From fa8387252e9702f596b2632ca6297f7d99ff9cc9 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Mon, 20 Apr 2015 17:16:18 +1000
Subject: [PATCH] tuple: add tuple iteration helpers

---
 Makefile.am    |   3 ++
 test/tuple.cpp |  38 +++++++++++++++++++
 tuple.cpp      |  19 ++++++++++
 tuple.hpp      | 100 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 160 insertions(+)
 create mode 100644 test/tuple.cpp
 create mode 100644 tuple.cpp
 create mode 100644 tuple.hpp

diff --git a/Makefile.am b/Makefile.am
index c7cead25..a54a3a02 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -176,6 +176,8 @@ UTIL_FILES   =		\
     tap.ipp		\
     time.cpp		\
     time.hpp		\
+    tuple.cpp		\
+    tuple.hpp		\
     types.hpp		\
     types/bits.hpp	\
     types/casts.hpp	\
@@ -284,6 +286,7 @@ TEST_BIN = 			\
     test/sha2			\
     test/signal			\
     test/stringid		\
+    test/tuple			\
     test/uri			\
     test/vector			\
     test/version
diff --git a/test/tuple.cpp b/test/tuple.cpp
new file mode 100644
index 00000000..ed4441c3
--- /dev/null
+++ b/test/tuple.cpp
@@ -0,0 +1,38 @@
+#include "tuple.hpp"
+
+#include "tap.hpp"
+
+#include <typeindex>
+
+int
+main ()
+{
+    util::TAP::logger tap;
+
+    {
+        auto tuple = std::make_tuple (1,2,3,4);
+        std::vector<int> expected {{ 1, 2, 3, 4 }};
+
+        std::vector<int> actual;
+        util::for_each ([&actual] (auto i) { actual.push_back (i); }, tuple);
+
+        tap.expect_eq (actual, expected, "value iteration");
+    }
+
+    {
+        auto tuple = std::make_tuple (1u, 1, 1.f, 1.);
+        std::vector<std::type_index> expected {
+            std::type_index (typeid (1u)),
+            std::type_index (typeid (1)),
+            std::type_index (typeid (1.f)),
+            std::type_index (typeid (1.))
+        };
+
+        std::vector<std::type_index> actual;
+        util::for_type<decltype(tuple)> ([&actual] (auto i) {
+            actual.push_back (typeid (typename decltype(i)::type));
+        });
+
+        tap.expect_eq (actual, expected, "type iteration");
+    }
+}
diff --git a/tuple.cpp b/tuple.cpp
new file mode 100644
index 00000000..d470aaa9
--- /dev/null
+++ b/tuple.cpp
@@ -0,0 +1,19 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "tuple.hpp"
+
+// Make sure _someone_ includes the header for syntax checking
diff --git a/tuple.hpp b/tuple.hpp
new file mode 100644
index 00000000..1e8c4e8e
--- /dev/null
+++ b/tuple.hpp
@@ -0,0 +1,100 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2015 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __UTIL_TUPLE_HPP
+#define __UTIL_TUPLE_HPP
+
+#include "types.hpp"
+
+#include <tuple>
+#include <type_traits>
+
+
+namespace util {
+    ///////////////////////////////////////////////////////////////////////////
+    /// call a provided object with type_tag<T> for each type in a tuple
+    template <
+        typename T,
+        typename F,
+        size_t S = 0
+    >
+    typename std::enable_if<
+        S == std::tuple_size<T>::value,
+        void
+    >::type
+    for_type (F)
+    { }
+
+
+    //-------------------------------------------------------------------------
+    template<
+        typename T,
+        typename F,
+        size_t S = 0
+    >
+    typename std::enable_if<
+        S < std::tuple_size<T>::value,
+        void
+    >::type
+    for_type (F f)
+    {
+        using E = typename std::tuple_element<S,T>::type;
+
+        f (type_tag<E> {});
+        for_type<T,F,S+1> (f);
+    }
+
+
+    //-------------------------------------------------------------------------
+    template <typename T, typename F>
+    auto for_type (F f, T t)
+    { return for_type<decltype(t)> (f); }
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    /// call a provided object with each value in a tuple
+    template <
+        size_t S = 0,
+        typename F,
+        typename ...T
+    >
+    typename std::enable_if<
+        S == sizeof...(T),
+        void
+    >::type
+    for_each (F, const std::tuple<T...>&)
+    { }
+
+
+    //-------------------------------------------------------------------------
+    template<
+        size_t S = 0,
+        typename F,
+        typename ...T
+    >
+    typename std::enable_if<
+        S < sizeof...(T),
+        void
+    >::type
+    for_each (F f, const std::tuple<T...> &t)
+    {
+        f (std::get<S> (t));
+        for_each<S+1,F,T...> (f, t);
+    }
+}
+
+
+#endif