cppystruct

Overview

cppystruct is a C++17, header-only, constexpr clone of Python's struct module. Write your struct format once, and use it seamlessly across C++ and Python.

#include "cppystruct.h"

// icmp_header can be any type that supports std::size and std::data and holds bytes
auto [type, code, checksum, p_id, sequence] = pystruct::unpack(PY_STRING('bbHHh'), icmp_header);

int leet = 1337;
auto runtimePacked = pystruct::pack(PY_STRING(">2i10s"), leet, 20, "String!");
// runtimePacked is an std::array filled with "\x00\x00\x059\x00\x00\x00\x10String!\x00\x00\x00"
// The format is "compiled" and has zero overhead in runtime

constexpr auto packed = pystruct::pack(PY_STRING("<2i10s"), 10, 20, "String!");
// packed is an std::array filled with "\x00\x01\x00\x00\x10\x00\x00\x00String!\x00\x00\x00"

Usage

cppystruct is a C++ header-only library, you can just add cppystruct/include to your include path and be ready to go! The library compiles cleanly on clang, GCC & MSVC. CI is set up for clang & MSVC.

Run Tests

mkdir build && cd build

# build the library & tests
cmake ..
cmake --build .

# run the tests
ctest .

Features

• Full support for python's struct format, including:
  • Byte order (little/big/network/native endian)
  • Strings (sized strings)
  • Repeat count for basic types
• Full interface
  • pack
  • unpack
  • calcsize
• Constexpr format - zero overhead to actual structs

Caveats

• float & double formats are not constexpr due to no constexpr reinterpret-cast
• A macro (PY_STRING) is used for the compile-time string because the UDL version is a gcc extension
• Compile time diagnostics are not beautiful
• Pascal strings (p format char) and pointer values (P format char) aren't supported

Contributing

cppystruct is developed on GitHub at karkason/cppystruct. To report an issue or send a pull request, use the issue tracker.