src: refactor callback #defines into C++ templates

Use template helpers instead of `#define`s to generate the raw C callbacks that are passed to the HTTP parser library. A nice effect of this is that it is more obvious what parameters the `Parser` methods take. PR-URL: #18133 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Jon Moss <[email protected]> Reviewed-By: Tobias Nießen <[email protected]> Reviewed-By: Joyee Cheung <[email protected]> Reviewed-By: Franziska Hinkelmann <[email protected]>

Author: addaleax

src/node_http_parser.cc

@@ -74,22 +74,6 @@ const uint32_t kOnMessageComplete = 3;
 constuint32_tkOnExecute = 4;
 
 
-#defineHTTP_CB(name) \
-staticintname(http_parser* p_){\
- Parser* self = ContainerOf(&Parser::parser_, p_); \
-return self->name##_(); \
- } \
-int name##_()
-
-
-#defineHTTP_DATA_CB(name) \
-staticintname(http_parser* p_, constchar* at, size_t length){\
- Parser* self = ContainerOf(&Parser::parser_, p_); \
-return self->name##_(at, length); \
- } \
-int name##_(constchar* at, size_t length)
-
-
 // helper class for the Parser
 structStringPtr{
 StringPtr(){
@@ -184,27 +168,27 @@ class Parser : public AsyncWrap{
  }
 
 
-HTTP_CB(on_message_begin){
+inton_message_begin(){
  num_fields_ = num_values_ = 0;
  url_.Reset();
  status_message_.Reset();
 return0;
  }
 
 
-HTTP_DATA_CB(on_url){
+inton_url(constchar* at, size_t length){
  url_.Update(at, length);
 return0;
  }
 
 
-HTTP_DATA_CB(on_status){
+inton_status(constchar* at, size_t length){
  status_message_.Update(at, length);
 return0;
  }
 
 
-HTTP_DATA_CB(on_header_field){
+inton_header_field(constchar* at, size_t length){
 if (num_fields_ == num_values_){
 // start of new field name
  num_fields_++;
@@ -226,7 +210,7 @@ class Parser : public AsyncWrap{
  }
 
 
-HTTP_DATA_CB(on_header_value){
+inton_header_value(constchar* at, size_t length){
 if (num_values_ != num_fields_){
 // start of new header value
  num_values_++;
@@ -242,7 +226,7 @@ class Parser : public AsyncWrap{
  }
 
 
-HTTP_CB(on_headers_complete){
+inton_headers_complete(){
 // Arguments for the on-headers-complete javascript callback. This
 // list needs to be kept in sync with the actual argument list for
 // `parserOnHeadersComplete` in lib/_http_common.js.
@@ -319,7 +303,7 @@ class Parser : public AsyncWrap{
  }
 
 
-HTTP_DATA_CB(on_body){
+inton_body(constchar* at, size_t length){
  EscapableHandleScope scope(env()->isolate());
 
  Local<Object> obj = object();
@@ -356,7 +340,7 @@ class Parser : public AsyncWrap{
  }
 
 
-HTTP_CB(on_message_complete){
+inton_message_complete(){
  HandleScope scope(env()->isolate());
 
 if (num_fields_)
@@ -753,21 +737,35 @@ class Parser : public AsyncWrap{
  StreamResource::Callback<StreamResource::AllocCb> prev_alloc_cb_;
  StreamResource::Callback<StreamResource::ReadCb> prev_read_cb_;
 int refcount_ = 1;
+
+// These are helper functions for filling `http_parser_settings`, which turn
+// a member function of Parser into a C-style HTTP parser callback.
+template <typename Parser, Parser> structProxy;
+template <typename Parser, typename ...Args, int (Parser::*Member)(Args...)>
+structProxy<int (Parser::*)(Args...), Member>{
+staticintRaw(http_parser* p, Args ... args){
+ Parser* parser = ContainerOf(&Parser::parser_, p);
+return (parser->*Member)(std::forward<Args>(args)...);
+ }
+ };
+
+typedefint (Parser::*Call)();
+typedefint (Parser::*DataCall)(constchar* at, size_t length);
+
 staticconststructhttp_parser_settings settings;
 
 friendclassScopedRetainParser;
 };
 
-
 conststructhttp_parser_settings Parser::settings ={
- Parser::on_message_begin,
- Parser::on_url,
- Parser::on_status,
- Parser::on_header_field,
- Parser::on_header_value,
- Parser::on_headers_complete,
- Parser::on_body,
- Parser::on_message_complete,
+Proxy<Call, &Parser::on_message_begin>::Raw,
+Proxy<DataCall, &Parser::on_url>::Raw,
+Proxy<DataCall, &Parser::on_status>::Raw,
+Proxy<DataCall, &Parser::on_header_field>::Raw,
+Proxy<DataCall, &Parser::on_header_value>::Raw,
+Proxy<Call, &Parser::on_headers_complete>::Raw,
+Proxy<DataCall, &Parser::on_body>::Raw,
+Proxy<Call, &Parser::on_message_complete>::Raw,
 nullptr, // on_chunk_header
 nullptr// on_chunk_complete
 };