// 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"; } }