gen_exports.py

#!/usr/bin/env python3
"""Write src/harfbuzz.cppm and src/ft.cppm from the pinned HarfBuzz headers.

src/harfbuzz.cppm exports, by `export using`, every type, enumerator and
function that <hb.h>, <hb-ot.h> and <hb-aat.h> declare (the upstream globals,
unchanged) and the C++ helpers of <hb-cplusplus.hh> (namespace hb). It
re-exports mcpplibs.mwrap.harfbuzz.ft and mcpplibs.mwrap.harfbuzz.macros.

src/ft.cppm exports the functions of <hb-ft.h>, the FreeType integration.
Their FreeType parameter types (FT_Face …) belong to FreeType, exported by
whatever brings FreeType in: mcpplibs.mwrap.freetype, or <ft2build.h>.

With --check, nothing is written and a difference fails.
"""
import argparse
from pathlib import Path
import sys

sys.path.insert(0, str(Path(__file__).resolve().parent))
from inventory import fetch, surface, CPLUSPLUS  # noqa: E402

ROOT = '''// Generated by tools/gen_exports.py from HarfBuzz 14.3.0's headers — do not
// edit by hand.
//
// mcpplibs.mwrap.harfbuzz — HarfBuzz, the OpenType text shaping engine, as a
// C++ module: the API of <hb.h>, <hb-ot.h> and <hb-aat.h> and the C++ helpers
// of <hb-cplusplus.hh>. Every exported name is the upstream entity, unchanged.
// The root re-exports the FreeType integration (<hb-ft.h>) and the macro
// mappings. The library is compat.harfbuzz, built from the same release.
module;
#include <hb.h>
#include <hb-ot.h>
#include <hb-aat.h>
#include <hb-cplusplus.hh>

export module mcpplibs.mwrap.harfbuzz;

export import mcpplibs.mwrap.harfbuzz.ft;
export import mcpplibs.mwrap.harfbuzz.macros;

// A using-declaration of a deprecated function is not a use of it; calling
// one through the module warns as calling it through the header does.
#if defined(__clang__) || defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#endif
'''

FT = '''// Generated by tools/gen_exports.py from HarfBuzz 14.3.0's <hb-ft.h> — do not
// edit by hand.
//
// mcpplibs.mwrap.harfbuzz.ft — HarfBuzz's FreeType integration: hb_face_t and
// hb_font_t over an FT_Face, and FreeType font functions for any hb_font_t.
// compat.harfbuzz always builds it (HAVE_FREETYPE over compat.freetype); the
// root module re-exports it. FT_Face and the other FreeType types are
// FreeType's own: import mcpplibs.mwrap.freetype, or include <ft2build.h>.
module;
#include <hb-ft.h>

export module mcpplibs.mwrap.harfbuzz.ft;

#if defined(__clang__) || defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
#endif
'''


def render(sf):
    out = [ROOT]
    out.append(f'// types: typedef names and struct/union tags ({len(sf.types)})')
    out += [f'export using ::{n};' for n in sf.types]
    out.append(f'\n// enumerators ({len(sf.enumerators)})')
    out += [f'export using ::{n};' for n in sf.enumerators]
    out.append(f'\n// functions ({len(sf.functions)})')
    out += [f'export using ::{n};' for n in sf.functions]
    out.append(f'\n// {CPLUSPLUS}: hb::shared_ptr / hb::unique_ptr over the vtable of each object type')
    out.append('export namespace hb {')
    out += [f'using hb::{n};' for n in sf.cplusplus]
    out.append('}  // namespace hb\n')
    root = '\n'.join(out)
    ft = '\n'.join([FT, f'// functions ({len(sf.ft_functions)})'] + [f'export using ::{n};' for n in sf.ft_functions]) + '\n'
    return root, ft


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--check', action='store_true')
    args = parser.parse_args()
    root = Path(__file__).resolve().parents[1]
    texts = render(surface(fetch(root)))
    stale = []
    for path, text in zip((root / 'src/harfbuzz.cppm', root / 'src/ft.cppm'), texts):
        current = path.read_text(encoding='utf-8') if path.exists() else None
        if current == text:
            continue
        if args.check:
            stale.append(path.relative_to(root).as_posix())
        else:
            path.parent.mkdir(exist_ok=True)
            path.write_text(text, encoding='utf-8', newline='\n')
            print('wrote', path.relative_to(root).as_posix())
    if stale:
        sys.exit('not what tools/gen_exports.py writes: ' + ', '.join(stale))


if __name__ == '__main__':
    main()