1 files changed, 173 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-param-reassign.js b/tools/node_modules/eslint/lib/rules/no-param-reassign.js
new file mode 100644
index 0000000000..f32e42ae2f
--- /dev/null
+++ b/tools/node_modules/eslint/lib/rules/no-param-reassign.js
@@ -0,0 +1,173 @@
+/**
+ * @fileoverview Disallow reassignment of function parameters.
+ * @author Nat Burns
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+const stopNodePattern = /(?:Statement|Declaration|Function(?:Expression)?|Program)$/;
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "disallow reassigning `function` parameters",
+            category: "Best Practices",
+            recommended: false
+        },
+
+        schema: [
+            {
+                oneOf: [
+                    {
+                        type: "object",
+                        properties: {
+                            props: {
+                                enum: [false]
+                            }
+                        },
+                        additionalProperties: false
+                    },
+                    {
+                        type: "object",
+                        properties: {
+                            props: {
+                                enum: [true]
+                            },
+                            ignorePropertyModificationsFor: {
+                                type: "array",
+                                items: {
+                                    type: "string"
+                                },
+                                uniqueItems: true
+                            }
+                        },
+                        additionalProperties: false
+                    }
+                ]
+            }
+        ]
+    },
+
+    create(context) {
+        const props = context.options[0] && Boolean(context.options[0].props);
+        const ignoredPropertyAssignmentsFor = context.options[0] && context.options[0].ignorePropertyModificationsFor || [];
+
+        /**
+         * Checks whether or not the reference modifies properties of its variable.
+         * @param {Reference} reference - A reference to check.
+         * @returns {boolean} Whether or not the reference modifies properties of its variable.
+         */
+        function isModifyingProp(reference) {
+            let node = reference.identifier;
+            let parent = node.parent;
+
+            while (parent && !stopNodePattern.test(parent.type)) {
+                switch (parent.type) {
+
+                    // e.g. foo.a = 0;
+                    case "AssignmentExpression":
+                        return parent.left === node;
+
+                    // e.g. ++foo.a;
+                    case "UpdateExpression":
+                        return true;
+
+                    // e.g. delete foo.a;
+                    case "UnaryExpression":
+                        if (parent.operator === "delete") {
+                            return true;
+                        }
+                        break;
+
+                    // EXCLUDES: e.g. cache.get(foo.a).b = 0;
+                    case "CallExpression":
+                        if (parent.callee !== node) {
+                            return false;
+                        }
+                        break;
+
+                    // EXCLUDES: e.g. cache[foo.a] = 0;
+                    case "MemberExpression":
+                        if (parent.property === node) {
+                            return false;
+                        }
+                        break;
+
+                    // EXCLUDES: e.g. ({ [foo]: a }) = bar;
+                    case "Property":
+                        if (parent.key === node) {
+                            return false;
+                        }
+
+                        break;
+
+                    // no default
+                }
+
+                node = parent;
+                parent = node.parent;
+            }
+
+            return false;
+        }
+
+        /**
+         * Reports a reference if is non initializer and writable.
+         * @param {Reference} reference - A reference to check.
+         * @param {int} index - The index of the reference in the references.
+         * @param {Reference[]} references - The array that the reference belongs to.
+         * @returns {void}
+         */
+        function checkReference(reference, index, references) {
+            const identifier = reference.identifier;
+
+            if (identifier &&
+                !reference.init &&
+
+                /*
+                 * Destructuring assignments can have multiple default value,
+                 * so possibly there are multiple writeable references for the same identifier.
+                 */
+                (index === 0 || references[index - 1].identifier !== identifier)
+            ) {
+                if (reference.isWrite()) {
+                    context.report({ node: identifier, message: "Assignment to function parameter '{{name}}'.", data: { name: identifier.name } });
+                } else if (props && isModifyingProp(reference) && ignoredPropertyAssignmentsFor.indexOf(identifier.name) === -1) {
+                    context.report({ node: identifier, message: "Assignment to property of function parameter '{{name}}'.", data: { name: identifier.name } });
+                }
+            }
+        }
+
+        /**
+         * Finds and reports references that are non initializer and writable.
+         * @param {Variable} variable - A variable to check.
+         * @returns {void}
+         */
+        function checkVariable(variable) {
+            if (variable.defs[0].type === "Parameter") {
+                variable.references.forEach(checkReference);
+            }
+        }
+
+        /**
+         * Checks parameters of a given function node.
+         * @param {ASTNode} node - A function node to check.
+         * @returns {void}
+         */
+        function checkForFunction(node) {
+            context.getDeclaredVariables(node).forEach(checkVariable);
+        }
+
+        return {
+
+            // `:exit` is needed for the `node.parent` property of identifier nodes.
+            "FunctionDeclaration:exit": checkForFunction,
+            "FunctionExpression:exit": checkForFunction,
+            "ArrowFunctionExpression:exit": checkForFunction
+        };
+
+    }
+};