libwebsockets
Lightweight C library for HTML5 websockets
lws_struct

Overview

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

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  • 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 ../lib/misc/lwsac/README.md "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