python.h

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// -*- lsst-c++ -*-
/*
 * LSST Data Management System
 * See COPYRIGHT file at the top of the source tree.
 *
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the LSST License Statement and
 * the GNU General Public License along with this program.  If not,
 * see <http://www.lsstcorp.org/LegalNotices/>.
 */

#ifndef LSST_UTILS_PYTHON_H
#define LSST_UTILS_PYTHON_H

#include "pybind11/pybind11.h"

#include <cstddef>
#include <memory>
#include <string>
#include <sstream>
#include <utility>

#include "lsst/pex/exceptions.h"

namespace lsst {
namespace utils {
namespace python {

template<typename T, typename PyClass>
inline void addSharedPtrEquality(PyClass & cls) {
    cls.def("__eq__",
            [](std::shared_ptr<T> self, std::shared_ptr<T> other) { return self.get() == other.get(); },
            pybind11::is_operator());
    cls.def("__ne__",
            [](std::shared_ptr<T> self, std::shared_ptr<T> other) { return self.get() != other.get(); },
            pybind11::is_operator());
}

template <class PyClass>
void addOutputOp(PyClass &cls, std::string const &method) {
    cls.def(method.c_str(), [](typename PyClass::type const &self) {
        std::ostringstream os;
        os << self;
        return os.str();
    });
}

template <class PyClass>
void addHash(PyClass &cls) {
    using Class = typename PyClass::type;
    cls.def("__hash__", [](Class const &self) {
        static auto const hash = std::hash<Class>();
        return hash(self);
    });
}

inline std::size_t cppIndex(std::ptrdiff_t size, std::ptrdiff_t i) {
    auto const i_orig = i;
    if (i < 0) {
        // index backwards from the end
        i += size;
    }
    if (i < 0 || i >= size) {
        std::ostringstream os;
        os << "Index " << i_orig << " not in range [" << -size << ", " << size - 1 << "]";
        throw pybind11::index_error(os.str());
    }
    return static_cast<std::size_t>(i);
}

inline std::pair<std::size_t, std::size_t> cppIndex(std::ptrdiff_t size_i, std::ptrdiff_t size_j,
                                                    std::ptrdiff_t i, std::ptrdiff_t j) {
    try {
        return {cppIndex(size_i, i), cppIndex(size_j, j)};
    } catch (lsst::pex::exceptions::OutOfRangeError) {
        std::ostringstream os;
        os << "Index (" << i << ", " << j << ") not in range ["
           << -size_i << ", " << size_i - 1 << "], ["
           << -size_j << ", " << size_j - 1 << "]";
        throw pybind11::index_error(os.str());
    }
}

}}}  // namespace lsst::utils::python

#endif