Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

src: refactor callback #defines into C++ templates #18133

Closed
wants to merge 2 commits into from
Closed

src: refactor callback #defines into C++ templates #18133

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
638de75
src: refactor callback #defines into C++ templates
addaleax Jan 13, 2018
821cf96
[squash] go with Joyee’s suggestion
addaleax Jan 13, 2018
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
68 changes: 35 additions & 33 deletions src/node_http_parser.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -72,22 +72,6 @@ const uint32_t kOnMessageComplete = 3;
const uint32_t kOnExecute = 4;


#define HTTP_CB(name) \
static int name(http_parser* p_) { \
Parser* self = ContainerOf(&Parser::parser_, p_); \
return self->name##_(); \
} \
int name##_()


#define HTTP_DATA_CB(name) \
static int name(http_parser* p_, const char* at, size_t length) { \
Parser* self = ContainerOf(&Parser::parser_, p_); \
return self->name##_(at, length); \
} \
int name##_(const char* at, size_t length)


// helper class for the Parser
struct StringPtr {
StringPtr() {
Expand Down Expand Up @@ -182,27 +166,27 @@ class Parser : public AsyncWrap {
}


HTTP_CB(on_message_begin) {
int on_message_begin() {
num_fields_ = num_values_ = 0;
url_.Reset();
status_message_.Reset();
return 0;
}


HTTP_DATA_CB(on_url) {
int on_url(const char* at, size_t length) {
url_.Update(at, length);
return 0;
}


HTTP_DATA_CB(on_status) {
int on_status(const char* at, size_t length) {
status_message_.Update(at, length);
return 0;
}


HTTP_DATA_CB(on_header_field) {
int on_header_field(const char* at, size_t length) {
if (num_fields_ == num_values_) {
// start of new field name
num_fields_++;
Expand All @@ -224,7 +208,7 @@ class Parser : public AsyncWrap {
}


HTTP_DATA_CB(on_header_value) {
int on_header_value(const char* at, size_t length) {
if (num_values_ != num_fields_) {
// start of new header value
num_values_++;
Expand All @@ -240,7 +224,7 @@ class Parser : public AsyncWrap {
}


HTTP_CB(on_headers_complete) {
int on_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.
Expand Down Expand Up @@ -317,7 +301,7 @@ class Parser : public AsyncWrap {
}


HTTP_DATA_CB(on_body) {
int on_body(const char* at, size_t length) {
EscapableHandleScope scope(env()->isolate());

Local<Object> obj = object();
Expand Down Expand Up @@ -354,7 +338,7 @@ class Parser : public AsyncWrap {
}


HTTP_CB(on_message_complete) {
int on_message_complete() {
HandleScope scope(env()->isolate());

if (num_fields_)
Expand Down Expand Up @@ -751,21 +735,39 @@ 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 <int (Parser::* Member)()>
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It's possible to make the template more generic and avoid code duplication like this:

template <typename Parser, Parser> struct Proxy;
template <typename Parser, typename ...Args, int (Parser::*Member)(Args...)>
struct Proxy<int (Parser::*)(Args...), Member> {
  static int Raw(http_parser* p, Args ... args) {
    Parser* parser = ContainerOf(&Parser::parser_, p);
    return (parser->*Member)(std::forward<Args>(args)...);
  }
};

typedef int(Parser::*Call)();
typedef int(Parser::*DataCall)(const char* at, size_t length);

const struct http_parser_settings Parser::settings = {
  Proxy<Call, &Parser::on_message_begin>::Raw,
  Proxy<DataCall, &Parser::on_url>::Raw,
  ...
}

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Wow! I tried going into that direction but couldn’t get it to compile 😄 Would you prefer your approach? I feel like the current version is already a lot to digest, but your approach is kind of cool…

Copy link
Member

@joyeecheung joyeecheung Jan 13, 2018 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I personally prefer DRYing code even it involves a bit more template magic (I mean, that's the point of using templates right XD)..but it's totally fine that you keep it this way.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@joyeecheung Okay, done! Kinda still can’t believe it works. 😄

struct HTTPCallback {
static int Raw(http_parser* p) {
Parser* parser = ContainerOf(&Parser::parser_, p);
return (parser->*Member)();
}
};

template <int (Parser::* Member)(const char* at, size_t length)>
struct HTTPDataCallback {
static int Raw(http_parser* p, const char* at, size_t length) {
Parser* parser = ContainerOf(&Parser::parser_, p);
return (parser->*Member)(at, length);
}
};

static const struct http_parser_settings settings;

friend class ScopedRetainParser;
};


const struct http_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,
HTTPCallback<&Parser::on_message_begin>::Raw,
HTTPDataCallback<&Parser::on_url>::Raw,
HTTPDataCallback<&Parser::on_status>::Raw,
HTTPDataCallback<&Parser::on_header_field>::Raw,
HTTPDataCallback<&Parser::on_header_value>::Raw,
HTTPCallback<&Parser::on_headers_complete>::Raw,
HTTPDataCallback<&Parser::on_body>::Raw,
HTTPCallback<&Parser::on_message_complete>::Raw,
nullptr, // on_chunk_header
nullptr // on_chunk_complete
};
Expand Down