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Add an enum-compatible bitset class. (#10492) 

## Summary of the Pull Request

This introduces a new TIL class that is equivalent in functionality to a `std::bitset`, but where the positions in the bitset are enum values. It also has a few additional methods allowing for setting and testing multiple positions at the same time. The idea is that this class could be used in place of the `WI_SetFlag` and `WI_IsFlagSet` macros when working with sets of flags.

## PR Checklist
* [x] Closes #10432
* [x] CLA signed.
* [x] Tests added/passed
* [ ] Documentation updated.
* [ ] Schema updated.
* [x] I've discussed this with core contributors already. Issue number where discussion took place: #10432

## Validation Steps Performed

I've added a few unit tests that verify the behaviour of all the new methods that aren't part of `std::bitset`. I've also tried it out as a replacement for the `GridLines` enum used in the renderer, and confirmed that it has all the functionality needed to replace that cleanly.
This commit is contained in:
James Holderness 2021-09-27 14:27:29 +01:00 committed by GitHub
parent 2be394f421
commit 09d0ac768a
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6 changed files with 305 additions and 0 deletions
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1
.github/actions/spelling/allow/apis.txt vendored
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@ -25,6 +25,7 @@ DERR
dlldata
DONTADDTORECENT
DWORDLONG
enumset
environstrings
EXPCMDFLAGS
EXPCMDSTATE

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src/inc/til.h
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@ -21,6 +21,7 @@
#include "til/replace.h"
#include "til/string.h"
#include "til/pmr.h"
#include "til/enumset.h"
// Use keywords on TraceLogging providers to specify the category
// of event that we are emitting for filtering purposes.

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src/inc/til/enumset.h Normal file
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// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.
#pragma once
#include <bitset>
namespace til // Terminal Implementation Library. Also: "Today I Learned"
{
// By design, this class hides several methods in the std::bitset class
// so they can be called with an enum parameter instead of a size_t, so
// we need to disable the "hides a non-virtual function" warning.
#pragma warning(push)
#pragma warning(disable : 26434)
// til::enumset is a subclass of std::bitset, storing a fixed size array of
// boolean elements, the positions in the array being identified by values
// from a given enumerated type. By default it holds the same number of
// bits as a size_t value.
template<typename Type, size_t Bits = std::numeric_limits<size_t>::digits>
class enumset : public std::bitset<Bits>
{
using _base = std::bitset<Bits>;
public:
using reference = typename _base::reference;
enumset() = default;
// Method Description:
// - Constructs a new bitset with the given list of positions set to true.
template<typename... Args, typename = std::enable_if_t<std::conjunction_v<std::is_same<Type, Args>...>>>
constexpr enumset(const Args... positions) noexcept :
_base((... | (1ULL << static_cast<size_t>(positions))))
{
}
// Method Description:
// - Returns the value of the bit at the given position.
constexpr bool operator[](const Type pos) const
{
return _base::operator[](static_cast<size_t>(pos));
}
// Method Description:
// - Returns a reference to the bit at the given position.
reference operator[](const Type pos)
{
return _base::operator[](static_cast<size_t>(pos));
}
// Method Description:
// - Returns the value of the bit at the given position.
// Throws std::out_of_range if it is not a valid position
// in the bitset.
bool test(const Type pos) const
{
return _base::test(static_cast<size_t>(pos));
}
// Method Description:
// - Returns true if any of the bits are set to true.
bool any() const noexcept
{
return _base::any();
}
// Method Description:
// - Returns true if any of the bits in the given positions are true.
template<typename... Args, typename = std::enable_if_t<std::conjunction_v<std::is_same<Type, Args>...>>>
bool any(const Args... positions) const noexcept
{
return (enumset{ positions... } & *this) != 0;
}
// Method Description:
// - Returns true if all of the bits are set to true.
bool all() const noexcept
{
return _base::all();
}
// Method Description:
// - Returns true if all of the bits in the given positions are true.
template<typename... Args, typename = std::enable_if_t<std::conjunction_v<std::is_same<Type, Args>...>>>
bool all(const Args... positions) const noexcept
{
return (enumset{ positions... } & *this) == enumset{ positions... };
}
// Method Description:
// - Sets the bit in the given position to the specified value.
enumset& set(const Type pos, const bool val = true)
{
_base::set(static_cast<size_t>(pos), val);
return *this;
}
// Method Description:
// - Resets the bit in the given position to false.
enumset& reset(const Type pos)
{
_base::reset(static_cast<size_t>(pos));
return *this;
}
// Method Description:
// - Flips the bit at the given position.
enumset& flip(const Type pos)
{
_base::flip(static_cast<size_t>(pos));
return *this;
}
// Method Description:
// - Sets all of the bits in the given positions to true.
template<typename... Args>
enumset& set_all(const Args... positions)
{
return (..., set(positions));
}
// Method Description:
// - Resets all of the bits in the given positions to false.
template<typename... Args>
enumset& reset_all(const Args... positions)
{
return (..., reset(positions));
}
};
#pragma warning(pop)
}

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src/til/ut_til/EnumSetTests.cpp Normal file
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// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.
#include "precomp.h"
#include "WexTestClass.h"
using namespace WEX::Logging;
class EnumSetTests
{
TEST_CLASS(EnumSetTests);
TEST_METHOD(Constructors)
{
enum class Flags
{
Zero,
One,
Two,
Three,
Four
};
{
Log::Comment(L"Default constructor with no bits set");
til::enumset<Flags> flags;
VERIFY_ARE_EQUAL(0b00000u, flags.to_ulong());
}
{
Log::Comment(L"Constructor with bit 3 set");
til::enumset<Flags> flags{ Flags::Three };
VERIFY_ARE_EQUAL(0b01000u, flags.to_ulong());
}
{
Log::Comment(L"Constructor with bits 0, 2, and 4 set");
til::enumset<Flags> flags{ Flags::Zero, Flags::Two, Flags::Four };
VERIFY_ARE_EQUAL(0b10101u, flags.to_ulong());
}
}
TEST_METHOD(SetResetFlipMethods)
{
enum class Flags
{
Zero,
One,
Two,
Three,
Four
};
Log::Comment(L"Start with no bits set");
til::enumset<Flags> flags;
VERIFY_ARE_EQUAL(0b00000u, flags.to_ulong());
Log::Comment(L"Set bit 2 to true");
flags.set(Flags::Two);
VERIFY_ARE_EQUAL(0b00100u, flags.to_ulong());
Log::Comment(L"Flip bit 4 to true");
flags.flip(Flags::Four);
VERIFY_ARE_EQUAL(0b10100u, flags.to_ulong());
Log::Comment(L"Set bit 0 to true");
flags.set(Flags::Zero);
VERIFY_ARE_EQUAL(0b10101u, flags.to_ulong());
Log::Comment(L"Reset bit 2 to false, leaving 0 and 4 true");
flags.reset(Flags::Two);
VERIFY_ARE_EQUAL(0b10001u, flags.to_ulong());
Log::Comment(L"Set bit 0 to false, leaving 4 true");
flags.set(Flags::Zero, false);
VERIFY_ARE_EQUAL(0b10000u, flags.to_ulong());
Log::Comment(L"Flip bit 4, leaving all bits false ");
flags.flip(Flags::Four);
VERIFY_ARE_EQUAL(0b00000u, flags.to_ulong());
Log::Comment(L"Set bits 0, 3, and 2");
flags.set_all(Flags::Zero, Flags::Three, Flags::Two);
VERIFY_ARE_EQUAL(0b01101u, flags.to_ulong());
Log::Comment(L"Reset bits 3, 4 (already reset), and 0, leaving 2 true");
flags.reset_all(Flags::Three, Flags::Four, Flags::Zero);
VERIFY_ARE_EQUAL(0b00100u, flags.to_ulong());
}
TEST_METHOD(TestMethods)
{
enum class Flags
{
Zero,
One,
Two,
Three,
Four
};
Log::Comment(L"Start with bits 0, 2, and 4 set");
til::enumset<Flags> flags{ Flags::Zero, Flags::Two, Flags::Four };
VERIFY_ARE_EQUAL(0b10101u, flags.to_ulong());
Log::Comment(L"Test bits 1 and 2 with the test method");
VERIFY_IS_FALSE(flags.test(Flags::One));
VERIFY_IS_TRUE(flags.test(Flags::Two));
Log::Comment(L"Test bit 3 and 4 with the array operator");
VERIFY_IS_FALSE(flags[Flags::Three]);
VERIFY_IS_TRUE(flags[Flags::Four]);
Log::Comment(L"Test if any bits are set");
VERIFY_IS_TRUE(flags.any());
Log::Comment(L"Test if either bit 1 or 3 are set");
VERIFY_IS_FALSE(flags.any(Flags::One, Flags::Three));
Log::Comment(L"Test if either bit 1 or 4 are set");
VERIFY_IS_TRUE(flags.any(Flags::One, Flags::Four));
Log::Comment(L"Test if all bits are set");
VERIFY_IS_FALSE(flags.all());
Log::Comment(L"Test if both bits 0 and 4 are set");
VERIFY_IS_TRUE(flags.all(Flags::Zero, Flags::Four));
Log::Comment(L"Test if both bits 0 and 3 are set");
VERIFY_IS_FALSE(flags.all(Flags::Zero, Flags::Three));
}
TEST_METHOD(ArrayReferenceOperator)
{
enum class Flags
{
Zero,
One,
Two,
Three,
Four
};
Log::Comment(L"Start with no bits set");
til::enumset<Flags> flags;
VERIFY_ARE_EQUAL(0b00000u, flags.to_ulong());
Log::Comment(L"Test bit 3 reference is false");
auto reference = flags[Flags::Three];
VERIFY_IS_FALSE(reference);
VERIFY_ARE_EQUAL(0b00000u, flags.to_ulong());
Log::Comment(L"Set bit 3 reference to true");
flags.set(Flags::Three);
VERIFY_IS_TRUE(reference);
VERIFY_ARE_EQUAL(0b01000u, flags.to_ulong());
Log::Comment(L"Reset bit 3 reference to false");
flags.reset(Flags::Three);
VERIFY_IS_FALSE(reference);
VERIFY_ARE_EQUAL(0b00000u, flags.to_ulong());
Log::Comment(L"Flip bit 3 reference to true");
reference.flip();
VERIFY_IS_TRUE(reference);
VERIFY_ARE_EQUAL(0b01000u, flags.to_ulong());
Log::Comment(L"Flip bit 3 reference back to false");
reference.flip();
VERIFY_IS_FALSE(reference);
VERIFY_ARE_EQUAL(0b00000u, flags.to_ulong());
}
};

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@ -17,6 +17,7 @@
<ClCompile Include="BitmapTests.cpp" />
<ClCompile Include="CoalesceTests.cpp" />
<ClCompile Include="ColorTests.cpp" />
<ClCompile Include="EnumSetTests.cpp" />
<ClCompile Include="MathTests.cpp" />
<ClCompile Include="mutex.cpp" />
<ClCompile Include="OperatorTests.cpp" />

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src/til/ut_til/til.unit.tests.vcxproj.filters
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@ -9,6 +9,7 @@
<ClCompile Include="BitmapTests.cpp" />
<ClCompile Include="CoalesceTests.cpp" />
<ClCompile Include="ColorTests.cpp" />
<ClCompile Include="EnumSetTests.cpp" />
<ClCompile Include="MathTests.cpp" />
<ClCompile Include="mutex.cpp" />
<ClCompile Include="OperatorTests.cpp" />