Restructure node graph project layout

node-graph/gstd/src/memo.rs

@@ -0,0 +1,28 @@
+use graphene_core::Node;
+use once_cell::sync::OnceCell;
+use std::borrow::Borrow;
+
+/// Caches the output of a given Node and acts as a proxy
+pub struct CacheNode<'n, 'c, CachedNode: Node + 'c> {
+    node: &'n CachedNode,
+    cache: OnceCell<CachedNode::Output<'c>>,
+}
+impl<'n: 'c, 'c, CashedNode: Node> Node for CacheNode<'n, 'c, CashedNode> {
+    type Output<'a> = &'a CashedNode::Output<'c> where 'c: 'a;
+    type Input<'a> = CashedNode::Input<'c> where 'c: 'a;
+    fn eval<'a, I: Borrow<Self::Input<'a>>>(&'a self, input: I) -> Self::Output<'a> {
+        self.cache.get_or_init(|| self.node.eval(input))
+    }
+}
+
+impl<'n, 'c, CachedNode: Node> CacheNode<'n, 'c, CachedNode> {
+    pub fn clear(&'n mut self) {
+        self.cache = OnceCell::new();
+    }
+    pub fn new(node: &'n CachedNode) -> CacheNode<'n, 'c, CachedNode> {
+        CacheNode {
+            node,
+            cache: OnceCell::new(),
+        }
+    }
+}