1 files changed, 147 insertions, 0 deletions
diff --git a/src/common/sfinae_helpers.h b/src/common/sfinae_helpers.h
new file mode 100644
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+++ b/src/common/sfinae_helpers.h
@@ -0,0 +1,147 @@
+// Copyright (c) 2016-2017, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once
+
+// the loose definitions of types in this file are, well, loose.
+//
+// these helpers aren't here for absolute type certainty at compile-time,
+// but rather to help with templated functions telling types apart.
+
+namespace sfinae
+{
+
+  typedef char true_type;
+
+  struct false_type { true_type a[2]; };
+
+  template <typename T>
+  struct is_not_container
+  {
+  private:
+
+    // does not have const iterator
+    template <typename C> static false_type c_iter(typename C::const_iterator*);
+    template <typename C> static true_type c_iter(...);
+
+    // does not have value_type
+    template <typename C> static false_type v_type(typename C::value_type*);
+    template <typename C> static true_type v_type(...);
+
+    // does not have key_type
+    template <typename C> static false_type k_type(typename C::key_type*);
+    template <typename C> static true_type k_type(...);
+
+    // does not have mapped_type
+    template <typename C> static false_type m_type(typename C::mapped_type*);
+    template <typename C> static true_type m_type(...);
+
+  public:
+
+    static const bool value = (
+      (
+        sizeof(c_iter<T>(0)) == sizeof(true_type) &&
+        sizeof(v_type<T>(0)) == sizeof(true_type) &&
+        sizeof(k_type<T>(0)) == sizeof(true_type) &&
+        sizeof(m_type<T>(0)) == sizeof(true_type)
+      )
+      || std::is_same<T, std::string>::value
+    );
+
+    typedef T type;
+  };
+
+  template <typename T>
+  struct is_vector_like
+  {
+  private:
+
+    // has const iterator
+    template <typename C> static true_type c_iter(typename C::const_iterator*);
+    template <typename C> static false_type c_iter(...);
+
+    // has value_type
+    template <typename C> static true_type v_type(typename C::value_type*);
+    template <typename C> static false_type v_type(...);
+
+    // does not have key_type
+    template <typename C> static false_type k_type(typename C::key_type*);
+    template <typename C> static true_type k_type(...);
+
+    // does not have mapped_type
+    template <typename C> static false_type m_type(typename C::mapped_type*);
+    template <typename C> static true_type m_type(...);
+
+  public:
+
+    static const bool value = (
+        sizeof(c_iter<T>(0)) == sizeof(true_type) &&
+        sizeof(v_type<T>(0)) == sizeof(true_type) &&
+        sizeof(k_type<T>(0)) == sizeof(true_type) &&
+        sizeof(m_type<T>(0)) == sizeof(true_type) &&
+        !std::is_same<T, std::string>::value
+    );
+
+    typedef T type;
+  };
+
+  template <typename T>
+  struct is_map_like
+  {
+  private:
+
+    // has const iterator
+    template <typename C> static true_type c_iter(typename C::const_iterator*);
+    template <typename C> static false_type c_iter(...);
+
+    // has value_type
+    template <typename C> static true_type v_type(typename C::value_type*);
+    template <typename C> static false_type v_type(...);
+
+    // has key_type
+    template <typename C> static true_type k_type(typename C::key_type*);
+    template <typename C> static false_type k_type(...);
+
+    // has mapped_type
+    template <typename C> static true_type m_type(typename C::mapped_type*);
+    template <typename C> static false_type m_type(...);
+
+  public:
+
+    static const bool value = (
+        sizeof(c_iter<T>(0)) == sizeof(true_type) &&
+        sizeof(v_type<T>(0)) == sizeof(true_type) &&
+        sizeof(k_type<T>(0)) == sizeof(true_type) &&
+        sizeof(m_type<T>(0)) == sizeof(true_type) &&
+        !std::is_same<T, std::string>::value
+    );
+
+    typedef T type;
+  };
+
+}  // namespace sfinae