// © 2018 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html #ifndef __CAPI_HELPER_H__ #define __CAPI_HELPER_H__ #include "unicode/utypes.h" U_NAMESPACE_BEGIN /** * An internal helper class to help convert between C and C++ APIs. */ template<typename CType, typename CPPType, int32_t kMagic> class IcuCApiHelper { public: /** * Convert from the C type to the C++ type (const version). */ static const CPPType* validate(const CType* input, UErrorCode& status); /** * Convert from the C type to the C++ type (non-const version). */ static CPPType* validate(CType* input, UErrorCode& status); /** * Convert from the C++ type to the C type (const version). */ const CType* exportConstForC() const; /** * Convert from the C++ type to the C type (non-const version). */ CType* exportForC(); /** * Invalidates the object. */ ~IcuCApiHelper(); private: /** * While the object is valid, fMagic equals kMagic. */ int32_t fMagic = kMagic; }; template<typename CType, typename CPPType, int32_t kMagic> const CPPType* IcuCApiHelper<CType, CPPType, kMagic>::validate(const CType* input, UErrorCode& status) { if (U_FAILURE(status)) { return nullptr; } if (input == nullptr) { status = U_ILLEGAL_ARGUMENT_ERROR; return nullptr; } auto* impl = reinterpret_cast<const CPPType*>(input); if (static_cast<const IcuCApiHelper<CType, CPPType, kMagic>*>(impl)->fMagic != kMagic) { status = U_INVALID_FORMAT_ERROR; return nullptr; } return impl; } template<typename CType, typename CPPType, int32_t kMagic> CPPType* IcuCApiHelper<CType, CPPType, kMagic>::validate(CType* input, UErrorCode& status) { auto* constInput = static_cast<const CType*>(input); auto* validated = validate(constInput, status); return const_cast<CPPType*>(validated); } template<typename CType, typename CPPType, int32_t kMagic> const CType* IcuCApiHelper<CType, CPPType, kMagic>::exportConstForC() const { return reinterpret_cast<const CType*>(static_cast<const CPPType*>(this)); } template<typename CType, typename CPPType, int32_t kMagic> CType* IcuCApiHelper<CType, CPPType, kMagic>::exportForC() { return reinterpret_cast<CType*>(static_cast<CPPType*>(this)); } template<typename CType, typename CPPType, int32_t kMagic> IcuCApiHelper<CType, CPPType, kMagic>::~IcuCApiHelper() { // head off application errors by preventing use of of deleted objects. fMagic = 0; } U_NAMESPACE_END #endif // __CAPI_HELPER_H__