1 files changed, 105 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/for-direction.js b/tools/node_modules/eslint/lib/rules/for-direction.js
new file mode 100644
index 0000000000..7178ced9db
--- /dev/null
+++ b/tools/node_modules/eslint/lib/rules/for-direction.js
@@ -0,0 +1,105 @@
+/**
+ * @fileoverview enforce "for" loop update clause moving the counter in the right direction.(for-direction)
+ * @author Aladdin-ADD<hh_2013@foxmail.com>
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "enforce \"for\" loop update clause moving the counter in the right direction.",
+            category: "Possible Errors",
+            recommended: false
+        },
+        fixable: null,
+        schema: []
+    },
+
+    create(context) {
+
+        /**
+         * report an error.
+         * @param {ASTNode} node the node to report.
+         * @returns {void}
+         */
+        function report(node) {
+            context.report({
+                node,
+                message: "The update clause in this loop moves the variable in the wrong direction."
+            });
+        }
+
+        /**
+         * check UpdateExpression add/sub the counter
+         * @param {ASTNode} update UpdateExpression to check
+         * @param {string} counter variable name to check
+         * @returns {int} if add return 1, if sub return -1, if nochange, return 0
+         */
+        function getUpdateDirection(update, counter) {
+            if (update.argument.type === "Identifier" && update.argument.name === counter) {
+                if (update.operator === "++") {
+                    return 1;
+                }
+                if (update.operator === "--") {
+                    return -1;
+                }
+            }
+            return 0;
+        }
+
+        /**
+         * check AssignmentExpression add/sub the counter
+         * @param {ASTNode} update AssignmentExpression to check
+         * @param {string} counter variable name to check
+         * @returns {int} if add return 1, if sub return -1, if nochange, return 0
+         */
+        function getAssignmentDirection(update, counter) {
+            if (update.left.name === counter) {
+                if (update.operator === "+=") {
+                    return 1;
+                }
+                if (update.operator === "-=") {
+                    return -1;
+                }
+            }
+            return 0;
+        }
+        return {
+            ForStatement(node) {
+
+                if (node.test && node.test.type === "BinaryExpression" && node.test.left.type === "Identifier" && node.update) {
+                    const counter = node.test.left.name;
+                    const operator = node.test.operator;
+                    const update = node.update;
+
+                    if (operator === "<" || operator === "<=") {
+
+                        // report error if update sub the counter (--, -=)
+                        if (update.type === "UpdateExpression" && getUpdateDirection(update, counter) < 0) {
+                            report(node);
+                        }
+
+                        if (update.type === "AssignmentExpression" && getAssignmentDirection(update, counter) < 0) {
+                            report(node);
+                        }
+                    } else if (operator === ">" || operator === ">=") {
+
+                        // report error if update add the counter (++, +=)
+                        if (update.type === "UpdateExpression" && getUpdateDirection(update, counter) > 0) {
+                            report(node);
+                        }
+
+                        if (update.type === "AssignmentExpression" && getAssignmentDirection(update, counter) > 0) {
+                            report(node);
+                        }
+                    }
+                }
+            }
+        };
+    }
+};