embed.h

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/*
    pybind11/embed.h: Support for embedding the interpreter

    Copyright (c) 2017 Wenzel Jakob <wenzel.jakob@epfl.ch>

    All rights reserved. Use of this source code is governed by a
    BSD-style license that can be found in the LICENSE file.
*/

#pragma once

#include "pybind11.h"
#include "eval.h"

#if defined(PYPY_VERSION)
#  error Embedding the interpreter is not supported with PyPy
#endif

#if PY_MAJOR_VERSION >= 3
#  define PYBIND11_EMBEDDED_MODULE_IMPL(name)            \
      extern "C" PyObject *pybind11_init_impl_##name() { \
          return pybind11_init_wrapper_##name();         \
      }
#else
#  define PYBIND11_EMBEDDED_MODULE_IMPL(name)            \
      extern "C" void pybind11_init_impl_##name() {      \
          pybind11_init_wrapper_##name();                \
      }
#endif

#define PYBIND11_EMBEDDED_MODULE(name, variable)                              \
    static void PYBIND11_CONCAT(pybind11_init_, name)(pybind11::module &);    \
    static PyObject PYBIND11_CONCAT(*pybind11_init_wrapper_, name)() {        \
        auto m = pybind11::module(PYBIND11_TOSTRING(name));                   \
        try {                                                                 \
            PYBIND11_CONCAT(pybind11_init_, name)(m);                         \
            return m.ptr();                                                   \
        } catch (pybind11::error_already_set &e) {                            \
            PyErr_SetString(PyExc_ImportError, e.what());                     \
            return nullptr;                                                   \
        } catch (const std::exception &e) {                                   \
            PyErr_SetString(PyExc_ImportError, e.what());                     \
            return nullptr;                                                   \
        }                                                                     \
    }                                                                         \
    PYBIND11_EMBEDDED_MODULE_IMPL(name)                                       \
    pybind11::detail::embedded_module name(PYBIND11_TOSTRING(name),           \
                               PYBIND11_CONCAT(pybind11_init_impl_, name));   \
    void PYBIND11_CONCAT(pybind11_init_, name)(pybind11::module &variable)


NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
NAMESPACE_BEGIN(detail)

struct embedded_module {
#if PY_MAJOR_VERSION >= 3
    using init_t = PyObject *(*)();
#else
    using init_t = void (*)();
#endif
    embedded_module(const char *name, init_t init) {
        if (Py_IsInitialized())
            pybind11_fail("Can't add new modules after the interpreter has been initialized");

        auto result = PyImport_AppendInittab(name, init);
        if (result == -1)
            pybind11_fail("Insufficient memory to add a new module");
    }
};

NAMESPACE_END(detail)


inline void initialize_interpreter(bool init_signal_handlers = true) {
    if (Py_IsInitialized())
        pybind11_fail("The interpreter is already running");

    Py_InitializeEx(init_signal_handlers ? 1 : 0);

    // Make .py files in the working directory available by default
    module::import("sys").attr("path").cast<list>().append(".");
}

inline void finalize_interpreter() {
    handle builtins(PyEval_GetBuiltins());
    const char *id = PYBIND11_INTERNALS_ID;

    // Get the internals pointer (without creating it if it doesn't exist).  It's possible for the
    // internals to be created during Py_Finalize() (e.g. if a py::capsule calls `get_internals()`
    // during destruction), so we get the pointer-pointer here and check it after Py_Finalize().
    detail::internals **internals_ptr_ptr = detail::get_internals_pp();
    // It could also be stashed in builtins, so look there too:
    if (builtins.contains(id) && isinstance<capsule>(builtins[id]))
        internals_ptr_ptr = capsule(builtins[id]);

    Py_Finalize();

    if (internals_ptr_ptr) {
        delete *internals_ptr_ptr;
        *internals_ptr_ptr = nullptr;
    }
}

class scoped_interpreter {
public:
    scoped_interpreter(bool init_signal_handlers = true) {
        initialize_interpreter(init_signal_handlers);
    }

    scoped_interpreter(const scoped_interpreter &) = delete;
    scoped_interpreter(scoped_interpreter &&other) noexcept { other.is_valid = false; }
    scoped_interpreter &operator=(const scoped_interpreter &) = delete;
    scoped_interpreter &operator=(scoped_interpreter &&) = delete;

    ~scoped_interpreter() {
        if (is_valid)
            finalize_interpreter();
    }

private:
    bool is_valid = true;
};

NAMESPACE_END(PYBIND11_NAMESPACE)