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libstdc++: Refactor seed sequence constraints in <random>

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Every use of _If_seed_seq in <random> and <ext/random> uses it with
enable_if. We can just move the enable_if into the helper alias instead
of repeating it everywhere.

libstdc++-v3/ChangeLog:

	* include/bits/random.h (__is_seed_seq): Replace with ...
	(_If_seed_seq_for): ... this.
	* include/ext/random: Adjust to use _If_seed_seq_for.
This commit is contained in:
Jonathan Wakely 2022-10-04 12:57:33 +01:00
parent e87879a9f5
commit 68ed966793
2 changed files with 27 additions and 18 deletions
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39
libstdc++-v3/include/bits/random.h
View file

@ -198,16 +198,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Engine& _M_g;
};
// Detect whether a template argument _Sseq is a valid seed sequence for
// a random number engine _Engine with result type _Res.
// Used to constrain _Engine::_Engine(_Sseq&) and _Engine::seed(_Sseq&)
// as required by [rand.eng.general].
template<typename _Sseq>
using __seed_seq_generate_t = decltype(
std::declval<_Sseq&>().generate(std::declval<uint_least32_t*>(),
std::declval<uint_least32_t*>()));
// Detect whether _Sseq is a valid seed sequence for
// a random number engine _Engine with result type _Res.
template<typename _Sseq, typename _Engine, typename _Res,
typename _GenerateCheck = __seed_seq_generate_t<_Sseq>>
using __is_seed_seq = __and_<
using _If_seed_seq_for = _Require<
__not_<is_same<__remove_cvref_t<_Sseq>, _Engine>>,
is_unsigned<typename _Sseq::result_type>,
__not_<is_convertible<_Sseq, _Res>>
@ -263,8 +266,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
"template argument substituting __m out of bounds");
template<typename _Sseq>
using _If_seed_seq = typename enable_if<__detail::__is_seed_seq<
_Sseq, linear_congruential_engine, _UIntType>::value>::type;
using _If_seed_seq
= __detail::_If_seed_seq_for<_Sseq, linear_congruential_engine,
_UIntType>;
public:
/** The type of the generated random value. */
@ -502,8 +506,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
"template argument substituting __f out of bound");
template<typename _Sseq>
using _If_seed_seq = typename enable_if<__detail::__is_seed_seq<
_Sseq, mersenne_twister_engine, _UIntType>::value>::type;
using _If_seed_seq
= __detail::_If_seed_seq_for<_Sseq, mersenne_twister_engine,
_UIntType>;
public:
/** The type of the generated random value. */
@ -702,8 +707,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
"template argument substituting __w out of bounds");
template<typename _Sseq>
using _If_seed_seq = typename enable_if<__detail::__is_seed_seq<
_Sseq, subtract_with_carry_engine, _UIntType>::value>::type;
using _If_seed_seq
= __detail::_If_seed_seq_for<_Sseq, subtract_with_carry_engine,
_UIntType>;
public:
/** The type of the generated random value. */
@ -894,8 +900,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typedef typename _RandomNumberEngine::result_type result_type;
template<typename _Sseq>
using _If_seed_seq = typename enable_if<__detail::__is_seed_seq<
_Sseq, discard_block_engine, result_type>::value>::type;
using _If_seed_seq
= __detail::_If_seed_seq_for<_Sseq, discard_block_engine,
result_type>;
// parameter values
static constexpr size_t block_size = __p;
@ -1113,8 +1120,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
"template argument substituting __w out of bounds");
template<typename _Sseq>
using _If_seed_seq = typename enable_if<__detail::__is_seed_seq<
_Sseq, independent_bits_engine, _UIntType>::value>::type;
using _If_seed_seq
= __detail::_If_seed_seq_for<_Sseq, independent_bits_engine,
_UIntType>;
public:
/** The type of the generated random value. */
@ -1336,8 +1344,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typedef typename _RandomNumberEngine::result_type result_type;
template<typename _Sseq>
using _If_seed_seq = typename enable_if<__detail::__is_seed_seq<
_Sseq, shuffle_order_engine, result_type>::value>::type;
using _If_seed_seq
= __detail::_If_seed_seq_for<_Sseq, shuffle_order_engine,
result_type>;
static constexpr size_t table_size = __k;

6
libstdc++-v3/include/ext/random
View file

@ -89,9 +89,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Sseq>
using _If_seed_seq
= typename std::enable_if<std::__detail::__is_seed_seq<
_Sseq, simd_fast_mersenne_twister_engine, result_type>::value
>::type;
= std::__detail::_If_seed_seq_for<_Sseq,
simd_fast_mersenne_twister_engine,
result_type>;
public:
static constexpr size_t state_size = _M_nstate * (16