njlr

genrule(
  name = 'single-header',
  out = 'mathutils.hpp',
  cmd = 'echo "' + single_header + '" > $OUT',
)

njlr

single_header = '\n'.join([
    '#ifndef MATHUTILS_HPP',
    '#define MATHUTILS_HPP',
    '',
  ] + [
    '#include <mathutils/' + i + '> ' for i, _ in mathutils_headers.items()
  ] + [
    '',
    '#endif',
    '',

njlr

{
 'add.hpp': 'mathutils/include/add.hpp', 
 'sub.hpp': 'mathutils/include/sub.hpp'
}

njlr

print subdir_glob([
 (‘mathutils/include’, ‘**/*.hpp’),
])

njlr

mathutils
├── include
│ ├── add.hpp
│ └── sub.hpp
└── src
 ├── add.cpp
 └── sub.cpp

njlr

#include <mathutils/mathutils.hpp>

njlr

#ifndef MATHUTILS_SINGLE_INCLUDE_HPP
#define MATHUTILS_SINGLE_INCLUDE_HPP

#include <mathutils/add.hpp>
#include <mathutils/sub.hpp>
// etc…

#endif

njlr

#include <mathutils/add.hpp>
#include <mathutils/sub.hpp>
// etc…

njlr

mathutils
└── include
 ├── add.hpp
 ├── sub.hpp
 └── …

njlr

  // ...

  virtual void copy(void* memory) const {
    new (memory) Model<F, ReturnType, Xs...>(f);
  }

  template<unsigned rhsSize, std::enable_if_t<(rhsSize <= size), bool> = 0>
  SmallFun(SmallFun<ReturnType(Xs...), rhsSize> const& rhs) {
    rhs.copy(memory);
  }