Initial import of libdpf.

Co-authored-by: Cursor <cursoragent@cursor.com>

include/dpf/subinterval_iterable.hpp

@@ -0,0 +1,81 @@
+/// @file dpf/subinterval_iterable.hpp
+/// @author Ryan Henry <ryan.henry@ucalgary.ca>
+/// @brief defines `dpf::subinterval_iterable` and associated helpers
+/// @copyright Copyright (c) 2019-2024 Ryan Henry and [others](@ref authors)
+/// @license Released under a GNU General Public v2.0 (GPLv2) license;
+///          see [LICENSE.md](@ref license) for details.
+
+#ifndef LIBDPF_INCLUDE_DPF_SUBINTERVAL_ITERABLE_HPP__
+#define LIBDPF_INCLUDE_DPF_SUBINTERVAL_ITERABLE_HPP__
+
+#include <cstddef>
+
+#include "hedley/hedley.h"
+
+namespace dpf
+{
+
+template <typename ChildT,
+          typename WordT>
+class setbit_index_iterable;  // forward declaration
+
+template <typename IteratorT>
+class subinterval_iterable
+{
+  public:
+    using iterator = IteratorT;
+    using size_type = std::size_t;
+
+    HEDLEY_NO_THROW
+    HEDLEY_ALWAYS_INLINE
+    explicit subinterval_iterable(iterator it, size_type buf_size, size_type from, size_type to, size_type preclip, size_type outputs_per_leaf, bool nonempty = true) noexcept
+      : it_{it}, buf_size_{buf_size}, from_{from}, to_{to},
+        length_{nonempty ? to_ - from_ : 0}, preclip_{preclip},
+        outputs_{outputs_per_leaf}, nonempty_{nonempty}
+    { }
+
+    HEDLEY_NO_THROW
+    HEDLEY_ALWAYS_INLINE
+    iterator begin() const noexcept
+    {
+        return it_ + preclip_;
+    }
+    HEDLEY_NO_THROW
+    HEDLEY_ALWAYS_INLINE
+    iterator cbegin() const noexcept
+    {
+        return it_ + preclip_;
+    }
+    HEDLEY_NO_THROW
+    HEDLEY_ALWAYS_INLINE
+    iterator end() const noexcept
+    {
+        if (!nonempty_)
+            return it_ + preclip_;
+        return it_ + preclip_ + length_ + 1;
+    }
+    HEDLEY_NO_THROW
+    HEDLEY_ALWAYS_INLINE
+    iterator cend() const noexcept
+    {
+        return end();
+    }
+
+  private:
+    iterator it_;
+    size_type buf_size_;
+    size_type from_;
+    size_type to_;
+    size_type length_;
+    size_type preclip_;
+    size_type outputs_;
+    bool nonempty_;
+
+    template <typename ChildT,
+              typename WordT>
+    friend class setbit_index_iterable;
+};  // class dpf::subinterval_iterable
+
+}  // namespace dpf
+
+#endif  // LIBDPF_INCLUDE_DPF_SUBINTERVAL_ITERABLE_HPP__