Enable lambdas in all sugar functions

ChangeLog

@@ -1,3 +1,16 @@
+2025-03-29 Iñaki Ucar <[email protected]>
+
+	* inst/include/Rcpp/traits/result_of.h: Reimplement traits::result_of using
+	std::result_of (up to C++14) or std::invoke_result (C++17 or later), which
+	supports previous use cases and enables lambdas
+	* inst/include/Rcpp/sugar/functions/sapply.h: Use new result_of interface
+	* inst/include/Rcpp/sugar/functions/lapply.h: Idem
+	* inst/include/Rcpp/sugar/functions/mapply/mapply_2.h: Idem
+	* inst/include/Rcpp/sugar/functions/mapply/mapply_3.h: Idem
+	* inst/include/Rcpp/sugar/matrix/outer.h: Idem
+	* inst/tinytest/cpp/sugar.cpp: New tests for previous sugar functions
+	* inst/tinytest/test_sugar.R: Idem
+
 2025-03-26  Dirk Eddelbuettel  <[email protected]>
 
 	* DESCRIPTION (Version, Date): Roll micro version and date

inst/include/Rcpp/sugar/functions/lapply.h

@@ -2,7 +2,8 @@
 //
 // lapply.h: Rcpp R/C++ interface class library -- lapply
 //
-// Copyright (C) 2010 - 2011 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2010 - 2024 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2025        Dirk Eddelbuettel, Romain Francois and Iñaki Ucar
 //
 // This file is part of Rcpp.
 //
@@ -33,7 +34,7 @@ class Lapply : public VectorBase<
 > {
 public:
 	typedef Rcpp::VectorBase<RTYPE,NA,T> VEC ;
-	typedef typename ::Rcpp::traits::result_of<Function>::type result_type ;
+	typedef typename ::Rcpp::traits::result_of<Function, T>::type result_type ;
 
 	Lapply( const VEC& vec_, Function fun_ ) :
 		vec(vec_), fun(fun_){}

inst/include/Rcpp/sugar/functions/mapply/mapply_2.h

@@ -2,7 +2,8 @@
 //
 // mapply_2.h: Rcpp R/C++ interface class library -- mapply_2
 //
-// Copyright (C) 2012 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2012 - 2024 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2025        Dirk Eddelbuettel, Romain Francois and Iñaki Ucar
 //
 // This file is part of Rcpp.
 //
@@ -32,13 +33,13 @@ template <int RTYPE,
 >
 class Mapply_2 : public VectorBase<
 	Rcpp::traits::r_sexptype_traits<
-		typename ::Rcpp::traits::result_of<Function>::type
+		typename ::Rcpp::traits::result_of<Function, T_1, T_2>::type
 	>::rtype ,
 	true ,
 	Mapply_2<RTYPE,NA_1,T_1,NA_2,T_2,Function>
 > {
 public:
-	typedef typename ::Rcpp::traits::result_of<Function>::type result_type ;
+	typedef typename ::Rcpp::traits::result_of<Function, T_1, T_2>::type result_type ;
 
 	Mapply_2( const T_1& vec_1_, const T_2& vec_2_, Function fun_ ) :
 		vec_1(vec_1_), vec_2(vec_2_), fun(fun_){}
@@ -62,14 +63,14 @@ template <int RTYPE,
 class Mapply_2_Vector_Primitive : public
     VectorBase<
 	    Rcpp::traits::r_sexptype_traits<
-	    	typename ::Rcpp::traits::result_of<Function>::type
+	    	typename ::Rcpp::traits::result_of<Function, T_1>::type
 	    >::rtype ,
 	    true ,
 	    Mapply_2_Vector_Primitive<RTYPE,NA_1,T_1,PRIM_2,Function>
     >
 {
 public:
-	typedef typename ::Rcpp::traits::result_of<Function>::type result_type ;
+	typedef typename ::Rcpp::traits::result_of<Function, T_1>::type result_type ;
 
 	Mapply_2_Vector_Primitive( const T_1& vec_1_, PRIM_2 prim_2_, Function fun_ ) :
 		vec_1(vec_1_), prim_2(prim_2_), fun(fun_){}
@@ -93,14 +94,14 @@ template <int RTYPE,
 class Mapply_2_Primitive_Vector : public
     VectorBase<
 	    Rcpp::traits::r_sexptype_traits<
-	    	typename ::Rcpp::traits::result_of<Function>::type
+	    	typename ::Rcpp::traits::result_of<Function, T_2>::type
 	    >::rtype ,
 	    true ,
 	    Mapply_2_Primitive_Vector<RTYPE,PRIM_1,NA_2,T_2,Function>
     >
 {
 public:
-	typedef typename ::Rcpp::traits::result_of<Function>::type result_type ;
+	typedef typename ::Rcpp::traits::result_of<Function, T_2>::type result_type ;
 
 	Mapply_2_Primitive_Vector( PRIM_1 prim_1_, const T_2& vec_2_, Function fun_ ) :
 		prim_1(prim_1_), vec_2(vec_2_), fun(fun_){}

inst/include/Rcpp/sugar/functions/mapply/mapply_3.h

@@ -2,7 +2,8 @@
 //
 // mapply_3.h: Rcpp R/C++ interface class library -- mapply_3
 //
-// Copyright (C) 2012 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2012 - 2024 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2025        Dirk Eddelbuettel, Romain Francois and Iñaki Ucar
 //
 // This file is part of Rcpp.
 //
@@ -33,13 +34,13 @@ template <
 >
 class Mapply_3 : public VectorBase<
 	Rcpp::traits::r_sexptype_traits<
-		typename ::Rcpp::traits::result_of<Function>::type
+		typename ::Rcpp::traits::result_of<Function, T_1, T_2, T_3>::type
 	>::rtype ,
 	true ,
 	Mapply_3<RTYPE_1,NA_1,T_1,RTYPE_2,NA_2,T_2,RTYPE_3,NA_3,T_3,Function>
 > {
 public:
-	typedef typename ::Rcpp::traits::result_of<Function>::type result_type ;
+	typedef typename ::Rcpp::traits::result_of<Function, T_1, T_2, T_3>::type result_type ;
 
     typedef Rcpp::VectorBase<RTYPE_1,NA_1,T_1> VEC_1 ;
 	typedef Rcpp::VectorBase<RTYPE_2,NA_2,T_2> VEC_2 ;

inst/include/Rcpp/sugar/functions/sapply.h

@@ -1,7 +1,8 @@
 
 // sapply.h: Rcpp R/C++ interface class library -- sapply
 //
-// Copyright (C) 2010 - 2023 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2010 - 2024 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2025        Dirk Eddelbuettel, Romain Francois and Iñaki Ucar
 //
 // This file is part of Rcpp.
 //
@@ -27,36 +28,16 @@
 namespace Rcpp{
 namespace sugar{
 
-template <typename Function, typename SugarExpression>
-struct sapply_application_result_of
-{
-#if __cplusplus >= 201103L
-    #if __cplusplus < 201703L
-        // deprecated by C++17, removed by C++2020, see https://en.cppreference.com/w/cpp/types/result_of
- 	    typedef typename ::std::result_of<Function(typename SugarExpression::stored_type)>::type type;
-    #else
-        // since C++17, see https://en.cppreference.com/w/cpp/types/result_of
-        typedef typename ::std::invoke_result<Function, typename SugarExpression::stored_type>::type type;
-    #endif
-#else
-    // TODO this else branch can likely go
-	typedef typename ::Rcpp::traits::result_of<Function>::type type;
-#endif
-};
-
-// template <typename Function, typename SugarExpression>
-// using sapply_application_result_of_t = typename sapply_application_result_of<Function, SugarExpression>::type;
-
 template <int RTYPE, bool NA, typename T, typename Function, bool NO_CONVERSION>
 class Sapply : public VectorBase<
 	Rcpp::traits::r_sexptype_traits<
-		typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type
+		typename ::Rcpp::traits::result_of<Function, T>::type
 	>::rtype ,
 	true ,
 	Sapply<RTYPE,NA,T,Function,NO_CONVERSION>
 > {
 public:
-	typedef typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type result_type ;
+	typedef typename ::Rcpp::traits::result_of<Function, T>::type result_type ;
 	const static int RESULT_R_TYPE =
 		Rcpp::traits::r_sexptype_traits<result_type>::rtype ;
 
@@ -87,13 +68,13 @@ class Sapply : public VectorBase<
 template <int RTYPE, bool NA, typename T, typename Function>
 class Sapply<RTYPE,NA,T,Function,true> : public VectorBase<
 	Rcpp::traits::r_sexptype_traits<
-		typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type
+		typename ::Rcpp::traits::result_of<Function, T>::type
 	>::rtype ,
 	true ,
 	Sapply<RTYPE,NA,T,Function,true>
 > {
 public:
-	typedef typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type result_type ;
+	typedef typename ::Rcpp::traits::result_of<Function, T>::type result_type ;
 	const static int RESULT_R_TYPE =
 		Rcpp::traits::r_sexptype_traits<result_type>::rtype ;
 
@@ -124,15 +105,15 @@ template <int RTYPE, bool NA, typename T, typename Function >
 inline sugar::Sapply<
     RTYPE,NA,T,Function,
     traits::same_type<
-        typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type ,
-        typename Rcpp::traits::storage_type< traits::r_sexptype_traits< typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type >::rtype >::type
+        typename ::Rcpp::traits::result_of<Function, T>::type ,
+        typename Rcpp::traits::storage_type< traits::r_sexptype_traits< typename ::Rcpp::traits::result_of<Function, T>::type >::rtype >::type
     >::value
 >
 sapply( const Rcpp::VectorBase<RTYPE,NA,T>& t, Function fun ){
 	return sugar::Sapply<RTYPE,NA,T,Function,
 	traits::same_type<
-        typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type ,
-        typename Rcpp::traits::storage_type< traits::r_sexptype_traits< typename ::Rcpp::sugar::sapply_application_result_of<Function, T>::type >::rtype >::type
+        typename ::Rcpp::traits::result_of<Function, T>::type ,
+        typename Rcpp::traits::storage_type< traits::r_sexptype_traits< typename ::Rcpp::traits::result_of<Function, T>::type >::rtype >::type
     >::value >( t, fun ) ;
 }
 

inst/include/Rcpp/sugar/matrix/outer.h

@@ -2,7 +2,8 @@
 //
 // outer.h: Rcpp R/C++ interface class library -- outer
 //
-// Copyright (C) 2010 - 2011 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2010 - 2024 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2025        Dirk Eddelbuettel, Romain Francois and Iñaki Ucar
 //
 // This file is part of Rcpp.
 //
@@ -31,13 +32,13 @@ template <int RTYPE,
           typename Function >
 class Outer : public MatrixBase<
     Rcpp::traits::r_sexptype_traits<
-        typename ::Rcpp::traits::result_of<Function>::type
+        typename ::Rcpp::traits::result_of<Function, LHS_T, RHS_T>::type
 	>::rtype ,
             true ,
     Outer<RTYPE,LHS_NA,LHS_T,RHS_NA,RHS_T,Function>
 > {
 public:
-    typedef typename ::Rcpp::traits::result_of<Function>::type result_type ;
+    typedef typename ::Rcpp::traits::result_of<Function, LHS_T, RHS_T>::type result_type ;
     const static int RESULT_R_TYPE =
         Rcpp::traits::r_sexptype_traits<result_type>::rtype ;
 

inst/include/Rcpp/traits/result_of.h

@@ -3,7 +3,8 @@
 //
 // result_of.h: Rcpp R/C++ interface class library -- traits to help wrap
 //
-// Copyright (C) 2010 - 2012 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2010 - 2024 Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2025        Dirk Eddelbuettel, Romain Francois and Iñaki Ucar
 //
 // This file is part of Rcpp.
 //
@@ -26,24 +27,20 @@
 namespace Rcpp{
 namespace traits{
 
-template <typename T>
+template <typename T, typename... Args>
 struct result_of{
-	typedef typename T::result_type type ;
-} ;
-
-template <typename RESULT_TYPE, typename INPUT_TYPE>
-struct result_of< RESULT_TYPE (*)(INPUT_TYPE) >{
-	typedef RESULT_TYPE type ;
-} ;
-
-template <typename RESULT_TYPE, typename U1, typename U2>
-struct result_of< RESULT_TYPE (*)(U1, U2) >{
-	typedef RESULT_TYPE type ;
+#if __cplusplus < 201703L
+    // deprecated by C++17, removed by C++2020, see https://en.cppreference.com/w/cpp/types/result_of
+    typedef typename ::std::result_of<T(typename Args::stored_type...)>::type type;
+#else
+    // since C++17, see https://en.cppreference.com/w/cpp/types/result_of
+    typedef typename ::std::invoke_result<T, typename Args::stored_type...>::type type;
+#endif
 } ;
 
-template <typename RESULT_TYPE, typename U1, typename U2, typename U3>
-struct result_of< RESULT_TYPE (*)(U1, U2, U3) >{
-	typedef RESULT_TYPE type ;
+template <typename T>
+struct result_of<T>{
+    typename T::result_type type ;
 } ;
 
 }

inst/tinytest/cpp/sugar.cpp

@@ -2,6 +2,7 @@
 // sugar.cpp: Rcpp R/C++ interface class library -- sugar unit tests
 //
 // Copyright (C) 2012 - 2025  Dirk Eddelbuettel and Romain Francois
+// Copyright (C) 2025         Dirk Eddelbuettel, Romain Francois and Iñaki Ucar
 //
 // This file is part of Rcpp.
 //
@@ -22,7 +23,6 @@
 using namespace Rcpp ;
 
 template <typename T>
-
 class square : public std::function<T(T)> {
 public:
 	T operator()( T t) const { return t*t ; }
@@ -222,11 +222,58 @@ NumericVector runit_na_omit( NumericVector xx ){
 }
 
 // [[Rcpp::export]]
-List runit_lapply( IntegerVector xx){
+List runit_lapply( NumericVector xx ){
+    List res = lapply( xx, square<double>() );
+    return res ;
+}
+
+// [[Rcpp::export]]
+List runit_lapply_rawfun( NumericVector xx){
+    List res = lapply( xx, raw_square );
+    return res ;
+}
+
+// [[Rcpp::export]]
+List runit_lapply_lambda(NumericVector xx){
+    List res = lapply(xx, [](double x) { return x*x; });
+    return res;
+}
+
+// [[Rcpp::export]]
+List runit_lapply_seq( IntegerVector xx){
     List res = lapply( xx, seq_len );
     return res ;
 }
 
+// [[Rcpp::export]]
+NumericVector runit_mapply2(NumericVector xx, NumericVector yy){
+    NumericVector res = mapply(xx, yy, std::plus<double>());
+    return res;
+}
+
+// [[Rcpp::export]]
+NumericVector runit_mapply2_lambda(NumericVector xx, NumericVector yy){
+    NumericVector res = mapply(xx, yy, [](double x, double y) { return x+y; });
+    return res;
+}
+
+// [[Rcpp::export]]
+NumericVector runit_mapply3_lambda(NumericVector xx, NumericVector yy, NumericVector zz){
+    NumericVector res = mapply(xx, yy, zz, [](double x, double y, double z) { return x+y+z; });
+    return res;
+}
+
+// [[Rcpp::export]]
+LogicalVector runit_mapply2_logical(NumericVector xx, NumericVector yy){
+    return all(mapply(xx, yy, std::plus<double>()) < 100.0);
+}
+
+// [[Rcpp::export]]
+List runit_mapply2_list(IntegerVector xx, IntegerVector yy){
+    List res = mapply(xx, yy, seq);
+    return res ;
+}
+
 // [[Rcpp::export]]
 List runit_minus( IntegerVector xx ){
     return List::create(
@@ -327,6 +374,12 @@ NumericVector runit_sapply_rawfun( NumericVector xx){
     return res ;
 }
 
+// [[Rcpp::export]]
+NumericVector runit_sapply_lambda(NumericVector xx){
+    NumericVector res = sapply(xx, [](double x) { return x*x; });
+    return res;
+}
+
 // [[Rcpp::export]]
 LogicalVector runit_sapply_square( NumericVector xx){
     return all( sapply( xx * xx , square<double>() ) < 10.0 );
@@ -444,6 +497,12 @@ NumericMatrix runit_outer( NumericVector xx, NumericVector yy){
     return m ;
 }
 
+// [[Rcpp::export]]
+NumericMatrix runit_outer_lambda(NumericVector xx, NumericVector yy){
+    NumericMatrix m = outer(xx, yy, [](double x, double y) { return x + y; });
+    return m ;
+}
+
 // [[Rcpp::export]]
 List runit_row( NumericMatrix xx ){
     return List::create(