Update three more uses of attribute getting for R 4.6.0 or later (#1450)

Author: eddelbuettel

ChangeLog

@@ -1,3 +1,11 @@
+2026-01-23  Dirk Eddelbuettel  <edd@debian.org>
+
+	* inst/include/Rcpp/DataFrame.h (nrow): Use R_nrow() with R >= 4.6.0
+	* inst/include/Rcpp/proxy/AttributeProxy.h (attributeNames): Use
+	R_getAttribNames() with R >= 4.6.0;
+	* inst/include/Rcpp/proxy/AttributeProxy.h (hasAttribute): Use
+	R_hasAttrib with R >= 4.6.0
+
 2026-01-22  Dirk Eddelbuettel  <edd@debian.org>
 
 	* DESCRIPTION (Version, Date): Roll micro version and date

inst/include/Rcpp/DataFrame.h

@@ -1,8 +1,7 @@
-// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; indent-tabs-mode: nil; -*-
-//
+
 // DataFrame.h: Rcpp R/C++ interface class library -- data frames
 //
-// Copyright (C) 2010 - 2025  Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2010 - 2026  Dirk Eddelbuettel and Romain Francois
 //
 // This file is part of Rcpp.
 //
@@ -67,8 +66,12 @@ namespace Rcpp{
         // discussed in #1430 is also possible and preferable. We also switch
         // to returning R_xlen_t which as upcast from int is safe
         inline R_xlen_t nrow() const {
+#if R_VERSION < R_Version(4,6,0)
             Shield<SEXP> rn{Rf_getAttrib(Parent::get__(), R_RowNamesSymbol)};
             return Rf_xlength(rn);
+#else
+            return R_nrow(Parent::get__());
+#endif
         }
 
         template <typename T>

inst/include/Rcpp/proxy/AttributeProxy.h

@@ -80,13 +80,11 @@ class AttributeProxyPolicy {
     std::vector<std::string> attributeNames() const {
         std::vector<std::string> v;
 #if R_VERSION >= R_Version(4, 6, 0)
-        auto visitor = [](SEXP name, SEXP attr, void* data) -> SEXP {
-            std::vector<std::string>* ptr = static_cast<std::vector<std::string>*>(data);
-            std::string s{CHAR(Rf_asChar(name))};
-            ptr->push_back(s);
-            return NULL;
-        };
-        R_mapAttrib(static_cast<const CLASS&>(*this).get__(), visitor, static_cast<void*>(&v));
+        SEXP attrs = R_getAttribNames( static_cast<const CLASS&>(*this));
+        R_xlen_t n = XLENGTH(attrs);
+        for (R_xlen_t i = 0; i < n; i++) {
+            v.push_back(std::string(CHAR(STRING_ELT(attrs, i))));
+        }
 #else
         SEXP attrs = ATTRIB( static_cast<const CLASS&>(*this).get__());
         while( attrs != R_NilValue ){
@@ -98,7 +96,11 @@ class AttributeProxyPolicy {
     }
 
     bool hasAttribute(const std::string& attr) const {
+#if R_VERSION >= R_Version(4, 6, 0)
+        return R_hasAttrib(static_cast<const CLASS&>(*this).get__(), Rf_install(attr.c_str()));
+#else
         return static_cast<const CLASS&>(*this).attr(attr) != R_NilValue;
+#endif
     }