Expose deparseSync

[jgoux]

Hello 👋,

I'm attempting to expose the pg_query_deparse_protobuf function.

I tried to follow the existing code, but I don't have any experience with C++ or NAPI so I'm stuck on the DeparseQuerySync function in sync.cc. 😅

I understand that pg_query_deparse_protobuf is expecting the struct PgQueryProtobuf as its 1st argument, but I'm not sure how to declare and pass it.

Right now it generates this error:

../src/sync.cc:8:33: error: no matching function for call to 'pg_query_deparse_protobuf'
  PgQueryDeparseResult result = pg_query_deparse_protobuf(parse_tree.c_str());
                                ^~~~~~~~~~~~~~~~~~~~~~~~~
../libpg_query/include/pg_query.h:95:22: note: candidate function not viable: no known conversion from 'const std::basic_string<char>::value_type *' (aka 'const char *') to 'PgQueryProtobuf' for 1st argument
PgQueryDeparseResult pg_query_deparse_protobuf(PgQueryProtobuf parse_tree);

Any help is appreciated. 🙏

EDIT:

In fact, it seems like pg_query_deparse_protobuf will only be able to accept the result of pg_query_parse_protobuf, so it won't work on the result of pg_query_parse if I understand correctly. 🤔
We would need to add a pg_query_deparse to libpg_query which would accept the result of pg_query_parse and skip the protobuf layer. I opened an issue about it: pganalyze/libpg_query#178.

I would love to have your feedback @pyramation on this matter, I saw you opened an issue about deparsing in libpg_query and you were interested in bringing it into this lib. 😄

[wesselvdv]

Might be interesting to just expose all the protobuf stuff. It’s a bit more efficient than json in terms of size.

[tomquist]

Opened #32 to address the protobuf issue by generating a protobuf message from the json parse tree, which gets sent over to the native library.