mirror of
https://github.com/mozilla/gecko-dev.git
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c2d3f05163
Differential Revision: https://phabricator.services.mozilla.com/D65498 --HG-- extra : moz-landing-system : lando
437 lines
13 KiB
C++
437 lines
13 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_storage_Variant_h__
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#define mozilla_storage_Variant_h__
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#include <utility>
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#include "nsIVariant.h"
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#include "nsMemory.h"
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#include "nsString.h"
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#include "nsTArray.h"
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#define VARIANT_BASE_IID \
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{ /* 78888042-0fa3-4f7a-8b19-7996f99bf1aa */ \
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0x78888042, 0x0fa3, 0x4f7a, { \
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0x8b, 0x19, 0x79, 0x96, 0xf9, 0x9b, 0xf1, 0xaa \
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} \
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}
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/**
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* This class is used by the storage module whenever an nsIVariant needs to be
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* returned. We provide traits for the basic sqlite types to make use easier.
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* The following types map to the indicated sqlite type:
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* int64_t -> INTEGER (use IntegerVariant)
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* double -> FLOAT (use FloatVariant)
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* nsString -> TEXT (use TextVariant)
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* nsCString -> TEXT (use UTF8TextVariant)
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* uint8_t[] -> BLOB (use BlobVariant)
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* nullptr -> NULL (use NullVariant)
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*
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* The kvstore component also reuses this class as a common implementation
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* of a simple threadsafe variant for the storage of primitive values only.
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* The BooleanVariant type has been introduced for kvstore use cases and should
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* be enhanced to provide full boolean variant support for mozStorage.
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*
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* Bug 1494102 tracks that work.
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*/
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namespace mozilla {
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namespace storage {
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////////////////////////////////////////////////////////////////////////////////
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//// Base Class
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class Variant_base : public nsIVariant {
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public:
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIVARIANT
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NS_DECLARE_STATIC_IID_ACCESSOR(VARIANT_BASE_IID)
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protected:
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virtual ~Variant_base() = default;
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};
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NS_DEFINE_STATIC_IID_ACCESSOR(Variant_base, VARIANT_BASE_IID)
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////////////////////////////////////////////////////////////////////////////////
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//// Traits
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/**
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* Generics
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*/
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template <typename DataType>
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struct variant_traits {
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static inline uint16_t type() { return nsIDataType::VTYPE_EMPTY; }
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};
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template <typename DataType, bool Adopting = false>
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struct variant_storage_traits {
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typedef DataType ConstructorType;
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typedef DataType StorageType;
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static inline void storage_conversion(const ConstructorType aData,
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StorageType* _storage) {
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*_storage = aData;
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}
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static inline void destroy(const StorageType& _storage) {}
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};
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#define NO_CONVERSION return NS_ERROR_CANNOT_CONVERT_DATA;
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template <typename DataType, bool Adopting = false>
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struct variant_boolean_traits {
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typedef typename variant_storage_traits<DataType, Adopting>::StorageType
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StorageType;
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static inline nsresult asBool(const StorageType&, bool*) { NO_CONVERSION }
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};
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template <typename DataType, bool Adopting = false>
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struct variant_integer_traits {
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typedef typename variant_storage_traits<DataType, Adopting>::StorageType
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StorageType;
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static inline nsresult asInt32(const StorageType&, int32_t*) { NO_CONVERSION }
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static inline nsresult asInt64(const StorageType&, int64_t*) { NO_CONVERSION }
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};
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template <typename DataType, bool Adopting = false>
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struct variant_float_traits {
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typedef typename variant_storage_traits<DataType, Adopting>::StorageType
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StorageType;
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static inline nsresult asDouble(const StorageType&, double*) { NO_CONVERSION }
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};
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template <typename DataType, bool Adopting = false>
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struct variant_text_traits {
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typedef typename variant_storage_traits<DataType, Adopting>::StorageType
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StorageType;
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static inline nsresult asUTF8String(const StorageType&, nsACString&) {
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NO_CONVERSION
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}
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static inline nsresult asString(const StorageType&, nsAString&) {
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NO_CONVERSION
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}
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};
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template <typename DataType, bool Adopting = false>
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struct variant_blob_traits {
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typedef typename variant_storage_traits<DataType, Adopting>::StorageType
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StorageType;
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static inline nsresult asArray(const StorageType&, uint16_t*, uint32_t*,
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void**) {
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NO_CONVERSION
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}
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};
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#undef NO_CONVERSION
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/**
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* BOOLEAN type
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*/
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template <>
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struct variant_traits<bool> {
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static inline uint16_t type() { return nsIDataType::VTYPE_BOOL; }
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};
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template <>
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struct variant_boolean_traits<bool> {
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static inline nsresult asBool(bool aValue, bool* _result) {
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*_result = aValue;
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return NS_OK;
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}
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// NB: It might be worth also providing conversions to int types.
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// NB: It'd be nice to implement asBool conversions for 0 and 1, too.
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// That would let us clean up some conversions in Places, such as:
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// https://searchfox.org/mozilla-central/rev/0640ea80fbc8d48f8b197cd363e2535c95a15eb3/toolkit/components/places/SQLFunctions.cpp#564-565
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// https://searchfox.org/mozilla-central/rev/0640ea80fbc8d48f8b197cd363e2535c95a15eb3/toolkit/components/places/SQLFunctions.cpp#1057
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// https://searchfox.org/mozilla-central/rev/0640ea80fbc8d48f8b197cd363e2535c95a15eb3/toolkit/components/places/nsNavHistory.cpp#3189
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};
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/**
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* INTEGER types
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*/
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template <>
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struct variant_traits<int64_t> {
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static inline uint16_t type() { return nsIDataType::VTYPE_INT64; }
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};
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template <>
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struct variant_integer_traits<int64_t> {
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static inline nsresult asInt32(int64_t aValue, int32_t* _result) {
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if (aValue > INT32_MAX || aValue < INT32_MIN)
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return NS_ERROR_CANNOT_CONVERT_DATA;
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*_result = static_cast<int32_t>(aValue);
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return NS_OK;
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}
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static inline nsresult asInt64(int64_t aValue, int64_t* _result) {
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*_result = aValue;
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return NS_OK;
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}
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};
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// xpcvariant just calls get double for integers...
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template <>
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struct variant_float_traits<int64_t> {
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static inline nsresult asDouble(int64_t aValue, double* _result) {
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*_result = double(aValue);
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return NS_OK;
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}
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};
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/**
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* FLOAT types
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*/
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template <>
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struct variant_traits<double> {
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static inline uint16_t type() { return nsIDataType::VTYPE_DOUBLE; }
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};
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template <>
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struct variant_float_traits<double> {
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static inline nsresult asDouble(double aValue, double* _result) {
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*_result = aValue;
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return NS_OK;
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}
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};
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/**
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* TEXT types
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*/
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template <>
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struct variant_traits<nsString> {
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static inline uint16_t type() { return nsIDataType::VTYPE_ASTRING; }
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};
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template <>
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struct variant_storage_traits<nsString> {
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typedef const nsAString& ConstructorType;
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typedef nsString StorageType;
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static inline void storage_conversion(ConstructorType aText,
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StorageType* _outData) {
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*_outData = aText;
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}
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static inline void destroy(const StorageType& _outData) {}
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};
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template <>
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struct variant_text_traits<nsString> {
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static inline nsresult asUTF8String(const nsString& aValue,
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nsACString& _result) {
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CopyUTF16toUTF8(aValue, _result);
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return NS_OK;
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}
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static inline nsresult asString(const nsString& aValue, nsAString& _result) {
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_result = aValue;
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return NS_OK;
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}
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};
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template <>
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struct variant_traits<nsCString> {
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static inline uint16_t type() { return nsIDataType::VTYPE_UTF8STRING; }
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};
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template <>
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struct variant_storage_traits<nsCString> {
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typedef const nsACString& ConstructorType;
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typedef nsCString StorageType;
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static inline void storage_conversion(ConstructorType aText,
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StorageType* _outData) {
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*_outData = aText;
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}
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static inline void destroy(const StorageType& aData) {}
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};
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template <>
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struct variant_text_traits<nsCString> {
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static inline nsresult asUTF8String(const nsCString& aValue,
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nsACString& _result) {
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_result = aValue;
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return NS_OK;
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}
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static inline nsresult asString(const nsCString& aValue, nsAString& _result) {
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CopyUTF8toUTF16(aValue, _result);
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return NS_OK;
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}
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};
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/**
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* BLOB types
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*/
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template <>
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struct variant_traits<uint8_t[]> {
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static inline uint16_t type() { return nsIDataType::VTYPE_ARRAY; }
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};
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template <>
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struct variant_storage_traits<uint8_t[], false> {
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typedef std::pair<const void*, int> ConstructorType;
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typedef FallibleTArray<uint8_t> StorageType;
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static inline void storage_conversion(ConstructorType aBlob,
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StorageType* _outData) {
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_outData->Clear();
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(void)_outData->AppendElements(static_cast<const uint8_t*>(aBlob.first),
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aBlob.second, fallible);
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}
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static inline void destroy(const StorageType& _outData) {}
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};
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template <>
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struct variant_storage_traits<uint8_t[], true> {
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typedef std::pair<uint8_t*, int> ConstructorType;
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typedef std::pair<uint8_t*, int> StorageType;
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static inline void storage_conversion(ConstructorType aBlob,
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StorageType* _outData) {
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*_outData = aBlob;
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}
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static inline void destroy(StorageType& aData) {
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if (aData.first) {
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free(aData.first);
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aData.first = nullptr;
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}
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}
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};
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template <>
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struct variant_blob_traits<uint8_t[], false> {
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static inline nsresult asArray(FallibleTArray<uint8_t>& aData,
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uint16_t* _type, uint32_t* _size,
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void** _result) {
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// For empty blobs, we return nullptr.
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if (aData.Length() == 0) {
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*_result = nullptr;
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*_type = nsIDataType::VTYPE_UINT8;
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*_size = 0;
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return NS_OK;
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}
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// Otherwise, we copy the array.
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*_result = moz_xmemdup(aData.Elements(), aData.Length() * sizeof(uint8_t));
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// Set type and size
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*_type = nsIDataType::VTYPE_UINT8;
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*_size = aData.Length();
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return NS_OK;
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}
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};
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template <>
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struct variant_blob_traits<uint8_t[], true> {
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static inline nsresult asArray(std::pair<uint8_t*, int>& aData,
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uint16_t* _type, uint32_t* _size,
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void** _result) {
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// For empty blobs, we return nullptr.
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if (aData.second == 0) {
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*_result = nullptr;
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*_type = nsIDataType::VTYPE_UINT8;
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*_size = 0;
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return NS_OK;
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}
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// Otherwise, transfer the data out.
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*_result = aData.first;
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aData.first = nullptr;
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MOZ_ASSERT(*_result); // We asked for it twice, better not use adopting!
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// Set type and size
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*_type = nsIDataType::VTYPE_UINT8;
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*_size = aData.second;
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return NS_OK;
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}
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};
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/**
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* nullptr type
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*/
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class NullVariant : public Variant_base {
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public:
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uint16_t GetDataType() override { return nsIDataType::VTYPE_EMPTY; }
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NS_IMETHOD GetAsAUTF8String(nsACString& _str) override {
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// Return a void string.
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_str.SetIsVoid(true);
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return NS_OK;
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}
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NS_IMETHOD GetAsAString(nsAString& _str) override {
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// Return a void string.
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_str.SetIsVoid(true);
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return NS_OK;
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}
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};
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////////////////////////////////////////////////////////////////////////////////
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//// Template Implementation
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template <typename DataType, bool Adopting = false>
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class Variant final : public Variant_base {
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~Variant() { variant_storage_traits<DataType, Adopting>::destroy(mData); }
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public:
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explicit Variant(
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const typename variant_storage_traits<DataType, Adopting>::ConstructorType
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aData) {
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variant_storage_traits<DataType, Adopting>::storage_conversion(aData,
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&mData);
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}
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uint16_t GetDataType() override { return variant_traits<DataType>::type(); }
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NS_IMETHOD GetAsBool(bool* _boolean) override {
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return variant_boolean_traits<DataType, Adopting>::asBool(mData, _boolean);
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}
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NS_IMETHOD GetAsInt32(int32_t* _integer) override {
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return variant_integer_traits<DataType, Adopting>::asInt32(mData, _integer);
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}
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NS_IMETHOD GetAsInt64(int64_t* _integer) override {
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return variant_integer_traits<DataType, Adopting>::asInt64(mData, _integer);
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}
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NS_IMETHOD GetAsDouble(double* _double) override {
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return variant_float_traits<DataType, Adopting>::asDouble(mData, _double);
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}
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NS_IMETHOD GetAsAUTF8String(nsACString& _str) override {
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return variant_text_traits<DataType, Adopting>::asUTF8String(mData, _str);
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}
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NS_IMETHOD GetAsAString(nsAString& _str) override {
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return variant_text_traits<DataType, Adopting>::asString(mData, _str);
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}
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NS_IMETHOD GetAsArray(uint16_t* _type, nsIID*, uint32_t* _size,
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void** _data) override {
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return variant_blob_traits<DataType, Adopting>::asArray(mData, _type, _size,
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_data);
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}
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private:
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typename variant_storage_traits<DataType, Adopting>::StorageType mData;
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};
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////////////////////////////////////////////////////////////////////////////////
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//// Handy typedefs! Use these for the right mapping.
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// Currently, BooleanVariant is only useful for kvstore.
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// Bug 1494102 tracks implementing full boolean variant support for mozStorage.
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typedef Variant<bool> BooleanVariant;
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typedef Variant<int64_t> IntegerVariant;
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typedef Variant<double> FloatVariant;
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typedef Variant<nsString> TextVariant;
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typedef Variant<nsCString> UTF8TextVariant;
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typedef Variant<uint8_t[], false> BlobVariant;
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typedef Variant<uint8_t[], true> AdoptedBlobVariant;
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} // namespace storage
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} // namespace mozilla
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#include "Variant_inl.h"
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#endif // mozilla_storage_Variant_h__
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