Add element access via at() to std::mdspan
#302
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at() to std::mdspan
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Given that SizeTypes can be signed, it should also check for indices[r] < 0. |
Thanks for this comment! Is this true for |
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Ah right, thanks for pointing this out! Edit: updated the pull request |
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Signed-off-by: Stephan Lachnit <[email protected]>
Signed-off-by: Stephan Lachnit <[email protected]>
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| // Check for negative indices | ||
| if constexpr(std::is_signed_v<SizeType>) { | ||
| if(index < 0) { | ||
| return true; | ||
| } | ||
| } |
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SizeType doesn't need to be integral here or even less-than comparable with int. mdspan behaves as if all operations on indices happen after conversion to index_type. Thus, should we consider instead converting to index_type first, as we do below?
| // Check for negative indices | |
| if constexpr(std::is_signed_v<SizeType>) { | |
| if(index < 0) { | |
| return true; | |
| } | |
| } | |
| // Check for negative indices | |
| if constexpr (std::is_signed_v<index_type>) { | |
| if (static_cast<index_type>(index) < 0) { | |
| return true; | |
| } | |
| } |
Closes #300
Possible implementation for ::at element access to mdspan with boundary checks. The boundary check is implemented with a for loop, as I did not see any other way to achieve this. The error message is inspired by the
std::span::aterror message from libstdc++ (gcc-mirror/gcc@1fa85dc).Note that this does not implement ::at element access to mdarray.