[Boost-commit] svn:boost r69022 - in trunk/boost/spirit/home: qi/detail support

Subject: [Boost-commit] svn:boost r69022 - in trunk/boost/spirit/home: qi/detail support
From: joel_at_[hidden]
Date: 2011-02-19 04:14:35

Author: djowel
Date: 2011-02-19 04:14:26 EST (Sat, 19 Feb 2011)
New Revision: 69022
URL: http://svn.boost.org/trac/boost/changeset/69022

Log:
Tweaks. Allow attribute compatibility on alternatives
Text files modified: 
   trunk/boost/spirit/home/qi/detail/alternative_function.hpp |    30 ++++++++++++++----------------          
   trunk/boost/spirit/home/support/attributes.hpp             |    23 +++++++++++++++++++++--                 
   trunk/boost/spirit/home/support/attributes_fwd.hpp         |    14 ++++++++++----                          
   3 files changed, 45 insertions(+), 22 deletions(-)

Modified: trunk/boost/spirit/home/qi/detail/alternative_function.hpp
==============================================================================
--- trunk/boost/spirit/home/qi/detail/alternative_function.hpp	(original)
+++ trunk/boost/spirit/home/qi/detail/alternative_function.hpp	2011-02-19 04:14:26 EST (Sat, 19 Feb 2011)
@@ -65,9 +65,19 @@
         template <typename Component>
         bool call_optional_or_variant(Component const& component, mpl::true_) const
         {
-            // if Attribute is an optional, then create an attribute for
-            // the Component with its expected type.
-            typename traits::attribute_of<Component, Context, Iterator>::type val;
+            // If Attribute is an optional, then create an attribute for the Component
+            // with the type optional::value_type. If the expected attribute is unused type,
+            // use it instead.
+            typedef typename
+                traits::attribute_of<Component, Context, Iterator>::type
+            expected_type;
+
+            typename mpl::if_<
+                is_same<expected_type, unused_type>,
+                unused_type,
+                typename Attribute::value_type>::type
+            val;
+
             if (component.parse(first, last, context, skipper, val))
             {
                 traits::assign_to(val, attr);
@@ -79,18 +89,7 @@
         template <typename Component>
         bool call_optional_or_variant(Component const& component, mpl::false_) const
         {
-#ifndef BOOST_SPIRIT_ALTERNATIVES_ALLOW_ATTR_COMPAT
-            // if Attribute is a variant, then create an attribute for
-            // the Component with its expected type.
-            typename traits::attribute_of<Component, Context, Iterator>::type val;
-            if (component.parse(first, last, context, skipper, val))
-            {
-                traits::assign_to(val, attr);
-                return true;
-            }
-            return false;
-#else
-            // if Attribute is a variant, then search the variant types for a
+            // If Attribute is a variant, then search the variant types for a
             // suitable substitute type.
 
             typename
@@ -105,7 +104,6 @@
                 return true;
             }
             return false;
-#endif
         }
 
         template <typename Component>

Modified: trunk/boost/spirit/home/support/attributes.hpp
==============================================================================
--- trunk/boost/spirit/home/support/attributes.hpp	(original)
+++ trunk/boost/spirit/home/support/attributes.hpp	2011-02-19 04:14:26 EST (Sat, 19 Feb 2011)
@@ -58,8 +58,8 @@
     // components.
     ///////////////////////////////////////////////////////////////////////////
 
-    // Find out if T is a substitute for Expected attribute
-    template <typename T, typename Expected, typename Enable = void>
+    // Find out if T can be a substitute for Expected attribute
+    template <typename T, typename Expected, typename Enable /*= void*/>
     struct is_substitute : is_same<T, Expected> {};
 
     template <typename T, typename Expected>
@@ -77,6 +77,25 @@
         >::type>
       : mpl::true_ {};
 
+    namespace detail
+    {
+        template <typename T, typename Expected>
+        struct value_type_is_substitute
+          : is_substitute<typename T::value_type, typename Expected::value_type>
+        {};
+    }
+
+    template <typename T, typename Expected>
+    struct is_substitute<T, Expected,
+        typename enable_if<
+            mpl::and_<
+                is_container<T>,
+                is_container<Expected>,
+                detail::value_type_is_substitute<T, Expected>
+            >
+        >::type>
+      : mpl::true_ {};
+
     template <typename T, typename Enable/* = void*/>
     struct is_proxy : mpl::false_ {};
 

Modified: trunk/boost/spirit/home/support/attributes_fwd.hpp
==============================================================================
--- trunk/boost/spirit/home/support/attributes_fwd.hpp	(original)
+++ trunk/boost/spirit/home/support/attributes_fwd.hpp	2011-02-19 04:14:26 EST (Sat, 19 Feb 2011)
@@ -50,6 +50,12 @@
 namespace boost { namespace spirit { namespace traits
 {
     ///////////////////////////////////////////////////////////////////////////
+    // Find out if T can be a substitute for Expected attribute
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename T, typename Expected, typename Enable = void>
+    struct is_substitute;
+
+    ///////////////////////////////////////////////////////////////////////////
     // Determine if T is a proxy
     ///////////////////////////////////////////////////////////////////////////
     template <typename T, typename Enable = void>
@@ -63,7 +69,7 @@
     ///////////////////////////////////////////////////////////////////////////
     template <typename Attribute, typename Enable = void>
     struct attribute_type;
-    
+
     ///////////////////////////////////////////////////////////////////////////
     // Retrieve the size of a fusion sequence (compile time)
     ///////////////////////////////////////////////////////////////////////////
@@ -152,7 +158,7 @@
     template <typename T, typename Attribute>
     typename spirit::result_of::attribute_as<T, Attribute>::type
     as(Attribute const& attr);
-    
+
     template <typename T, typename Attribute>
     bool valid_as(Attribute const& attr);
 
@@ -194,7 +200,7 @@
 
     template <typename T, typename Enable = void>
     struct is_container;
-    
+
     template <typename T, typename Enable = void>
     struct is_iterator_range;
 
@@ -263,7 +269,7 @@
 
     ///////////////////////////////////////////////////////////////////////////
     // transform attribute types exposed from compound operator components
-    /////////////////////////////////////////////////////////////////////////// 
+    ///////////////////////////////////////////////////////////////////////////
     template <typename Attribute, typename Domain>
     struct alternative_attribute_transform;