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cloneNode.js
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cloneNode.js
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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;
if (has(node, "typeAnnotation")) {
newNode.typeAnnotation = deep
? cloneIfNodeOrArray(node.typeAnnotation, true)
: node.typeAnnotation;
}
} 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 = {
...node.extra,
};
}
return newNode;
}