Added const qualifiers for functor call operators

Author: oleksandr-pavlyk

dpctl/tensor/libtensor/include/kernels/elementwise_functions/abs.hpp

@@ -61,7 +61,7 @@ template <typename argT, typename resT> struct AbsFunctor
     using supports_sg_loadstore = typename std::negation<
         std::disjunction<is_complex<resT>, is_complex<argT>>>;
 
-    resT operator()(const argT &x)
+    resT operator()(const argT &x) const
     {
 
         if constexpr (std::is_same_v<argT, bool> ||

dpctl/tensor/libtensor/include/kernels/elementwise_functions/acos.hpp

@@ -63,7 +63,7 @@ template <typename argT, typename resT> struct AcosFunctor
     using supports_sg_loadstore = typename std::negation<
         std::disjunction<is_complex<resT>, is_complex<argT>>>;
 
-    resT operator()(const argT &in)
+    resT operator()(const argT &in) const
     {
         if constexpr (is_complex<argT>::value) {
             using realT = typename argT::value_type;

dpctl/tensor/libtensor/include/kernels/elementwise_functions/acosh.hpp

@@ -63,7 +63,7 @@ template <typename argT, typename resT> struct AcoshFunctor
     using supports_sg_loadstore = typename std::negation<
         std::disjunction<is_complex<resT>, is_complex<argT>>>;
 
-    resT operator()(const argT &in)
+    resT operator()(const argT &in) const
     {
         if constexpr (is_complex<argT>::value) {
             using realT = typename argT::value_type;

dpctl/tensor/libtensor/include/kernels/elementwise_functions/add.hpp

@@ -58,14 +58,15 @@ template <typename argT1, typename argT2, typename resT> struct AddFunctor
     using supports_vec = std::negation<
         std::disjunction<tu_ns::is_complex<argT1>, tu_ns::is_complex<argT2>>>;
 
-    resT operator()(const argT1 &in1, const argT2 &in2)
+    resT operator()(const argT1 &in1, const argT2 &in2) const
     {
         return in1 + in2;
     }
 
     template <int vec_sz>
-    sycl::vec<resT, vec_sz> operator()(const sycl::vec<argT1, vec_sz> &in1,
-                                       const sycl::vec<argT2, vec_sz> &in2)
+    sycl::vec<resT, vec_sz>
+    operator()(const sycl::vec<argT1, vec_sz> &in1,
+               const sycl::vec<argT2, vec_sz> &in2) const
     {
         auto tmp = in1 + in2;
         if constexpr (std::is_same_v<resT,

dpctl/tensor/libtensor/include/kernels/elementwise_functions/asin.hpp

@@ -63,7 +63,7 @@ template <typename argT, typename resT> struct AsinFunctor
     using supports_sg_loadstore = typename std::negation<
         std::disjunction<is_complex<resT>, is_complex<argT>>>;
 
-    resT operator()(const argT &in)
+    resT operator()(const argT &in) const
     {
         if constexpr (is_complex<argT>::value) {
             using realT = typename argT::value_type;

dpctl/tensor/libtensor/include/kernels/elementwise_functions/asinh.hpp

@@ -63,7 +63,7 @@ template <typename argT, typename resT> struct AsinhFunctor
     using supports_sg_loadstore = typename std::negation<
         std::disjunction<is_complex<resT>, is_complex<argT>>>;
 
-    resT operator()(const argT &in)
+    resT operator()(const argT &in) const
     {
         if constexpr (is_complex<argT>::value) {
             using realT = typename argT::value_type;

dpctl/tensor/libtensor/include/kernels/elementwise_functions/atan.hpp

@@ -64,7 +64,7 @@ template <typename argT, typename resT> struct AtanFunctor
     using supports_sg_loadstore = typename std::negation<
         std::disjunction<is_complex<resT>, is_complex<argT>>>;
 
-    resT operator()(const argT &in)
+    resT operator()(const argT &in) const
     {
         if constexpr (is_complex<argT>::value) {
             using realT = typename argT::value_type;

dpctl/tensor/libtensor/include/kernels/elementwise_functions/atan2.hpp

@@ -55,7 +55,7 @@ template <typename argT1, typename argT2, typename resT> struct Atan2Functor
     using supports_sg_loadstore = std::true_type;
     using supports_vec = std::false_type;
 
-    resT operator()(const argT1 &in1, const argT2 &in2)
+    resT operator()(const argT1 &in1, const argT2 &in2) const
     {
         if (std::isinf(in2) && !std::signbit(in2)) {
             if (std::isfinite(in1)) {

dpctl/tensor/libtensor/include/kernels/elementwise_functions/atanh.hpp

@@ -64,7 +64,7 @@ template <typename argT, typename resT> struct AtanhFunctor
     using supports_sg_loadstore = typename std::negation<
         std::disjunction<is_complex<resT>, is_complex<argT>>>;
 
-    resT operator()(const argT &in)
+    resT operator()(const argT &in) const
     {
         if constexpr (is_complex<argT>::value) {
             using realT = typename argT::value_type;

dpctl/tensor/libtensor/include/kernels/elementwise_functions/bitwise_and.hpp

@@ -57,7 +57,7 @@ struct BitwiseAndFunctor
     using supports_sg_loadstore = typename std::true_type;
     using supports_vec = typename std::true_type;
 
-    resT operator()(const argT1 &in1, const argT2 &in2)
+    resT operator()(const argT1 &in1, const argT2 &in2) const
     {
         using tu_ns::convert_impl;
 
@@ -70,8 +70,9 @@ struct BitwiseAndFunctor
     }
 
     template <int vec_sz>
-    sycl::vec<resT, vec_sz> operator()(const sycl::vec<argT1, vec_sz> &in1,
-                                       const sycl::vec<argT2, vec_sz> &in2)
+    sycl::vec<resT, vec_sz>
+    operator()(const sycl::vec<argT1, vec_sz> &in1,
+               const sycl::vec<argT2, vec_sz> &in2) const
     {
 
         if constexpr (std::is_same_v<resT, bool>) {