// Return a C++ type from the table in idl.h
static std::string GenTypeBasic(const Parser &parser, const Type &type,
bool real_enum) {
static const char *ctypename[] = {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE) #CTYPE,
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
};
return real_enum && type.enum_def
? WrapInNameSpace(parser, *type.enum_def)
: ctypename[type.base_type];
}
// Return a C++ pointer type, specialized to the actual struct/table types,
// and vector element types.
static std::string GenTypePointer(const Parser &parser, const Type &type) {
switch (type.base_type) {
case BASE_TYPE_STRING:
return "flatbuffers::String";
case BASE_TYPE_VECTOR:
return "flatbuffers::Vector<" +
GenTypeWire(parser, type.VectorType(), "", false) + ">";
case BASE_TYPE_STRUCT: {
return WrapInNameSpace(parser, *type.struct_def);
}
case BASE_TYPE_UNION:
// fall through
default:
return "void";
}
}
std::string BaseGenerator::WrapInNameSpace(const Definition &def) const {
return WrapInNameSpace(def.defined_namespace, def.name);
}
static std::string WrapInNameSpace(const Parser &parser,
const Definition &def) {
return WrapInNameSpace(parser, def.defined_namespace, def.name);
}
// 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) {
if (struct_def.generated) return;
std::string &code = *code_ptr;
// Generate an accessor struct, with methods of the form:
// type name() const { return GetField<type>(offset, defaultval); }
GenComment(struct_def.doc_comment, code_ptr);
code += "struct " + struct_def.name;
code += " FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table";
code += " {\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.
GenComment(field.doc_comment, code_ptr, " ");
code += " " + GenTypeGet(parser, field.value.type, " ", "const ", " *",
true);
code += field.name + "() const { return ";
// Call a different accessor for pointers, that indirects.
std::string call = IsScalar(field.value.type.base_type)
? "GetField<"
: (IsStruct(field.value.type) ? "GetStruct<" : "GetPointer<");
call += GenTypeGet(parser, field.value.type, "", "const ", " *", false);
call += ">(" + NumToString(field.value.offset);
// Default value as second arg for non-pointer types.
if (IsScalar(field.value.type.base_type))
call += ", " + field.value.constant;
call += ")";
code += GenUnderlyingCast(parser, field, true, call);
code += "; }\n";
auto nested = field.attributes.Lookup("nested_flatbuffer");
if (nested) {
auto nested_root = parser.structs_.Lookup(nested->constant);
assert(nested_root); // Guaranteed to exist by parser.
code += " const " + nested_root->name + " *" + field.name;
code += "_nested_root() const { return flatbuffers::GetRoot<";
code += nested_root->name + ">(" + field.name + "()->Data()); }\n";
}
// Generate a comparison function for this field if it is a key.
if (field.key) {
code += " bool KeyCompareLessThan(const " + struct_def.name;
code += " *o) const { return ";
if (field.value.type.base_type == BASE_TYPE_STRING) code += "*";
code += field.name + "() < ";
if (field.value.type.base_type == BASE_TYPE_STRING) code += "*";
code += "o->" + field.name + "(); }\n";
code += " int KeyCompareWithValue(";
if (field.value.type.base_type == BASE_TYPE_STRING) {
code += "const char *val) const { return strcmp(" + field.name;
code += "()->c_str(), val); }\n";
} else {
code += GenTypeBasic(parser, field.value.type, false);
code += " val) const { return " + field.name + "() < val ? -1 : ";
code += field.name + "() > val; }\n";
}
}
}
}
// Generate a verifier function that can check a buffer from an untrusted
// source will never cause reads outside the buffer.
code += " bool Verify(flatbuffers::Verifier &verifier) const {\n";
code += " return VerifyTableStart(verifier)";
std::string prefix = " &&\n ";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end();
++it) {
auto &field = **it;
if (!field.deprecated) {
code += prefix + "VerifyField";
if (field.required) code += "Required";
code += "<" + GenTypeSize(parser, field.value.type);
code += ">(verifier, " + NumToString(field.value.offset);
code += " /* " + field.name + " */)";
switch (field.value.type.base_type) {
case BASE_TYPE_UNION:
code += prefix + "Verify" + field.value.type.enum_def->name;
code += "(verifier, " + field.name + "(), " + field.name + "_type())";
break;
case BASE_TYPE_STRUCT:
if (!field.value.type.struct_def->fixed) {
code += prefix + "verifier.VerifyTable(" + field.name;
code += "())";
}
break;
case BASE_TYPE_STRING:
code += prefix + "verifier.Verify(" + field.name + "())";
break;
case BASE_TYPE_VECTOR:
code += prefix + "verifier.Verify(" + field.name + "())";
switch (field.value.type.element) {
case BASE_TYPE_STRING: {
code += prefix + "verifier.VerifyVectorOfStrings(" + field.name;
code += "())";
break;
}
case BASE_TYPE_STRUCT: {
if (!field.value.type.struct_def->fixed) {
code += prefix + "verifier.VerifyVectorOfTables(" + field.name;
code += "())";
}
break;
}
default:
break;
}
break;
default:
break;
}
}
}
code += prefix + "verifier.EndTable()";
code += ";\n }\n";
code += "};\n\n";
// Generate a builder struct, with methods of the form:
// void add_name(type name) { fbb_.AddElement<type>(offset, name, default); }
code += "struct " + struct_def.name;
code += "Builder {\n flatbuffers::FlatBufferBuilder &fbb_;\n";
code += " flatbuffers::uoffset_t start_;\n";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end();
++it) {
auto &field = **it;
if (!field.deprecated) {
code += " void add_" + field.name + "(";
code += GenTypeWire(parser, field.value.type, " ", true) + field.name;
code += ") { fbb_.Add";
if (IsScalar(field.value.type.base_type)) {
code += "Element<" + GenTypeWire(parser, field.value.type, "", false);
code += ">";
} else if (IsStruct(field.value.type)) {
code += "Struct";
} else {
code += "Offset";
}
code += "(" + NumToString(field.value.offset) + ", ";
code += GenUnderlyingCast(parser, field, false, field.name);
if (IsScalar(field.value.type.base_type))
code += ", " + field.value.constant;
code += "); }\n";
}
}
code += " " + struct_def.name;
code += "Builder(flatbuffers::FlatBufferBuilder &_fbb) : fbb_(_fbb) ";
code += "{ start_ = fbb_.StartTable(); }\n";
code += " " + struct_def.name + "Builder &operator=(const ";
code += struct_def.name + "Builder &);\n";
code += " flatbuffers::Offset<" + struct_def.name;
code += "> Finish() {\n auto o = flatbuffers::Offset<" + struct_def.name;
code += ">(fbb_.EndTable(start_, ";
code += NumToString(struct_def.fields.vec.size()) + "));\n";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end();
++it) {
auto &field = **it;
if (!field.deprecated && field.required) {
code += " fbb_.Required(o, " + NumToString(field.value.offset);
code += "); // " + field.name + "\n";
}
}
code += " return o;\n }\n};\n\n";
// Generate a convenient CreateX function that uses the above builder
// to create a table in one go.
code += "inline flatbuffers::Offset<" + struct_def.name + "> Create";
code += struct_def.name;
code += "(flatbuffers::FlatBufferBuilder &_fbb";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end();
++it) {
auto &field = **it;
if (!field.deprecated) {
code += ",\n " + GenTypeWire(parser, field.value.type, " ", true);
code += field.name + " = ";
if (field.value.type.enum_def && IsScalar(field.value.type.base_type)) {
auto ev = field.value.type.enum_def->ReverseLookup(
static_cast<int>(StringToInt(field.value.constant.c_str())), false);
if (ev) {
code += WrapInNameSpace(parser,
field.value.type.enum_def->defined_namespace,
GenEnumVal(*field.value.type.enum_def, *ev,
opts));
} else {
code += GenUnderlyingCast(parser, field, true, field.value.constant);
}
} else {
code += field.value.constant;
}
}
}
code += ") {\n " + struct_def.name + "Builder builder_(_fbb);\n";
for (size_t size = struct_def.sortbysize ? sizeof(largest_scalar_t) : 1;
size;
size /= 2) {
for (auto it = struct_def.fields.vec.rbegin();
it != struct_def.fields.vec.rend();
++it) {
auto &field = **it;
if (!field.deprecated &&
(!struct_def.sortbysize ||
size == SizeOf(field.value.type.base_type))) {
code += " builder_.add_" + field.name + "(" + field.name + ");\n";
}
}
}
code += " return builder_.Finish();\n}\n\n";
}
// Generate an enum declaration and an enum string lookup table.
static void GenEnum(const Parser &parser, EnumDef &enum_def,
std::string *code_ptr, std::string *code_ptr_post,
const GeneratorOptions &opts) {
if (enum_def.generated) return;
std::string &code = *code_ptr;
std::string &code_post = *code_ptr_post;
GenComment(enum_def.doc_comment, code_ptr);
code += "enum " + enum_def.name + " {\n";
for (auto it = enum_def.vals.vec.begin();
it != enum_def.vals.vec.end();
++it) {
auto &ev = **it;
GenComment(ev.doc_comment, code_ptr, " ");
code += " " + GenEnumVal(enum_def, ev, opts) + " = ";
code += NumToString(ev.value);
code += (it + 1) != enum_def.vals.vec.end() ? ",\n" : "\n";
}
code += "};\n\n";
// Generate a generate string table for enum values.
// Problem is, if values are very sparse that could generate really big
// tables. Ideally in that case we generate a map lookup instead, but for
// the moment we simply don't output a table at all.
auto range = enum_def.vals.vec.back()->value -
enum_def.vals.vec.front()->value + 1;
// Average distance between values above which we consider a table
// "too sparse". Change at will.
static const int kMaxSparseness = 5;
if (range / static_cast<int64_t>(enum_def.vals.vec.size()) < kMaxSparseness) {
code += "inline const char **EnumNames" + enum_def.name + "() {\n";
code += " static const char *names[] = { ";
auto val = enum_def.vals.vec.front()->value;
for (auto it = enum_def.vals.vec.begin();
it != enum_def.vals.vec.end();
++it) {
while (val++ != (*it)->value) code += "\"\", ";
code += "\"" + (*it)->name + "\", ";
}
code += "nullptr };\n return names;\n}\n\n";
code += "inline const char *EnumName" + enum_def.name;
code += "(" + enum_def.name + " e) { return EnumNames" + enum_def.name + "()[e";
if (enum_def.vals.vec.front()->value)
code += " - " + GenEnumVal(enum_def, *enum_def.vals.vec.front(), opts);
code += "]; }\n\n";
}
if (enum_def.is_union) {
// Generate a verifier function for this union that can be called by the
// table verifier functions. It uses a switch case to select a specific
// verifier function to call, this should be safe even if the union type
// has been corrupted, since the verifiers will simply fail when called
// on the wrong type.
auto signature = "inline bool Verify" + enum_def.name +
"(flatbuffers::Verifier &verifier, " +
"const void *union_obj, " + enum_def.name + " type)";
code += signature + ";\n\n";
code_post += signature + " {\n switch (type) {\n";
for (auto it = enum_def.vals.vec.begin();
it != enum_def.vals.vec.end();
++it) {
auto &ev = **it;
code_post += " case " + GenEnumVal(enum_def, ev, opts);
if (!ev.value) {
code_post += ": return true;\n"; // "NONE" enum value.
} else {
code_post += ": return verifier.VerifyTable(reinterpret_cast<const ";
code_post += WrapInNameSpace(parser, *ev.struct_def);
code_post += " *>(union_obj));\n";
}
}
code_post += " default: return false;\n }\n}\n\n";
}
}
