1 files changed, 51 insertions, 0 deletions
diff --git a/preact/compat/src/forwardRef.js b/preact/compat/src/forwardRef.js
new file mode 100644
index 0000000..39585cb
--- /dev/null
+++ b/preact/compat/src/forwardRef.js
@@ -0,0 +1,51 @@
+import { options } from 'preact';
+import { assign } from './util';
+
+let oldDiffHook = options._diff;
+options._diff = vnode => {
+	if (vnode.type && vnode.type._forwarded && vnode.ref) {
+		vnode.props.ref = vnode.ref;
+		vnode.ref = null;
+	}
+	if (oldDiffHook) oldDiffHook(vnode);
+};
+
+export const REACT_FORWARD_SYMBOL =
+	(typeof Symbol != 'undefined' &&
+		Symbol.for &&
+		Symbol.for('react.forward_ref')) ||
+	0xf47;
+
+/**
+ * Pass ref down to a child. This is mainly used in libraries with HOCs that
+ * wrap components. Using `forwardRef` there is an easy way to get a reference
+ * of the wrapped component instead of one of the wrapper itself.
+ * @param {import('./index').ForwardFn} fn
+ * @returns {import('./internal').FunctionComponent}
+ */
+export function forwardRef(fn) {
+	// We always have ref in props.ref, except for
+	// mobx-react. It will call this function directly
+	// and always pass ref as the second argument.
+	function Forwarded(props, ref) {
+		let clone = assign({}, props);
+		delete clone.ref;
+		ref = props.ref || ref;
+		return fn(
+			clone,
+			!ref || (typeof ref === 'object' && !('current' in ref)) ? null : ref
+		);
+	}
+
+	// mobx-react checks for this being present
+	Forwarded.$$typeof = REACT_FORWARD_SYMBOL;
+	// mobx-react heavily relies on implementation details.
+	// It expects an object here with a `render` property,
+	// and prototype.render will fail. Without this
+	// mobx-react throws.
+	Forwarded.render = Forwarded;
+
+	Forwarded.prototype.isReactComponent = Forwarded._forwarded = true;
+	Forwarded.displayName = 'ForwardRef(' + (fn.displayName || fn.name) + ')';
+	return Forwarded;
+}