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Rework nested<> to be cleaner, see bug #76.

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This commit is contained in:
Benoit Jacob 2010-11-23 11:11:40 -05:00
parent 4c5932f8f5
commit ee38dbf1e6
1 changed files with 14 additions and 26 deletions
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40
Eigen/src/Core/util/XprHelper.h
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@ -308,41 +308,29 @@ struct ref_selector
*/
template<typename T, int n=1, typename PlainObject = typename eval<T>::type> struct nested
{
// this is a direct port of the logic used when Dynamic was 33331, to make an atomic commit.
enum {
_ScalarReadCost = NumTraits<typename traits<T>::Scalar>::ReadCost,
ScalarReadCost = _ScalarReadCost == Dynamic ? 33331 : int(_ScalarReadCost),
_CoeffReadCost = int(traits<T>::CoeffReadCost),
CoeffReadCost = _CoeffReadCost == Dynamic ? 33331 : int(_CoeffReadCost),
N = n == Dynamic ? 33331 : n,
CostEval = (N+1) * int(ScalarReadCost),
CostNoEval = (N-1) * int(CoeffReadCost)
};
typedef typename conditional<
( int(traits<T>::Flags) & EvalBeforeNestingBit ) ||
( int(CostEval) <= int(CostNoEval) ),
PlainObject,
typename ref_selector<T>::type
>::type type;
/* this is what the above logic should be updated to look like:
enum {
// for the purpose of this test, to keep it reasonably simple, we arbitrarily choose a value of Dynamic values.
// the choice of 10000 makes it larger than any practical fixed value and even most dynamic values.
// in extreme cases where these assumptions would be wrong, we would still at worst suffer performance issues
// (poor choice of temporaries).
// it's important that this value can still be squared without integer overflowing.
DynamicAsInteger = 10000,
ScalarReadCost = NumTraits<typename traits<T>::Scalar>::ReadCost,
ScalarReadCostAsInteger = ScalarReadCost == Dynamic ? DynamicAsInteger : ScalarReadCost,
CoeffReadCost = traits<T>::CoeffReadCost,
CostEval = n == Dynamic || ScalarReadCost == Dynamic ? int(Dynamic) : (n+1) * int(ScalarReadCost),
CostNoEval = n == Dynamic || (CoeffReadCost == Dynamic && n>1) ? int(Dynamic) : (n-1) * int(CoeffReadCost)
CoeffReadCostAsInteger = CoeffReadCost == Dynamic ? DynamicAsInteger : CoeffReadCost,
NAsInteger = n == Dynamic ? int(DynamicAsInteger) : n,
CostEvalAsInteger = (NAsInteger+1) * ScalarReadCostAsInteger + CoeffReadCostAsInteger,
CostNoEvalAsInteger = NAsInteger * CoeffReadCostAsInteger
};
typedef typename conditional<
( int(traits<T>::Flags) & EvalBeforeNestingBit ) ||
( int(CostNoEval) == Dynamic ? true
: int(CostEval) == Dynamic ? false
: int(CostEval) <= int(CostNoEval) ),
( (int(traits<T>::Flags) & EvalBeforeNestingBit) ||
int(CostEvalAsInteger) < int(CostNoEvalAsInteger)
),
PlainObject,
typename ref_selector<T>::type
>::type type;
*/
};
template<unsigned int Flags> struct are_flags_consistent