From b72c46f21ff1fad5aaffc171338ecc1c78bd789f Mon Sep 17 00:00:00 2001
From: Harpreet Sangar <happy_san@protonmail.com>
Date: Thu, 30 Mar 2023 09:52:10 +0530
Subject: [PATCH] Handle null filter tree.

---
 include/filter.h     |  5 +++++
 src/filter.cpp       | 10 +++++++++-
 test/filter_test.cpp |  6 ++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/include/filter.h b/include/filter.h
index 41ccfac8..babee59d 100644
--- a/include/filter.h
+++ b/include/filter.h
@@ -53,6 +53,11 @@ public:
                                       collection_name(collection_name),
                                       index(index),
                                       filter_node(filter_node) {
+        if (filter_node == nullptr) {
+            is_valid = false;
+            return;
+        }
+
         // Generate the iterator tree and then initialize each node.
         if (filter_node->isOperator) {
             left_it = new filter_result_iterator_t(collection_name, index, filter_node->left);
diff --git a/src/filter.cpp b/src/filter.cpp
index d40a5564..27c21198 100644
--- a/src/filter.cpp
+++ b/src/filter.cpp
@@ -207,6 +207,10 @@ void filter_result_iterator_t::next() {
 }
 
 void filter_result_iterator_t::init() {
+    if (filter_node == nullptr) {
+        return;
+    }
+
     if (filter_node->isOperator) {
         if (filter_node->filter_operator == AND) {
             and_filter_iterators();
@@ -494,7 +498,7 @@ int filter_result_iterator_t::valid(uint32_t id) {
 }
 
 Option<bool> filter_result_iterator_t::init_status() {
-    if (filter_node->isOperator) {
+    if (filter_node != nullptr && filter_node->isOperator) {
         auto left_status = left_it->init_status();
 
         return !left_status.ok() ? left_status : right_it->init_status();
@@ -546,6 +550,10 @@ bool filter_result_iterator_t::contains_atleast_one(const void *obj) {
 }
 
 void filter_result_iterator_t::reset() {
+    if (filter_node == nullptr) {
+        return;
+    }
+
     if (filter_node->isOperator) {
         // Reset the subtrees then apply operators to arrive at the first valid doc.
         left_it->reset();
diff --git a/test/filter_test.cpp b/test/filter_test.cpp
index af7145f2..6a952c57 100644
--- a/test/filter_test.cpp
+++ b/test/filter_test.cpp
@@ -61,6 +61,12 @@ TEST_F(FilterTest, FilterTreeIterator) {
 
     const std::string doc_id_prefix = std::to_string(coll->get_collection_id()) + "_" + Collection::DOC_ID_PREFIX + "_";
     filter_node_t* filter_tree_root = nullptr;
+
+    auto iter_null_filter_tree_test = filter_result_iterator_t(coll->get_name(), coll->_get_index(), filter_tree_root);
+
+    ASSERT_TRUE(iter_null_filter_tree_test.init_status().ok());
+    ASSERT_FALSE(iter_null_filter_tree_test.valid());
+
     Option<bool> filter_op = filter::parse_filter_query("name: foo", coll->get_schema(), store, doc_id_prefix,
                                                         filter_tree_root);
     ASSERT_TRUE(filter_op.ok());