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Diffstat (limited to 'storage/Variant.h')
| -rw-r--r-- | storage/Variant.h | 435 |
1 files changed, 435 insertions, 0 deletions
diff --git a/storage/Variant.h b/storage/Variant.h new file mode 100644 index 0000000000..420ca94b94 --- /dev/null +++ b/storage/Variant.h @@ -0,0 +1,435 @@ +/* -*- 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) + * + * 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: + // https://searchfox.org/mozilla-central/rev/0640ea80fbc8d48f8b197cd363e2535c95a15eb3/toolkit/components/places/SQLFunctions.cpp#564-565 + // https://searchfox.org/mozilla-central/rev/0640ea80fbc8d48f8b197cd363e2535c95a15eb3/toolkit/components/places/SQLFunctions.cpp#1057 + // https://searchfox.org/mozilla-central/rev/0640ea80fbc8d48f8b197cd363e2535c95a15eb3/toolkit/components/places/nsNavHistory.cpp#3189 +}; + +/** + * 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__ |