[Boost-commit] svn:boost r56386 - in trunk/boost/spirit: home/karma/nonterminal home/qi/nonterminal home/support repository/home/karma/nonterminal repository/home/qi/nonterminal

Subject: [Boost-commit] svn:boost r56386 - in trunk/boost/spirit: home/karma/nonterminal home/qi/nonterminal home/support repository/home/karma/nonterminal repository/home/qi/nonterminal
From: hartmut.kaiser_at_[hidden]
Date: 2009-09-26 12:23:12

Author: hkaiser
Date: 2009-09-26 12:23:11 EDT (Sat, 26 Sep 2009)
New Revision: 56386
URL: http://svn.boost.org/trac/boost/changeset/56386

Log:
Spirit: started to add attribute transformation capabilities
Text files modified: 
   trunk/boost/spirit/home/karma/nonterminal/rule.hpp               |    11 +-                                      
   trunk/boost/spirit/home/qi/nonterminal/rule.hpp                  |     8 +                                       
   trunk/boost/spirit/home/support/attributes.hpp                   |   143 ++++++++++++++++++++++++++++++++++++--- 
   trunk/boost/spirit/repository/home/karma/nonterminal/subrule.hpp |    12 +-                                      
   trunk/boost/spirit/repository/home/qi/nonterminal/subrule.hpp    |    12 +-                                      
   5 files changed, 155 insertions(+), 31 deletions(-)

Modified: trunk/boost/spirit/home/karma/nonterminal/rule.hpp
==============================================================================
--- trunk/boost/spirit/home/karma/nonterminal/rule.hpp	(original)
+++ trunk/boost/spirit/home/karma/nonterminal/rule.hpp	2009-09-26 12:23:11 EDT (Sat, 26 Sep 2009)
@@ -221,8 +221,8 @@
             if (f)
             {
                 // Create an attribute if none is supplied. 
-                typedef traits::make_attribute<attr_type, Attribute> 
-                    make_attribute;
+                typedef traits::make_transformed_attribute<
+                    attr_type, Attribute const> make_attribute;
 
                 // If you are seeing a compilation error here, you are probably
                 // trying to use a rule or a grammar which has inherited
@@ -250,13 +250,14 @@
             if (f)
             {
                 // Create an attribute if none is supplied. 
-                typedef traits::make_attribute<attr_type, Attribute> 
-                    make_attribute;
+                typedef traits::make_transformed_attribute<
+                    attr_type, Attribute const> make_attribute;
 
                 // If you are seeing a compilation error here, you are probably
                 // trying to use a rule or a grammar which has inherited
                 // attributes, passing values of incompatible types for them.
-                context_type context(make_attribute::call(attr), params, caller_context);
+                context_type context(make_attribute::call(attr)
+                  , params, caller_context);
 
                 // If you are seeing a compilation error here stating that the 
                 // third parameter can't be converted to a karma::reference

Modified: trunk/boost/spirit/home/qi/nonterminal/rule.hpp
==============================================================================
--- trunk/boost/spirit/home/qi/nonterminal/rule.hpp	(original)
+++ trunk/boost/spirit/home/qi/nonterminal/rule.hpp	2009-09-26 12:23:11 EDT (Sat, 26 Sep 2009)
@@ -212,7 +212,9 @@
         {
             if (f)
             {
-                typedef traits::make_attribute<attr_type, Attribute> make_attribute;
+                // Create an attribute if none is supplied. 
+                typedef traits::make_transformed_attribute<
+                    attr_type, Attribute> make_attribute;
 
                 typename make_attribute::type attr_ = make_attribute::call(attr);
 
@@ -241,7 +243,9 @@
         {
             if (f)
             {
-                typedef traits::make_attribute<attr_type, Attribute> make_attribute;
+                // Create an attribute if none is supplied. 
+                typedef traits::make_transformed_attribute<
+                    attr_type, Attribute> make_attribute;
 
                 typename make_attribute::type attr_ = make_attribute::call(attr);
 

Modified: trunk/boost/spirit/home/support/attributes.hpp
==============================================================================
--- trunk/boost/spirit/home/support/attributes.hpp	(original)
+++ trunk/boost/spirit/home/support/attributes.hpp	2009-09-26 12:23:11 EDT (Sat, 26 Sep 2009)
@@ -303,16 +303,79 @@
     };
 
     ///////////////////////////////////////////////////////////////////////////
+    // transform_attribute
+    //
+    // Sometimes the user needs to transform the attribute types for certain
+    // attributes. This template can be used as a customization point, where 
+    // the user is able specify specific transformation rules for any attribute
+    // type.
+    template <typename Destination, typename Source>
+    struct transform_attribute
+    {
+        static Destination call(Source& val) { return Destination(val); }
+    };
+
+    template <typename Destination, typename Source>
+    struct transform_attribute<Destination, Source const>
+    {
+        static Destination call(Source const& val) { return Destination(val); }
+    };
+
+    // The default is not to do any transformation
+    template <typename Attribute>
+    struct transform_attribute<Attribute, Attribute>
+    {
+        static Attribute& call(Attribute& val) { return val; }
+    };
+
+    template <typename Attribute>
+    struct transform_attribute<Attribute, Attribute const>
+    {
+        static Attribute const& call(Attribute const& val) { return val; }
+    };
+
+    // unused_type needs some special handling
+    template <>
+    struct transform_attribute<unused_type, unused_type>
+    {
+        static unused_type call(unused_type) { return unused; }
+    };
+
+    template <>
+    struct transform_attribute<unused_type, unused_type const>
+      : transform_attribute<unused_type, unused_type>
+    {};
+
+    template <typename Attribute>
+    struct transform_attribute<unused_type, Attribute>
+      : transform_attribute<unused_type, unused_type>
+    {};
+
+    template <typename Attribute>
+    struct transform_attribute<unused_type, Attribute const>
+      : transform_attribute<unused_type, unused_type>
+    {};
+
+    template <typename Attribute>
+    struct transform_attribute<Attribute, unused_type>
+      : transform_attribute<unused_type, unused_type>
+    {};
+
+    template <typename Attribute>
+    struct transform_attribute<Attribute, unused_type const>
+      : transform_attribute<unused_type, unused_type>
+    {};
+
+    ///////////////////////////////////////////////////////////////////////////
     // make_attribute
     //
-    // All parsers and generators have specific attribute or parameter types.
-    // Spirit parsers are passed an attribute and Spirit generators
-    // are passed a parameter; these are either references to the expected
-    // type, or an unused_type -- to flag that we do not care about the
-    // attribute/parameter. For semantic actions, however, we need to have a
-    // real value to pass to the semantic action. If the client did not
-    // provide one, we will have to synthesize the value. This class
-    // takes care of that.
+    // All parsers and generators have specific attribute types.
+    // Spirit parsers and generators are passed an attribute; these are either 
+    // references to the expected type, or an unused_type -- to flag that we do 
+    // not care about the attribute. For semantic actions, however, we need to 
+    // have a real value to pass to the semantic action. If the client did not
+    // provide one, we will have to synthesize the value. This class takes care 
+    // of that.
     ///////////////////////////////////////////////////////////////////////////
     template <typename Attribute, typename ActualAttribute>
     struct make_attribute
@@ -353,14 +416,12 @@
     template <typename Attribute, typename ActualAttribute>
     struct make_attribute<Attribute&, ActualAttribute>
       : make_attribute<Attribute, ActualAttribute>
-    {
-    };
+    {};
 
     template <typename Attribute, typename ActualAttribute>
     struct make_attribute<Attribute const&, ActualAttribute>
       : make_attribute<Attribute, ActualAttribute>
-    {
-    };
+    {};
 
     template <typename ActualAttribute>
     struct make_attribute<unused_type, ActualAttribute>
@@ -374,6 +435,64 @@
     };
 
     ///////////////////////////////////////////////////////////////////////////
+    template <typename Attribute, typename ActualAttribute>
+    struct make_transformed_attribute
+    {
+        // We assume that as soon as the source and destination attribute types
+        // are not the same we need to create a new instance of the destination
+        // in order to do the conversion. In this case we can't just pass 
+        // through the references anymore (as it's done in the template 
+        // make_attribute above).
+        typedef typename remove_const<ActualAttribute>::type 
+            non_const_actual_attribute;
+
+        typedef typename 
+            mpl::if_<
+                is_same<non_const_actual_attribute, Attribute>
+              , ActualAttribute&
+              , Attribute>::type
+        attribute_type;
+
+        typedef typename
+            mpl::if_<
+                is_same<non_const_actual_attribute, unused_type>
+              , typename remove_const<Attribute>::type
+              , attribute_type>::type
+        type;
+
+        static Attribute call(unused_type)
+        {
+             // synthesize the attribute/parameter
+            return boost::get(value_initialized<Attribute>());
+        }
+
+        template <typename T>
+        static type call(T& value)
+        {
+            // create the proper attribute transformation
+            typedef transform_attribute<Attribute, ActualAttribute> transform;
+
+            // return either the transformed value or pass 'value' through
+            return transform::call(value); 
+        }
+    };
+
+    template <typename Attribute, typename ActualAttribute>
+    struct make_transformed_attribute<Attribute&, ActualAttribute>
+      : make_attribute<Attribute, ActualAttribute>
+    {};
+
+    template <typename Attribute, typename ActualAttribute>
+    struct make_transformed_attribute<Attribute const&, ActualAttribute>
+      : make_attribute<Attribute, ActualAttribute>
+    {};
+
+    template <typename ActualAttribute>
+    struct make_transformed_attribute<unused_type, ActualAttribute>
+      : make_attribute<unused_type, ActualAttribute>
+    {};
+
+    ///////////////////////////////////////////////////////////////////////////
     // swap_impl
     //
     // Swap (with proper handling of unused_types)

Modified: trunk/boost/spirit/repository/home/karma/nonterminal/subrule.hpp
==============================================================================
--- trunk/boost/spirit/repository/home/karma/nonterminal/subrule.hpp	(original)
+++ trunk/boost/spirit/repository/home/karma/nonterminal/subrule.hpp	2009-09-26 12:23:11 EDT (Sat, 26 Sep 2009)
@@ -200,8 +200,8 @@
             context_type;
 
             // Create an attribute if none is supplied.
-            typedef traits::make_attribute<subrule_attr_type, Attribute>
-                make_attribute;
+            typedef traits::make_transformed_attribute<
+                subrule_attr_type, Attribute const> make_attribute;
 
             // If you are seeing a compilation error here, you are probably
             // trying to use a subrule which has inherited attributes,
@@ -233,14 +233,14 @@
             context_type;
 
             // Create an attribute if none is supplied.
-            typedef traits::make_attribute<subrule_attr_type, Attribute>
-                make_attribute;
+            typedef traits::make_transformed_attribute<
+                subrule_attr_type, Attribute const> make_attribute;
 
             // If you are seeing a compilation error here, you are probably
             // trying to use a subrule which has inherited attributes,
             // passing values of incompatible types for them.
-            context_type context(*this, make_attribute::call(attr)
-              , params, caller_context);
+            context_type context(*this, make_attribute::call(attr), params
+              , caller_context);
 
             return def.binder(sink, context, delimiter);
         }

Modified: trunk/boost/spirit/repository/home/qi/nonterminal/subrule.hpp
==============================================================================
--- trunk/boost/spirit/repository/home/qi/nonterminal/subrule.hpp	(original)
+++ trunk/boost/spirit/repository/home/qi/nonterminal/subrule.hpp	2009-09-26 12:23:11 EDT (Sat, 26 Sep 2009)
@@ -196,9 +196,9 @@
             context_type;
 
             // prepare attribute
-            typedef
-                traits::make_attribute<subrule_attr_type, Attribute>
-            make_attribute;
+            typedef traits::make_transformed_attribute<
+                subrule_attr_type, Attribute> make_attribute;
+
             typename make_attribute::type attr_ = make_attribute::call(attr);
 
             // If you are seeing a compilation error here, you are probably
@@ -233,9 +233,9 @@
             context_type;
 
             // prepare attribute
-            typedef
-                traits::make_attribute<subrule_attr_type, Attribute>
-            make_attribute;
+            typedef traits::make_transformed_attribute<
+                subrule_attr_type, Attribute> make_attribute;
+
             typename make_attribute::type attr_ = make_attribute::call(attr);
 
             // If you are seeing a compilation error here, you are probably