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use crate::bpmn::schema::{FormalExpression, ScriptTask};
use crate::data_object::DataObject;
use crate::sys::task;
use async_trait::async_trait;
use thiserror::Error;
#[cfg(feature = "rhai")]
pub mod rhai;
pub trait EngineInfo {
fn namespace(&self) -> Option<&str> {
None
}
fn mime_type(&self) -> Option<&str> {
None
}
}
pub trait EngineContextProvider {
type Context: EngineContext;
fn new_context(&self) -> Self::Context;
}
pub trait EngineContext {
fn clear(&mut self) -> &mut Self;
fn set(&mut self, name: &str, value: Box<dyn DataObject>) -> &mut Self;
}
#[async_trait]
pub trait Engine<Expr>: EngineInfo + EngineContextProvider + Send + Sync
where
Expr: Send + Sync + Unpin + 'static,
{
async fn eval<T>(
&self,
code: &Expr,
context: &mut <Self as EngineContextProvider>::Context,
) -> Result<T, EvaluationError>
where
T: Send + Sync + Clone + 'static;
}
#[derive(Error, Debug)]
pub enum EvaluationError {
#[error("unsupported language {language:?}")]
UnsupportedLanguage { language: Option<String> },
#[error("evaluation error {error:?}")]
EvaluationError {
#[from]
error: Box<dyn std::error::Error + Send>,
},
#[error("result type mismatch, expected {expected}, got {got}")]
ResultTypeError { expected: String, got: String },
#[error("empty expression or script")]
Empty,
#[error("execution error {0:?}")]
ExecutionError(ExecutionError),
}
#[derive(Debug)]
pub enum ExecutionError {
Cancelled,
Panicked,
UnknownCause,
}
#[cfg(not(target_arch = "wasm32"))]
impl From<task::JoinError> for EvaluationError {
fn from(err: task::JoinError) -> Self {
if err.is_cancelled() {
return Self::ExecutionError(ExecutionError::Cancelled);
}
if err.is_panic() {
return Self::ExecutionError(ExecutionError::Panicked);
}
Self::ExecutionError(ExecutionError::UnknownCause)
}
}
#[cfg(target_arch = "wasm32")]
impl From<task::JoinError> for EvaluationError {
fn from(_err: task::JoinError) -> Self {
Self::ExecutionError(ExecutionError::UnknownCause)
}
}
pub struct MultiLanguageEngine {
default_namespace: Option<String>,
default_mime_type: Option<String>,
#[cfg(feature = "rhai")]
pub rhai: rhai::Rhai,
}
impl MultiLanguageEngine {
pub fn new() -> Self {
Self {
#[cfg(not(feature = "rhai"))]
default_namespace: None,
#[cfg(feature = "rhai")]
default_namespace: Some(rhai::RHAI_URI.to_owned()),
#[cfg(not(feature = "rhai"))]
default_mime_type: None,
#[cfg(feature = "rhai")]
default_mime_type: Some(rhai::RHAI_MIME.to_owned()),
#[cfg(feature = "rhai")]
rhai: Default::default(),
}
}
pub fn set_default_namespace<S: Into<String>>(&mut self, ns: S) {
self.default_namespace.replace(ns.into());
}
pub fn set_default_mime_type<S: Into<String>>(&mut self, mime_type: S) {
self.default_mime_type.replace(mime_type.into());
}
}
impl EngineInfo for MultiLanguageEngine {}
#[async_trait]
impl Engine<FormalExpression> for MultiLanguageEngine {
async fn eval<T>(
&self,
code: &FormalExpression,
context: &mut <Self as EngineContextProvider>::Context,
) -> Result<T, EvaluationError>
where
T: Send + Sync + Clone + 'static,
{
let language = match code.language.as_ref() {
None => self.default_namespace.as_ref(),
Some(language) => Some(language),
};
match language {
None => return Err(EvaluationError::UnsupportedLanguage { language: None }),
Some(language) => {
#[cfg(feature = "rhai")]
if let Some(ns) = self.rhai.namespace() {
if ns == language {
return self.rhai.eval(code, &mut context.rhai_context).await;
}
}
return Err(EvaluationError::UnsupportedLanguage {
language: Some(language.into()),
});
}
}
}
}
#[async_trait]
impl Engine<ScriptTask> for MultiLanguageEngine {
async fn eval<T>(
&self,
code: &ScriptTask,
context: &mut <Self as EngineContextProvider>::Context,
) -> Result<T, EvaluationError>
where
T: Send + Sync + Clone + 'static,
{
let language = match code.script_format.as_ref() {
None => self.default_mime_type.as_ref(),
Some(language) => Some(language),
};
match language {
None => return Err(EvaluationError::UnsupportedLanguage { language: None }),
Some(language) => {
#[cfg(feature = "rhai")]
if let Some(t) = self.rhai.mime_type() {
if t == language {
return self.rhai.eval(code, &mut context.rhai_context).await;
}
}
return Err(EvaluationError::UnsupportedLanguage {
language: Some(language.into()),
});
}
}
}
}
pub struct MultiLanguageEngineContext {
#[cfg(feature = "rhai")]
rhai_context: rhai::Context,
}
impl EngineContext for MultiLanguageEngineContext {
fn clear(&mut self) -> &mut Self {
#[cfg(feature = "rhai")]
self.rhai_context.clear();
self
}
fn set(&mut self, name: &str, value: Box<dyn DataObject>) -> &mut Self {
#[cfg(feature = "rhai")]
self.rhai_context.set(name, dyn_clone::clone_box(&*value));
self
}
}
impl EngineContextProvider for MultiLanguageEngine {
type Context = MultiLanguageEngineContext;
fn new_context(&self) -> Self::Context {
MultiLanguageEngineContext {
#[cfg(feature = "rhai")]
rhai_context: self.rhai.new_context(),
}
}
}
impl Default for MultiLanguageEngine {
fn default() -> Self {
MultiLanguageEngine::new()
}
}
#[cfg(test)]
mod tests {
use super::*;
use bpxe_internal_macros as bpxe_im;
use crate::language::rhai::*;
#[bpxe_im::test]
async fn dispatch_to_rhai_evaluation() {
let e = MultiLanguageEngine::new();
assert!(e
.eval::<bool>(
&FormalExpression {
language: Some(RHAI_URI.to_string()),
content: Some("true".into()),
..Default::default()
},
&mut e.new_context()
)
.await
.unwrap());
}
}