1 files changed, 118 insertions, 0 deletions
diff --git a/libbutl/vector-view.hxx b/libbutl/vector-view.hxx
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+++ b/libbutl/vector-view.hxx
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+// file      : libbutl/vector-view.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#pragma once
+
+#include <vector>
+#include <cstddef>   // size_t, ptrdiff_t
+#include <utility>   // swap()
+#include <iterator>  // reverse_iterator
+#include <stdexcept> // out_of_range
+
+#include <libbutl/export.hxx>
+
+namespace butl
+{
+  // In our version a const view allows the modification of the elements
+  // unless T is made const (the same semantics as in smart pointers).
+  //
+  // @@ If T is const T1, could be useful to have a c-tor from vector<T1>.
+  //
+  template <typename T>
+  class vector_view
+  {
+  public:
+    using value_type = T;
+    using pointer = T*;
+    using reference = T&;
+    using const_pointer = const T*;
+    using const_reference = const T&;
+    using size_type = std::size_t;
+    using difference_type = std::ptrdiff_t;
+
+    using iterator = T*;
+    using const_iterator = const T*;
+    using reverse_iterator = std::reverse_iterator<iterator>;
+    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+
+    // construct/copy/destroy:
+    //
+    vector_view (): data_ (nullptr), size_ (0) {}
+    vector_view (T* d, size_type s): data_ (d), size_ (s) {}
+
+    template <typename T1, typename A>
+    vector_view (std::vector<T1, A>& v)
+        : data_ (v.data ()), size_ (v.size ()) {}
+
+    template <typename T1, typename A>
+    vector_view (const std::vector<T1, A>& v)
+        : data_ (v.data ()), size_ (v.size ()) {}
+
+    template <typename T1>
+    vector_view (const vector_view<T1>& v)
+        : data_ (v.data ()), size_ (v.size ()) {}
+
+    vector_view (vector_view&&) = default;
+    vector_view (const vector_view&) = default;
+    vector_view& operator= (vector_view&&) = default;
+    vector_view& operator= (const vector_view&) = default;
+
+    // iterators:
+    //
+    iterator               begin() const {return data_;}
+    iterator               end() const {return data_ + size_;}
+
+    const_iterator         cbegin() const {return data_;}
+    const_iterator         cend() const {return data_ + size_;}
+
+    reverse_iterator       rbegin() const {return reverse_iterator (end ());}
+    reverse_iterator       rend() const {return reverse_iterator (begin ());}
+
+    const_reverse_iterator crbegin() const {
+      return const_reverse_iterator (cend ());}
+    const_reverse_iterator crend() const {
+      return const_reverse_iterator (cbegin ());}
+
+    // capacity:
+    //
+    size_type size() const {return size_;}
+    bool      empty() const {return size_ == 0;}
+
+    // element access:
+    //
+    reference  operator[](size_type n) const {return data_[n];}
+    reference  front() const {return data_[0];}
+    reference  back() const {return data_[size_ - 1];}
+
+    reference  at(size_type n) const
+    {
+      if (n >= size_)
+        throw std::out_of_range ("index out of range");
+      return data_[n];
+    }
+
+    // data access:
+    //
+    T* data() const {return data_;}
+
+    // modifiers:
+    //
+    void assign (T* d, size_type s) {data_ = d; size_ = s;}
+    void clear () {data_ = nullptr; size_ = 0;}
+    void swap (vector_view& v) {
+      std::swap (data_, v.data_); std::swap (size_, v.size_);}
+
+  private:
+    T* data_;
+    size_type size_;
+  };
+
+  //@@ TODO.
+  //
+  template<typename T> bool operator== (vector_view<T> l, vector_view<T> r);
+  template<typename T> bool operator!= (vector_view<T> l, vector_view<T> r);
+  template<typename T> bool operator<  (vector_view<T> l, vector_view<T> r);
+  template<typename T> bool operator>  (vector_view<T> l, vector_view<T> r);
+  template<typename T> bool operator<= (vector_view<T> l, vector_view<T> r);
+  template<typename T> bool operator>= (vector_view<T> l, vector_view<T> r);
+}