intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 104 insertions, 0 deletions

diff --git a/util/generic/iterator_range.h b/util/generic/iterator_range.h
new file mode 100644
index 0000000000..9f4d02da29
--- /dev/null
+++ b/util/generic/iterator_range.h
@@ -0,0 +1,104 @@
+#pragma once
+
+#include <util/system/yassert.h>
+
+#include <iterator>
+#include <utility>
+
+template <typename TBegin, typename TEnd = TBegin>
+struct TIteratorRange {
+    using TElement = std::remove_reference_t<decltype(*std::declval<TBegin>())>;
+
+    TIteratorRange(TBegin begin, TEnd end)
+        : Begin_(begin)
+        , End_(end)
+    {
+    }
+
+    TIteratorRange()
+        : TIteratorRange(TBegin{}, TEnd{})
+    {
+    }
+
+    TBegin begin() const {
+        return Begin_;
+    }
+
+    TEnd end() const {
+        return End_;
+    }
+
+    bool empty() const {
+        // because range based for requires exactly '!='
+        return !(Begin_ != End_);
+    }
+
+private:
+    TBegin Begin_;
+    TEnd End_;
+};
+
+template <class TIterator>
+class TIteratorRange<TIterator, TIterator> {
+public:
+    using iterator = TIterator;
+    using const_iterator = TIterator;
+    using value_type = typename std::iterator_traits<iterator>::value_type;
+    using reference = typename std::iterator_traits<iterator>::reference;
+    using const_reference = typename std::iterator_traits<const_iterator>::reference;
+    using difference_type = typename std::iterator_traits<iterator>::difference_type;
+    using size_type = std::size_t;
+
+    TIteratorRange()
+        : Begin_()
+        , End_()
+    {
+    }
+
+    TIteratorRange(TIterator begin, TIterator end)
+        : Begin_(begin)
+        , End_(end)
+    {
+    }
+
+    TIterator begin() const {
+        return Begin_;
+    }
+
+    TIterator end() const {
+        return End_;
+    }
+
+    Y_PURE_FUNCTION bool empty() const {
+        return Begin_ == End_;
+    }
+
+    size_type size() const {
+        return End_ - Begin_;
+    }
+
+    reference operator[](size_t at) const {
+        Y_ASSERT(at < size());
+
+        return *(Begin_ + at);
+    }
+
+private:
+    TIterator Begin_;
+    TIterator End_;
+};
+
+template <class TIterator>
+TIteratorRange<TIterator> MakeIteratorRange(TIterator begin, TIterator end) {
+    return TIteratorRange<TIterator>(begin, end);
+}
+
+template <class TIterator>
+TIteratorRange<TIterator> MakeIteratorRange(const std::pair<TIterator, TIterator>& range) {
+    return TIteratorRange<TIterator>(range.first, range.second);
+}
+
+template <class TBegin, class TEnd>
+TIteratorRange<TBegin, TEnd> MakeIteratorRange(TBegin begin, TEnd end) {
+    return {begin, end};
+}