Skip to content

Commit

Permalink
C++ generated code now has constants for vtable offsets.
Browse files Browse the repository at this point in the history 
Besides making the generated code looking a lot more readable,
it also allows you to use these offsets in calls to
Table::CheckField, to see if a field is present in a table.

Change-Id: I1b4cc350c4f27c4e474c31add40c701ef4ae63b2
Tested: On Linux.
  • Loading branch information
Wouter van Oortmerssen committed Nov 30, 2015
1 parent 6d1ff8a commit 1fa803d
Show file tree
Hide file tree
Showing 3 changed files with 203 additions and 142 deletions.
56 changes: 32 additions & 24 deletions samples/monster_generated.h
View file
Expand Up @@ -59,41 +59,49 @@ MANUALLY_ALIGNED_STRUCT(4) Vec3 FLATBUFFERS_FINAL_CLASS {
STRUCT_END(Vec3, 12);

struct Monster FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
const Vec3 *pos() const { return GetStruct<const Vec3 *>(4); }
Vec3 *mutable_pos() { return GetStruct<Vec3 *>(4); }
int16_t mana() const { return GetField<int16_t>(6, 150); }
bool mutate_mana(int16_t _mana) { return SetField(6, _mana); }
int16_t hp() const { return GetField<int16_t>(8, 100); }
bool mutate_hp(int16_t _hp) { return SetField(8, _hp); }
const flatbuffers::String *name() const { return GetPointer<const flatbuffers::String *>(10); }
flatbuffers::String *mutable_name() { return GetPointer<flatbuffers::String *>(10); }
const flatbuffers::Vector<uint8_t> *inventory() const { return GetPointer<const flatbuffers::Vector<uint8_t> *>(14); }
flatbuffers::Vector<uint8_t> *mutable_inventory() { return GetPointer<flatbuffers::Vector<uint8_t> *>(14); }
Color color() const { return static_cast<Color>(GetField<int8_t>(16, 2)); }
bool mutate_color(Color _color) { return SetField(16, static_cast<int8_t>(_color)); }
enum {
VT_POS = 4,
VT_MANA = 6,
VT_HP = 8,
VT_NAME = 10,
VT_INVENTORY = 14,
VT_COLOR = 16,
};
const Vec3 *pos() const { return GetStruct<const Vec3 *>(VT_POS); }
Vec3 *mutable_pos() { return GetStruct<Vec3 *>(VT_POS); }
int16_t mana() const { return GetField<int16_t>(VT_MANA, 150); }
bool mutate_mana(int16_t _mana) { return SetField(VT_MANA, _mana); }
int16_t hp() const { return GetField<int16_t>(VT_HP, 100); }
bool mutate_hp(int16_t _hp) { return SetField(VT_HP, _hp); }
const flatbuffers::String *name() const { return GetPointer<const flatbuffers::String *>(VT_NAME); }
flatbuffers::String *mutable_name() { return GetPointer<flatbuffers::String *>(VT_NAME); }
const flatbuffers::Vector<uint8_t> *inventory() const { return GetPointer<const flatbuffers::Vector<uint8_t> *>(VT_INVENTORY); }
flatbuffers::Vector<uint8_t> *mutable_inventory() { return GetPointer<flatbuffers::Vector<uint8_t> *>(VT_INVENTORY); }
Color color() const { return static_cast<Color>(GetField<int8_t>(VT_COLOR, 2)); }
bool mutate_color(Color _color) { return SetField(VT_COLOR, static_cast<int8_t>(_color)); }
bool Verify(flatbuffers::Verifier &verifier) const {
return VerifyTableStart(verifier) &&
VerifyField<Vec3>(verifier, 4 /* pos */) &&
VerifyField<int16_t>(verifier, 6 /* mana */) &&
VerifyField<int16_t>(verifier, 8 /* hp */) &&
VerifyField<flatbuffers::uoffset_t>(verifier, 10 /* name */) &&
VerifyField<Vec3>(verifier, VT_POS) &&
VerifyField<int16_t>(verifier, VT_MANA) &&
VerifyField<int16_t>(verifier, VT_HP) &&
VerifyField<flatbuffers::uoffset_t>(verifier, VT_NAME) &&
verifier.Verify(name()) &&
VerifyField<flatbuffers::uoffset_t>(verifier, 14 /* inventory */) &&
VerifyField<flatbuffers::uoffset_t>(verifier, VT_INVENTORY) &&
verifier.Verify(inventory()) &&
VerifyField<int8_t>(verifier, 16 /* color */) &&
VerifyField<int8_t>(verifier, VT_COLOR) &&
verifier.EndTable();
}
};

struct MonsterBuilder {
flatbuffers::FlatBufferBuilder &fbb_;
flatbuffers::uoffset_t start_;
void add_pos(const Vec3 *pos) { fbb_.AddStruct(4, pos); }
void add_mana(int16_t mana) { fbb_.AddElement<int16_t>(6, mana, 150); }
void add_hp(int16_t hp) { fbb_.AddElement<int16_t>(8, hp, 100); }
void add_name(flatbuffers::Offset<flatbuffers::String> name) { fbb_.AddOffset(10, name); }
void add_inventory(flatbuffers::Offset<flatbuffers::Vector<uint8_t>> inventory) { fbb_.AddOffset(14, inventory); }
void add_color(Color color) { fbb_.AddElement<int8_t>(16, static_cast<int8_t>(color), 2); }
void add_pos(const Vec3 *pos) { fbb_.AddStruct(Monster::VT_POS, pos); }
void add_mana(int16_t mana) { fbb_.AddElement<int16_t>(Monster::VT_MANA, mana, 150); }
void add_hp(int16_t hp) { fbb_.AddElement<int16_t>(Monster::VT_HP, hp, 100); }
void add_name(flatbuffers::Offset<flatbuffers::String> name) { fbb_.AddOffset(Monster::VT_NAME, name); }
void add_inventory(flatbuffers::Offset<flatbuffers::Vector<uint8_t>> inventory) { fbb_.AddOffset(Monster::VT_INVENTORY, inventory); }
void add_color(Color color) { fbb_.AddElement<int8_t>(Monster::VT_COLOR, static_cast<int8_t>(color), 2); }
MonsterBuilder(flatbuffers::FlatBufferBuilder &_fbb) : fbb_(_fbb) { start_ = fbb_.StartTable(); }
MonsterBuilder &operator=(const MonsterBuilder &);
flatbuffers::Offset<Monster> Finish() {
Expand Down
29 changes: 24 additions & 5 deletions src/idl_gen_cpp.cpp
View file
Expand Up @@ -242,6 +242,12 @@ std::string GenUnderlyingCast(const Parser &parser, const FieldDef &field,
: val;
}

std::string GenFieldOffsetName(const FieldDef &field) {
std::string uname = field.name;
std::transform(uname.begin(), uname.end(), uname.begin(), ::toupper);
return "VT_" + uname;
}

// Generate an accessor struct, builder structs & function for a table.
static void GenTable(const Parser &parser, StructDef &struct_def,
const GeneratorOptions &opts, std::string *code_ptr) {
Expand All @@ -254,6 +260,19 @@ static void GenTable(const Parser &parser, StructDef &struct_def,
code += "struct " + struct_def.name;
code += " FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table";
code += " {\n";
// Generate field id constants.
code += " enum {\n";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end();
++it) {
auto &field = **it;
if (!field.deprecated) { // Deprecated fields won't be accessible.
code += " " + GenFieldOffsetName(field) + " = ";
code += NumToString(field.value.offset) + ",\n";
}
}
code += " };\n";
// Generate the accessors.
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end();
++it) {
Expand All @@ -268,7 +287,7 @@ static void GenTable(const Parser &parser, StructDef &struct_def,
auto accessor = is_scalar
? "GetField<"
: (IsStruct(field.value.type) ? "GetStruct<" : "GetPointer<");
auto offsetstr = NumToString(field.value.offset);
auto offsetstr = GenFieldOffsetName(field);
auto call =
accessor +
GenTypeGet(parser, field.value.type, "", "const ", " *", false) +
Expand Down Expand Up @@ -347,8 +366,7 @@ static void GenTable(const Parser &parser, StructDef &struct_def,
code += prefix + "VerifyField";
if (field.required) code += "Required";
code += "<" + GenTypeSize(parser, field.value.type);
code += ">(verifier, " + NumToString(field.value.offset);
code += " /* " + field.name + " */)";
code += ">(verifier, " + GenFieldOffsetName(field) + ")";
switch (field.value.type.base_type) {
case BASE_TYPE_UNION:
code += prefix + "Verify" + field.value.type.enum_def->name;
Expand Down Expand Up @@ -412,7 +430,7 @@ static void GenTable(const Parser &parser, StructDef &struct_def,
} else {
code += "Offset";
}
code += "(" + NumToString(field.value.offset) + ", ";
code += "(" + struct_def.name + "::" + GenFieldOffsetName(field) + ", ";
code += GenUnderlyingCast(parser, field, false, field.name);
if (IsScalar(field.value.type.base_type))
code += ", " + field.value.constant;
Expand All @@ -433,7 +451,8 @@ static void GenTable(const Parser &parser, StructDef &struct_def,
++it) {
auto &field = **it;
if (!field.deprecated && field.required) {
code += " fbb_.Required(o, " + NumToString(field.value.offset);
code += " fbb_.Required(o, ";
code += struct_def.name + "::" + GenFieldOffsetName(field);
code += "); // " + field.name + "\n";
}
}
Expand Down

0 comments on commit 1fa803d

Please sign in to comment.