ArrayView.h

/*
 * AUI Framework - Declarative UI toolkit for modern C++20
 * Copyright (C) 2020-2024 Alex2772 and Contributors
 *
 * SPDX-License-Identifier: MPL-2.0
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
 
#pragma once
 
#include <span>
#include <AUI/Util/ARaiiHelper.h>
#include "Globals.h"
#include "Converter.h"
 
namespace aui::jni {
    namespace detail {
        struct CastHelper {
            jobject value;
 
            template<typename T>
            operator T() const noexcept {
                return static_cast<T>(value);
            }
        };
    }

    template<convertible T>
    class ArrayView: public GlobalRef {
    public:
        using GlobalRef::GlobalRef;
 
        static ArrayView allocate(std::size_t size) {
            return (aui::jni::env()->*TypedMethods<T>::NewArray)(size);
        }
 
        std::size_t size() const noexcept {
            return aui::jni::env()->GetArrayLength((jarray)asObject());
        }
 
        template<aui::invocable<std::span<const T>> Callback>
        void view(Callback&& callback) const {
            //TypedMethods<T>::
            jboolean isCopy;
            auto ptr = (aui::jni::env()->*TypedMethods<T>::GetArrayElements)(detail::CastHelper{asObject()}, &isCopy);
            ARaiiHelper releaser = [&] {
                (aui::jni::env()->*TypedMethods<T>::ReleaseArrayElements)(detail::CastHelper{asObject()}, ptr, JNI_ABORT);
            };
 
            callback(std::span<const T>(ptr, size()));
        }
 
        template<aui::invocable<std::span<T>> Callback>
        void modify(Callback&& callback) const {
            //TypedMethods<T>::
            jboolean isCopy;
            auto ptr = (aui::jni::env()->*TypedMethods<T>::GetArrayElements)(detail::CastHelper{asObject()}, &isCopy);
            ARaiiHelper releaser = [&] {
                (aui::jni::env()->*TypedMethods<T>::ReleaseArrayElements)(detail::CastHelper{asObject()}, ptr, 0);
            };
 
            callback(std::span<T>(ptr, size()));
        }
 
        void set(std::span<const T> data, std::size_t at = 0) {
            (aui::jni::env()->*TypedMethods<T>::SetArrayRegion)(detail::CastHelper{asObject()}, at, data.size(), data.data());
        }
    };
 
    template<convertible T>
    struct Converter<ArrayView<T>>: public Converter<std::string> {
        static constexpr auto signature = "["_asl + ::aui::jni::signature_v<T>;
 
        static ArrayView<T> fromJni(jobject val) {
            return val;
        }
 
        static jobject toJni(const ArrayView<T>& value) {
            return value.asObject();
        }
    };
}

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