Function registry

parcel_core::Registry maps function names to the definitions used when checking and compiling expressions. Its supporting types are in parcel_core::registry.

Registry methods

impl Registry {
    pub fn builtin() -> Self;
    pub fn insert(&mut self, entry: FunctionEntry);
    pub fn get(&self, name: &str) -> Option<&FunctionEntry>;
    pub fn visible_to(&self, owner: Option<&str>) -> Registry;
    pub fn entries(&self) -> impl Iterator<Item = &FunctionEntry>;
}

Method	Arguments and result
builtin	Creates a registry containing parcel’s built-in functions.
insert	Takes ownership of an entry; replaces any entry with the same name.
get	Looks up a name and borrows the entry, or returns None.
visible_to	Creates a registry containing built-ins and functions for the supplied owner; None selects built-ins only.
entries	Borrows all current entries through an iterator.

use parcel_core::Registry;

let registry = Registry::builtin();
let redact = registry.get("redact").expect("built-in function");
assert!(redact.is_builtin());

FunctionEntry

Field	Type	Meaning
name	String	Function name used in expressions.
version	u32	Function revision.
signatures	Vec<Signature>	Supported argument and return types.
deterministic	bool	Whether identical inputs produce identical outputs.
nulls	Nulls	Null handling; currently Nulls::Propagate.
cost	Cost	Execution cost: Cheap, Moderate, or Expensive.
pushdown	Pushdown	Optimization hint: None or Monotone.
owner	String	Owner identifier; built-ins use core.
hash	String	Hash of implementation identity and manifest.
module	Option<String>	WebAssembly module hash, or None for built-ins.

impl FunctionEntry {
    pub fn user(
        manifest: &FunctionManifest,
        owner: &str,
        module_sha256: &str,
    ) -> Result<FunctionEntry, String>;
    pub fn pin(&self) -> FunctionPin;
    pub fn is_builtin(&self) -> bool;
}

user constructs metadata from a manifest, owner, and module hash; invalid names or signatures return an error. It does not load executable code. wasm::install loads the module and creates an entry together. pin returns the exact implementation identity. is_builtin is true when module is absent.

FunctionManifest

Field	Type	Meaning
name	String	Exported function name.
version	u32	Function revision.
signatures	Vec<String>	Signature strings, such as (string) -> bool; a v1 function has one signature.
deterministic	bool	Defaults to true when deserializing.
cost	Cost	Defaults to Moderate when deserializing.

Signature and FunctionPin

Type	Public fields
Signature	args: Vec<Type> for ordered argument types; ret: Type for the return type.
FunctionPin	name: String, version: u32, hash: String identifying an exact function implementation.

pub fn parse_signature(s: &str) -> Result<Signature, String>;

Parses a signature such as (string, int) -> bool. Returns an error for malformed signatures or unsupported scalar types.