDeclarator":
return id === parent.id;
case "CatchClause":
return id === parent.param;
default:
return false;
}
}
/**
* Determines whether an identifier is in property position.
* @param {ASTNode} id The identifier.
* @param {ASTNode} parent The identifier's parent AST node.
* @returns {Boolean} true when the identifier is in property position.
*/
function isProperty(id, parent) {
switch (parent.type) {
case "MemberExpression":
return id === parent.property && !parent.computed;
case "Property":
return id === parent.key;
default:
return false;
}
}
/**
* Pushes a new scope object on the scope stack.
* @returns {void}
*/
function pushScope() {
scopeStack.push([]);
}
/**
* Removes the topmost scope object from the scope stack.
* @returns {void}
*/
function popScope() {
scopeStack.pop();
}
/**
* Declares the given names in the topmost scope object.
* @param {[String]} names A list of names to declare.
* @returns {void}
*/
function declare(names) {
[].push.apply(scopeStack[scopeStack.length - 1], names);
}
//--------------------------------------------------------------------------
// Public API
//--------------------------------------------------------------------------
/**
* Declares all relevant identifiers for module imports.
* @param {ASTNode} node The AST node representing an import.
* @returns {void}
* @private
*/
function declareImports(node) {
declare([node.local.name]);
if (node.imported && node.imported.name !== node.local.name) {
declare([node.imported.name]);
}
}
/**
* Declares all relevant identifiers for classes.
* @param {ASTNode} node The AST node representing a class.
* @returns {void}
* @private
*/
function declareClass(node) {
if (node.id) {
declare([node.id.name]);
}
pushScope();
}
/**
* Declares all relevant identifiers for classes.
* @param {ASTNode} node The AST node representing a class.
* @returns {void}
* @private
*/
function declareClassMethod(node) {
pushScope();
declare([node.key.name]);
}
/**
* Add declarations based on the type of node being passed.
* @param {ASTNode} node The node containing declarations.
* @returns {void}
* @private
*/
function declareByNodeType(node) {
var declarations = [];
switch (node.type) {
case "Identifier":
declarations.push(node.name);
break;
case "ObjectPattern":
node.properties.forEach(function(property) {
declarations.push(property.key.name);
if (property.value) {
declarations.push(property.value.name);
}
});
break;
case "ArrayPattern":
node.elements.forEach(function(element) {
if (element) {
declarations.push(element.name);
}
});
break;
case "AssignmentPattern":
declareByNodeType(node.left);
break;
case "RestElement":
declareByNodeType(node.argument);
break;
// no default
}
declare(declarations);
}
/**
* Adds declarations of the function parameters and pushes the scope
* @param {ASTNode} node The node containing declarations.
* @returns {void}
* @private
*/
function functionHandler(node) {
pushScope();
node.params.forEach(function(param) {
declareByNodeType(param);
});
declare(node.rest ? [node.rest.name] : []);
declare(["arguments"]);
}
/**
* Adds declaration of the function name in its parent scope then process the function
* @param {ASTNode} node The node containing declarations.
* @returns {void}
* @private
*/
function functionDeclarationHandler(node) {
declare(node.id ? [node.id.name] : []);
functionHandler(node);
}
/**
* Process function declarations and declares its name in its own scope
* @param {ASTNode} node The node containing declarations.
* @returns {void}
* @private
*/
function functionExpressionHandler(node) {
functionHandler(node);
declare(node.id ? [node.id.name] : []);
}
function variableDeclarationHandler(node) {
node.declarations.forEach(function(declaration) {
declareByNodeType(declaration.id);
});
}
return {
"Program": function() {
var scope = context.getScope();
scopeStack = [scope.variables.map(function(v) {
return v.name;
})];
// global return creates another scope
if (context.ecmaFeatures.globalReturn) {
scope = scope.childScopes[0];
scopeStack.push(scope.variables.map(function(v) {
return v.name;
}));
}
},
"ImportSpecifier": declareImports,
"ImportDefaultSpecifier": declareImports,
"ImportNamespaceSpecifier": declareImports,
"BlockStatement": function(node) {
var statements = node.body;
pushScope();
statements.forEach(function(stmt) {
if (stmt.type === "VariableDeclaration") {
variableDeclarationHandler(stmt);
} else if (stmt.type === "FunctionDeclaration") {
declare([stmt.id.name]);
}
});
},
"VariableDeclaration": function (node) {
variableDeclarationHandler(node);
},
"BlockStatement:exit": popScope,
"CatchClause": function(node) {
pushScope();
declare([node.param.name]);
},
"CatchClause:exit": popScope,
"FunctionDeclaration": functionDeclarationHandler,
"FunctionDeclaration:exit": popScope,
"ClassDeclaration": declareClass,
"ClassDeclaration:exit": popScope,
"ClassExpression": declareClass,
"ClassExpression:exit": popScope,
"MethodDefinition": declareClassMethod,
"MethodDefinition:exit": popScope,
"FunctionExpression": functionExpressionHandler,
"FunctionExpression:exit": popScope,
// Arrow functions cannot have names
"ArrowFunctionExpression": functionHandler,
"ArrowFunctionExpression:exit": popScope,
"ForStatement": function() {
pushScope();
},
"ForStatement:exit": popScope,
"ForInStatement": function() {
pushScope();
},
"ForInStatement:exit": popScope,
"ForOfStatement": function() {
pushScope();
},
"ForOfStatement:exit": popScope,
"Identifier": function(node) {
var ancestor = context.getAncestors().pop();
if (isDeclaration(node, ancestor) || isProperty(node, ancestor) || ancestor.type === "LabeledStatement") {
return;
}
for (var i = 0, l = scopeStack.length; i < l; i++) {
if (scopeStack[i].indexOf(node.name) > -1) {
return;
}
}
context.report(node, "\"" + node.name + "\" used outside of binding context.");
}
};
};
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