gecko-dev/storage/Variant.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
* 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/. */
#ifndef mozilla_storage_Variant_h__
#define mozilla_storage_Variant_h__
#include <utility>
#include "nsIVariant.h"
#include "nsString.h"
#include "nsTArray.h"
#define VARIANT_BASE_IID \
{ /* 78888042-0fa3-4f7a-8b19-7996f99bf1aa */ \
0x78888042, 0x0fa3, 0x4f7a, \
{ 0x8b, 0x19, 0x79, 0x96, 0xf9, 0x9b, 0xf1, 0xaa } \
}
/**
* This class is used by the storage module whenever an nsIVariant needs to be
* returned. We provide traits for the basic sqlite types to make use easier.
* The following types map to the indicated sqlite type:
* int64_t -> INTEGER (use IntegerVariant)
* double -> FLOAT (use FloatVariant)
* nsString -> TEXT (use TextVariant)
* nsCString -> TEXT (use UTF8TextVariant)
* uint8_t[] -> BLOB (use BlobVariant)
* nullptr -> NULL (use NullVariant)
*/
namespace mozilla {
namespace storage {
////////////////////////////////////////////////////////////////////////////////
//// Base Class
class Variant_base : public nsIVariant
{
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIVARIANT
NS_DECLARE_STATIC_IID_ACCESSOR(VARIANT_BASE_IID)
protected:
virtual ~Variant_base() { }
};
NS_DEFINE_STATIC_IID_ACCESSOR(Variant_base,
VARIANT_BASE_IID)
////////////////////////////////////////////////////////////////////////////////
//// Traits
/**
* Generics
*/
template <typename DataType>
struct variant_traits
{
static inline uint16_t type() { return nsIDataType::VTYPE_EMPTY; }
};
template <typename DataType, bool Adopting=false>
struct variant_storage_traits
{
typedef DataType ConstructorType;
typedef DataType StorageType;
static inline void storage_conversion(const ConstructorType aData, StorageType* _storage)
{
*_storage = aData;
}
static inline void destroy(const StorageType& _storage)
{ }
};
#define NO_CONVERSION return NS_ERROR_CANNOT_CONVERT_DATA;
template <typename DataType, bool Adopting=false>
struct variant_integer_traits
{
typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
static inline nsresult asInt32(const StorageType &, int32_t *) { NO_CONVERSION }
static inline nsresult asInt64(const StorageType &, int64_t *) { NO_CONVERSION }
};
template <typename DataType, bool Adopting=false>
struct variant_float_traits
{
typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
static inline nsresult asDouble(const StorageType &, double *) { NO_CONVERSION }
};
template <typename DataType, bool Adopting=false>
struct variant_text_traits
{
typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
static inline nsresult asUTF8String(const StorageType &, nsACString &) { NO_CONVERSION }
static inline nsresult asString(const StorageType &, nsAString &) { NO_CONVERSION }
};
template <typename DataType, bool Adopting=false>
struct variant_blob_traits
{
typedef typename variant_storage_traits<DataType, Adopting>::StorageType StorageType;
static inline nsresult asArray(const StorageType &, uint16_t *, uint32_t *, void **)
{ NO_CONVERSION }
};
#undef NO_CONVERSION
/**
* INTEGER types
*/
template < >
struct variant_traits<int64_t>
{
static inline uint16_t type() { return nsIDataType::VTYPE_INT64; }
};
template < >
struct variant_integer_traits<int64_t>
{
static inline nsresult asInt32(int64_t aValue,
int32_t *_result)
{
if (aValue > INT32_MAX || aValue < INT32_MIN)
return NS_ERROR_CANNOT_CONVERT_DATA;
*_result = static_cast<int32_t>(aValue);
return NS_OK;
}
static inline nsresult asInt64(int64_t aValue,
int64_t *_result)
{
*_result = aValue;
return NS_OK;
}
};
// xpcvariant just calls get double for integers...
template < >
struct variant_float_traits<int64_t>
{
static inline nsresult asDouble(int64_t aValue,
double *_result)
{
*_result = double(aValue);
return NS_OK;
}
};
/**
* FLOAT types
*/
template < >
struct variant_traits<double>
{
static inline uint16_t type() { return nsIDataType::VTYPE_DOUBLE; }
};
template < >
struct variant_float_traits<double>
{
static inline nsresult asDouble(double aValue,
double *_result)
{
*_result = aValue;
return NS_OK;
}
};
/**
* TEXT types
*/
template < >
struct variant_traits<nsString>
{
static inline uint16_t type() { return nsIDataType::VTYPE_ASTRING; }
};
template < >
struct variant_storage_traits<nsString>
{
typedef const nsAString & ConstructorType;
typedef nsString StorageType;
static inline void storage_conversion(ConstructorType aText, StorageType* _outData)
{
*_outData = aText;
}
static inline void destroy(const StorageType& _outData)
{ }
};
template < >
struct variant_text_traits<nsString>
{
static inline nsresult asUTF8String(const nsString &aValue,
nsACString &_result)
{
CopyUTF16toUTF8(aValue, _result);
return NS_OK;
}
static inline nsresult asString(const nsString &aValue,
nsAString &_result)
{
_result = aValue;
return NS_OK;
}
};
template < >
struct variant_traits<nsCString>
{
static inline uint16_t type() { return nsIDataType::VTYPE_UTF8STRING; }
};
template < >
struct variant_storage_traits<nsCString>
{
typedef const nsACString & ConstructorType;
typedef nsCString StorageType;
static inline void storage_conversion(ConstructorType aText, StorageType* _outData)
{
*_outData = aText;
}
static inline void destroy(const StorageType &aData)
{ }
};
template < >
struct variant_text_traits<nsCString>
{
static inline nsresult asUTF8String(const nsCString &aValue,
nsACString &_result)
{
_result = aValue;
return NS_OK;
}
static inline nsresult asString(const nsCString &aValue,
nsAString &_result)
{
CopyUTF8toUTF16(aValue, _result);
return NS_OK;
}
};
/**
* BLOB types
*/
template < >
struct variant_traits<uint8_t[]>
{
static inline uint16_t type() { return nsIDataType::VTYPE_ARRAY; }
};
template < >
struct variant_storage_traits<uint8_t[], false>
{
typedef std::pair<const void *, int> ConstructorType;
typedef FallibleTArray<uint8_t> StorageType;
static inline void storage_conversion(ConstructorType aBlob, StorageType* _outData)
{
_outData->Clear();
(void)_outData->AppendElements(static_cast<const uint8_t *>(aBlob.first),
aBlob.second, fallible);
}
static inline void destroy(const StorageType& _outData)
{ }
};
template < >
struct variant_storage_traits<uint8_t[], true>
{
typedef std::pair<uint8_t *, int> ConstructorType;
typedef std::pair<uint8_t *, int> StorageType;
static inline void storage_conversion(ConstructorType aBlob, StorageType* _outData)
{
*_outData = aBlob;
}
static inline void destroy(StorageType &aData)
{
if (aData.first) {
free(aData.first);
aData.first = nullptr;
}
}
};
template < >
struct variant_blob_traits<uint8_t[], false>
{
static inline nsresult asArray(FallibleTArray<uint8_t> &aData,
uint16_t *_type,
uint32_t *_size,
void **_result)
{
// For empty blobs, we return nullptr.
if (aData.Length() == 0) {
*_result = nullptr;
*_type = nsIDataType::VTYPE_UINT8;
*_size = 0;
return NS_OK;
}
// Otherwise, we copy the array.
*_result = nsMemory::Clone(aData.Elements(), aData.Length() * sizeof(uint8_t));
NS_ENSURE_TRUE(*_result, NS_ERROR_OUT_OF_MEMORY);
// Set type and size
*_type = nsIDataType::VTYPE_UINT8;
*_size = aData.Length();
return NS_OK;
}
};
template < >
struct variant_blob_traits<uint8_t[], true>
{
static inline nsresult asArray(std::pair<uint8_t *, int> &aData,
uint16_t *_type,
uint32_t *_size,
void **_result)
{
// For empty blobs, we return nullptr.
if (aData.second == 0) {
*_result = nullptr;
*_type = nsIDataType::VTYPE_UINT8;
*_size = 0;
return NS_OK;
}
// Otherwise, transfer the data out.
*_result = aData.first;
aData.first = nullptr;
MOZ_ASSERT(*_result); // We asked for it twice, better not use adopting!
// Set type and size
*_type = nsIDataType::VTYPE_UINT8;
*_size = aData.second;
return NS_OK;
}
};
/**
* nullptr type
*/
class NullVariant : public Variant_base
{
public:
NS_IMETHOD GetDataType(uint16_t *_type)
{
NS_ENSURE_ARG_POINTER(_type);
*_type = nsIDataType::VTYPE_EMPTY;
return NS_OK;
}
NS_IMETHOD GetAsAUTF8String(nsACString &_str)
{
// Return a void string.
_str.Truncate(0);
_str.SetIsVoid(true);
return NS_OK;
}
NS_IMETHOD GetAsAString(nsAString &_str)
{
// Return a void string.
_str.Truncate(0);
_str.SetIsVoid(true);
return NS_OK;
}
};
////////////////////////////////////////////////////////////////////////////////
//// Template Implementation
template <typename DataType, bool Adopting=false>
class Variant final : public Variant_base
{
~Variant()
{
variant_storage_traits<DataType, Adopting>::destroy(mData);
}
public:
explicit Variant(const typename variant_storage_traits<DataType, Adopting>::ConstructorType aData)
{
variant_storage_traits<DataType, Adopting>::storage_conversion(aData, &mData);
}
NS_IMETHOD GetDataType(uint16_t *_type)
{
*_type = variant_traits<DataType>::type();
return NS_OK;
}
NS_IMETHOD GetAsInt32(int32_t *_integer)
{
return variant_integer_traits<DataType, Adopting>::asInt32(mData, _integer);
}
NS_IMETHOD GetAsInt64(int64_t *_integer)
{
return variant_integer_traits<DataType, Adopting>::asInt64(mData, _integer);
}
NS_IMETHOD GetAsDouble(double *_double)
{
return variant_float_traits<DataType, Adopting>::asDouble(mData, _double);
}
NS_IMETHOD GetAsAUTF8String(nsACString &_str)
{
return variant_text_traits<DataType, Adopting>::asUTF8String(mData, _str);
}
NS_IMETHOD GetAsAString(nsAString &_str)
{
return variant_text_traits<DataType, Adopting>::asString(mData, _str);
}
NS_IMETHOD GetAsArray(uint16_t *_type,
nsIID *,
uint32_t *_size,
void **_data)
{
return variant_blob_traits<DataType, Adopting>::asArray(mData, _type, _size, _data);
}
private:
typename variant_storage_traits<DataType, Adopting>::StorageType mData;
};
////////////////////////////////////////////////////////////////////////////////
//// Handy typedefs! Use these for the right mapping.
typedef Variant<int64_t> IntegerVariant;
typedef Variant<double> FloatVariant;
typedef Variant<nsString> TextVariant;
typedef Variant<nsCString> UTF8TextVariant;
typedef Variant<uint8_t[], false> BlobVariant;
typedef Variant<uint8_t[], true> AdoptedBlobVariant;
} // namespace storage
} // namespace mozilla
#include "Variant_inl.h"
#endif // mozilla_storage_Variant_h__