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added equal assignment operator Array<T>::operator=(ArrayView<T const> &) #266

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Merged
merged 2 commits into from
Sep 3, 2022
Merged

added equal assignment operator Array<T>::operator=(ArrayView<T const> &) #266

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f045104
added equal assignment operator Array<T>::operator=(ArrayView<T const…
rrsettgast Aug 31, 2022
3584cb1
added doxygen for new operator
rrsettgast Sep 2, 2022
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22 changes: 22 additions & 0 deletions src/Array.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,28 @@ class Array : public ArrayView< T,
return *this;
}

/**
* @brief Copy assignment operator, performs a deep copy of rhs.
* @param rhs Source for the assignment.
* @return *this.
*/
LVARRAY_HOST_DEVICE
Array & operator=( typename ParentClass::ViewTypeConst const & rhs )
{
bufferManipulation::copyInto( this->m_dataBuffer, this->size(), rhs.dataBuffer(), rhs.size() );

INDEX_TYPE const * const dims = rhs.dims();
INDEX_TYPE const * const strides = rhs.strides();
for( int i = 0; i < NDIM; ++i )
{
this->m_dims[ i ] = dims[ i ];
this->m_strides[ i ] = strides[ i ];
}

setSingleParameterResizeIndex( rhs.getSingleParameterResizeIndex() );
return *this;
}

/**
* @brief Move assignment operator, performs a shallow copy of rhs.
* @param rhs Source for the assignment.
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14 changes: 9 additions & 5 deletions src/ArrayView.hpp
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Expand Up @@ -85,6 +85,10 @@ class ArrayView
/// The integer type used for indexing.
using IndexType = INDEX_TYPE;

/// The type when the data type is const.
using ViewTypeConst = ArrayView< std::remove_const_t< T > const, NDIM, USD, INDEX_TYPE, BUFFER_TYPE >;
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@corbett5 corbett5 Sep 1, 2022

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Just curious but is the std::remove_const necessary? I thought you don't have problems with duplicate const.

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@rrsettgast rrsettgast Sep 2, 2022 •
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I had put in ArrayVIew<T>::operator=( ArrayView<T> const&), ArrayVIew<T>::operator=( ViewTypeConst const &), but then thought better of it. I felt it was a little unclear what the intent of the operator is, and whether it would be a source of bugs. I did put in the std::remove_const because I was getting some errors in the using, but now I am not sure I was this is what fixed the problem I was having. Also:

https://stackoverflow.com/questions/5781222/duplicate-const-qualifier-allowed-in-c-but-not-in-c

but when I remove the std::remove_const it compiles fine now. I could remove it, but I feel it is better to be explicit about it...not that this is valid reasoning.

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@rrsettgast rrsettgast Sep 2, 2022

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...but then again, if I do something like this:

  array1d<double> a;
  arrayView1d<double const> aView = a;
  arrayView1d<double const>::ViewTypeConst anotherView = a;

  std::cout<<LvArray::system::demangle(typeid(anotherView).name())<<std::endl;

it outputs:

LvArray::ArrayView<double const, 1, 0, int, LvArray::ChaiBuffer>

So it is dropping the redundant const. If you dry to do:

double const const a = 1.0;

you get:

/usr/WS2/settgast/Codes/geosx/GEOSX_wave/src/main/main.cpp:34:14: error: duplicate 'const' declaration specifier [-Werror,-Wduplicate-decl-specifier]
double const const aScalar = 1.0;

so looks like it is illegal, but the compiler drops the second const when it is an alias??

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@klevzoff klevzoff Sep 3, 2022

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I think in http://eel.is/c++draft/dcl.type.cv#1 this sentence

Each cv-qualifier shall appear at most once in a cv-qualifier-seq.

refers to language grammar, i.e. what goes into text of a program, so it prohibits literally typing const const anywhere. But then

Redundant cv-qualifications are ignored.
[Note [2]: For example, these could be introduced by typedefs. — end note]

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@corbett5 corbett5 Sep 5, 2022

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I had put in ArrayVIew<T>::operator=( ArrayView<T> const&), ArrayVIew<T>::operator=( ViewTypeConst const &), but then thought better of it

We rely on the shallow copy semantics of ArrayView in at least once place where we construct the element accessors. Plus it'd be weird to have the copy constructor do something so different from the assignment operator.



/// The type when all inner array classes are converted to const views.
using NestedViewType = ArrayView< std::remove_reference_t< typeManipulation::NestedViewType< T > >,
NDIM, USD, INDEX_TYPE, BUFFER_TYPE >;
Expand Down Expand Up @@ -274,12 +278,12 @@ class ArrayView
* @return Return a new ArrayView where @c T is @c const.
*/
inline LVARRAY_HOST_DEVICE constexpr
ArrayView< T const, NDIM, USD, INDEX_TYPE, BUFFER_TYPE > toViewConst() const &
ViewTypeConst toViewConst() const &
{
return ArrayView< T const, NDIM, USD, INDEX_TYPE, BUFFER_TYPE >( m_dims,
m_strides,
m_singleParameterResizeIndex,
m_dataBuffer );
return ViewTypeConst( m_dims,
m_strides,
m_singleParameterResizeIndex,
m_dataBuffer );
}

/**
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