tools: move eslint from tools to tools/node_modules

This is required because we need to add the babel-eslint dependency
and it has to be able to resolve "eslint".
babel-eslint is required to support future ES features such as async
iterators and import.meta.

Refs: https://github.com/nodejs/node/pull/17755
PR-URL: https://github.com/nodejs/node/pull/17820
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

1 files changed, 149 insertions, 0 deletions

diff --git a/tools/node_modules/eslint/lib/rules/vars-on-top.js b/tools/node_modules/eslint/lib/rules/vars-on-top.js
new file mode 100644
index 0000000000..f74db905b1
--- /dev/null
+++ b/tools/node_modules/eslint/lib/rules/vars-on-top.js
@@ -0,0 +1,149 @@
+/**
+ * @fileoverview Rule to enforce var declarations are only at the top of a function.
+ * @author Danny Fritz
+ * @author Gyandeep Singh
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "require `var` declarations be placed at the top of their containing scope",
+            category: "Best Practices",
+            recommended: false
+        },
+
+        schema: []
+    },
+
+    create(context) {
+        const errorMessage = "All 'var' declarations must be at the top of the function scope.";
+
+        //--------------------------------------------------------------------------
+        // Helpers
+        //--------------------------------------------------------------------------
+
+        /**
+         * @param {ASTNode} node - any node
+         * @returns {boolean} whether the given node structurally represents a directive
+         */
+        function looksLikeDirective(node) {
+            return node.type === "ExpressionStatement" &&
+                node.expression.type === "Literal" && typeof node.expression.value === "string";
+        }
+
+        /**
+         * Check to see if its a ES6 import declaration
+         * @param {ASTNode} node - any node
+         * @returns {boolean} whether the given node represents a import declaration
+         */
+        function looksLikeImport(node) {
+            return node.type === "ImportDeclaration" || node.type === "ImportSpecifier" ||
+                node.type === "ImportDefaultSpecifier" || node.type === "ImportNamespaceSpecifier";
+        }
+
+        /**
+         * Checks whether a given node is a variable declaration or not.
+         *
+         * @param {ASTNode} node - any node
+         * @returns {boolean} `true` if the node is a variable declaration.
+         */
+        function isVariableDeclaration(node) {
+            return (
+                node.type === "VariableDeclaration" ||
+                (
+                    node.type === "ExportNamedDeclaration" &&
+                    node.declaration &&
+                    node.declaration.type === "VariableDeclaration"
+                )
+            );
+        }
+
+        /**
+         * Checks whether this variable is on top of the block body
+         * @param {ASTNode} node - The node to check
+         * @param {ASTNode[]} statements - collection of ASTNodes for the parent node block
+         * @returns {boolean} True if var is on top otherwise false
+         */
+        function isVarOnTop(node, statements) {
+            const l = statements.length;
+            let i = 0;
+
+            // skip over directives
+            for (; i < l; ++i) {
+                if (!looksLikeDirective(statements[i]) && !looksLikeImport(statements[i])) {
+                    break;
+                }
+            }
+
+            for (; i < l; ++i) {
+                if (!isVariableDeclaration(statements[i])) {
+                    return false;
+                }
+                if (statements[i] === node) {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        /**
+         * Checks whether variable is on top at the global level
+         * @param {ASTNode} node - The node to check
+         * @param {ASTNode} parent - Parent of the node
+         * @returns {void}
+         */
+        function globalVarCheck(node, parent) {
+            if (!isVarOnTop(node, parent.body)) {
+                context.report({ node, message: errorMessage });
+            }
+        }
+
+        /**
+         * Checks whether variable is on top at functional block scope level
+         * @param {ASTNode} node - The node to check
+         * @param {ASTNode} parent - Parent of the node
+         * @param {ASTNode} grandParent - Parent of the node's parent
+         * @returns {void}
+         */
+        function blockScopeVarCheck(node, parent, grandParent) {
+            if (!(/Function/.test(grandParent.type) &&
+                    parent.type === "BlockStatement" &&
+                    isVarOnTop(node, parent.body))) {
+                context.report({ node, message: errorMessage });
+            }
+        }
+
+        //--------------------------------------------------------------------------
+        // Public API
+        //--------------------------------------------------------------------------
+
+        return {
+            VariableDeclaration(node) {
+                const ancestors = context.getAncestors();
+                let parent = ancestors.pop();
+                let grandParent = ancestors.pop();
+
+                if (node.kind === "var") { // check variable is `var` type and not `let` or `const`
+                    if (parent.type === "ExportNamedDeclaration") {
+                        node = parent;
+                        parent = grandParent;
+                        grandParent = ancestors.pop();
+                    }
+
+                    if (parent.type === "Program") { // That means its a global variable
+                        globalVarCheck(node, parent);
+                    } else {
+                        blockScopeVarCheck(node, parent, grandParent);
+                    }
+                }
+            }
+        };
+
+    }
+};