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Implemented first, last, subspan.

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This commit is contained in:
Neil MacIntosh
2016-03-18 16:49:29 -07:00
parent 3d4c34966a
commit c8a412f028
2 changed files with 45 additions and 94 deletions
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include/span.h
+39 -8
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@@ -234,19 +234,50 @@ public:
~span() noexcept = default;
constexpr span& operator=(const span& other) noexcept = default;
constexpr span& operator=(span&& other) noexcept = default;
#if 0 // TODO
// [span.sub], span subviews
template <ptrdiff_t Count>
constexpr span<element_type, Count> first() const;
constexpr span<element_type, Count> first() const
{
Expects(Count >= 0 && Count <= size());
return { data(), Count };
}
template <ptrdiff_t Count>
constexpr span<element_type, Count> last() const;
constexpr span<element_type, Count> last() const
{
Expects(Count >= 0 && Count <= size());
return{ Count == 0 ? data() : data() + (size() - Count), Count };
}
template <ptrdiff_t Offset, ptrdiff_t Count = dynamic_extent>
constexpr span<element_type, Count> subspan() const;
constexpr span<element_type, dynamic_extent> first(index_type count) const;
constexpr span<element_type, dynamic_extent> last(index_type count) const;
constexpr span<element_type, dynamic_extent> subspan(index_type offset, index_type count = dynamic_extent) const;
#endif
constexpr span<element_type, Count> subspan() const
{
Expects((Offset == 0 || Offset > 0 && Offset <= size()) &&
(Count == dynamic_extent || Count >= 0 && Offset + Count <= size()));
return { data() + Offset, Count == dynamic_extent ? size() - Offset : Count };
}
constexpr span<element_type, dynamic_extent> first(index_type count) const
{
Expects(count >= 0 && count <= size());
return { data(), count };
}
constexpr span<element_type, dynamic_extent> last(index_type count) const
{
Expects(count >= 0 && count <= size());
return { count == 0 ? data() : data() + (size() - count), count };
}
constexpr span<element_type, dynamic_extent> subspan(index_type offset,
index_type count = dynamic_extent) const
{
Expects((offset == 0 || offset > 0 && offset <= size()) &&
(count == dynamic_extent || count >= 0 && offset + count <= size()));
return { data() + offset, count == dynamic_extent ? size() - offset : count };
}
// [span.obs], span observers
constexpr index_type length() const noexcept { return size(); }
constexpr index_type size() const noexcept { return storage_.size(); }