Fixes for DataFrame::nrows(), following @romainfrancois commit (closes #120)

Author: kevinushey

ChangeLog

@@ -1,3 +1,7 @@
+2014-02-23  Kevin Ushey <[email protected]>
+
+        * inst/include/Rcpp/DataFrame.h: better nrows behavior
+
 2014-02-17  Romain Francois <[email protected]>
 
         * inst/include/Rcpp/traits/un_pointer.h: fix bug in un_pointer for object<T>

inst/NEWS.Rd

@@ -15,6 +15,8 @@
       as the vector .sort() method. These fixes ensure that sugar functions
       depending on IndexHash (unique, sort_unique, match) will now properly
       handle NA and NaN values for numeric vectors.
+      \item DataFrame::nrows now more accurately mimics R's internal behavior
+      (checks the row.names attribute)
     }
     \item Changes in Rcpp Attributes
       \itemize{

inst/include/Rcpp/DataFrame.h

@@ -60,7 +60,12 @@ namespace Rcpp{
         }
 
         inline int nrows() const {
-            return Rf_length( VECTOR_ELT(Parent::get__(), 0) );     
+            SEXP rn = Rf_getAttrib( Parent::get__(), R_RowNamesSymbol );
+            if (TYPEOF(rn) == INTSXP && LENGTH(rn) == 2 && INTEGER(rn)[0] == NA_INTEGER)
+                return INTEGER(rn)[1];
+            if (Rf_isNull(rn))
+                return 0;
+            return LENGTH(rn);
         }
 
         static DataFrame_Impl create(){