1 files changed, 88 insertions, 0 deletions
diff --git a/extra/guile/scm/group.hpp b/extra/guile/scm/group.hpp
new file mode 100644
index 000000000000..69cd385820cb
--- /dev/null
+++ b/extra/guile/scm/group.hpp
@@ -0,0 +1,88 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#pragma once
+
+#include <scm/detail/define.hpp>
+#include <string>
+
+namespace scm {
+namespace detail {
+
+template <typename Tag, int Seq=0>
+struct definer
+{
+    using this_t = definer;
+    using next_t = definer<Tag, Seq + 1>;
+
+    std::string group_name_ = {};
+
+    definer() = default;
+    definer(definer&&) = default;
+
+    template <int Seq2,
+              typename Enable=std::enable_if_t<Seq2 + 1 == Seq>>
+    definer(definer<Tag, Seq2>)
+    {}
+
+    template <typename Fn>
+    next_t define(std::string name, Fn fn) &&
+    {
+        define_impl<this_t>(name, fn);
+        return { std::move(*this) };
+    }
+
+    template <typename Fn>
+    next_t maker(Fn fn) &&
+    {
+        define_impl<this_t>("make", fn);
+        return { std::move(*this) };
+    }
+};
+
+template <typename Tag, int Seq=0>
+struct group_definer
+{
+    using this_t = group_definer;
+    using next_t = group_definer<Tag, Seq + 1>;
+
+    std::string group_name_ = {};
+
+    group_definer(std::string name)
+        : group_name_{std::move(name)} {}
+
+    group_definer(group_definer&&) = default;
+
+    template <int Seq2,
+              typename Enable=std::enable_if_t<Seq2 + 1 == Seq>>
+    group_definer(group_definer<Tag, Seq2>)
+    {}
+
+    template <typename Fn>
+    next_t define(std::string name, Fn fn) &&
+    {
+        define_impl<this_t>(group_name_ + "-" + name, fn);
+        return { std::move(*this) };
+    }
+};
+
+} // namespace detail
+
+template <typename Tag=void>
+detail::definer<Tag> group()
+{
+    return {};
+}
+
+template <typename Tag=void>
+detail::group_definer<Tag> group(std::string name)
+{
+    return { std::move(name) };
+}
+
+} // namespace scm