Add t.cloneNode and deprecate t.clone and t.cloneDeep (#7149)

packages/babel-types/src/clone/clone.js

@@ -1,16 +1,12 @@
 // @flow
 
+import cloneNode from "./cloneNode";
+
 /**
- * Create a shallow clone of a `node` excluding `_private` properties.
+ * Create a shallow clone of a `node`, including only
+ * properties belonging to the node.
+ * @deprecated Use t.cloneNode instead.
  */
 export default function clone<T: Object>(node: T): T {
-  if (!node) return node;
-  const newNode = (({}: any): T);
-
-  Object.keys(node).forEach(key => {
-    if (key[0] === "_") return;
-    newNode[key] = node[key];
-  });
-
-  return newNode;
+  return cloneNode(node, /* deep */ false);
 }

packages/babel-types/src/clone/cloneDeep.js

@@ -1,28 +1,12 @@
 // @flow
 
+import cloneNode from "./cloneNode";
+
 /**
  * Create a deep clone of a `node` and all of it's child nodes
- * excluding `_private` properties.
+ * including only properties belonging to the node.
+ * @deprecated Use t.cloneNode instead.
  */
 export default function cloneDeep<T: Object>(node: T): T {
-  if (!node) return node;
-  const newNode = (({}: any): T);
-
-  Object.keys(node).forEach(key => {
-    if (key[0] === "_") return;
-
-    let val = node[key];
-
-    if (val) {
-      if (val.type) {
-        val = cloneDeep(val);
-      } else if (Array.isArray(val)) {
-        val = val.map(cloneDeep);
-      }
-    }
-
-    newNode[key] = val;
-  });
-
-  return newNode;
+  return cloneNode(node);
 }

packages/babel-types/src/clone/cloneNode.js

@@ -0,0 +1,69 @@
+import { NODE_FIELDS } from "../definitions";
+
+const has = Function.call.bind(Object.prototype.hasOwnProperty);
+
+function cloneIfNode(obj, deep) {
+  if (
+    obj &&
+    typeof obj.type === "string" &&
+    // CommentLine and CommentBlock are used in File#comments, but they are
+    // not defined in babel-types
+    obj.type !== "CommentLine" &&
+    obj.type !== "CommentBlock"
+  ) {
+    return cloneNode(obj, deep);
+  }
+
+  return obj;
+}
+
+function cloneIfNodeOrArray(obj, deep) {
+  if (Array.isArray(obj)) {
+    return obj.map(node => cloneIfNode(node, deep));
+  }
+  return cloneIfNode(obj, deep);
+}
+
+/**
+ * Create a clone of a `node` including only properties belonging to the node.
+ * If the second parameter is `false`, cloneNode performs a shallow clone.
+ */
+export default function cloneNode<T: Object>(node: T, deep: boolean = true): T {
+  if (!node) return node;
+
+  const { type } = node;
+  const newNode = (({ type }: any): T);
+
+  // Special-case identifiers since they are the most cloned nodes.
+  if (type === "Identifier") {
+    newNode.name = node.name;
+  } else if (!has(NODE_FIELDS, type)) {
+    throw new Error(`Unknown node type: "${type}"`);
+  } else {
+    for (const field of Object.keys(NODE_FIELDS[type])) {
+      if (has(node, field)) {
+        newNode[field] = deep
+          ? cloneIfNodeOrArray(node[field], true)
+          : node[field];
+      }
+    }
+  }
+
+  if (has(node, "loc")) {
+    newNode.loc = node.loc;
+  }
+  if (has(node, "leadingComments")) {
+    newNode.leadingComments = node.leadingComments;
+  }
+  if (has(node, "innerComments")) {
+    newNode.innerComments = node.innerCmments;
+  }
+  if (has(node, "trailingComments")) {
+    newNode.trailingComments = node.trailingComments;
+  }
+  if (has(node, "extra")) {
+    newNode.extra = Object.assign({}, node.extra);
+  }
+
+  return newNode;
+}

packages/babel-types/src/converters/toKeyAlias.js

@@ -1,6 +1,6 @@
 // @flow
 import { isIdentifier, isStringLiteral } from "../validators/generated";
-import cloneDeep from "../clone/cloneDeep";
+import cloneNode from "../clone/cloneNode";
 import removePropertiesDeep from "../modifications/removePropertiesDeep";
 
 export default function toKeyAlias(
@@ -16,7 +16,7 @@ export default function toKeyAlias(
   } else if (isStringLiteral(key)) {
     alias = JSON.stringify(key.value);
   } else {
-    alias = JSON.stringify(removePropertiesDeep(cloneDeep(key)));
+    alias = JSON.stringify(removePropertiesDeep(cloneNode(key)));
   }
 
   if (node.computed) {

packages/babel-types/src/index.js

@@ -17,6 +17,7 @@ export {
 export * from "./builders/generated";
 
 // clone
+export { default as cloneNode } from "./clone/cloneNode";
 export { default as clone } from "./clone/clone";
 export { default as cloneDeep } from "./clone/cloneDeep";
 export { default as cloneWithoutLoc } from "./clone/cloneWithoutLoc";