first/last constructor working.
diff --git a/include/span.h b/include/span.h
index b8c1196..38cf9f5 100644
--- a/include/span.h
+++ b/include/span.h
@@ -96,13 +96,20 @@
// [span.cons], span constructors, copy, assignment, and destructor
constexpr span() noexcept : data_(nullptr), size_(0)
{ static_assert(extent == dynamic_extent || extent == 0, "Cannot default initialize a fixed-length span."); }
- constexpr span(nullptr_t) noexcept : span() {}
+
+ constexpr span(nullptr_t) noexcept : span()
+ {}
+
constexpr span(pointer ptr, index_type count) : data_(ptr), size_(count)
- { Expects((!ptr && count == 0) || (ptr && count >= 0)); }
-#if 0 // TODO
- constexpr span(pointer firstElem, pointer lastElem);
+ { Expects(((!ptr && count == 0) || (ptr && count >= 0)) && (extent == dynamic_extent || extent == count)); }
+
+ constexpr span(pointer firstElem, pointer lastElem) : data_(firstElem), size_(std::distance(firstElem, lastElem))
+ { Expects(size_ >= 0 && (extent == dynamic_extent || extent == size_)); }
+
template <size_t N>
- constexpr span(element_type(&arr)[N]);
+ constexpr span(element_type(&arr)[N]) {}
+
+#if 0 // TODO
template <size_t N>
constexpr span(array<remove_const_t<element_type>, N>& arr);
template <size_t N>
@@ -139,11 +146,13 @@
constexpr index_type size_bytes() const noexcept { return size() * sizeof(element_type); }
constexpr bool empty() const noexcept { return size() == 0; }
-#if 0 // TODO
// [span.elem], span element access
- constexpr reference operator[](index_type idx) const;
- constexpr reference operator()(index_type idx) const;
-#endif
+ constexpr reference operator[](index_type idx) const
+ {
+ Expects(idx >= 0 && idx < size_);
+ return data_[idx];
+ }
+ constexpr reference operator()(index_type idx) const { return this->operator[](idx); }
constexpr pointer data() const noexcept { return data_; }
#if 0 // TODO
// [span.iter], span iterator support