use read-only variants of {STRING/VECTOR}_PTR (#1317)

* use read-only variants of {STRING/VECTOR}_PTR

* another const_cast

* one more const

* fix version checks

* require newer R

Author: kevinushey

ChangeLog

@@ -1,3 +1,11 @@
+2024-07-07  Kevin Ushey  <[email protected]>
+
+	* inst/include/Rcpp/internal/SEXP_Iterator.h: Avoid using VECTOR_PTR
+	* inst/include/Rcpp/vector/Subsetter.h: Avoid using STRING_PTR
+	* inst/include/RcppCommon.h: Include compatibility defines
+	* src/barrier.cpp: Avoid using {STRING/VECTOR}_PTR
+	* inst/include/Rcpp/r/compat.h: Include compatibility defines
+
 2024-06-22  Dirk Eddelbuettel  <[email protected]>
 
 	* DESCRIPTION (Version, Date): Roll micro version

inst/include/Rcpp/internal/SEXP_Iterator.h

@@ -37,7 +37,7 @@ class SEXP_Iterator {
 
 		SEXP_Iterator( ): ptr(){} ;
 		SEXP_Iterator( const SEXP_Iterator& other) : ptr(other.ptr){} ;
-		SEXP_Iterator( const VECTOR& vec ) : ptr( get_vector_ptr(vec) ){} ;
+		SEXP_Iterator( const VECTOR& vec ) : ptr( RCPP_VECTOR_PTR(vec) ){} ;
 
 		SEXP_Iterator& operator=(const SEXP_Iterator& other){ ptr = other.ptr ; return *this ;}
 

inst/include/Rcpp/r/compat.h

@@ -0,0 +1,39 @@
+
+//
+// compat.h: Rcpp R/C++ interface class library -- compatibility defines
+//
+// Copyright (C) 2024         Dirk Eddelbuettel, Kevin Ushey
+//
+// This file is part of Rcpp.
+//
+// Rcpp is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 2 of the License, or
+// (at your option) any later version.
+//
+// Rcpp is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Rcpp.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef RCPP_R_COMPAT_H
+#define RCPP_R_COMPAT_H
+
+#include <Rversion.h>
+
+#if R_VERSION >= R_Version(4, 4, 2)
+# define RCPP_STRING_PTR STRING_PTR_RO
+#else
+# define RCPP_STRING_PTR STRING_PTR
+#endif
+
+#if R_VERSION >= R_Version(4, 4, 2)
+# define RCPP_VECTOR_PTR VECTOR_PTR_RO
+#else
+# define RCPP_VECTOR_PTR VECTOR_PTR
+#endif
+
+#endif /* RCPP_R_COMPAT_H */

inst/include/Rcpp/vector/Subsetter.h

@@ -174,10 +174,10 @@ class SubsetProxy {
         indices.reserve(rhs_n);
         SEXP names = Rf_getAttrib(lhs, R_NamesSymbol);
         if (Rf_isNull(names)) stop("names is null");
-        SEXP* namesPtr = STRING_PTR(names);
-        SEXP* rhsPtr = STRING_PTR(rhs);
+        const SEXP* namesPtr = RCPP_STRING_PTR(names);
+        const SEXP* rhsPtr = RCPP_STRING_PTR(rhs);
         for (R_xlen_t i = 0; i < rhs_n; ++i) {
-            SEXP* match = std::find(namesPtr, namesPtr + lhs_n, *(rhsPtr + i));
+            const SEXP* match = std::find(namesPtr, namesPtr + lhs_n, *(rhsPtr + i));
             if (match == namesPtr + lhs_n)
                 stop("not found");
             indices.push_back(match - namesPtr);

inst/include/RcppCommon.h

@@ -28,6 +28,7 @@
 // #define RCPP_DEBUG_MODULE_LEVEL 1
 
 #include <Rcpp/r/headers.h>
+#include <Rcpp/r/compat.h>
 
 /**
  * \brief Rcpp API

src/api.cpp

@@ -112,7 +112,7 @@ namespace Rcpp {
         case BCODESXP:  	return "BCODESXP";
         case EXTPTRSXP: 	return "EXTPTRSXP";
         case WEAKREFSXP:    return "WEAKREFSXP";
-#if R_Version >= R_Version(4,4,0)					// replaces S4SXP in R 4.4.0
+#if R_VERSION >= R_Version(4,4,0)					// replaces S4SXP in R 4.4.0
         case OBJSXP:    	return Rf_isS4(x) ? "S4SXP" : "OBJSXP"; 	// cf src/main/inspect.c
 #else
         case S4SXP:     	return "S4SXP";

src/barrier.cpp

@@ -22,11 +22,15 @@
 #define COMPILING_RCPP
 
 #define USE_RINTERNALS
+
+#include <algorithm>
 #include <Rinternals.h>
+
 #include <Rcpp/barrier.h>
-#include "internal.h"
-#include <algorithm>
 #include <Rcpp/protection/Shield.h>
+#include <Rcpp/r/compat.h>
+
+#include "internal.h"
 
 // [[Rcpp::register]]
 SEXP get_string_elt(SEXP x, R_xlen_t i) {			// #nocov start
@@ -50,7 +54,8 @@ void char_set_string_elt(SEXP x, R_xlen_t i, const char* value) {
 
 // [[Rcpp::register]]
 SEXP* get_string_ptr(SEXP x) {
-    return STRING_PTR(x);
+    // TODO: should we deprecate this?
+    return const_cast<SEXP*>(RCPP_STRING_PTR(x));
 }
 
 // [[Rcpp::register]]
@@ -65,7 +70,8 @@ void set_vector_elt(SEXP x, R_xlen_t i, SEXP value) {
 
 // [[Rcpp::register]]
 SEXP* get_vector_ptr(SEXP x) {
-    return VECTOR_PTR(x);							// #nocov end
+    // TODO: should we deprecate this?
+    return const_cast<SEXP*>(RCPP_VECTOR_PTR(x));							// #nocov end
 }
 
 // [[Rcpp::register]]