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Merged
StephanTLavavej merged 5 commits into from
Nov 7, 2020
Merged

Improve type traits usage #1413

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c424ec3
Use is_empty_v.
StephanTLavavej Nov 1, 2020
0d33af2
Use is_same_v.
StephanTLavavej Nov 1, 2020
f84b293
Use static_cast<_Uty>.
StephanTLavavej Nov 1, 2020
795b3b8
Use `if constexpr` with is_signed_v.
StephanTLavavej Nov 1, 2020
39b77a9
Use is_signed_v.
StephanTLavavej Nov 1, 2020
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28 changes: 12 additions & 16 deletions stl/inc/random
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Original file line number Diff line number Diff line change
Expand Up @@ -1824,12 +1824,12 @@ private:
result_type _Eval(_Engine& _Eng, _Ty _Min, _Ty _Max) const { // compute next value in range [_Min, _Max]
_Rng_from_urng<_Uty, _Engine> _Generator(_Eng);

const _Uty _Umin = _Adjust(_Uty(_Min));
const _Uty _Umax = _Adjust(_Uty(_Max));
const _Uty _Umin = _Adjust(static_cast<_Uty>(_Min));
const _Uty _Umax = _Adjust(static_cast<_Uty>(_Max));

_Uty _Uret;

if (_Umax - _Umin == _Uty(-1)) {
if (_Umax - _Umin == static_cast<_Uty>(-1)) {
_Uret = static_cast<_Uty>(_Generator._Get_all_bits());
} else {
_Uret = static_cast<_Uty>(_Generator(static_cast<_Uty>(_Umax - _Umin + 1)));
Expand All @@ -1839,23 +1839,19 @@ private:
}

static _Uty _Adjust(_Uty _Uval) { // convert signed ranges to unsigned ranges and vice versa
return _Adjust(_Uval, is_signed<_Ty>{});
}

static _Uty _Adjust(_Uty _Uval, true_type) { // convert signed ranges to unsigned ranges and vice versa
const _Uty _Adjuster = (_Uty(-1) >> 1) + 1; // 2^(N-1)
if _CONSTEXPR_IF (is_signed_v<_Ty>) {
const _Uty _Adjuster = (static_cast<_Uty>(-1) >> 1) + 1; // 2^(N-1)

if (_Uval < _Adjuster) {
return static_cast<_Uty>(_Uval + _Adjuster);
} else {
return static_cast<_Uty>(_Uval - _Adjuster);
if (_Uval < _Adjuster) {
return static_cast<_Uty>(_Uval + _Adjuster);
} else {
return static_cast<_Uty>(_Uval - _Adjuster);
}
} else { // _Ty is already unsigned, do nothing
return _Uval;
}
}

static _Uty _Adjust(_Uty _Uval, false_type) { // _Ty is already unsigned, do nothing
return _Uval;
}

param_type _Par;
};

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2 changes: 1 addition & 1 deletion stl/inc/xmemory
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Expand Up @@ -397,7 +397,7 @@ struct _Get_propagate_on_container_swap<_Ty, void_t<typename _Ty::propagate_on_c
// STRUCT TEMPLATE _Get_is_always_equal
template <class _Ty, class = void>
struct _Get_is_always_equal {
using type = typename is_empty<_Ty>::type;
using type = bool_constant<is_empty_v<_Ty>>;
};

template <class _Ty>
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2 changes: 1 addition & 1 deletion stl/inc/xtree
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Expand Up @@ -1759,7 +1759,7 @@ protected:
_Nodeptr _Newroot = _Scary->_Myhead; // point at nil node

if (!_Rootnode->_Isnil) { // copy or move a node, then any subtrees
typename is_same<key_type, value_type>::type _Is_set;
bool_constant<is_same_v<key_type, value_type>> _Is_set;
_Nodeptr _Pnode = _Copy_or_move(_Rootnode->_Myval, _Movefl, _Is_set);
_Pnode->_Parent = _Wherenode;
_Pnode->_Color = _Rootnode->_Color;
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3 changes: 2 additions & 1 deletion stl/inc/xutility
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Expand Up @@ -5466,7 +5466,8 @@ _NODISCARD constexpr bool _Within_limits(const _Ty& _Val, false_type, false_type
template <class _InIt, class _Ty>
_NODISCARD constexpr bool _Within_limits(_InIt, const _Ty& _Val) { // check whether _Val is within the limits of _Elem
using _Elem = remove_pointer_t<_InIt>;
return _Within_limits(_Val, is_signed<_Elem>{}, is_signed<_Ty>{}, bool_constant<-1 == static_cast<_Ty>(-1)>{});
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@barcharcraz barcharcraz Nov 5, 2020

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I don't like this change as much as the others, I think it impacts clarity more. I'm OK with it if the throughput improvement is actually decent though.

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@StephanTLavavej StephanTLavavej Nov 6, 2020

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It was enough to show up on @xiangfan-ms's radar. Clarity will be dramatically improved when we can if constexprize this, hopefully soon.

return _Within_limits(_Val, bool_constant<is_signed_v<_Elem>>{}, bool_constant<is_signed_v<_Ty>>{},
bool_constant<-1 == static_cast<_Ty>(-1)>{});
}

template <class _InIt>
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