[Boost-commit] svn:boost r43441 - trunk/libs/xpressive/proto/example

From: eric_at_[hidden]
Date: 2008-03-01 14:32:57

Author: eric_niebler
Date: 2008-03-01 14:32:56 EST (Sat, 01 Mar 2008)
New Revision: 43441
URL: http://svn.boost.org/trac/boost/changeset/43441

Log:
add map_assign example
Added:
   trunk/libs/xpressive/proto/example/map_assign.cpp   (contents, props changed)
Text files modified: 
   trunk/libs/xpressive/proto/example/Jamfile.v2  |     5 +++++                                   
   trunk/libs/xpressive/proto/example/futures.cpp |     2 +-                                      
   2 files changed, 6 insertions(+), 1 deletions(-)

Modified: trunk/libs/xpressive/proto/example/Jamfile.v2
==============================================================================
--- trunk/libs/xpressive/proto/example/Jamfile.v2	(original)
+++ trunk/libs/xpressive/proto/example/Jamfile.v2	2008-03-01 14:32:56 EST (Sat, 01 Mar 2008)
@@ -58,3 +58,8 @@
         futures.cpp
     ;
 
+exe map_assign
+    :
+        map_assign.cpp
+    ;
+

Modified: trunk/libs/xpressive/proto/example/futures.cpp
==============================================================================
--- trunk/libs/xpressive/proto/example/futures.cpp	(original)
+++ trunk/libs/xpressive/proto/example/futures.cpp	2008-03-01 14:32:56 EST (Sat, 01 Mar 2008)
@@ -120,7 +120,7 @@
     tuple<A, B, C>          t1 = (a && b && c).get();
     tuple<A, C>             t2 = ((a || a) && c).get();
     tuple<A, B, C>          t3 = ((a && b || a && b) && c).get();
-    tuple<tuple<A, B>, C>   t4 = (( ab || ab) && c).get();
+    tuple<tuple<A, B>, C>   t4 = ((ab || ab) && c).get();
 
     return 0;
 }

Added: trunk/libs/xpressive/proto/example/map_assign.cpp
==============================================================================
--- (empty file)
+++ trunk/libs/xpressive/proto/example/map_assign.cpp	2008-03-01 14:32:56 EST (Sat, 01 Mar 2008)
@@ -0,0 +1,105 @@
+//[ MapAssign
+//  Copyright 2008 Eric Niebler. Distributed under the Boost
+//  Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// This is a port of map_list_assign from the Boost.Assign library.
+// It has the advantage of being more efficient at runtime by not
+// building any temporary container that requires dynamic allocation.
+
+#include <map>
+#include <string>
+#include <iostream>
+#include <boost/xpressive/proto/proto.hpp>
+#include <boost/xpressive/proto/transform.hpp>
+
+using namespace boost;
+using namespace proto;
+
+struct map_list_of_tag
+{};
+
+// A simple callable function object that inserts a
+// (key,value) pair into a map.
+struct insert
+  : callable
+{
+    template<typename Sig>
+    struct result;
+    
+    template<typename This, typename Map, typename Key, typename Value>
+    struct result<This(Map, Key, Value)>
+      : add_reference<Map>
+    {};
+    
+    template<typename Map, typename Key, typename Value>
+    Map &operator()(Map &map, Key const &key, Value const &value) const
+    {
+        map.insert(typename Map::value_type(key, value));
+        return map;
+    }
+};
+
+// The grammmar for valid map-list expressions, and a
+// transform that populates the map.
+struct MapListOf
+  : or_<
+        when<
+            function<terminal<map_list_of_tag>, terminal<_>, terminal<_> >
+          , insert(_visitor, _arg(_arg1), _arg(_arg2))
+        >
+      , when<
+            function<MapListOf, terminal<_>, terminal<_> >
+          , insert(MapListOf(_arg0), _arg(_arg1), _arg(_arg2))
+        >
+    >
+{};
+
+template<typename Expr>
+struct map_list_of_expr;
+
+struct map_list_of_dom
+  : domain<pod_generator<map_list_of_expr>, MapListOf>
+{};
+
+// An expression wrapper that provides a conversion to a
+// map that uses the MapListOf 
+template<typename Expr>
+struct map_list_of_expr
+{
+    BOOST_PROTO_EXTENDS(Expr, map_list_of_expr, map_list_of_dom)
+    BOOST_PROTO_EXTENDS_FUNCTION(Expr, map_list_of_expr, map_list_of_dom)
+    
+    template<typename Map>
+    operator Map() const
+    {
+        Map map;
+        return MapListOf()(*this, 0, map);
+    }
+};
+
+map_list_of_expr<terminal<map_list_of_tag>::type> const map_list_of = {{{}}};
+
+int main()
+{
+    // Initialize a map:
+    std::map<std::string, int> op = 
+        map_list_of
+            ("<",1)
+            ("<=",2)
+            (">",3)
+            (">=",4)
+            ("=",5)
+            ("<>",6)
+        ;
+
+    std::cout << "\"<\"  --> " << op["<"] << std::endl;
+    std::cout << "\"<=\" --> " << op["<="] << std::endl;
+    std::cout << "\">\"  --> " << op[">"] << std::endl;
+    std::cout << "\">=\" --> " << op[">="] << std::endl;
+    std::cout << "\"=\"  --> " << op["="] << std::endl;
+    std::cout << "\"<>\" --> " << op["<>"] << std::endl;
+
+    return 0;
+}
+//]