add non scalar default bfbs support

Author: thejtshow

include/flatbuffers/idl.h

@@ -226,9 +226,12 @@ struct Type {
 struct Value {
   Value()
       : constant("0"),
+        has_non_scalar_constant(false),
         offset(static_cast<voffset_t>(~(static_cast<voffset_t>(0U)))) {}
   Type type;
   std::string constant;
+  // not the most elegant solution, but much better than a full refactor.
+  bool has_non_scalar_constant;
   voffset_t offset;
 };
 
@@ -342,11 +345,9 @@ struct FieldDef : public Definition {
 
   bool Deserialize(Parser &parser, const reflection::Field *field);
 
-  bool IsScalarOptional() const {
-    return IsScalar() && IsOptional();
-  }
+  bool IsScalarOptional() const { return IsScalar() && IsOptional(); }
   bool IsScalar() const {
-      return ::flatbuffers::IsScalar(value.type.base_type);
+    return ::flatbuffers::IsScalar(value.type.base_type);
   }
   bool IsOptional() const { return presence == kOptional; }
   bool IsRequired() const { return presence == kRequired; }
@@ -710,7 +711,7 @@ struct IDLOptions {
   /********************************** Python **********************************/
   bool python_no_type_prefix_suffix;
   bool python_typing;
-  bool python_decode_obj_api_strings=false;
+  bool python_decode_obj_api_strings = false;
 
   // The target Python version. Can be one of the following:
   // -  "0"
@@ -1255,10 +1256,9 @@ class Parser : public ParserState {
 // These functions return nullptr on success, or an error string,
 // which may happen if the flatbuffer cannot be encoded in JSON (e.g.,
 // it contains non-UTF-8 byte arrays in String values).
-extern bool GenerateTextFromTable(const Parser &parser,
-                                         const void *table,
-                                         const std::string &tablename,
-                                         std::string *text);
+extern bool GenerateTextFromTable(const Parser &parser, const void *table,
+                                  const std::string &tablename,
+                                  std::string *text);
 extern const char *GenerateText(const Parser &parser, const void *flatbuffer,
                                 std::string *text);
 extern const char *GenerateTextFile(const Parser &parser,

include/flatbuffers/reflection_generated.h

@@ -45,7 +45,7 @@ struct SchemaFileBuilder;
 struct Schema;
 struct SchemaBuilder;
 
-enum BaseType {
+enum BaseType : int8_t {
   None = 0,
   UType = 1,
   Bool = 2,
@@ -128,7 +128,7 @@ inline const char *EnumNameBaseType(BaseType e) {
 }
 
 /// New schema language features that are not supported by old code generators.
-enum AdvancedFeatures {
+enum AdvancedFeatures : uint64_t {
   AdvancedArrayFeatures = 1ULL,
   AdvancedUnionFeatures = 2ULL,
   OptionalScalars = 4ULL,
@@ -617,7 +617,8 @@ struct Field FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
     VT_DOCUMENTATION = 24,
     VT_OPTIONAL = 26,
     VT_PADDING = 28,
-    VT_OFFSET64 = 30
+    VT_OFFSET64 = 30,
+    VT_DEFAULT_NON_SCALAR = 32
   };
   const ::flatbuffers::String *name() const {
     return GetPointer<const ::flatbuffers::String *>(VT_NAME);
@@ -675,6 +676,9 @@ struct Field FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
   bool offset64() const {
     return GetField<uint8_t>(VT_OFFSET64, 0) != 0;
   }
+  const ::flatbuffers::String *default_non_scalar() const {
+    return GetPointer<const ::flatbuffers::String *>(VT_DEFAULT_NON_SCALAR);
+  }
   bool Verify(::flatbuffers::Verifier &verifier) const {
     return VerifyTableStart(verifier) &&
            VerifyOffsetRequired(verifier, VT_NAME) &&
@@ -697,6 +701,8 @@ struct Field FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {
            VerifyField<uint8_t>(verifier, VT_OPTIONAL, 1) &&
            VerifyField<uint16_t>(verifier, VT_PADDING, 2) &&
            VerifyField<uint8_t>(verifier, VT_OFFSET64, 1) &&
+           VerifyOffset(verifier, VT_DEFAULT_NON_SCALAR) &&
+           verifier.VerifyString(default_non_scalar()) &&
            verifier.EndTable();
   }
 };
@@ -747,6 +753,9 @@ struct FieldBuilder {
   void add_offset64(bool offset64) {
     fbb_.AddElement<uint8_t>(Field::VT_OFFSET64, static_cast<uint8_t>(offset64), 0);
   }
+  void add_default_non_scalar(::flatbuffers::Offset<::flatbuffers::String> default_non_scalar) {
+    fbb_.AddOffset(Field::VT_DEFAULT_NON_SCALAR, default_non_scalar);
+  }
   explicit FieldBuilder(::flatbuffers::FlatBufferBuilder &_fbb)
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
@@ -775,10 +784,12 @@ inline ::flatbuffers::Offset<Field> CreateField(
     ::flatbuffers::Offset<::flatbuffers::Vector<::flatbuffers::Offset<::flatbuffers::String>>> documentation = 0,
     bool optional = false,
     uint16_t padding = 0,
-    bool offset64 = false) {
+    bool offset64 = false,
+    ::flatbuffers::Offset<::flatbuffers::String> default_non_scalar = 0) {
   FieldBuilder builder_(_fbb);
   builder_.add_default_real(default_real);
   builder_.add_default_integer(default_integer);
+  builder_.add_default_non_scalar(default_non_scalar);
   builder_.add_documentation(documentation);
   builder_.add_attributes(attributes);
   builder_.add_type(type);
@@ -809,10 +820,12 @@ inline ::flatbuffers::Offset<Field> CreateFieldDirect(
     const std::vector<::flatbuffers::Offset<::flatbuffers::String>> *documentation = nullptr,
     bool optional = false,
     uint16_t padding = 0,
-    bool offset64 = false) {
+    bool offset64 = false,
+    const char *default_non_scalar = nullptr) {
   auto name__ = name ? _fbb.CreateString(name) : 0;
   auto attributes__ = attributes ? _fbb.CreateVectorOfSortedTables<reflection::KeyValue>(attributes) : 0;
   auto documentation__ = documentation ? _fbb.CreateVector<::flatbuffers::Offset<::flatbuffers::String>>(*documentation) : 0;
+  auto default_non_scalar__ = default_non_scalar ? _fbb.CreateString(default_non_scalar) : 0;
   return reflection::CreateField(
       _fbb,
       name__,
@@ -828,7 +841,8 @@ inline ::flatbuffers::Offset<Field> CreateFieldDirect(
       documentation__,
       optional,
       padding,
-      offset64);
+      offset64,
+      default_non_scalar__);
 }
 
 struct Object FLATBUFFERS_FINAL_CLASS : private ::flatbuffers::Table {

reflection/reflection.fbs

@@ -88,6 +88,7 @@ table Field {
     padding:uint16 = 0; 
     /// If the field uses 64-bit offsets.
     offset64:bool = false;
+    default_non_scalar:string;
 }
 
 table Object {  // Used for both tables and structs.

src/binary_annotator.cpp

@@ -418,6 +418,12 @@ BinaryAnnotator::VTable *BinaryAnnotator::GetOrBuildVTable(
                                ? std::to_string(field->default_real())
                                : std::to_string(field->default_integer());
           default_label += "> (";
+        } else if ((field->type()->base_type() == reflection::String ||
+                    field->type()->base_type() == reflection::Vector) &&
+                   field->default_non_scalar() != nullptr) {
+          default_label += "<defaults to \"";
+          default_label += field->default_non_scalar()->str();
+          default_label += "\"> (";
         } else {
           default_label += "<null> (";
         }

src/idl_parser.cpp

@@ -994,6 +994,7 @@ CheckedError Parser::ParseField(StructDef &struct_def) {
             "Default values for strings and vectors are not supported in one "
             "of the specified programming languages");
       }
+      field->value.has_non_scalar_constant = true;
     }
 
     if (IsVector(type) && field->value.constant != "0" &&
@@ -4042,6 +4043,8 @@ Offset<reflection::Field> FieldDef::Serialize(FlatBufferBuilder *builder,
   auto docs__ = parser.opts.binary_schema_comments && !doc_comment.empty()
                     ? builder->CreateVectorOfStrings(doc_comment)
                     : 0;
+  auto default_non_scalar__ =
+      value.has_non_scalar_constant ? builder->CreateString(value.constant) : 0;
   double d;
   StringToNumber(value.constant.c_str(), &d);
   return reflection::CreateField(
@@ -4050,7 +4053,8 @@ Offset<reflection::Field> FieldDef::Serialize(FlatBufferBuilder *builder,
       IsInteger(value.type.base_type) ? StringToInt(value.constant.c_str()) : 0,
       // result may be platform-dependent if underlying is float (not double)
       IsFloat(value.type.base_type) ? d : 0.0, deprecated, IsRequired(), key,
-      attr__, docs__, IsOptional(), static_cast<uint16_t>(padding), offset64);
+      attr__, docs__, IsOptional(), static_cast<uint16_t>(padding), offset64,
+      default_non_scalar__);
   // 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.
 }
@@ -4064,6 +4068,10 @@ bool FieldDef::Deserialize(Parser &parser, const reflection::Field *field) {
     value.constant = NumToString(field->default_integer());
   } else if (IsFloat(value.type.base_type)) {
     value.constant = FloatToString(field->default_real(), 17);
+  } else if (IsString(value.type) || IsVector(value.type)) {
+    value.constant =
+        field->default_non_scalar() ? field->default_non_scalar()->str() : "";
+    value.has_non_scalar_constant = true;
   }
   presence = FieldDef::MakeFieldPresence(field->optional(), field->required());
   padding = field->padding();