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Add a guard_value utility for scoped temporary assignment

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Celtic Minstrel 2021-04-11 18:09:58 -04:00 • committed by Celtic Minstrel
parent 72cede2c8a
commit 508bc2519e
4 changed files with 47 additions and 0 deletions
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1
projectfiles/VC16/wesnoth.vcxproj
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@ -4135,6 +4135,7 @@
<ClInclude Include="..\..\src\utils\parse_network_address.hpp" />
<ClInclude Include="..\..\src\utils\reference_counter.hpp" />
<ClInclude Include="..\..\src\utils\scope_exit.hpp" />
<ClInclude Include="..\..\src\utils\guard_value.hpp" />
<ClInclude Include="..\..\src\variable.hpp" />
<ClInclude Include="..\..\src\variable_info.hpp" />
<ClInclude Include="..\..\src\variable_info_detail.hpp" />

1
projectfiles/VC16/wesnoth.vcxproj.filters
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@ -3032,6 +3032,7 @@
<Filter>Desktop</Filter>
</ClInclude>
<ClInclude Include="..\..\src\utils\scope_exit.hpp" />
<ClInclude Include="..\..\src\utils\guard_value.hpp" />
<ClInclude Include="..\..\src\serialization\schema\key.hpp">
<Filter>Serialization\Schema</Filter>
</ClInclude>

2
projectfiles/Xcode/The Battle for Wesnoth.xcodeproj/project.pbxproj
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@ -2119,6 +2119,7 @@
9197979A261A6FCA001E8133 /* wml_equivalence.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = wml_equivalence.hpp; sourceTree = "<group>"; };
9197979B261A6FCA001E8133 /* wml_equivalence.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = wml_equivalence.cpp; sourceTree = "<group>"; };
919797A6261A6FDB001E8133 /* test_macro_define.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = test_macro_define.cpp; sourceTree = "<group>"; };
919797DF2623A28D001E8133 /* guard_value.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = guard_value.hpp; sourceTree = "<group>"; };
919B37F71BAF789D00E0094C /* synced_user_choice.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = synced_user_choice.cpp; sourceTree = "<group>"; };
919B37F91BAF78AB00E0094C /* synced_user_choice.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; path = synced_user_choice.hpp; sourceTree = "<group>"; };
91A214E41CAD618700927AEA /* gettext.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = gettext.hpp; sourceTree = "<group>"; };
@ -4217,6 +4218,7 @@
91C55DA21CC078820040012E /* context_free_grammar_generator.cpp */,
91C55DA31CC078820040012E /* context_free_grammar_generator.hpp */,
EC5012711E06185600C4DFC6 /* general.hpp */,
919797DF2623A28D001E8133 /* guard_value.hpp */,
46DF5BCC1F46173700BE6D24 /* irdya_datetime.cpp */,
46DF5BCB1F46173700BE6D24 /* irdya_datetime.hpp */,
911F471B1CAE5A7E00F47035 /* iterable_pair.hpp */,

43
src/utils/guard_value.hpp Normal file
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@ -0,0 +1,43 @@
/*
Copyright (C) 2003 - 2018 the Battle for Wesnoth Project https://www.wesnoth.org/
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY.
See the COPYING file for more details.
*/
#pragma once
namespace utils {
/**
* Data-based RAII scope guard.
* Assigns a value to a specific location, then restores the old value once it goes out of scope.
*/
template<typename T>
class guard_value {
T* ref_;
T old_val_;
public:
/**
* @param ref The memory location being guarded
* @param new_val The new value to temporarily assign to that location
*/
guard_value(T& ref, T new_val)
: ref_(&ref)
, old_val_(ref)
{
ref = new_val;
}
~guard_value()
{
*ref_ = old_val_;
}
};
}