File indexing completed on 2024-06-23 05:08:44

 /*
     SPDX-FileCopyrightText: 2019 Volker Krause <vkrause@kde.org>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
 #ifndef KANDROIDEXTRAS_JNISIGNATURE_H
 #define KANDROIDEXTRAS_JNISIGNATURE_H
 
 #include "jnitypes.h"
 
 #include "jni.h"
 #include <cstdint>
 #include <utility>
 
 namespace KAndroidExtras {
 
 namespace Jni {
 template <typename T> class Array;
 }
 
 /** @cond internal */
 namespace Internal {
 
 /** Compile-time concat-able string. */
 template <char... String>
 struct StaticString {
     inline operator const char*() const
     {
         static const char data[] = { String..., 0 };
         return data;
     }
 };
 
 /** Compile-time strlen. */
 constexpr inline int static_strlen(const char *str)
 {
     return str[0] == '\0' ? 0 : static_strlen(str + 1) + 1;
 }
 
 /** Compile-time concat for two StaticString. */
 template <char... String1, char... String2>
 constexpr inline auto static_concat(const StaticString<String1...>&, const StaticString<String2...>&)
 {
     return StaticString<String1..., String2...>();
 }
 
 /** Compile-time concept for N StaticString. */
 template <typename String1, typename String2, class... Strings>
 constexpr inline auto static_concat(const String1& str1, const String2& str2, const Strings&... strs)
 {
     return static_concat(static_concat(str1, str2), strs...);
 }
 
 /** Conversion from const char* literals to StaticString. */
 template <typename, typename> struct staticStringFromJniType;
 template <typename T, std::size_t... Indexes>
 struct staticStringFromJniType<T, std::index_sequence<Indexes...>>
 {
     typedef StaticString<Jni::typeName<T>()[Indexes]...> value;
 };
 
 /** Meta function for assembling JNI signatures. */
 template <typename T>
 struct JniSignature
 {
     constexpr inline auto operator()() const
     {
         using namespace Internal;
         return static_concat(StaticString<'L'>(), typename staticStringFromJniType<T, std::make_index_sequence<static_strlen(Jni::typeName<T>())>>::value(), StaticString<';'>());
     }
 };
 
 template <> struct JniSignature<jboolean> { constexpr inline auto operator()() const { return StaticString<'Z'>(); } };
 template <> struct JniSignature<jbyte> { constexpr inline auto operator()() const { return StaticString<'B'>(); } };
 template <> struct JniSignature<jchar> { constexpr inline auto operator()() const { return StaticString<'C'>(); } };
 template <> struct JniSignature<jshort> { constexpr inline auto operator()() const { return StaticString<'S'>(); } };
 template <> struct JniSignature<jint> { constexpr inline auto operator()() const { return StaticString<'I'>(); } };
 template <> struct JniSignature<jlong> { constexpr inline auto operator()() const { return StaticString<'J'>(); } };
 template <> struct JniSignature<jfloat> { constexpr inline auto operator()() const { return StaticString<'F'>(); } };
 template <> struct JniSignature<jdouble> { constexpr inline auto operator()() const { return StaticString<'D'>(); } };
 template <> struct JniSignature<void> { constexpr inline auto operator()() const { return StaticString<'V'>(); } };
 // special case due to jboolean != bool
 template <> struct JniSignature<bool> { constexpr inline auto operator()() const { return StaticString<'Z'>(); } };
 
 template <typename T>
 struct JniSignature<T*>
 {
     constexpr inline auto operator()() const
     {
         using namespace Internal;
         return static_concat(StaticString<'['>(), JniSignature<T>()());
     }
 };
 
 template <typename T>
 struct JniSignature<Jni::Array<T>>
 {
     constexpr inline auto operator()() const
     {
         using namespace Internal;
         return static_concat(StaticString<'['>(), JniSignature<T>()());
     }
 };
 
 template <typename RetT, typename... Args>
 struct JniSignature<RetT(Args...)>
 {
     constexpr inline auto operator()() const
     {
         using namespace Internal;
         return static_concat(StaticString<'('>(), JniSignature<Args>()()..., StaticString<')'>(), JniSignature<RetT>()());
     }
 };
 }
 /** @endcond */
 
 /** Helper methods to deal with JNI. */
 namespace Jni
 {
     /** Returns the JNI signature string for the template argument types. */
     template <typename... Args> constexpr __attribute__((__unused__)) Internal::JniSignature<Args...> signature = {};
 }
 
 }
 
 #endif // KANDROIDEXTRAS_JNISIGNATURE_H