Changeset 693 for trunk/include/mapnik/value.hpp

Timestamp:

04/12/08 11:22:27 (7 months ago)

Author:

tom

Message:

Revert previous fix for #89 and add a new improved fix that enhances the
value class to have a proper null type and do comparisions SQL style so
that null is neither equal nor not equal to other things.

Files:

• trunk/include/mapnik/value.hpp (modified) (15 diffs)

trunk/include/mapnik/value.hpp

@@ -40 +40 @@
 namespace mapnik  {
    
-   typedef boost::variant<bool,int,double,UnicodeString> value_base;
+   struct value_null
+   {
+   };
+   
+   typedef boost::variant<value_null,bool,int,double,UnicodeString> value_base;
    
    namespace impl {
@@ -47 +51 @@
       {
             template <typename T, typename U>
-            bool operator() (const T &, const U & ) const
+            bool operator() (const T &, const U &) const
             {
                return false;
@@ -73 +77 @@
                return  lhs == rhs;
             }
+
+            bool operator() (value_null, value_null) const
+            {
+               return false;
+            }
       };
       
+      struct not_equals
+         : public boost::static_visitor<bool>
+      {
+            template <typename T, typename U>
+            bool operator() (const T &, const U &) const
+            {
+               return true;
+            }
+        
+            template <typename T>
+            bool operator() (T lhs, T rhs) const
+            {
+               return lhs != rhs;
+            }
+            
+            bool operator() (int lhs, double rhs) const
+            {
+               return  lhs != rhs;
+            }
+        
+            bool operator() (double lhs, int rhs) const
+            {
+               return  lhs != rhs;
+            }
+        
+            bool operator() (UnicodeString const& lhs, 
+                             UnicodeString const& rhs) const
+            {
+               return  lhs != rhs;
+            }
+
+            bool operator() (value_null, value_null) const
+            {
+               return false;
+            }
+
+            template <typename T>
+            bool operator() (value_null, const T &) const
+            {
+               return false;
+            }
+
+            template <typename T>
+            bool operator() (const T &, value_null) const
+            {
+               return false;
+            }
+      };
+
       struct greater_than
          : public boost::static_visitor<bool>
       {
             template <typename T, typename U>
-            bool operator()( const T &, const U & ) const
-            {
-               return false;
-            }
-        
-            template <typename T>
-            bool operator()( T lhs, T rhs ) const
+            bool operator()(const T &, const U &) const
+            {
+               return false;
+            }
+        
+            template <typename T>
+            bool operator()(T lhs, T rhs) const
             {
                return lhs > rhs;
@@ -103 +161 @@
             {
                return  lhs > rhs;
+            }
+
+            bool operator() (value_null, value_null) const
+            {
+               return false;
             }
       };
@@ -110 +173 @@
       { 
             template <typename T, typename U>
-            bool operator()( const T &, const U & ) const
+            bool operator()(const T &, const U &) const
             {
                return false;
@@ -131 +194 @@
             }
         
-            bool operator() (UnicodeString const& lhs, UnicodeString const& rhs ) const
+            bool operator() (UnicodeString const& lhs, UnicodeString const& rhs) const
             {
                return lhs >= rhs;
+            }
+
+            bool operator() (value_null, value_null) const
+            {
+               return false;
             }
       };
@@ -141 +209 @@
       { 
             template <typename T, typename U>
-            bool operator()( const T &, const U & ) const
-            {
-               return false;
-            }
-        
-            template <typename T>
-            bool operator()( T  lhs,T  rhs) const
+            bool operator()(const T &, const U &) const
+            {
+               return false;
+            }
+        
+            template <typename T>
+            bool operator()(T lhs, T rhs) const
             {
                return lhs < rhs;
@@ -162 +230 @@
             }
         
-            bool operator()( UnicodeString const& lhs, 
-                             UnicodeString const& rhs ) const
+            bool operator()(UnicodeString const& lhs, 
+                            UnicodeString const& rhs ) const
             {
                return lhs < rhs;
+            }
+
+            bool operator() (value_null, value_null) const
+            {
+               return false;
             }
       };
@@ -173 +246 @@
       { 
             template <typename T, typename U>
-            bool operator()( const T &, const U & ) const
-            {
-               return false;
-            }
-        
-            template <typename T>
-            bool operator()(T lhs, T rhs ) const
+            bool operator()(const T &, const U &) const
+            {
+               return false;
+            }
+        
+            template <typename T>
+            bool operator()(T lhs, T rhs) const
             {
                return lhs <= rhs;
@@ -195 +268 @@
         
             template <typename T>
-            bool operator()( UnicodeString const& lhs, 
-                             UnicodeString const& rhs ) const
+            bool operator()(UnicodeString const& lhs, 
+                            UnicodeString const& rhs ) const
             {
                return lhs <= rhs;
+            }
+
+            bool operator() (value_null, value_null) const
+            {
+               return false;
             }
       };
@@ -387 +465 @@
                return ss.str();
             }
-      };
+            
+            std::string operator() (value_null const& val) const
+            {
+               return "";
+            }
+       };
 
       struct to_unicode : public boost::static_visitor<UnicodeString>
@@ -411 +494 @@
                out << std::setprecision(16) << val;
                return UnicodeString(out.str().c_str());
+            }
+            
+            UnicodeString operator() (value_null const& val) const
+            {
+               return UnicodeString("");
             }
       };
@@ -456 +544 @@
                return ss.str();
             }
+
+            std::string operator() (value_null const& val) const
+            {
+               return "null";
+            }
       };
    }
-    
+
    class value
    {
@@ -469 +562 @@
       public:
          value ()
-            : base_(0) {}
+            : base_(value_null()) {}
         
          template <typename T> value(T _val_)
@@ -481 +574 @@
          bool operator!=(value const& other) const
          {
-            return !(boost::apply_visitor(impl::equals(),base_,other.base_));
+            return boost::apply_visitor(impl::not_equals(),base_,other.base_);
          }