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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 = {
+ meta: {
+ docs: {
+ description: "enforce the use of variables within the scope they are defined",
+ category: "Best Practices",
+ recommended: false
+ },
+
+ schema: []
+ },
+
+ create(context) {
+ let stack = [];
+
+ /**
+ * Makes a block scope.
+ * @param {ASTNode} node - A node of a scope.
+ * @returns {void}
+ */
+ function enterScope(node) {
+ stack.push(node.range);
+ }
+
+ /**
+ * Pops the last block scope.
+ * @returns {void}
+ */
+ function exitScope() {
+ stack.pop();
+ }
+
+ /**
+ * Reports a given reference.
+ * @param {eslint-scope.Reference} reference - A reference to report.
+ * @returns {void}
+ */
+ function report(reference) {
+ const identifier = reference.identifier;
+
+ context.report({ node: identifier, message: "'{{name}}' used outside of binding context.", data: { name: identifier.name } });
+ }
+
+ /**
+ * Finds and reports references which are outside of valid scopes.
+ * @param {ASTNode} node - A node to get variables.
+ * @returns {void}
+ */
+ function checkForVariables(node) {
+ if (node.kind !== "var") {
+ return;
+ }
+
+ // Defines a predicate to check whether or not a given reference is outside of valid scope.
+ const scopeRange = stack[stack.length - 1];
+
+ /**
+ * Check if a reference is out of scope
+ * @param {ASTNode} reference node to examine
+ * @returns {boolean} True is its outside the scope
+ * @private
+ */
+ function isOutsideOfScope(reference) {
+ const idRange = reference.identifier.range;
+
+ return idRange[0] < scopeRange[0] || idRange[1] > scopeRange[1];
+ }
+
+ // Gets declared variables, and checks its references.
+ const variables = context.getDeclaredVariables(node);
+
+ for (let i = 0; i < variables.length; ++i) {
+
+ // Reports.
+ variables[i]
+ .references
+ .filter(isOutsideOfScope)
+ .forEach(report);
+ }
+ }
+
+ return {
+ Program(node) {
+ stack = [node.range];
+ },
+
+ // Manages scopes.
+ BlockStatement: enterScope,
+ "BlockStatement:exit": exitScope,
+ ForStatement: enterScope,
+ "ForStatement:exit": exitScope,
+ ForInStatement: enterScope,
+ "ForInStatement:exit": exitScope,
+ ForOfStatement: enterScope,
+ "ForOfStatement:exit": exitScope,
+ SwitchStatement: enterScope,
+ "SwitchStatement:exit": exitScope,
+ CatchClause: enterScope,
+ "CatchClause:exit": exitScope,
+
+ // Finds and reports references which are outside of valid scope.
+ VariableDeclaration: checkForVariables
+ };
+
+ }
+};