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hehe, the complicated nesting scheme in Flagged in the previous commit

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was a sign that we were doing something wrong. In fact, having
NestByValue as a special case of Flagged was wrong, and the previous
commit, while not buggy, was inefficient because then when the resulting
NestByValue xpr was nested -- hence copied -- the original xpr which was
already nested by value was copied again; hence instead of 1 copy we got
3 copies.
The solution was to ressuscitate the old Temporary.h (renamed
NestByValue.h) as it was the right approach.
This commit is contained in:
Benoit Jacob
2008-05-28 05:14:16 +00:00
parent aebecae510
commit f54760c889
10 changed files with 108 additions and 24 deletions
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5
Eigen/src/Core/util/Meta.h
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@@ -192,11 +192,14 @@ template<typename T> struct ei_unref<T&> { typedef T type; };
template<typename T> struct ei_unconst { typedef T type; };
template<typename T> struct ei_unconst<const T> { typedef T type; };
template<typename T> struct ei_must_nest_by_value { enum { ret = false }; };
template<typename T> struct ei_must_nest_by_value<NestByValue<T> > { enum { ret = true }; };
template<typename T, int n=1> struct ei_nested
{
typedef typename ei_meta_if<
ei_traits<T>::Flags & NestByValueBit,
ei_must_nest_by_value<T>::ret,
T,
typename ei_meta_if<
int(ei_traits<T>::Flags) & EvalBeforeNestingBit