Merge pull request #1729 from kkaefer/value_hash

Support boost::hash() for mapnik::value

include/mapnik/unicode.hpp

@@ -51,4 +51,10 @@ private:
 };
 }
 
+namespace icu_50 {
+inline std::size_t hash_value(const UnicodeString& val) {
+    return val.hashCode();
+}
+}
+
 #endif // MAPNIK_UNICODE_HPP

include/mapnik/value.hpp

@@ -36,6 +36,7 @@
 #include <boost/variant/variant.hpp>
 #include <boost/scoped_array.hpp>
 #include <boost/concept_check.hpp>
+#include <boost/functional/hash.hpp>
 
 // stl
 #include <iostream>
@@ -905,6 +906,10 @@ operator << (std::basic_ostream<charT,traits>& out,
     return out;
 }
 
+inline std::size_t hash_value(const value& val) {
+    return hash_value(val.base());
+}
+
 } // namespace value_adl_barrier
 
 using value_adl_barrier::value;

include/mapnik/value_types.hpp

@@ -78,6 +78,10 @@ struct value_null
     }
 };
 
+inline std::size_t hash_value(const value_null& val) {
+    return 0;
+}
+
 inline std::ostream& operator<< (std::ostream & out,value_null const& v)
 {
     return out;