Add support for parsing proto map fields (#7613)

* Add support for proto 3 map to fbs gen

* Run clang-format

* Update proto golden test

* Rename variables

* Remove iostream

* Remove iostream

* Run clang format

Co-authored-by: Derek Bailey <derekbailey@google.com>

include/flatbuffers/idl.h

@@ -489,11 +489,11 @@ inline bool IsVector(const Type &type) {
   return type.base_type == BASE_TYPE_VECTOR;
 }
 
-inline bool IsVectorOfStruct(const Type& type) {
+inline bool IsVectorOfStruct(const Type &type) {
   return IsVector(type) && IsStruct(type.VectorType());
 }
 
-inline bool IsVectorOfTable(const Type& type) {
+inline bool IsVectorOfTable(const Type &type) {
   return IsVector(type) && IsTable(type.VectorType());
 }
 
@@ -1031,6 +1031,7 @@ class Parser : public ParserState {
   FLATBUFFERS_CHECKED_ERROR ParseService(const char *filename);
   FLATBUFFERS_CHECKED_ERROR ParseProtoFields(StructDef *struct_def,
                                              bool isextend, bool inside_oneof);
+  FLATBUFFERS_CHECKED_ERROR ParseProtoMapField(StructDef *struct_def);
   FLATBUFFERS_CHECKED_ERROR ParseProtoOption();
   FLATBUFFERS_CHECKED_ERROR ParseProtoKey();
   FLATBUFFERS_CHECKED_ERROR ParseProtoDecl();

src/idl_gen_fbs.cpp

@@ -137,6 +137,7 @@ std::string GenerateFBS(const Parser &parser, const std::string &file_name) {
         schema += "  " + field.name + ":" + GenType(field.value.type);
         if (field.value.constant != "0") schema += " = " + field.value.constant;
         if (field.IsRequired()) schema += " (required)";
+        if (field.key) schema += " (key)";
         schema += ";\n";
       }
     }

src/idl_parser.cpp

@@ -507,6 +507,8 @@ CheckedError Parser::Next() {
       case ')':
       case '[':
       case ']':
+      case '<':
+      case '>':
       case ',':
       case ':':
       case ';':
@@ -2896,6 +2898,8 @@ CheckedError Parser::ParseProtoFields(StructDef *struct_def, bool isextend,
       NEXT();
       while (!Is(';')) { NEXT(); }  // A variety of formats, just skip.
       NEXT();
+    } else if (IsIdent("map")) {
+      ECHECK(ParseProtoMapField(struct_def));
     } else {
       std::vector<std::string> field_comment = doc_comment_;
       // Parse the qualifier.
@@ -3030,6 +3034,41 @@ CheckedError Parser::ParseProtoFields(StructDef *struct_def, bool isextend,
   return NoError();
 }
 
+CheckedError Parser::ParseProtoMapField(StructDef *struct_def) {
+  NEXT();
+  EXPECT('<');
+  Type key_type;
+  ECHECK(ParseType(key_type));
+  EXPECT(',');
+  Type value_type;
+  ECHECK(ParseType(value_type));
+  EXPECT('>');
+  auto field_name = attribute_;
+  NEXT();
+  EXPECT('=');
+  EXPECT(kTokenIntegerConstant);
+  EXPECT(';');
+
+  auto entry_table_name = ConvertCase(field_name, Case::kUpperCamel) + "Entry";
+  StructDef *entry_table;
+  ECHECK(StartStruct(entry_table_name, &entry_table));
+  entry_table->has_key = true;
+  FieldDef *key_field;
+  ECHECK(AddField(*entry_table, "key", key_type, &key_field));
+  key_field->key = true;
+  FieldDef *value_field;
+  ECHECK(AddField(*entry_table, "value", value_type, &value_field));
+
+  Type field_type;
+  field_type.base_type = BASE_TYPE_VECTOR;
+  field_type.element = BASE_TYPE_STRUCT;
+  field_type.struct_def = entry_table;
+  FieldDef *field;
+  ECHECK(AddField(*struct_def, field_name, field_type, &field));
+
+  return NoError();
+}
+
 CheckedError Parser::ParseProtoKey() {
   if (token_ == '(') {
     NEXT();

tests/proto_test.cpp

@@ -201,4 +201,4 @@ void ParseProtoBufAsciiTest() {
 }
 
 }  // namespace tests
-}  // namespace flatbuffers
+}  // namespace flatbuffers

tests/prototest/GenerateProtoGoldens.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+#
+# Copyright 2022 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+pushd "$(dirname $0)" >/dev/null
+
+./../../flatc --proto test.proto && mv test.fbs test_include.golden
+./../../flatc --proto --gen-all test.proto && mv test.fbs test.golden
+./../../flatc --proto --oneof-union test.proto && mv test.fbs test_union_include.golden
+./../../flatc --proto --gen-all --oneof-union test.proto && mv test.fbs test_union.golden
+./../../flatc --proto --gen-all --proto-namespace-suffix test_namespace_suffix test.proto && mv test.fbs test_suffix.golden
+./../../flatc --proto --gen-all --proto-namespace-suffix test_namespace_suffix --oneof-union test.proto && mv test.fbs test_union_suffix.golden

tests/prototest/test.golden

@@ -54,6 +54,8 @@ table ProtoMessage {
   u:float = +inf;
   v:float = +inf;
   w:float = -inf;
+  grades:[proto.test.ProtoMessage_.GradesEntry];
+  other_message_map:[proto.test.ProtoMessage_.OtherMessageMapEntry];
 }
 
 namespace proto.test.ProtoMessage_;
@@ -73,3 +75,13 @@ table Anonymous0 {
   t:proto.test.ProtoMessage_.OtherMessage;
 }
 
+table GradesEntry {
+  key:string (key);
+  value:float;
+}
+
+table OtherMessageMapEntry {
+  key:string (key);
+  value:proto.test.ProtoMessage_.OtherMessage;
+}
+

tests/prototest/test.proto

@@ -71,4 +71,7 @@ message ProtoMessage {
   optional float u = 34 [default = inf];
   optional float v = 35 [default = +inf];
   optional float w = 36 [default = -inf];
+
+  map<string, float> grades = 37;
+  map<string, OtherMessage> other_message_map = 38;
 }

tests/prototest/test_include.golden

@@ -52,6 +52,8 @@ table ProtoMessage {
   u:float = +inf;
   v:float = +inf;
   w:float = -inf;
+  grades:[proto.test.ProtoMessage_.GradesEntry];
+  other_message_map:[proto.test.ProtoMessage_.OtherMessageMapEntry];
 }
 
 namespace proto.test.ProtoMessage_;
@@ -71,3 +73,13 @@ table Anonymous0 {
   t:proto.test.ProtoMessage_.OtherMessage;
 }
 
+table GradesEntry {
+  key:string (key);
+  value:float;
+}
+
+table OtherMessageMapEntry {
+  key:string (key);
+  value:proto.test.ProtoMessage_.OtherMessage;
+}
+

tests/prototest/test_suffix.golden

@@ -54,6 +54,8 @@ table ProtoMessage {
   u:float = +inf;
   v:float = +inf;
   w:float = -inf;
+  grades:[proto.test.test_namespace_suffix.ProtoMessage_.GradesEntry];
+  other_message_map:[proto.test.test_namespace_suffix.ProtoMessage_.OtherMessageMapEntry];
 }
 
 namespace proto.test.test_namespace_suffix.ProtoMessage_;
@@ -73,3 +75,13 @@ table Anonymous0 {
   t:proto.test.test_namespace_suffix.ProtoMessage_.OtherMessage;
 }
 
+table GradesEntry {
+  key:string (key);
+  value:float;
+}
+
+table OtherMessageMapEntry {
+  key:string (key);
+  value:proto.test.test_namespace_suffix.ProtoMessage_.OtherMessage;
+}
+

tests/prototest/test_union.golden

@@ -64,6 +64,8 @@ table ProtoMessage {
   u:float = +inf;
   v:float = +inf;
   w:float = -inf;
+  grades:[proto.test.ProtoMessage_.GradesEntry];
+  other_message_map:[proto.test.ProtoMessage_.OtherMessageMapEntry];
 }
 
 namespace proto.test.ProtoMessage_;
@@ -75,3 +77,13 @@ table OtherMessage {
   foo_bar_baz:proto.test.ProtoMessage_.OtherMessage_.ProtoEnum;
 }
 
+table GradesEntry {
+  key:string (key);
+  value:float;
+}
+
+table OtherMessageMapEntry {
+  key:string (key);
+  value:proto.test.ProtoMessage_.OtherMessage;
+}
+

tests/prototest/test_union_include.golden

@@ -62,6 +62,8 @@ table ProtoMessage {
   u:float = +inf;
   v:float = +inf;
   w:float = -inf;
+  grades:[proto.test.ProtoMessage_.GradesEntry];
+  other_message_map:[proto.test.ProtoMessage_.OtherMessageMapEntry];
 }
 
 namespace proto.test.ProtoMessage_;
@@ -73,3 +75,13 @@ table OtherMessage {
   foo_bar_baz:proto.test.ProtoMessage_.OtherMessage_.ProtoEnum;
 }
 
+table GradesEntry {
+  key:string (key);
+  value:float;
+}
+
+table OtherMessageMapEntry {
+  key:string (key);
+  value:proto.test.ProtoMessage_.OtherMessage;
+}
+

tests/prototest/test_union_suffix.golden

@@ -64,6 +64,8 @@ table ProtoMessage {
   u:float = +inf;
   v:float = +inf;
   w:float = -inf;
+  grades:[proto.test.test_namespace_suffix.ProtoMessage_.GradesEntry];
+  other_message_map:[proto.test.test_namespace_suffix.ProtoMessage_.OtherMessageMapEntry];
 }
 
 namespace proto.test.test_namespace_suffix.ProtoMessage_;
@@ -75,3 +77,13 @@ table OtherMessage {
   foo_bar_baz:proto.test.test_namespace_suffix.ProtoMessage_.OtherMessage_.ProtoEnum;
 }
 
+table GradesEntry {
+  key:string (key);
+  value:float;
+}
+
+table OtherMessageMapEntry {
+  key:string (key);
+  value:proto.test.test_namespace_suffix.ProtoMessage_.OtherMessage;
+}
+