Fixed: 'repeated_field[-1]' should return nothing.

Author: mpartel

expected/postgres_protobuf.out

@@ -205,6 +205,12 @@ aaa
 bbb
 ccc
 (3 rows)
+SELECT protobuf_query_multi(
+  'pgpb.test.ExampleMessage:repeated_string[-1]',
+  '\x1a036161611a036262621a03636363'::BYTEA
+) AS result;
+result
+(0 rows)
 SELECT protobuf_query_multi(
   'pgpb.test.ExampleMessage:repeated_inner[0].inner_repeated[*]',
   '\x2a0a120361626312036465662a0a12036161611203626262'::BYTEA

generate_test_cases.rb

@@ -239,6 +239,7 @@ def pg_quote(s)
       test_query('pgpb.test.ExampleMessage:repeated_string[2]', ['ccc'])
       test_query('pgpb.test.ExampleMessage:repeated_string[3]', [])
       test_query('pgpb.test.ExampleMessage:repeated_string[*]', ['aaa', 'bbb', 'ccc'])
+      test_query('pgpb.test.ExampleMessage:repeated_string[-1]', [])
     end
 
     with_proto('repeated_inner: { inner_repeated: "abc", inner_repeated: "def" }, repeated_inner { inner_repeated: "aaa", inner_repeated: "bbb" }') do

querying.cpp

@@ -611,7 +611,7 @@ class FieldSelector : public ProtobufVisitor {
         wanted_field_(wanted_field),
         ty_(ty),
         is_packed_(is_packed),
-        wanted_index_(-1),
+        wanted_index_(),
         state_(State::Scanning),
         current_field_(0),
         current_index_(0) {
@@ -675,7 +675,7 @@ class FieldSelector : public ProtobufVisitor {
   const int wanted_field_;
   const pb::FieldDescriptor::Type ty_;
   const bool is_packed_;
-  int wanted_index_;
+  std::optional<int> wanted_index_;
 
   enum class State {
     Scanning,
@@ -688,7 +688,7 @@ class FieldSelector : public ProtobufVisitor {
 
   bool ShouldEmitCurrentIndex() const {
     return current_field_ == wanted_field_ &&
-           (wanted_index_ == -1 || current_index_ == wanted_index_);
+           (!wanted_index_.has_value() || current_index_ == wanted_index_.value());
   }
 };
 

sql/postgres_protobuf.sql

@@ -123,6 +123,10 @@ SELECT protobuf_query_multi(
   'pgpb.test.ExampleMessage:repeated_string[*]',
   '\x1a036161611a036262621a03636363'::BYTEA
 ) AS result;
+SELECT protobuf_query_multi(
+  'pgpb.test.ExampleMessage:repeated_string[-1]',
+  '\x1a036161611a036262621a03636363'::BYTEA
+) AS result;
 SELECT protobuf_query_multi(
   'pgpb.test.ExampleMessage:repeated_inner[0].inner_repeated[*]',
   '\x2a0a120361626312036465662a0a12036161611203626262'::BYTEA