Initial example for inductive natural numbers

Author: solodon4

code/test/unit/CMakeLists.txt

@@ -28,6 +28,7 @@ example04
 example04-smart-ptr
 example04-smart-ptr-bind-ptr
 example05
+example06-smart-ptr
 exp
 exp2
 expr

code/test/unit/example06-smart-ptr.cpp

@@ -0,0 +1,109 @@
+//
+//  Mach7: Pattern Matching Library for C++
+//
+//  Copyright 2011-2013, Texas A&M University.
+//  Copyright 2014-2015, Yuriy Solodkyy.
+//  All rights reserved.
+//
+//  Redistribution and use in source and binary forms, with or without
+//  modification, are permitted provided that the following conditions are met:
+//
+//      * Redistributions of source code must retain the above copyright
+//        notice, this list of conditions and the following disclaimer.
+//
+//      * 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.
+//
+//      * Neither the names of Mach7 project 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 HOLDERS 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.
+
+///
+/// \file
+///
+/// This file is a part of Mach7 library test suite.
+///
+/// \author Yuriy Solodkyy <yuriy.solodkyy@gmail.com>
+///
+/// \see https://parasol.tamu.edu/mach7/
+/// \see https://github.com/solodon4/Mach7
+/// \see https://github.com/solodon4/SELL
+///
+
+#include <iostream>
+#include <mach7/type_switchN-patterns.hpp> // Support for N-ary Match statement on patterns
+#include <mach7/patterns/address.hpp>      // Address and dereference combinators
+#include <mach7/patterns/bindings.hpp>     // Mach7 support for bindings on arbitrary UDT
+#include <mach7/patterns/constructor.hpp>  // Support for constructor patterns
+#include <mach7/patterns/primitive.hpp>    // Wildcard, variable and value patterns
+#include <xtl/adapters/std/memory.hpp>     // XTL subtyping adapters for standard smart pointers
+
+using namespace mch;
+
+//------------------------------------------------------------------------------
+
+struct Nat
+{ 
+    virtual ~Nat() {}
+};
+
+typedef std::unique_ptr<Nat> NatPtr;
+
+struct O : Nat
+{
+};
+
+struct S : Nat
+{
+    S(Nat* n) : e(n) {}
+    NatPtr e;
+};
+
+//------------------------------------------------------------------------------
+
+namespace mch ///< Mach7 library namespace
+{
+template <> struct bindings<O> { };
+template <> struct bindings<S> { Members(S::e); };
+} // of namespace mch
+
+//------------------------------------------------------------------------------
+
+int evl(const Nat& n)
+{
+    var<const Nat&> e;
+
+    Match(n)
+    {
+        Case(C<O>()  ) return 0;
+        Case(C<S>(&e)) return evl(e) + 1;
+    }
+    EndMatch
+
+    XTL_UNREACHABLE; // To avoid warning that control may reach end of a non-void function
+}
+
+//------------------------------------------------------------------------------
+
+int main()
+{
+    NatPtr a(new S(new S(new O)));
+    NatPtr b(new S(new O));
+
+    std::cout << evl(*a) << std::endl;
+    std::cout << evl(*b) << std::endl;
+}
+
+//------------------------------------------------------------------------------