Add 'const' case to complement 'plain', 'reference' and 'const reference'

Author: eddelbuettel

ChangeLog

@@ -1,5 +1,7 @@
 2013-09-15  Dirk Eddelbuettel  <edd@debian.org>
 
+	* inst/include/Rcpp/InputParameter.h (Rcpp): Add 'const' case
+
 	* inst/unitTests/cpp/Vector.cpp: New unit tests for std::vector
 	conversions, using both int and double arguments
 	* inst/unitTests/runit.Vector.R: R complement of these tests

inst/include/Rcpp/InputParameter.h

@@ -50,6 +50,19 @@ namespace Rcpp {
     private:
         T obj ;
     } ;
+
+    // same for const
+    template <typename T>
+    class ConstInputParameter {
+    public:
+        typedef const T const_nonref ;
+        ConstInputParameter(SEXP x_) : obj( as<T>(x_) ){}
+        
+        inline operator const_nonref() { return obj ; }
+        
+    private:
+        T obj ;
+    } ;
 
     // same for const references
     template <typename T>
@@ -74,6 +87,10 @@ namespace Rcpp {
             typedef typename Rcpp::ReferenceInputParameter<T> type ;
         } ;
         template <typename T>
+        struct input_parameter<const T> {
+            typedef typename Rcpp::ConstInputParameter<T> type ;
+        } ;
+        template <typename T>
         struct input_parameter<const T&> {
             typedef typename Rcpp::ConstReferenceInputParameter<T> type ;
         } ;