1 files changed, 159 insertions, 0 deletions
diff --git a/tools/eslint/lib/rules/no-mixed-requires.js b/tools/eslint/lib/rules/no-mixed-requires.js
new file mode 100644
index 0000000000..d75fc56abb
--- /dev/null
+++ b/tools/eslint/lib/rules/no-mixed-requires.js
@@ -0,0 +1,159 @@
+/**
+ * @fileoverview Rule to enforce grouped require statements for Node.JS
+ * @author Raphael Pigulla
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = function(context) {
+
+    /**
+     * Returns the list of built-in modules.
+     *
+     * @returns {string[]} An array of built-in Node.js modules.
+     */
+    function getBuiltinModules() {
+        // This list is generated using `require("repl")._builtinLibs.concat('repl').sort()`
+        // This particular list is as per nodejs v0.12.2 and iojs v0.7.1
+        return [
+            "assert", "buffer", "child_process", "cluster", "crypto",
+            "dgram", "dns", "domain", "events", "fs", "http", "https",
+            "net", "os", "path", "punycode", "querystring", "readline",
+            "repl", "smalloc", "stream", "string_decoder", "tls", "tty",
+            "url", "util", "v8", "vm", "zlib"
+        ];
+    }
+
+    var BUILTIN_MODULES = getBuiltinModules();
+
+    var DECL_REQUIRE = "require",
+        DECL_UNINITIALIZED = "uninitialized",
+        DECL_OTHER = "other";
+
+    var REQ_CORE = "core",
+        REQ_FILE = "file",
+        REQ_MODULE = "module",
+        REQ_COMPUTED = "computed";
+
+    /**
+     * Determines the type of a declaration statement.
+     * @param {ASTNode} initExpression The init node of the VariableDeclarator.
+     * @returns {string} The type of declaration represented by the expression.
+     */
+    function getDeclarationType(initExpression) {
+        if (!initExpression) {
+            // "var x;"
+            return DECL_UNINITIALIZED;
+        }
+
+        if (initExpression.type === "CallExpression" &&
+            initExpression.callee.type === "Identifier" &&
+            initExpression.callee.name === "require"
+        ) {
+            // "var x = require('util');"
+            return DECL_REQUIRE;
+        } else if (initExpression.type === "MemberExpression") {
+            // "var x = require('glob').Glob;"
+            return getDeclarationType(initExpression.object);
+        }
+
+        // "var x = 42;"
+        return DECL_OTHER;
+    }
+
+    /**
+     * Determines the type of module that is loaded via require.
+     * @param {ASTNode} initExpression The init node of the VariableDeclarator.
+     * @returns {string} The module type.
+     */
+    function inferModuleType(initExpression) {
+        if (initExpression.type === "MemberExpression") {
+            // "var x = require('glob').Glob;"
+            return inferModuleType(initExpression.object);
+        } else if (initExpression.arguments.length === 0) {
+            // "var x = require();"
+            return REQ_COMPUTED;
+        }
+
+        var arg = initExpression.arguments[0];
+
+        if (arg.type !== "Literal" || typeof arg.value !== "string") {
+            // "var x = require(42);"
+            return REQ_COMPUTED;
+        }
+
+        if (BUILTIN_MODULES.indexOf(arg.value) !== -1) {
+            // "var fs = require('fs');"
+            return REQ_CORE;
+        } else if (/^\.{0,2}\//.test(arg.value)) {
+            // "var utils = require('./utils');"
+            return REQ_FILE;
+        } else {
+            // "var async = require('async');"
+            return REQ_MODULE;
+        }
+    }
+
+    /**
+     * Check if the list of variable declarations is mixed, i.e. whether it
+     * contains both require and other declarations.
+     * @param {ASTNode} declarations The list of VariableDeclarators.
+     * @returns {boolean} True if the declarations are mixed, false if not.
+     */
+    function isMixed(declarations) {
+        var contains = {};
+
+        declarations.forEach(function (declaration) {
+            var type = getDeclarationType(declaration.init);
+            contains[type] = true;
+        });
+
+        return !!(
+            contains[DECL_REQUIRE] &&
+            (contains[DECL_UNINITIALIZED] || contains[DECL_OTHER])
+        );
+    }
+
+    /**
+     * Check if all require declarations in the given list are of the same
+     * type.
+     * @param {ASTNode} declarations The list of VariableDeclarators.
+     * @returns {boolean} True if the declarations are grouped, false if not.
+     */
+    function isGrouped(declarations) {
+        var found = {};
+
+        declarations.forEach(function (declaration) {
+            if (getDeclarationType(declaration.init) === DECL_REQUIRE) {
+                found[inferModuleType(declaration.init)] = true;
+            }
+        });
+
+        return Object.keys(found).length <= 1;
+    }
+
+
+    return {
+
+        "VariableDeclaration": function(node) {
+            var grouping = !!context.options[0];
+
+            if (isMixed(node.declarations)) {
+                context.report(
+                    node,
+                    "Do not mix 'require' and other declarations."
+                );
+            } else if (grouping && !isGrouped(node.declarations)) {
+                context.report(
+                    node,
+                    "Do not mix core, module, file and computed requires."
+                );
+            }
+        }
+    };
+
+};