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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 "nsMemory.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)
*
* The kvstore component also reuses this class as a common implementation
* of a simple threadsafe variant for the storage of primitive values only.
* The BooleanVariant type has been introduced for kvstore use cases and should
* be enhanced to provide full boolean variant support for mozStorage.
*
* Bug 1494102 tracks that work.
*/
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() = default;
};
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_boolean_traits {
typedef typename variant_storage_traits<DataType, Adopting>::StorageType
StorageType;
static inline nsresult asBool(const StorageType&, bool*) { NO_CONVERSION }
};
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
/**
* BOOLEAN type
*/
template <>
struct variant_traits<bool> {
static inline uint16_t type() { return nsIDataType::VTYPE_BOOL; }
};
template <>
struct variant_boolean_traits<bool> {
static inline nsresult asBool(bool aValue, bool* _result) {
*_result = aValue;
return NS_OK;
}
// NB: It might be worth also providing conversions to int types.
// NB: It'd be nice to implement asBool conversions for 0 and 1, too.
// That would let us clean up some conversions in Places, such as:
};
/**
* 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 = moz_xmemdup(aData.Elements(), aData.Length() * sizeof(uint8_t));
// 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:
uint16_t GetDataType() override { return nsIDataType::VTYPE_EMPTY; }
NS_IMETHOD GetAsAUTF8String(nsACString& _str) override {
// Return a void string.
_str.SetIsVoid(true);
return NS_OK;
}
NS_IMETHOD GetAsAString(nsAString& _str) override {
// Return a void string.
_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);
}
uint16_t GetDataType() override { return variant_traits<DataType>::type(); }
NS_IMETHOD GetAsBool(bool* _boolean) override {
return variant_boolean_traits<DataType, Adopting>::asBool(mData, _boolean);
}
NS_IMETHOD GetAsInt32(int32_t* _integer) override {
return variant_integer_traits<DataType, Adopting>::asInt32(mData, _integer);
}
NS_IMETHOD GetAsInt64(int64_t* _integer) override {
return variant_integer_traits<DataType, Adopting>::asInt64(mData, _integer);
}
NS_IMETHOD GetAsDouble(double* _double) override {
return variant_float_traits<DataType, Adopting>::asDouble(mData, _double);
}
NS_IMETHOD GetAsAUTF8String(nsACString& _str) override {
return variant_text_traits<DataType, Adopting>::asUTF8String(mData, _str);
}
NS_IMETHOD GetAsAString(nsAString& _str) override {
return variant_text_traits<DataType, Adopting>::asString(mData, _str);
}
NS_IMETHOD GetAsArray(uint16_t* _type, nsIID*, uint32_t* _size,
void** _data) override {
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.
// Currently, BooleanVariant is only useful for kvstore.
// Bug 1494102 tracks implementing full boolean variant support for mozStorage.
typedef Variant<bool> BooleanVariant;
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__