bool CppGenerator::Generate(const FileDescriptor* file,const string& parameter,GeneratorContext* generator_context,string* error) const {std::vector
    
     
       > options;ParseGeneratorParameter(parameter, &options);// -----------------------------------------------------------------// parse generator options// TODO(kenton): If we ever have more options, we may want to create a// class that encapsulates them which we can pass down to all the// generator classes. Currently we pass dllexport_decl down to all of// them via the constructors, but we don't want to have to add another// constructor parameter for every option.// If the dllexport_decl option is passed to the compiler, we need to write// it in front of every symbol that should be exported if this .proto is// compiled into a Windows DLL. E.g., if the user invokes the protocol// compiler as:// protoc --cpp_out=dllexport_decl=FOO_EXPORT:outdir foo.proto// then we'll define classes like this:// class FOO_EXPORT Foo {// ...// }// FOO_EXPORT is a macro which should expand to __declspec(dllexport) or// __declspec(dllimport) depending on what is being compiled.//