Extend rfl::AllowRawPtrs to std::string_view (getml#460)

Author: lixin-wei

include/rfl/parsing/Parser_string_view.hpp

@@ -1,6 +1,7 @@
 #ifndef RFL_PARSING_PARSER_STRING_VIEW_HPP_
 #define RFL_PARSING_PARSER_STRING_VIEW_HPP_
 
+#include <cstring>
 #include <map>
 #include <string>
 #include <string_view>
@@ -19,12 +20,24 @@ template <class R, class W, class ProcessorsType>
 struct Parser<R, W, std::string_view, ProcessorsType> {
   using InputVarType = typename R::InputVarType;
 
-  static Result<std::string_view> read(const R&, const InputVarType&) noexcept {
-    static_assert(always_false_v<R>,
-                  "Reading into std::string_view is dangerous and "
-                  "therefore unsupported. "
-                  "Please consider using std::string instead.");
-    return error("Unsupported.");
+  static Result<std::string_view> read(const R& _r,
+                                       const InputVarType& _var) noexcept {
+    if constexpr (!ProcessorsType::allow_raw_ptrs_) {
+      static_assert(always_false_v<R>,
+                    "Reading into std::string_view is dangerous and "
+                    "therefore unsupported. "
+                    "Please consider using std::string instead, or use the "
+                    "rfl::AllowRawPtrs processor.");
+      return error("Unsupported.");
+    } else {
+      return Parser<R, W, std::string, ProcessorsType>::read(_r, _var)
+          .transform([](std::string&& str) {
+            char* data =
+                new char[str.size() + 1];  // +1 for the null terminator
+            std::memcpy(data, str.data(), str.size() + 1);
+            return std::string_view(data, str.size());
+          });
+    }
   }
 
   template <class P>

tests/json/test_pointer_fields.cpp

@@ -40,5 +40,14 @@ TEST(json, test_pointer_fields) {
 
   delete homer.children;
   delete homer2.children;
+
+  // test string_view
+  const std::string_view str = "wa oh what a coincidence";
+  const auto json_str_view = rfl::json::write(str);
+  const auto str_view_back =
+      rfl::json::read<std::string_view, rfl::AllowRawPtrs>(json_str_view)
+          .value();
+  EXPECT_EQ(str, str_view_back);
+  delete str_view_back.data();
 }
 }  // namespace test_pointer_fields