Added doc comments to the binary schema.

Change-Id: I87f291ab6e07b1425850cae25ed500db594f17c8
Tested: on Linux.

8 files changed, 81 insertions, 18 deletions

diff --git a/docs/source/Compiler.md b/docs/source/Compiler.md
index 6d881cc8..a155df46 100755
--- a/docs/source/Compiler.md
+++ b/docs/source/Compiler.md
@@ -114,6 +114,8 @@ Additional options:
     to the reflection/reflection.fbs schema. Loading this binary file is the
     basis for reflection functionality.
 
+-   `--bfbs-comments`: Add doc comments to the binary schema files.
+
 -   `--conform FILE` : Specify a schema the following schemas should be
     an evolution of. Gives errors if not. Useful to check if schema
     modifications don't break schema evolution rules.
diff --git a/include/flatbuffers/idl.h b/include/flatbuffers/idl.h
index 2e09b39a..5b7a72a3 100644
--- a/include/flatbuffers/idl.h
+++ b/include/flatbuffers/idl.h
@@ -356,6 +356,7 @@ struct IDLOptions {
   bool union_value_namespacing;
   bool allow_non_utf8;
   std::string include_prefix;
+  bool binary_schema_comments;
 
   // Possible options for the more general generator below.
   enum Language {
@@ -396,6 +397,7 @@ struct IDLOptions {
       cpp_object_api_pointer_type("std::unique_ptr"),
       union_value_namespacing(true),
       allow_non_utf8(false),
+      binary_schema_comments(false),
       lang(IDLOptions::kJava),
       lang_to_generate(0) {}
 };
diff --git a/include/flatbuffers/reflection_generated.h b/include/flatbuffers/reflection_generated.h
index df745f23..8379dcf5 100644
--- a/include/flatbuffers/reflection_generated.h
+++ b/include/flatbuffers/reflection_generated.h
@@ -294,7 +294,8 @@ struct Enum FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
     VT_VALUES = 6,
     VT_IS_UNION = 8,
     VT_UNDERLYING_TYPE = 10,
-    VT_ATTRIBUTES = 12
+    VT_ATTRIBUTES = 12,
+    VT_DOCUMENTATION = 14
   };
   const flatbuffers::String *name() const {
     return GetPointer<const flatbuffers::String *>(VT_NAME);
@@ -317,6 +318,9 @@ struct Enum FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
   const flatbuffers::Vector<flatbuffers::Offset<KeyValue>> *attributes() const {
     return GetPointer<const flatbuffers::Vector<flatbuffers::Offset<KeyValue>> *>(VT_ATTRIBUTES);
   }
+  const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *documentation() const {
+    return GetPointer<const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *>(VT_DOCUMENTATION);
+  }
   bool Verify(flatbuffers::Verifier &verifier) const {
     return VerifyTableStart(verifier) &&
            VerifyFieldRequired<flatbuffers::uoffset_t>(verifier, VT_NAME) &&
@@ -330,6 +334,9 @@ struct Enum FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
            VerifyField<flatbuffers::uoffset_t>(verifier, VT_ATTRIBUTES) &&
            verifier.Verify(attributes()) &&
            verifier.VerifyVectorOfTables(attributes()) &&
+           VerifyField<flatbuffers::uoffset_t>(verifier, VT_DOCUMENTATION) &&
+           verifier.Verify(documentation()) &&
+           verifier.VerifyVectorOfStrings(documentation()) &&
            verifier.EndTable();
   }
 };
@@ -352,13 +359,16 @@ struct EnumBuilder {
   void add_attributes(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes) {
     fbb_.AddOffset(Enum::VT_ATTRIBUTES, attributes);
   }
+  void add_documentation(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation) {
+    fbb_.AddOffset(Enum::VT_DOCUMENTATION, documentation);
+  }
   EnumBuilder(flatbuffers::FlatBufferBuilder &_fbb)
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
   EnumBuilder &operator=(const EnumBuilder &);
   flatbuffers::Offset<Enum> Finish() {
-    const auto end = fbb_.EndTable(start_, 5);
+    const auto end = fbb_.EndTable(start_, 6);
     auto o = flatbuffers::Offset<Enum>(end);
     fbb_.Required(o, Enum::VT_NAME);
     fbb_.Required(o, Enum::VT_VALUES);
@@ -373,8 +383,10 @@ inline flatbuffers::Offset<Enum> CreateEnum(
     flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<EnumVal>>> values = 0,
     bool is_union = false,
     flatbuffers::Offset<Type> underlying_type = 0,
-    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes = 0) {
+    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes = 0,
+    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation = 0) {
   EnumBuilder builder_(_fbb);
+  builder_.add_documentation(documentation);
   builder_.add_attributes(attributes);
   builder_.add_underlying_type(underlying_type);
   builder_.add_values(values);
@@ -389,14 +401,16 @@ inline flatbuffers::Offset<Enum> CreateEnumDirect(
     const std::vector<flatbuffers::Offset<EnumVal>> *values = nullptr,
     bool is_union = false,
     flatbuffers::Offset<Type> underlying_type = 0,
-    const std::vector<flatbuffers::Offset<KeyValue>> *attributes = nullptr) {
+    const std::vector<flatbuffers::Offset<KeyValue>> *attributes = nullptr,
+    const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
   return reflection::CreateEnum(
       _fbb,
       name ? _fbb.CreateString(name) : 0,
       values ? _fbb.CreateVector<flatbuffers::Offset<EnumVal>>(*values) : 0,
       is_union,
       underlying_type,
-      attributes ? _fbb.CreateVector<flatbuffers::Offset<KeyValue>>(*attributes) : 0);
+      attributes ? _fbb.CreateVector<flatbuffers::Offset<KeyValue>>(*attributes) : 0,
+      documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0);
 }
 
 struct Field FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
@@ -410,7 +424,8 @@ struct Field FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
     VT_DEPRECATED = 16,
     VT_REQUIRED = 18,
     VT_KEY = 20,
-    VT_ATTRIBUTES = 22
+    VT_ATTRIBUTES = 22,
+    VT_DOCUMENTATION = 24
   };
   const flatbuffers::String *name() const {
     return GetPointer<const flatbuffers::String *>(VT_NAME);
@@ -448,6 +463,9 @@ struct Field FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
   const flatbuffers::Vector<flatbuffers::Offset<KeyValue>> *attributes() const {
     return GetPointer<const flatbuffers::Vector<flatbuffers::Offset<KeyValue>> *>(VT_ATTRIBUTES);
   }
+  const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *documentation() const {
+    return GetPointer<const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *>(VT_DOCUMENTATION);
+  }
   bool Verify(flatbuffers::Verifier &verifier) const {
     return VerifyTableStart(verifier) &&
            VerifyFieldRequired<flatbuffers::uoffset_t>(verifier, VT_NAME) &&
@@ -464,6 +482,9 @@ struct Field FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
            VerifyField<flatbuffers::uoffset_t>(verifier, VT_ATTRIBUTES) &&
            verifier.Verify(attributes()) &&
            verifier.VerifyVectorOfTables(attributes()) &&
+           VerifyField<flatbuffers::uoffset_t>(verifier, VT_DOCUMENTATION) &&
+           verifier.Verify(documentation()) &&
+           verifier.VerifyVectorOfStrings(documentation()) &&
            verifier.EndTable();
   }
 };
@@ -501,13 +522,16 @@ struct FieldBuilder {
   void add_attributes(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes) {
     fbb_.AddOffset(Field::VT_ATTRIBUTES, attributes);
   }
+  void add_documentation(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation) {
+    fbb_.AddOffset(Field::VT_DOCUMENTATION, documentation);
+  }
   FieldBuilder(flatbuffers::FlatBufferBuilder &_fbb)
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
   FieldBuilder &operator=(const FieldBuilder &);
   flatbuffers::Offset<Field> Finish() {
-    const auto end = fbb_.EndTable(start_, 10);
+    const auto end = fbb_.EndTable(start_, 11);
     auto o = flatbuffers::Offset<Field>(end);
     fbb_.Required(o, Field::VT_NAME);
     fbb_.Required(o, Field::VT_TYPE);
@@ -526,10 +550,12 @@ inline flatbuffers::Offset<Field> CreateField(
     bool deprecated = false,
     bool required = false,
     bool key = false,
-    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes = 0) {
+    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes = 0,
+    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation = 0) {
   FieldBuilder builder_(_fbb);
   builder_.add_default_real(default_real);
   builder_.add_default_integer(default_integer);
+  builder_.add_documentation(documentation);
   builder_.add_attributes(attributes);
   builder_.add_type(type);
   builder_.add_name(name);
@@ -552,7 +578,8 @@ inline flatbuffers::Offset<Field> CreateFieldDirect(
     bool deprecated = false,
     bool required = false,
     bool key = false,
-    const std::vector<flatbuffers::Offset<KeyValue>> *attributes = nullptr) {
+    const std::vector<flatbuffers::Offset<KeyValue>> *attributes = nullptr,
+    const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
   return reflection::CreateField(
       _fbb,
       name ? _fbb.CreateString(name) : 0,
@@ -564,7 +591,8 @@ inline flatbuffers::Offset<Field> CreateFieldDirect(
       deprecated,
       required,
       key,
-      attributes ? _fbb.CreateVector<flatbuffers::Offset<KeyValue>>(*attributes) : 0);
+      attributes ? _fbb.CreateVector<flatbuffers::Offset<KeyValue>>(*attributes) : 0,
+      documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0);
 }
 
 struct Object FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
@@ -574,7 +602,8 @@ struct Object FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
     VT_IS_STRUCT = 8,
     VT_MINALIGN = 10,
     VT_BYTESIZE = 12,
-    VT_ATTRIBUTES = 14
+    VT_ATTRIBUTES = 14,
+    VT_DOCUMENTATION = 16
   };
   const flatbuffers::String *name() const {
     return GetPointer<const flatbuffers::String *>(VT_NAME);
@@ -600,6 +629,9 @@ struct Object FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
   const flatbuffers::Vector<flatbuffers::Offset<KeyValue>> *attributes() const {
     return GetPointer<const flatbuffers::Vector<flatbuffers::Offset<KeyValue>> *>(VT_ATTRIBUTES);
   }
+  const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *documentation() const {
+    return GetPointer<const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *>(VT_DOCUMENTATION);
+  }
   bool Verify(flatbuffers::Verifier &verifier) const {
     return VerifyTableStart(verifier) &&
            VerifyFieldRequired<flatbuffers::uoffset_t>(verifier, VT_NAME) &&
@@ -613,6 +645,9 @@ struct Object FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
            VerifyField<flatbuffers::uoffset_t>(verifier, VT_ATTRIBUTES) &&
            verifier.Verify(attributes()) &&
            verifier.VerifyVectorOfTables(attributes()) &&
+           VerifyField<flatbuffers::uoffset_t>(verifier, VT_DOCUMENTATION) &&
+           verifier.Verify(documentation()) &&
+           verifier.VerifyVectorOfStrings(documentation()) &&
            verifier.EndTable();
   }
 };
@@ -638,13 +673,16 @@ struct ObjectBuilder {
   void add_attributes(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes) {
     fbb_.AddOffset(Object::VT_ATTRIBUTES, attributes);
   }
+  void add_documentation(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation) {
+    fbb_.AddOffset(Object::VT_DOCUMENTATION, documentation);
+  }
   ObjectBuilder(flatbuffers::FlatBufferBuilder &_fbb)
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
   ObjectBuilder &operator=(const ObjectBuilder &);
   flatbuffers::Offset<Object> Finish() {
-    const auto end = fbb_.EndTable(start_, 6);
+    const auto end = fbb_.EndTable(start_, 7);
     auto o = flatbuffers::Offset<Object>(end);
     fbb_.Required(o, Object::VT_NAME);
     fbb_.Required(o, Object::VT_FIELDS);
@@ -659,8 +697,10 @@ inline flatbuffers::Offset<Object> CreateObject(
     bool is_struct = false,
     int32_t minalign = 0,
     int32_t bytesize = 0,
-    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes = 0) {
+    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<KeyValue>>> attributes = 0,
+    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation = 0) {
   ObjectBuilder builder_(_fbb);
+  builder_.add_documentation(documentation);
   builder_.add_attributes(attributes);
   builder_.add_bytesize(bytesize);
   builder_.add_minalign(minalign);
@@ -677,7 +717,8 @@ inline flatbuffers::Offset<Object> CreateObjectDirect(
     bool is_struct = false,
     int32_t minalign = 0,
     int32_t bytesize = 0,
-    const std::vector<flatbuffers::Offset<KeyValue>> *attributes = nullptr) {
+    const std::vector<flatbuffers::Offset<KeyValue>> *attributes = nullptr,
+    const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
   return reflection::CreateObject(
       _fbb,
       name ? _fbb.CreateString(name) : 0,
@@ -685,7 +726,8 @@ inline flatbuffers::Offset<Object> CreateObjectDirect(
       is_struct,
       minalign,
       bytesize,
-      attributes ? _fbb.CreateVector<flatbuffers::Offset<KeyValue>>(*attributes) : 0);
+      attributes ? _fbb.CreateVector<flatbuffers::Offset<KeyValue>>(*attributes) : 0,
+      documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0);
 }
 
 struct Schema FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
diff --git a/reflection/reflection.fbs b/reflection/reflection.fbs
index 57f234c6..76ccf85c 100644
--- a/reflection/reflection.fbs
+++ b/reflection/reflection.fbs
@@ -51,6 +51,7 @@ table Enum {
     is_union:bool = false;
     underlying_type:Type (required);
     attributes:[KeyValue];
+    documentation:[string];
 }
 
 table Field {
@@ -64,6 +65,7 @@ table Field {
     required:bool = false;
     key:bool = false;
     attributes:[KeyValue];
+    documentation:[string];
 }
 
 table Object {  // Used for both tables and structs.
@@ -73,6 +75,7 @@ table Object {  // Used for both tables and structs.
     minalign:int;
     bytesize:int;  // For structs.
     attributes:[KeyValue];
+    documentation:[string];
 }
 
 table Schema {
diff --git a/src/flatc.cpp b/src/flatc.cpp
index 053f112b..ed13c2ad 100644
--- a/src/flatc.cpp
+++ b/src/flatc.cpp
@@ -93,6 +93,7 @@ std::string FlatCompiler::GetUsageString(const char* program_name) const {
       "  --proto            Input is a .proto, translate to .fbs.\n"
       "  --grpc             Generate GRPC interfaces for the specified languages\n"
       "  --schema           Serialize schemas instead of JSON (use with -b)\n"
+      "  --bfbs-comments    Add doc comments to the binary schema files.\n"
       "  --conform FILE     Specify a schema the following schemas should be\n"
       "                     an evolution of. Gives errors if not.\n"
       "  --conform-includes Include path for the schema given with --conform\n"
@@ -204,6 +205,8 @@ int FlatCompiler::Compile(int argc, const char** argv) {
         exit(0);
       } else if(arg == "--grpc") {
         grpc_enabled = true;
+      } else if(arg == "--bfbs-comments") {
+        opts.binary_schema_comments = true;
       } else {
         for (size_t i = 0; i < params_.num_generators; ++i) {
           if (arg == params_.generators[i].generator_opt_long ||
diff --git a/src/idl_parser.cpp b/src/idl_parser.cpp
index 454abd30..7adfcca2 100644
--- a/src/idl_parser.cpp
+++ b/src/idl_parser.cpp
@@ -2086,7 +2086,11 @@ Offset<reflection::Object> StructDef::Serialize(FlatBufferBuilder *builder,
                                   fixed,
                                   static_cast<int>(minalign),
                                   static_cast<int>(bytesize),
-                                  SerializeAttributes(builder, parser));
+                                  SerializeAttributes(builder, parser),
+                                  parser.opts.binary_schema_comments
+                                    ? builder->CreateVectorOfStrings(
+                                        doc_comment)
+                                    : 0);
 }
 
 Offset<reflection::Field> FieldDef::Serialize(FlatBufferBuilder *builder,
@@ -2106,7 +2110,10 @@ Offset<reflection::Field> FieldDef::Serialize(FlatBufferBuilder *builder,
                                  deprecated,
                                  required,
                                  key,
-                                 SerializeAttributes(builder, parser));
+                                 SerializeAttributes(builder, parser),
+                                 parser.opts.binary_schema_comments
+                                   ? builder->CreateVectorOfStrings(doc_comment)
+                                   : 0);
   // TODO: value.constant is almost always "0", we could save quite a bit of
   // space by sharing it. Same for common values of value.type.
 }
@@ -2123,7 +2130,10 @@ Offset<reflection::Enum> EnumDef::Serialize(FlatBufferBuilder *builder,
                                 builder->CreateVector(enumval_offsets),
                                 is_union,
                                 underlying_type.Serialize(builder),
-                                SerializeAttributes(builder, parser));
+                                SerializeAttributes(builder, parser),
+                                parser.opts.binary_schema_comments
+                                  ? builder->CreateVectorOfStrings(doc_comment)
+                                  : 0);
 }
 
 Offset<reflection::EnumVal> EnumVal::Serialize(FlatBufferBuilder *builder) const
diff --git a/tests/generate_code.sh b/tests/generate_code.sh
index 0510b01d..a5354ebc 100755
--- a/tests/generate_code.sh
+++ b/tests/generate_code.sh
@@ -17,6 +17,7 @@
 ../flatc --cpp --java --csharp --go --binary --python --js --php --grpc --gen-mutable --gen-object-api --no-includes monster_test.fbs monsterdata_test.json
 ../flatc --cpp --java --csharp --go --binary --python --js --php --gen-mutable -o namespace_test namespace_test/namespace_test1.fbs namespace_test/namespace_test2.fbs
 ../flatc --cpp -o union_vector ./union_vector/union_vector.fbs
+../flatc -b --schema --bfbs-comments monster_test.fbs
 cd ../samples
 ../flatc --cpp --gen-mutable --gen-object-api monster.fbs
 cd ../reflection
diff --git a/tests/monster_test.bfbs b/tests/monster_test.bfbs
index 41d9edb1..21f3c000 100644
--- a/tests/monster_test.bfbs
+++ b/tests/monster_test.bfbs