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// © 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__
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