From df1ef68cd8e8582724ce1192bfc202e0b9aeaf0c Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Tue, 28 Sep 2021 19:24:31 +0300
Subject: Get rid of C++ modules related code and rename *.mxx files to *.hxx

---
 libbutl/small-list.hxx | 150 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 libbutl/small-list.hxx

(limited to 'libbutl/small-list.hxx')

diff --git a/libbutl/small-list.hxx b/libbutl/small-list.hxx
new file mode 100644
index 0000000..aaeef22
--- /dev/null
+++ b/libbutl/small-list.hxx
@@ -0,0 +1,150 @@
+// file      : libbutl/small-list.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#pragma once
+
+#include <list>
+#include <cstddef> // size_t
+#include <utility> // move()
+
+#include <libbutl/small-allocator.hxx>
+
+#include <libbutl/export.hxx>
+
+namespace butl
+{
+  // Issues and limitations.
+  //
+  // - VC's implementation of std::list allocates an extra "headnode"
+  //   (something to do with additional iterator stability guarantees). Which
+  //   means only empty small list will actually be "small". As a result,
+  //   unless you don't care about VC, you should use small_forward_list
+  //   instead.
+  //
+  // - Because small_allocator currently expects us to allocate the entire
+  //   small buffer and there is no reserve() in std::list, we currently
+  //   only support N==1 (which we static_assert).
+  //
+  // - swap() is deleted (see notes below).
+  //
+  // - The implementation doesn't allocate T but rather a "node" that normally
+  //   consists of two pointers (prev/next) and T.
+  //
+  template <typename T>
+  using small_list_node =
+#if   defined (_MSC_VER)
+  std::_List_node<T, void*>;
+#elif defined (__GLIBCXX__)
+  std::_List_node<T>;
+#elif defined (_LIBCPP_VERSION)
+  std::__list_node<T, void*>;
+#else
+#error unknown standard library implementation
+#endif
+
+  template <typename T, std::size_t N>
+  using small_list_buffer = small_allocator_buffer<small_list_node<T>, N>;
+
+  template <typename T, std::size_t N>
+  class small_list:
+    private small_list_buffer<T, N>,
+    public std::list<T, small_allocator<T, N, small_list_buffer<T, N>>>
+  {
+    static_assert (N == 1, "only small_list or 1 currently supported");
+
+  public:
+    static constexpr const std::size_t small_size = N;
+
+    using buffer_type = small_list_buffer<T, N>;
+    using allocator_type = small_allocator<T, N, buffer_type>;
+    using base_type = std::list<T, allocator_type>;
+
+    small_list ()
+      : base_type (allocator_type (this)) {}
+
+    small_list (std::initializer_list<T> v)
+      : base_type (allocator_type (this))
+    {
+      static_cast<base_type&> (*this) = v;
+    }
+
+    template <typename I>
+    small_list (I b, I e)
+      : base_type (allocator_type (this))
+    {
+      this->assign (b, e);
+    }
+
+    explicit
+    small_list (std::size_t n)
+      : base_type (allocator_type (this))
+    {
+      this->resize (n);
+    }
+
+    small_list (std::size_t n, const T& x)
+      : base_type (allocator_type (this))
+    {
+      this->assign (n, x);
+    }
+
+    small_list (const small_list& v)
+      : buffer_type (), base_type (allocator_type (this))
+    {
+      static_cast<base_type&> (*this) = v;
+    }
+
+    small_list&
+    operator= (const small_list& v)
+    {
+      // Note: propagate_on_container_copy_assignment = false
+      //
+      static_cast<base_type&> (*this) = v;
+      return *this;
+    }
+
+    small_list (small_list&& v)
+      : base_type (allocator_type (this))
+    {
+      *this = std::move (v); // Delegate to operator=(&&).
+    }
+
+    small_list&
+    operator= (small_list&& v)
+    {
+      // libstdc++'s implementation prior to GCC 6 is broken (calls swap()).
+      // Since there is no easy way to determine this library's version, for
+      // now this is always enabled.
+      //
+      // Similarly, VC14's implementation of operator=(&&) swaps pointers
+      // without regard for allocator (fixed in 15).
+      //
+#if defined(__GLIBCXX__) || (defined(_MSC_VER) && _MSC_VER <= 1900)
+      this->clear ();
+      for (T& x: v)
+        this->push_back (std::move (x));
+      v.clear ();
+#else
+      // Note: propagate_on_container_move_assignment = false
+      //
+      static_cast<base_type&> (*this) = std::move (v);
+#endif
+
+      return *this;
+    }
+
+    small_list&
+    operator= (std::initializer_list<T> v)
+    {
+      static_cast<base_type&> (*this) = v;
+      return *this;
+    }
+
+    // Implementing swap() under small buffer optimization is not trivial, to
+    // say the least (think of swapping two such buffers of different sizes).
+    // One easy option would be to force both in to the heap.
+    //
+    void
+    swap (small_list&) = delete;
+  };
+}
-- 
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