diff -r d8475431bbbb -r 8e85e6bbefdf lemon/utility.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lemon/utility.h	Mon May 23 04:48:14 2005 +0000
@@ -0,0 +1,152 @@
+/* -*- C++ -*-
+ * lemon/utility.h - Part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi
+ * Kutatocsoport (Egervary Research Group on Combinatorial Optimization,
+ * EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ * This file contains a modified version of the enable_if library from BOOST.
+ * See the appropriate copyright notice below.
+ */
+
+// Boost enable_if library
+
+// Copyright 2003 © The Trustees of Indiana University.
+
+// Use, modification, and distribution is subject to the Boost Software
+// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+//    Authors: Jaakko Järvi (jajarvi at osl.iu.edu)
+//             Jeremiah Willcock (jewillco at osl.iu.edu)
+//             Andrew Lumsdaine (lums at osl.iu.edu)
+
+
+#ifndef LEMON_UTILITY_H
+#define LEMON_UTILITY_H
+
+namespace lemon
+{
+
+  /// Basic type for defining "tags". A "YES" condition for enable_if.
+
+  /// \todo This should go to a separate "basic_types.h" (or something)
+  /// file.
+  struct True {
+    static const bool value = true;
+  };
+
+  /// Basic type for defining "tags". A "NO" condition for enable_if.
+  struct False {
+    static const bool value = false;
+  };
+
+  template <typename T>
+  struct Wrap {
+    const T &value;
+    Wrap(const T &t) : value(t) {}
+  };
+
+  /**************** dummy class to avoid ambiguity ****************/
+
+  template<int T> struct dummy { dummy(int) {} };
+
+  /**************** enable_if from BOOST ****************/
+ 
+  template <bool B, class T = void>
+  struct enable_if_c {
+    typedef T type;
+  };
+
+  template <class T>
+  struct enable_if_c<false, T> {};
+
+  template <class Cond, class T = void> 
+  struct enable_if : public enable_if_c<Cond::value, T> {};
+
+  template <bool B, class T>
+  struct lazy_enable_if_c {
+    typedef typename T::type type;
+  };
+
+  template <class T>
+  struct lazy_enable_if_c<false, T> {};
+
+  template <class Cond, class T> 
+  struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {};
+
+
+  template <bool B, class T = void>
+  struct disable_if_c {
+    typedef T type;
+  };
+
+  template <class T>
+  struct disable_if_c<true, T> {};
+
+  template <class Cond, class T = void> 
+  struct disable_if : public disable_if_c<Cond::value, T> {};
+
+  template <bool B, class T>
+  struct lazy_disable_if_c {
+    typedef typename T::type type;
+  };
+
+  template <class T>
+  struct lazy_disable_if_c<true, T> {};
+
+  template <class Cond, class T> 
+  struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {};
+
+  // smart referencing
+
+  template <typename _Type, typename Enable = void>
+  struct SmartReference {
+    typedef _Type& Type;
+  };
+  
+  template <typename _Type>
+  struct SmartReference<
+    _Type, 
+    typename enable_if<typename _Type::NeedCopy, void>::type
+  > {
+    typedef _Type Type;
+  };
+
+  template <typename _Type, typename Enable = void>
+  struct SmartConstReference {
+    typedef const _Type& Type;
+  };
+  
+  template <typename _Type>
+  struct SmartConstReference<
+    _Type, 
+    typename enable_if<typename _Type::NeedCopy, void>::type
+  > {
+    typedef const _Type Type;
+  };
+
+  template <typename _Type, typename Enable = void>
+  struct SmartParameter {
+    typedef _Type& Type;
+  };
+  
+  template <typename _Type>
+  struct SmartParameter<
+    _Type, 
+    typename enable_if<typename _Type::NeedCopy, void>::type
+  > {
+    typedef const _Type& Type;
+  };
+
+} // namespace lemon
+
+#endif