1 files changed, 80 insertions, 0 deletions
diff --git a/ace/IfThenElse.h b/ace/IfThenElse.h
new file mode 100644
index 00000000000..6a65c636058
--- /dev/null
+++ b/ace/IfThenElse.h
@@ -0,0 +1,80 @@
+// -*- C++ -*-
+
+//=============================================================================
+/**
+ *  @file    IfThenElse.h
+ *
+ *  ACE::IfThenElse traits template based on the IfThenElse template
+ *  described in the book "C++ Templates" by Vandevoorde and
+ *  Josuttis.
+ *
+ *  $Id$
+ *
+ *  @author Ossama Othman <ossama@dre.vanderbilt.edu>
+ */
+//=============================================================================
+
+#ifndef ACE_IF_THEN_ELSE_H
+#define ACE_IF_THEN_ELSE_H
+
+namespace ACE
+{
+
+  /**
+   * @struct IfThenElse
+   *
+   * @brief Compile-time selection of type based on a boolean value.
+   *
+   * This primary template selects the second or third argument based
+   * on the value of the boolean first argument.
+   *
+   * Usage example:
+   *
+   *   template <typename T>
+   *   class Foo
+   *   {
+   *   public:
+   *     // Set @c TheType to be the larger of @a T and @a int.
+   *     typedef typename IfThenElse<(sizeof (T) > sizeof (int)),
+   *                                 T,
+   *                                 int>::result_type TheType;
+   *   };
+   *
+   * You will of course need to
+   * @note This merely a forward declaration since we really only care
+   *       about the partial specializations below.
+   */
+  template <bool C, typename Ta, typename Tb>
+  struct IfThenElse;
+
+  /**
+   * @struct IfThenElse
+   *
+   * @brief Select of type @a Ta if boolean value is @c true.
+   *
+   * This partial specialization selects the type @a Ta if the boolean
+   * first argument is @c true.
+   */
+  template <typename Ta, typename Tb>
+  struct IfThenElse<true, Ta, Tb>
+  {
+    typedef Ta result_type;
+  };
+
+  /**
+   * @struct IfThenElse
+   *
+   * @brief Select of type @a Tb if boolean value is @c false.
+   *
+   * This partial specialization selects the type @a Tb if the boolean
+   * first argument is @c false.
+   */
+  template <typename Ta, typename Tb>
+  struct IfThenElse<false, Ta, Tb>
+  {
+    typedef Tb result_type;
+  };
+
+}
+
+#endif  /* ACE_IF_THEN_ELSE_H */