libwebsockets/READMEs/README.lws_struct.md
Andy Green 38fb0e31da lws_struct
lws_struct JSON + sqlite3 serializer and deserializer


See READMEs/README.lws_struct.md
2019-04-06 06:08:47 +08:00

1.5 KiB

lws_struct

Overview

lws_struct provides a lightweight method for serializing and deserializing C structs to and from JSON, and to and from sqlite3.

lws_struct overview

  • you provide a metadata array describing struct members one-time, then call generic apis to serialize and deserialize

  • supports flat structs, single child struct pointers, and unbounded arrays / linked-lists of child objects automatically using lws_dll2 linked-lists

  • supports boolean and C types char, int, long, long long in explicitly signed and unsigned forms

  • supports both char * type string members where the unbounded content is separate and pointed to, and fixed length char array[] type members where the content is part of the struct

  • huge linear strings are supported by storing to a temp lwsac of chained chunks, which is written into a single linear chunk in the main lwsac once the total string length is known

  • deserialization allocates into an lwsac, so everything is inside as few heap allocations as possible while still able to expand to handle arbitrary array or strins sizes

  • when deserialized structs are finished with, a single call to free the lwsac frees the whole thing without having to walk it

  • stateful serializaton and deserialization allows as-you-get packets incremental parsing and production of chunks of as-you-can-send incremental serialization output cleanly

Examples