CORELIB|JSON: added experimental BSON support if nlohmann::json Adapter is used.

- added readbsonbuffer and writebsonbuffer to core library for ...
... Tuple <--> BSON Buffer conversion.

Author: Florian Thake

changelog.txt

@@ -8,6 +8,10 @@ NOTE: The dates are not the release dates, but a last commit date.
 ================
 VERSION 0.16.0 (not released yet, pre-release)
 ================
+    CORELIB|JSON: added experimental BSON support if nlohmann::json Adapter is used.
+    - added readbsonbuffer and writebsonbuffer to core library for ...
+    ... Tuple <--> BSON Buffer conversion.
+
     CLEAN: finally removed deprecated CoreLibrary::ExitScript().
     - Please, use _Exit val instead or directly throw teascript::control::Exit_Script from C++.
 

extensions/include/teascript/ext/JsonAdapterNlohmann.hpp

@@ -40,6 +40,12 @@ class JsonAdapterNlohmann
     static ValueObject ToValueObject( Context &rContext, JsonType const &json );
 
     static void FromValueObject( ValueObject const &rObj, JsonType &rOut );
+
+
+    // nlohmann supports different binary formats. We support BSON here.
+
+    static ValueObject FromBSON( Context &rContext, Buffer const &rBuffer );
+    static ValueObject ToBSON( ValueObject const &rObj );
 };
 
 } // namespace teascript

extensions/source/JsonAdapterNlohmann.cpp

@@ -158,4 +158,25 @@ void JsonAdapterNlohmann::FromValueObject( ValueObject const &rObj, JsonType & r
     }
 }
 
+ValueObject JsonAdapterNlohmann::FromBSON( Context &rContext, Buffer const &rBuffer )
+{
+    auto json = nlohmann::json::from_bson( rBuffer );
+    return ToValueObject( rContext, json );
+}
+
+ValueObject JsonAdapterNlohmann::ToBSON( ValueObject const &rObj )
+{
+    JsonType json;
+    try {
+        FromValueObject( rObj, json );
+    } catch( std::exception const & ) {
+        // TODO better error handling! Use Error once it exist!
+        return ValueObject( false );
+    }
+
+    Buffer  bson = nlohmann::json::to_bson( json );
+    return ValueObject( std::move( bson ) );
+}
+
+
 } // namespace teascript

include/teascript/CoreLibrary.hpp

@@ -2066,6 +2066,23 @@ class CoreLibrary
                 ValueObject val{std::move( func ), cfg_mutable};
                 tea_add_var( "json_array_remove", std::move( val ) ); // missing _ is intended
             }
+
+            // EXPERIMENTAL BSON support (nlohmann adapter must be used!)
+# if TEASCRIPT_BSONSUPPORT
+            // readbsonbuffer : Any ( Buffer ) --> creates a value of appropriate type from the given BSON buffer (or a TypeInfo on error).
+            {
+                auto func = std::make_shared< LibraryFunction< decltype(JsonSupport<>::ReadBsonBuffer) > >( &JsonSupport<>::ReadBsonBuffer );
+                ValueObject val{std::move( func ), cfg_mutable};
+                tea_add_var( "readbsonbuffer", std::move( val ) ); // missing _ is intended
+            }
+
+            // writebsonbuffer : Buffer|Bool ( Any ) --> creates a Bson buffer (or false on error).
+            {
+                auto func = std::make_shared< LibraryFunction< decltype(JsonSupport<>::WriteBsonBuffer) > >( &JsonSupport<>::WriteBsonBuffer );
+                ValueObject val{std::move( func ), cfg_mutable};
+                tea_add_var( "writebsonbuffer", std::move( val ) ); // missing _ is intended
+            }
+# endif
 #endif
         }
 

include/teascript/JsonSupport.hpp

@@ -46,6 +46,10 @@ namespace teascript {
 using JsonAdapter = JsonAdapterPico;
 }
 #elif TEASCRIPT_JSONSUPPORT == TEASCRIPT_JSON_NLOHMANN
+# if !defined( TEASCRIPT_BSONSUPPORT)
+// nlohmann supports BSON
+#  define TEASCRIPT_BSONSUPPORT     1
+# endif
 #if __has_include("teascript/ext/JsonAdapterNlohmann.hpp")
 # include "teascript/ext/JsonAdapterNlohmann.hpp"
 #else
@@ -76,6 +80,9 @@ using JsonAdapter = JsonAdapterBoost;
 # error unsupported JSON flavor for TeaScript
 #endif
 
+#if !defined( TEASCRIPT_BSONSUPPORT)
+# define TEASCRIPT_BSONSUPPORT     0
+#endif
 
 namespace teascript {
 
@@ -117,6 +124,23 @@ class JsonSupport
     {
         Adapter::FromValueObject( rObj, rOut );
     }
+
+    // EXPERIMENTAL BSON support (nlohmann adapter must be used!)
+#if TEASCRIPT_BSONSUPPORT
+    /// Constructs a ValueObject structure from the given BSON buffer.
+    static ValueObject ReadBsonBuffer( Context &rContext, Buffer const &rBuffer )
+    {
+        return Adapter::FromBSON( rContext, rBuffer );
+    }
+
+    /// Constructs a Bson buffer from the given ValueObject. 
+    /// \return the constructed buffer or false on error.
+    /// \note the object must only contain supported types and layout for Json.
+    static ValueObject WriteBsonBuffer( ValueObject const &rObj )
+    {
+        return Adapter::ToBSON( rObj );
+    }
+#endif
 };
 
 } // namespace teascript