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Added indexable properties on enums (#59)
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 - _to_index which return value 0... size-1
        (even if enums are note sequential)
 - _from_index used for other way around
 - _from_index_nothrow no throw version
 - _from_index_unchecked returns invalid enum
        in case arg>=size

Code and test cases added.
No documentation updates (my English is too poor for that)
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@Shelim @aantron
Shelim authored and aantron committed Sep 6, 2018
1 parent e5549fb commit 97d38d8
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Showing 2 changed files with 135 additions and 0 deletions.
45 changes: 45 additions & 0 deletions enum.h
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Original file line number Diff line number Diff line change
Expand Up @@ -343,6 +343,12 @@ BETTER_ENUMS_CONSTEXPR_ static T* _or_null(optional<T*> maybe)
return maybe ? *maybe : BETTER_ENUMS_NULLPTR;
}

template <typename T>
BETTER_ENUMS_CONSTEXPR_ static T _or_zero(optional<T> maybe)
{
return maybe ? *maybe : T::_from_integral_unchecked(0);
}



// Functional sequencing. This is essentially a comma operator wrapped in a
Expand Down Expand Up @@ -615,6 +621,15 @@ class Enum { \
_from_integral_unchecked(_integral value); \
BETTER_ENUMS_CONSTEXPR_ static _optional \
_from_integral_nothrow(_integral value); \
\
BETTER_ENUMS_CONSTEXPR_ std::size_t _to_index() const; \
BETTER_ENUMS_IF_EXCEPTIONS( \
BETTER_ENUMS_CONSTEXPR_ static Enum _from_index(std::size_t value); \
) \
BETTER_ENUMS_CONSTEXPR_ static Enum \
_from_index_unchecked(std::size_t value); \
BETTER_ENUMS_CONSTEXPR_ static _optional \
_from_index_nothrow(std::size_t value); \
\
ToStringConstexpr const char* _to_string() const; \
BETTER_ENUMS_IF_EXCEPTIONS( \
Expand Down Expand Up @@ -727,6 +742,36 @@ BETTER_ENUMS_CONSTEXPR_ inline Enum::_integral Enum::_to_integral() const \
return _integral(_value); \
} \
\
BETTER_ENUMS_CONSTEXPR_ inline std::size_t Enum::_to_index() const \
{ \
return *_from_value_loop(_value); \
} \
\
BETTER_ENUMS_CONSTEXPR_ inline Enum \
Enum::_from_index_unchecked(std::size_t index) \
{ \
return \
::better_enums::_or_zero(_from_index_nothrow(index)); \
} \
\
BETTER_ENUMS_CONSTEXPR_ inline Enum::_optional \
Enum::_from_index_nothrow(std::size_t index) \
{ \
return \
index >= _size() ? \
_optional() : \
_optional(BETTER_ENUMS_NS(Enum)::_value_array[index]); \
} \
\
BETTER_ENUMS_IF_EXCEPTIONS( \
BETTER_ENUMS_CONSTEXPR_ inline Enum Enum::_from_index(std::size_t index) \
{ \
return \
::better_enums::_or_throw(_from_index_nothrow(index), \
#Enum "::_from_index: invalid argument"); \
} \
) \
\
BETTER_ENUMS_CONSTEXPR_ inline Enum \
Enum::_from_integral_unchecked(_integral value) \
{ \
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90 changes: 90 additions & 0 deletions test/cxxtest/general.h
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Original file line number Diff line number Diff line change
Expand Up @@ -313,6 +313,96 @@ class EnumTests : public CxxTest::TestSuite {
+test::Namespaced::One);
TS_ASSERT_EQUALS(strcmp(*test::Namespaced::_names().begin(), "One"), 0);
}

void test_to_index()
{
TS_ASSERT_EQUALS((+Channel::Red)._to_index(), 0);
TS_ASSERT_EQUALS((+Channel::Green)._to_index(), 1);
TS_ASSERT_EQUALS((+Channel::Blue)._to_index(), 2);

TS_ASSERT_EQUALS((+Depth::HighColor)._to_index(), 0);
TS_ASSERT_EQUALS((+Depth::TrueColor)._to_index(), 1);

TS_ASSERT_EQUALS((+Compression::None)._to_index(), 0);
TS_ASSERT_EQUALS((+Compression::Huffman)._to_index(), 1);
// TS_ASSERT_EQUALS((+Compression::Default)._to_index(), 2); // This won't pass as Compression::Huffman == Compression::Default
}

void test_from_index()
{
TS_ASSERT_EQUALS((+Channel::Red), Channel::_from_index(0));
TS_ASSERT_EQUALS((+Channel::Green), Channel::_from_index(1));
TS_ASSERT_EQUALS((+Channel::Blue), Channel::_from_index(2));
TS_ASSERT_THROWS(Channel::_from_index(42), std::runtime_error);

TS_ASSERT_EQUALS((+Depth::HighColor), Depth::_from_index(0));
TS_ASSERT_EQUALS((+Depth::TrueColor), Depth::_from_index(1));
TS_ASSERT_THROWS(Depth::_from_index(42), std::runtime_error);

TS_ASSERT_EQUALS((+Compression::None), Compression::_from_index(0));
TS_ASSERT_EQUALS((+Compression::Huffman), Compression::_from_index(1));
TS_ASSERT_EQUALS((+Compression::Default), Compression::_from_index(2));
TS_ASSERT_THROWS(Compression::_from_index(42), std::runtime_error);
}

void test_from_index_nothrow()
{
better_enums::optional<Channel> maybe_channel = Channel::_from_index_nothrow(0);
TS_ASSERT(maybe_channel);
TS_ASSERT_EQUALS(*maybe_channel, +Channel::Red);

maybe_channel = Channel::_from_index_nothrow(1);
TS_ASSERT(maybe_channel);
TS_ASSERT_EQUALS(*maybe_channel, +Channel::Green);

maybe_channel = Channel::_from_index_nothrow(2);
TS_ASSERT(maybe_channel);
TS_ASSERT_EQUALS(*maybe_channel, +Channel::Blue);

maybe_channel = Channel::_from_index_nothrow(45);
TS_ASSERT(!maybe_channel);

better_enums::optional<Depth> maybe_depth = Depth::_from_index_nothrow(0);
TS_ASSERT(maybe_depth);
TS_ASSERT_EQUALS(*maybe_depth, +Depth::HighColor);

maybe_depth = Depth::_from_index_nothrow(1);
TS_ASSERT(maybe_depth);
TS_ASSERT_EQUALS(*maybe_depth, +Depth::TrueColor);

maybe_depth = Depth::_from_index_nothrow(45);
TS_ASSERT(!maybe_depth);

better_enums::optional<Compression> maybe_compression = Compression::_from_index_nothrow(0);
TS_ASSERT(maybe_compression);
TS_ASSERT_EQUALS(*maybe_compression, +Compression::None);

maybe_compression = Compression::_from_index_nothrow(1);
TS_ASSERT(maybe_compression);
TS_ASSERT_EQUALS(*maybe_compression, +Compression::Huffman);

maybe_compression = Compression::_from_index_nothrow(2);
TS_ASSERT(maybe_compression);
TS_ASSERT_EQUALS(*maybe_compression, +Compression::Default);

maybe_compression = Compression::_from_index_nothrow(45);
TS_ASSERT(!maybe_compression);
}

void test_from_index_unchecked()
{

TS_ASSERT_EQUALS((+Channel::Red), Channel::_from_index_unchecked(0));
TS_ASSERT_EQUALS((+Channel::Green), Channel::_from_index_unchecked(1));
TS_ASSERT_EQUALS((+Channel::Blue), Channel::_from_index_unchecked(2));

TS_ASSERT_EQUALS((+Depth::HighColor), Depth::_from_index_unchecked(0));
TS_ASSERT_EQUALS((+Depth::TrueColor), Depth::_from_index_unchecked(1));

TS_ASSERT_EQUALS((+Compression::None), Compression::_from_index_unchecked(0));
TS_ASSERT_EQUALS((+Compression::Huffman), Compression::_from_index_unchecked(1));
TS_ASSERT_EQUALS((+Compression::Default), Compression::_from_index_unchecked(2));
}
};


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