1 files changed, 137 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-duplicate-imports.js b/tools/node_modules/eslint/lib/rules/no-duplicate-imports.js
new file mode 100644
index 0000000000..d12c3a56df
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+++ b/tools/node_modules/eslint/lib/rules/no-duplicate-imports.js
@@ -0,0 +1,137 @@
+/**
+ * @fileoverview Restrict usage of duplicate imports.
+ * @author Simen Bekkhus
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/**
+ * Returns the name of the module imported or re-exported.
+ *
+ * @param {ASTNode} node - A node to get.
+ * @returns {string} the name of the module, or empty string if no name.
+ */
+function getValue(node) {
+    if (node && node.source && node.source.value) {
+        return node.source.value.trim();
+    }
+
+    return "";
+}
+
+/**
+ * Checks if the name of the import or export exists in the given array, and reports if so.
+ *
+ * @param {RuleContext} context - The ESLint rule context object.
+ * @param {ASTNode} node - A node to get.
+ * @param {string} value - The name of the imported or exported module.
+ * @param {string[]} array - The array containing other imports or exports in the file.
+ * @param {string} message - A message to be reported after the name of the module
+ *
+ * @returns {void} No return value
+ */
+function checkAndReport(context, node, value, array, message) {
+    if (array.indexOf(value) !== -1) {
+        context.report({
+            node,
+            message: "'{{module}}' {{message}}",
+            data: {
+                module: value,
+                message
+            }
+        });
+    }
+}
+
+/**
+ * @callback nodeCallback
+ * @param {ASTNode} node - A node to handle.
+ */
+
+/**
+ * Returns a function handling the imports of a given file
+ *
+ * @param {RuleContext} context - The ESLint rule context object.
+ * @param {boolean} includeExports - Whether or not to check for exports in addition to imports.
+ * @param {string[]} importsInFile - The array containing other imports in the file.
+ * @param {string[]} exportsInFile - The array containing other exports in the file.
+ *
+ * @returns {nodeCallback} A function passed to ESLint to handle the statement.
+ */
+function handleImports(context, includeExports, importsInFile, exportsInFile) {
+    return function(node) {
+        const value = getValue(node);
+
+        if (value) {
+            checkAndReport(context, node, value, importsInFile, "import is duplicated.");
+
+            if (includeExports) {
+                checkAndReport(context, node, value, exportsInFile, "import is duplicated as export.");
+            }
+
+            importsInFile.push(value);
+        }
+    };
+}
+
+/**
+ * Returns a function handling the exports of a given file
+ *
+ * @param {RuleContext} context - The ESLint rule context object.
+ * @param {string[]} importsInFile - The array containing other imports in the file.
+ * @param {string[]} exportsInFile - The array containing other exports in the file.
+ *
+ * @returns {nodeCallback} A function passed to ESLint to handle the statement.
+ */
+function handleExports(context, importsInFile, exportsInFile) {
+    return function(node) {
+        const value = getValue(node);
+
+        if (value) {
+            checkAndReport(context, node, value, exportsInFile, "export is duplicated.");
+            checkAndReport(context, node, value, importsInFile, "export is duplicated as import.");
+
+            exportsInFile.push(value);
+        }
+    };
+}
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "disallow duplicate module imports",
+            category: "ECMAScript 6",
+            recommended: false
+        },
+
+        schema: [{
+            type: "object",
+            properties: {
+                includeExports: {
+                    type: "boolean"
+                }
+            },
+            additionalProperties: false
+        }]
+    },
+
+    create(context) {
+        const includeExports = (context.options[0] || {}).includeExports,
+            importsInFile = [],
+            exportsInFile = [];
+
+        const handlers = {
+            ImportDeclaration: handleImports(context, includeExports, importsInFile, exportsInFile)
+        };
+
+        if (includeExports) {
+            handlers.ExportNamedDeclaration = handleExports(context, importsInFile, exportsInFile);
+            handlers.ExportAllDeclaration = handleExports(context, importsInFile, exportsInFile);
+        }
+
+        return handlers;
+    }
+};