2 files changed, 12 insertions, 2 deletions
diff --git a/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java b/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java
index 5fdd505..6054711 100644
--- a/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java
+++ b/src/main/java/org/zwobble/couscous/ast/structure/NodeStructure.java
@@ -3,11 +3,22 @@ package org.zwobble.couscous.ast.structure;
 import org.zwobble.couscous.ast.*;
 import org.zwobble.couscous.ast.visitors.NodeMapper;
 
+import java.util.function.Predicate;
 import java.util.stream.Stream;
 
 import static org.zwobble.couscous.util.ExtraStreams.concatStreams;
 
 public class NodeStructure {
+    public static Stream<? extends Node> descendantNodesAndSelf(Node node, Predicate<Node> predicate) {
+        return Stream.concat(Stream.of(node), descendantNodes(node, predicate));
+    }
+
+    public static Stream<? extends Node> descendantNodes(Node node, Predicate<Node> predicate) {
+        return childNodes(node)
+            .filter(predicate)
+            .flatMap(child -> descendantNodesAndSelf(child, predicate));
+    }
+
     public static Stream<? extends Node> descendantNodesAndSelf(Node node) {
         return Stream.concat(Stream.of(node), descendantNodes(node));
     }
diff --git a/src/main/java/org/zwobble/couscous/interpreter/Executor.java b/src/main/java/org/zwobble/couscous/interpreter/Executor.java
index c9528be..556e7d1 100644
--- a/src/main/java/org/zwobble/couscous/interpreter/Executor.java
+++ b/src/main/java/org/zwobble/couscous/interpreter/Executor.java
@@ -37,9 +37,8 @@ public class Executor implements StatementNodeMapper<Optional<InterpreterValue>>
     }
 
     private static Stream<VariableNode> findDeclarations(List<StatementNode> body) {
-        // TODO: add filter argument to descendantNodesAndSelf to allow recursion to be stopped early
         return body.stream()
-            .flatMap(NodeStructure::descendantNodesAndSelf)
+            .flatMap(statement -> descendantNodesAndSelf(statement, node -> node instanceof StatementNode))
             .flatMap(node -> node.accept(new NodeMapperWithDefault<Stream<VariableNode>>(Stream.empty()) {
                 @Override
                 public Stream<VariableNode> visit(LocalVariableDeclarationNode localVariableDeclaration) {