Add arbitrary string type to the native object API (#4218)

* Custom strings are very common for optimizations around small objects
  or growth style optimizations, i.e.: grow at 1.57 times vs doubling vs..

  A second common strategy is to cooperate w/ the memory allocator
  see FBString[1] and seastar[2] string for examples.

[1] fbstring: https://github.com/facebook/folly/blob/master/folly/docs/FBString.md
[2] sstring: https://github.com/scylladb/seastar/blob/master/core/sstring.hh

2 files changed, 11 insertions, 1 deletions

diff --git a/include/flatbuffers/flatbuffers.h b/include/flatbuffers/flatbuffers.h
index ce657c04..ea78aeee 100644
--- a/include/flatbuffers/flatbuffers.h
+++ b/include/flatbuffers/flatbuffers.h
@@ -981,6 +981,15 @@ FLATBUFFERS_FINAL_CLASS
   }
 
   /// @brief Store a string in the buffer, which can contain any binary data.
+  /// @param[in] str A const reference to a std::string like type with support
+  /// of T::c_str() and T::length() to store in the buffer.
+  /// @return Returns the offset in the buffer where the string starts.
+  template<typename T>
+    Offset<String> CreateString(const T &str) {
+    return CreateString(str.c_str(), str.length());
+  }
+
+  /// @brief Store a string in the buffer, which can contain any binary data.
   /// If a string with this exact contents has already been serialized before,
   /// instead simply returns the offset of the existing string.
   /// @param[in] str A const char pointer to the data to be stored as a string.
diff --git a/include/flatbuffers/idl.h b/include/flatbuffers/idl.h
index 5b7a72a3..d4d737d3 100644
--- a/include/flatbuffers/idl.h
+++ b/include/flatbuffers/idl.h
@@ -353,6 +353,7 @@ struct IDLOptions {
   bool escape_proto_identifiers;
   bool generate_object_based_api;
   std::string cpp_object_api_pointer_type;
+  std::string cpp_object_api_string_type;
   bool union_value_namespacing;
   bool allow_non_utf8;
   std::string include_prefix;
@@ -479,6 +480,7 @@ class Parser : public ParserState {
     known_attributes_["idempotent"] = true;
     known_attributes_["cpp_type"] = true;
     known_attributes_["cpp_ptr_type"] = true;
+    known_attributes_["cpp_str_type"] = true;
     known_attributes_["native_inline"] = true;
     known_attributes_["native_type"] = true;
     known_attributes_["native_default"] = true;
@@ -743,4 +745,3 @@ bool GenerateGoGRPC(const Parser &parser,
 }  // namespace flatbuffers
 
 #endif  // FLATBUFFERS_IDL_H_
-