From f9af31624f5cac5aa14956a29ed3896404cf1d27 Mon Sep 17 00:00:00 2001
From: Arnaud Mimart <33665250+amimart@users.noreply.github.com>
Date: Mon, 22 May 2023 18:21:44 +0200
Subject: [PATCH] feat(cognitarium): handle query engine for loop join

---
 contracts/okp4-cognitarium/src/querier/engine.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/contracts/okp4-cognitarium/src/querier/engine.rs b/contracts/okp4-cognitarium/src/querier/engine.rs
index 8c160316..c78ac1b6 100644
--- a/contracts/okp4-cognitarium/src/querier/engine.rs
+++ b/contracts/okp4-cognitarium/src/querier/engine.rs
@@ -33,7 +33,13 @@ impl<'a> QueryEngine<'a> {
             QueryNode::CartesianProductJoin { left, right } => {
                 Box::new(move |_| Box::new(iter::empty()))
             }
-            QueryNode::ForLoopJoin { left, right } => Box::new(move |_| Box::new(iter::empty())),
+            QueryNode::ForLoopJoin { left, right } => {
+                let left = self.eval_node(left);
+                let right = self.eval_node(right);
+                Box::new(move |vars| -> ResolvedVariablesIterator {
+                    Box::new(left(vars).flat_map(move |v| right(v)))
+                })
+            }
             QueryNode::Skip { child, first } => {
                 let upstream = self.eval_node(child);
                 Box::new(move |vars| -> ResolvedVariablesIterator {