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Diffstat (limited to 'absl/types/span.h')
| -rw-r--r-- | absl/types/span.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/absl/types/span.h b/absl/types/span.h index bce18ebc..ea1808d3 100644 --- a/absl/types/span.h +++ b/absl/types/span.h @@ -485,6 +485,40 @@ class Span { : (base_internal::ThrowStdOutOfRange("pos > size()"), Span()); } + // Span::first() + // + // Returns a `Span` containing first `len` elements. Parameter `len` is of + // type `size_type` and thus non-negative. `len` value must be <= size(). + // + // Examples: + // + // std::vector<int> vec = {10, 11, 12, 13}; + // absl::MakeSpan(vec).first(1); // {10} + // absl::MakeSpan(vec).first(3); // {10, 11, 12} + // absl::MakeSpan(vec).first(5); // throws std::out_of_range + constexpr Span first(size_type len) const { + return (len <= size()) + ? Span(data(), len) + : (base_internal::ThrowStdOutOfRange("len > size()"), Span()); + } + + // Span::last() + // + // Returns a `Span` containing last `len` elements. Parameter `len` is of + // type `size_type` and thus non-negative. `len` value must be <= size(). + // + // Examples: + // + // std::vector<int> vec = {10, 11, 12, 13}; + // absl::MakeSpan(vec).last(1); // {13} + // absl::MakeSpan(vec).last(3); // {11, 12, 13} + // absl::MakeSpan(vec).last(5); // throws std::out_of_range + constexpr Span last(size_type len) const { + return (len <= size()) + ? Span(data() + size() - len, len) + : (base_internal::ThrowStdOutOfRange("len > size()"), Span()); + } + // Support for absl::Hash. template <typename H> friend H AbslHashValue(H h, Span v) { |