Branch at revision 46530

[SVN r46531]

doc/optional.qbk

@@ -22,7 +22,7 @@ Distributed under the Boost Software License, Version 1.0.
 [/ Cited Boost resources ]
 
 [def __BOOST_VARIANT__ [@../../../variant/index.html Boost.Variant]]
-[def __BOOST_TRIBOOL__ [@../../../tribool/index.html boost::tribool]]
+[def __BOOST_TRIBOOL__ [@../../../../doc/html/tribool.html boost::tribool]]
 
 [def __OPTIONAL_POINTEE__ [@../../../utility/OptionalPointee.html OptionalPointee]]
 [def __COPY_CONSTRUCTIBLE__ [@../../../utility/CopyConstructible.html Copy Constructible]]

include/boost/optional/optional.hpp

@@ -1,4 +1,4 @@
-// Copyright (C) 2003, Fernando Luis Cacciola Carballal.
+// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal.
 //
 // Use, modification, and distribution is subject to the Boost Software
 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -9,6 +9,9 @@
 // You are welcome to contact the author at:
 //  fernando_cacciola@hotmail.com
 //
+// Revisions:
+// 27 Apr 2008 (improved swap) Fernando Cacciola, Niels Dekker, Thorsten Ottosen
+// 
 #ifndef BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
 #define BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
 
@@ -19,6 +22,7 @@
 #include "boost/assert.hpp"
 #include "boost/type.hpp"
 #include "boost/type_traits/alignment_of.hpp"
+#include "boost/type_traits/has_nothrow_constructor.hpp"
 #include "boost/type_traits/type_with_alignment.hpp"
 #include "boost/type_traits/remove_reference.hpp"
 #include "boost/type_traits/is_reference.hpp"
@@ -28,6 +32,7 @@
 #include "boost/detail/reference_content.hpp"
 #include "boost/none.hpp"
 #include "boost/utility/compare_pointees.hpp"
+#include "boost/utility/in_place_factory.hpp"
 
 #include "boost/optional/optional_fwd.hpp"
 
@@ -571,6 +576,14 @@ class optional : public optional_detail::optional_base<T>
         return *this ;
       }
 
+    void swap( optional & arg )
+      {
+        // allow for Koenig lookup
+        using boost::swap ;
+        swap(*this, arg);
+      }
+
+
     // Returns a reference to the value if this is initialized, otherwise,
     // the behaviour is UNDEFINED
     // No-throw
@@ -878,44 +891,77 @@ namespace optional_detail {
 #define BOOST_OPTIONAL_STD_SWAP_INTRODUCED_AT_NS_SCOPE
 #endif
 
-// optional's swap:
-// If both are initialized, calls swap(T&, T&). If this swap throws, both will remain initialized but their values are now unspecified.
-// If only one is initialized, calls U.reset(*I), THEN I.reset().
-// If U.reset(*I) throws, both are left UNCHANGED (U is kept uinitialized and I is never reset)
-// If both are uninitialized, do nothing (no-throw)
-template<class T>
-inline
-void optional_swap ( optional<T>& x, optional<T>& y )
-{
-  if ( !x && !!y )
+  template<bool use_default_constructor> struct swap_selector;
+
+  template<>
+  struct swap_selector<true>
   {
-    x.reset(*y);
-    y.reset();
-  }
-  else if ( !!x && !y )
+    template<class T>
+    static void optional_swap ( optional<T>& x, optional<T>& y )
     {
-    y.reset(*x);
-    x.reset();
-  }
-  else if ( !!x && !!y )
-  {
-// GCC > 3.2 and all other compilers have the using declaration at function scope (FLC)
+     bool hasX = x;
+     bool hasY = y;
+
+     if ( !hasX && !hasY )
+       return;
+
+     if( !hasX )
+         x = boost::in_place();
+     else if ( !hasY )
+         y = boost::in_place();
+
+   // GCC > 3.2 and all other compilers have the using declaration at function scope (FLC)
 #ifndef BOOST_OPTIONAL_STD_SWAP_INTRODUCED_AT_NS_SCOPE
      // allow for Koenig lookup
      using std::swap ;
 #endif
      swap(*x,*y);
+
+     if( !hasX )
+         y = boost::none ;
+     else if( !hasY )
+         x = boost::none ;
     }
-}
+  };
+
+  template<>
+  struct swap_selector<false>
+  {
+    template<class T>
+    static void optional_swap ( optional<T>& x, optional<T>& y )
+    {
+      if ( !x && !!y )
+      {
+        x = *y;
+        y = boost::none ;
+      }
+      else if ( !!x && !y )
+      {
+        y = *x ;
+        x = boost::none ;
+      }
+      else if ( !!x && !!y )
+      {
+    // GCC > 3.2 and all other compilers have the using declaration at function scope (FLC)
+    #ifndef BOOST_OPTIONAL_STD_SWAP_INTRODUCED_AT_NS_SCOPE
+        // allow for Koenig lookup
+        using std::swap ;
+    #endif
+        swap(*x,*y);
+      }
+    }
+  };
 
 } // namespace optional_detail
 
+template<class T>
+struct optional_swap_should_use_default_constructor : has_nothrow_default_constructor<T> {} ;
+
 template<class T> inline void swap ( optional<T>& x, optional<T>& y )
 {
-  optional_detail::optional_swap(x,y);
+  optional_detail::swap_selector<optional_swap_should_use_default_constructor<T>::value>::optional_swap(x, y);
 }
 
-
 } // namespace boost
 
 #endif

include/boost/optional/optional_fwd.hpp

@@ -1,4 +1,4 @@
-// Copyright (C) 2003, Fernando Luis Cacciola Carballal.
+// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal.
 //
 // Use, modification, and distribution is subject to the Boost Software
 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -9,6 +9,9 @@
 // You are welcome to contact the author at:
 //  fernando_cacciola@hotmail.com
 //
+// Revisions:
+// 10 May 2008 (added swap related forward declaration) Niels Dekker
+// 
 #ifndef BOOST_OPTIONAL_OPTIONAL_FWD_FLC_19NOV2002_HPP
 #define BOOST_OPTIONAL_OPTIONAL_FWD_FLC_19NOV2002_HPP
 
@@ -16,6 +19,10 @@ namespace boost {
 
 template<class T> class optional ;
 
+template<class T> void swap ( optional<T>& , optional<T>& ) ;
+
+template<class T> struct optional_swap_should_use_default_constructor ;
+
 } // namespace boost
 
 #endif

index.html

@@ -4,7 +4,7 @@
 </head>
 <body>
 Automatic redirection failed, please go to
-<a href="doc/optional.html">doc/html/index.html</a>.&nbsp;<hr>
+<a href="doc/html/index.html">doc/html/index.html</a>.&nbsp;<hr>
 <p><EFBFBD> Copyright Beman Dawes, 2001</p>
 <p>Distributed under the Boost Software License, Version 1.0. (See accompanying 
 file <a href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or copy 

test/optional_test.cpp

@@ -1,4 +1,4 @@
-// Copyright (C) 2003, Fernando Luis Cacciola Carballal.
+// Copyright (C) 2003, 2008 Fernando Luis Cacciola Carballal.
 //
 // Use, modification, and distribution is subject to the Boost Software
 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -9,6 +9,9 @@
 // You are welcome to contact the author at:
 //  fernando_cacciola@hotmail.com
 //
+// Revisions:
+// 12 May 2008 (added more swap tests)
+//
 #include<iostream>
 #include<stdexcept>
 #include<string>
@@ -16,6 +19,8 @@
 #define BOOST_ENABLE_ASSERT_HANDLER
 
 #include "boost/bind/apply.hpp" // Included just to test proper interaction with boost::apply<> as reported by Daniel Wallin
+#include "boost/mpl/bool.hpp"
+#include "boost/mpl/bool_fwd.hpp"  // For mpl::true_ and mpl::false_
 
 #include "boost/optional/optional.hpp"
 
@@ -927,6 +932,337 @@ void test_conversions2()
   BOOST_CHECK(*get(&opt1) == static_cast<double>(f));
 }
 
+
+namespace optional_swap_test
+{
+  class default_ctor_exception : public std::exception {} ;
+  class copy_ctor_exception : public std::exception {} ;
+  class assignment_exception : public std::exception {} ;
+
+  //
+  // Base class for swap test classes.  Its assignment should not be called, when swapping
+  // optional<T> objects.  (The default std::swap would do so.)
+  //
+  class base_class_with_forbidden_assignment
+  {
+  public:
+    base_class_with_forbidden_assignment & operator=(const base_class_with_forbidden_assignment &)
+    {
+      BOOST_CHECK(!"The assignment should not be used while swapping!");
+      throw assignment_exception();
+    }
+
+    virtual ~base_class_with_forbidden_assignment() {}
+  };
+
+  //
+  // Class without default constructor
+  //
+  class class_without_default_ctor : public base_class_with_forbidden_assignment
+  {
+  public:
+    char data;
+    explicit class_without_default_ctor(char arg) : data(arg) {}
+  };
+
+  //
+  // Class whose default constructor should not be used by optional::swap!
+  //
+  class class_whose_default_ctor_should_not_be_used : public base_class_with_forbidden_assignment
+  {
+  public:
+    char data;
+    explicit class_whose_default_ctor_should_not_be_used(char arg) : data(arg) {}
+
+    class_whose_default_ctor_should_not_be_used()
+    {
+      BOOST_CHECK(!"This default constructor should not be used while swapping!");
+      throw default_ctor_exception();
+    }
+  };
+
+  //
+  // Class whose default constructor should be used by optional::swap.
+  // Its copy constructor should be avoided!
+  //
+  class class_whose_default_ctor_should_be_used : public base_class_with_forbidden_assignment
+  {
+  public:
+    char data;
+    explicit class_whose_default_ctor_should_be_used(char arg) : data(arg) { }
+
+    class_whose_default_ctor_should_be_used() : data('\0') { }
+
+    class_whose_default_ctor_should_be_used(const class_whose_default_ctor_should_be_used &)
+    {
+      BOOST_CHECK(!"This copy constructor should not be used while swapping!");
+      throw copy_ctor_exception();
+    }
+  };
+
+  //
+  // Class template whose default constructor should be used by optional::swap.
+  // Its copy constructor should be avoided!
+  //
+  template <class T>
+  class template_whose_default_ctor_should_be_used : public base_class_with_forbidden_assignment
+  {
+  public:
+    T data;
+    explicit template_whose_default_ctor_should_be_used(T arg) : data(arg) { }
+
+    template_whose_default_ctor_should_be_used() : data('\0') { }
+
+    template_whose_default_ctor_should_be_used(const template_whose_default_ctor_should_be_used &)
+    {
+      BOOST_CHECK(!"This copy constructor should not be used while swapping!");
+      throw copy_ctor_exception();
+    }
+  };
+
+  //
+  // Class whose explicit constructor should be used by optional::swap.
+  // Its other constructors should be avoided!
+  //
+  class class_whose_explicit_ctor_should_be_used : public base_class_with_forbidden_assignment
+  {
+  public:
+    char data;
+    explicit class_whose_explicit_ctor_should_be_used(char arg) : data(arg) { }
+
+    class_whose_explicit_ctor_should_be_used()
+    {
+      BOOST_CHECK(!"This default constructor should not be used while swapping!");
+      throw default_ctor_exception();
+    }
+
+    class_whose_explicit_ctor_should_be_used(const class_whose_explicit_ctor_should_be_used &)
+    {
+      BOOST_CHECK(!"This copy constructor should not be used while swapping!");
+      throw copy_ctor_exception();
+    }
+  };
+
+  void swap(class_whose_default_ctor_should_not_be_used & lhs, class_whose_default_ctor_should_not_be_used & rhs)
+  {
+    std::swap(lhs.data, rhs.data);
+  }
+
+  void swap(class_whose_default_ctor_should_be_used & lhs, class_whose_default_ctor_should_be_used & rhs)
+  {
+    std::swap(lhs.data, rhs.data);
+  }
+
+  void swap(class_without_default_ctor & lhs, class_without_default_ctor & rhs)
+  {
+    std::swap(lhs.data, rhs.data);
+  }
+
+  void swap(class_whose_explicit_ctor_should_be_used & lhs, class_whose_explicit_ctor_should_be_used & rhs)
+  {
+    std::swap(lhs.data, rhs.data);
+  }
+
+  template <class T>
+  void swap(template_whose_default_ctor_should_be_used<T> & lhs, template_whose_default_ctor_should_be_used<T> & rhs)
+  {
+    std::swap(lhs.data, rhs.data);
+  }
+
+  //
+  // optional<T>::swap should be customized when neither the copy constructor
+  // nor the default constructor of T are supposed to be used when swapping, e.g.,
+  // for the following type T = class_whose_explicit_ctor_should_be_used.
+  //
+  void swap(boost::optional<class_whose_explicit_ctor_should_be_used> & x, boost::optional<class_whose_explicit_ctor_should_be_used> & y)
+  {
+    bool hasX = x;
+    bool hasY = y;
+
+    if ( !hasX && !hasY )
+     return;
+
+    if( !hasX )
+       x = boost::in_place('\0');
+    else if ( !hasY )
+       y = boost::in_place('\0');
+    
+    optional_swap_test::swap(*x,*y);
+
+     if( !hasX )
+         y = boost::none ;
+     else if( !hasY )
+         x = boost::none ;
+  }
+
+
+} // End of namespace optional_swap_test.
+
+
+namespace boost {
+
+//
+// Compile time tweaking on whether or not swap should use the default constructor:
+//
+
+template <> struct optional_swap_should_use_default_constructor<
+  optional_swap_test::class_whose_default_ctor_should_be_used> : mpl::true_ {} ;
+
+template <> struct optional_swap_should_use_default_constructor<
+  optional_swap_test::class_whose_default_ctor_should_not_be_used> : mpl::false_ {} ;
+
+template <class T> struct optional_swap_should_use_default_constructor<
+  optional_swap_test::template_whose_default_ctor_should_be_used<T> > : mpl::true_ {} ;
+
+
+//
+// Specialization of boost::swap:
+//
+template <> 
+void swap(optional<optional_swap_test::class_whose_explicit_ctor_should_be_used> & x, optional<optional_swap_test::class_whose_explicit_ctor_should_be_used> & y)
+{
+  optional_swap_test::swap(x, y);
+}
+
+} // namespace boost
+
+
+namespace std {
+
+//
+// Specializations of std::swap:
+//
+
+template <> 
+void swap(optional_swap_test::class_whose_default_ctor_should_be_used & x, optional_swap_test::class_whose_default_ctor_should_be_used & y)
+{
+  optional_swap_test::swap(x, y);
+}
+
+template <> 
+void swap(optional_swap_test::class_whose_default_ctor_should_not_be_used & x, optional_swap_test::class_whose_default_ctor_should_not_be_used & y)
+{
+  optional_swap_test::swap(x, y);
+}
+
+template <> 
+void swap(optional_swap_test::class_without_default_ctor & x, optional_swap_test::class_without_default_ctor & y)
+{
+  optional_swap_test::swap(x, y);
+}
+
+template <> 
+void swap(optional_swap_test::class_whose_explicit_ctor_should_be_used & x, optional_swap_test::class_whose_explicit_ctor_should_be_used & y)
+{
+  optional_swap_test::swap(x, y);
+}
+
+} // namespace std
+
+
+//
+// Tests whether the swap function works properly for optional<T>.
+// Assumes that T has one data member, of type char.
+// Returns true iff the test is passed.
+//
+template <class T>
+bool test_swap_function( T const* )
+{
+  const boost::unit_test::counter_t counter_before_test = boost::minimal_test::errors_counter();
+  try
+  {
+    optional<T> obj1;
+    optional<T> obj2('a');
+
+    // Self-swap should not have any effect.
+    swap(obj1, obj1);
+    swap(obj2, obj2);
+    BOOST_CHECK(!obj1);
+    BOOST_CHECK(!!obj2 && obj2->data == 'a');
+
+    // Call non-member swap.
+    swap(obj1, obj2);
+
+    // Test if obj1 and obj2 are really swapped.
+    BOOST_CHECK(!!obj1 && obj1->data == 'a');
+    BOOST_CHECK(!obj2);
+
+    // Call non-member swap one more time.
+    swap(obj1, obj2);
+
+    // Test if obj1 and obj2 are swapped back.
+    BOOST_CHECK(!obj1);
+    BOOST_CHECK(!!obj2 && obj2->data == 'a');
+  }
+  catch(const std::exception &)
+  {
+    // The swap function should not throw, for our test cases.
+    return false ;
+  }
+  return boost::minimal_test::errors_counter() == counter_before_test ;
+}
+
+//
+// Tests whether the optional<T>::swap member function works properly.
+// Assumes that T has one data member, of type char. 
+// Returns true iff the test is passed.
+//
+template <class T>
+bool test_swap_member_function( T const* )
+{
+  const boost::unit_test::counter_t counter_before_test = boost::minimal_test::errors_counter();
+  try
+  {
+    optional<T> obj1;
+    optional<T> obj2('a');
+
+    // Self-swap should not have any effect.
+    obj1.swap(obj1);
+    obj2.swap(obj2);
+    BOOST_CHECK(!obj1);
+    BOOST_CHECK(!!obj2 && obj2->data == 'a');
+
+    // Call member swap.
+    obj1.swap(obj2);
+
+    // Test if obj1 and obj2 are really swapped.
+    BOOST_CHECK(!!obj1 && obj1->data == 'a');
+    BOOST_CHECK(!obj2);
+
+    // Call member swap one more time.
+    obj1.swap(obj2);
+
+    // Test if obj1 and obj2 are swapped back.
+    BOOST_CHECK(!obj1);
+    BOOST_CHECK(!!obj2 && obj2->data == 'a');
+  }
+  catch(const std::exception &)
+  {
+    // The optional<T>::swap member function should not throw, for our test cases.
+    return false ;
+  }
+  return boost::minimal_test::errors_counter() == counter_before_test ;
+}
+
+
+//
+// Tests compile time tweaking of swap, by means of
+// optional_swap_should_use_default_constructor.
+//
+void test_swap_tweaking()
+{
+  BOOST_CHECK( test_swap_function( ARG(optional_swap_test::class_without_default_ctor) ) );
+  BOOST_CHECK( test_swap_function( ARG(optional_swap_test::class_whose_default_ctor_should_be_used) ) );
+  BOOST_CHECK( test_swap_function( ARG(optional_swap_test::class_whose_default_ctor_should_not_be_used) ) );
+  BOOST_CHECK( test_swap_function( ARG(optional_swap_test::class_whose_explicit_ctor_should_be_used) ) );
+  BOOST_CHECK( test_swap_function( ARG(optional_swap_test::template_whose_default_ctor_should_be_used<char>) ) );
+  BOOST_CHECK( test_swap_member_function( ARG(optional_swap_test::class_without_default_ctor) ) );
+  BOOST_CHECK( test_swap_member_function( ARG(optional_swap_test::class_whose_default_ctor_should_be_used) ) );
+  BOOST_CHECK( test_swap_member_function( ARG(optional_swap_test::class_whose_default_ctor_should_not_be_used) ) );
+  BOOST_CHECK( test_swap_member_function( ARG(optional_swap_test::class_whose_explicit_ctor_should_be_used) ) );
+  BOOST_CHECK( test_swap_member_function( ARG(optional_swap_test::template_whose_default_ctor_should_be_used<char>) ) );
+}
+
 int test_main( int, char* [] )
 {
   try
@@ -936,6 +1272,7 @@ int test_main( int, char* [] )
     test_no_implicit_conversions();
     test_conversions1();
     test_conversions2();
+    test_swap_tweaking();
   }
   catch ( ... )
   {