Introduction

OS / Compiler GCC 13 GCC 14 GCC 15 Clang 14 Clang 15 Clang 17
Ubuntu 22.04 gcc13 gcc14 gcc15 clang14 clang15 clang17
Ubuntu 24.04 gcc13 gcc14 gcc15 clang14 clang15 clang17
macOS gcc13 gcc14 gcc15 clang14 clang15 clang17
Windows gcc13 gcc13 gcc13 clang14 clang15 clang17

H5CPP compiler is an LLVM/Clang–powered reverse schema compiler. Instead of forcing you to design schemas up front, the H5CPP compiler dives into your existing C and C++ code, extracts full type graphs, and automatically generates persistence descriptors. Born out of the H5CPP header-only library, the compiler eliminates the grind of hand-crafting shim code for HDF5 compound datatypes. Mark a variable with a persistence operator (like h5::write), and the H5CPP compiler will walk the AST, discover every dependent type, and in clean topological order emit a ready-to-use header with HDF5 descriptors. Self-contained, include-guarded, and built to drop straight into your workflow.

The payoff? Non-intrusive, reflection-driven persistence for modern C and C++ — the ease of Python or Java–style serialization, but with the raw performance, type safety, and zero-overhead ethos that C and C++ demand. Complex POD structs? Deeply nested arrays? STL containers? No problem. The H5CPP compiler handles them with ease. Today it supports std::vector, tomorrow an ever-growing slice of the STL universe. 

std::vector<sn::example::Record> vec   = h5::utils::get_test_data<sn::example::Record>(20);  // mark vec with an h5:: operator and delegate  // the details to h5cpp compiler h5::write(fd, "orm/partial/vector one_shot", vec ); ````  ### Example Structs  ```cpp namespace sn {  namespace typecheck {  struct Record {  char _char; unsigned char _uchar; short _short; unsigned short _ushort;  int _int; unsigned int _uint; long _long; unsigned long _ulong;  long long int _llong; unsigned long long _ullong;  float _float; double _double; long double _ldouble;  bool _bool;  // wide characters are not supported in HDF5  // wchar_t _wchar; char16_t _wchar16; char32_t _wchar32;  };  }   namespace other {  struct Record {  MyUInt idx;  MyUInt aa;  double field_02[3];  typecheck::Record field_03[4];  };  }   namespace example {  struct Record {  MyUInt idx;  float field_02[7];  sn::other::Record field_03[5];  sn::other::Record field_04[5]; // optimized out, same as previous  other::Record field_05[3][8]; // array of arrays  };  }   namespace not_supported_yet {  // NON POD: not supported in phase 1  struct Container {  double idx;  std::string field_05; // non-POD  std::vector<example::Record> field_02; // non-POD  };  }   /* BEGIN IGNORED STRUCT */  // These structs are not referenced with h5::read|h5::write|h5::create  struct IgnoredRecord {  signed long int idx;  float field_0n;  };  /* END IGNORED STRUCT */ }