deno/core/extensions.rs
2021-04-30 15:51:48 -04:00

128 lines
3.4 KiB
Rust

use crate::error::AnyError;
use crate::{OpFn, OpState};
pub type SourcePair = (&'static str, &'static str);
pub type OpPair = (&'static str, Box<OpFn>);
pub type OpMiddlewareFn = dyn Fn(&'static str, Box<OpFn>) -> Box<OpFn>;
pub type OpStateFn = dyn Fn(&mut OpState) -> Result<(), AnyError>;
#[derive(Default)]
pub struct Extension {
js_files: Option<Vec<SourcePair>>,
ops: Option<Vec<OpPair>>,
opstate_fn: Option<Box<OpStateFn>>,
middleware_fn: Option<Box<OpMiddlewareFn>>,
initialized: bool,
}
// Note: this used to be a trait, but we "downgraded" it to a single concrete type
// for the initial iteration, it will likely become a trait in the future
impl Extension {
pub fn builder() -> ExtensionBuilder {
Default::default()
}
/// returns JS source code to be loaded into the isolate (either at snapshotting,
/// or at startup). as a vector of a tuple of the file name, and the source code.
pub(crate) fn init_js(&self) -> Vec<SourcePair> {
match &self.js_files {
Some(files) => files.clone(),
None => vec![],
}
}
/// Called at JsRuntime startup to initialize ops in the isolate.
pub(crate) fn init_ops(&mut self) -> Option<Vec<OpPair>> {
// TODO(@AaronO): maybe make op registration idempotent
if self.initialized {
panic!("init_ops called twice: not idempotent or correct");
}
self.initialized = true;
self.ops.take()
}
/// Allows setting up the initial op-state of an isolate at startup.
pub(crate) fn init_state(&self, state: &mut OpState) -> Result<(), AnyError> {
match &self.opstate_fn {
Some(ofn) => ofn(state),
None => Ok(()),
}
}
/// init_middleware lets us middleware op registrations, it's called before init_ops
pub(crate) fn init_middleware(&mut self) -> Option<Box<OpMiddlewareFn>> {
self.middleware_fn.take()
}
}
// Provides a convenient builder pattern to declare Extensions
#[derive(Default)]
pub struct ExtensionBuilder {
js: Vec<SourcePair>,
ops: Vec<OpPair>,
state: Option<Box<OpStateFn>>,
middleware: Option<Box<OpMiddlewareFn>>,
}
impl ExtensionBuilder {
pub fn js(&mut self, js_files: Vec<SourcePair>) -> &mut Self {
self.js.extend(js_files);
self
}
pub fn ops(&mut self, ops: Vec<OpPair>) -> &mut Self {
self.ops.extend(ops);
self
}
pub fn state<F>(&mut self, opstate_fn: F) -> &mut Self
where
F: Fn(&mut OpState) -> Result<(), AnyError> + 'static,
{
self.state = Some(Box::new(opstate_fn));
self
}
pub fn middleware<F>(&mut self, middleware_fn: F) -> &mut Self
where
F: Fn(&'static str, Box<OpFn>) -> Box<OpFn> + 'static,
{
self.middleware = Some(Box::new(middleware_fn));
self
}
pub fn build(&mut self) -> Extension {
let js_files = Some(std::mem::take(&mut self.js));
let ops = Some(std::mem::take(&mut self.ops));
Extension {
js_files,
ops,
opstate_fn: self.state.take(),
middleware_fn: self.middleware.take(),
initialized: false,
}
}
}
/// Helps embed JS files in an extension. Returns Vec<(&'static str, &'static str)>
/// representing the filename and source code.
///
/// Example:
/// ```ignore
/// include_js_files!(
/// prefix "deno:extensions/hello",
/// "01_hello.js",
/// "02_goodbye.js",
/// )
/// ```
#[macro_export]
macro_rules! include_js_files {
(prefix $prefix:literal, $($file:literal,)+) => {
vec![
$((
concat!($prefix, "/", $file),
include_str!($file),
),)+
]
};
}