Crate larvae_worm 

The guest side of the larvae worm ABI.

A worm is a wasm32 module that larvae loads and calls. wasm has no strings. Thus all data crosses as an offset and a length into the linear memory of the module. This crate owns that protocol, so a worm author does not write it:

larvae_worm::frontend!(|source: &str, config: &str| -> anyhow::Result<String> {
    luaux::compile_configured(source, Backend::Vide, &Config::parse(config)?)
});

The macro is not the only entry point. abi is public and documented. Thus a worm with an unusual design can export the raw functions itself, without a copy of the macro.

The ABI

A worm exports memory, plus:

export	signature
larvae_alloc	(len: u32) -> ptr
larvae_dealloc	(ptr, len: u32)
larvae_transform	(src_ptr, src_len, cfg_ptr, cfg_len) -> *header
larvae_init	(cfg_ptr, cfg_len, rules_ptr, rules_len)
larvae_visit	(rule, epoch, node_id)

larvae_transform returns a pointer to a three word header, [out_ptr, out_len, ok]. ok is 1 when the bytes are output and 0 when they are an error message. The header lives in a static, so the host does not free it. The host calls larvae_dealloc(out_ptr, out_len) when it has read the payload out.

Re-exports

pub use node::Node;

Modules

abi

The raw ABI, for a worm that wants the exports without frontend!

node

The guest side of the node API, so a rule reads an ordinary type and not offsets

Macros

frontend

Define a front-end worm. It takes source text and returns transformed source.

rules

Define the rule half of a worm.

Constants

ABI_VERSION

The ABI revision this crate implements. It must match api in worm.toml.