dioxus/packages/desktop/src/eval.rs

use dioxus_html::prelude::{EvalError, EvalProvider, Evaluator};
use generational_box::{AnyStorage, GenerationalBox, UnsyncStorage};

use crate::{query::Query, DesktopContext};

/// Reprents the desktop-target's provider of evaluators.
pub struct DesktopEvalProvider {
    pub(crate) desktop_ctx: DesktopContext,
}

impl DesktopEvalProvider {
    pub fn new(desktop_ctx: DesktopContext) -> Self {
        Self { desktop_ctx }
    }
}

impl EvalProvider for DesktopEvalProvider {
    fn new_evaluator(&self, js: String) -> GenerationalBox<Box<dyn Evaluator>> {
        DesktopEvaluator::create(self.desktop_ctx.clone(), js)
    }
}

/// Represents a desktop-target's JavaScript evaluator.
pub(crate) struct DesktopEvaluator {
    query: Query<serde_json::Value>,
}

impl DesktopEvaluator {
    /// Creates a new evaluator for desktop-based targets.
    pub fn create(desktop_ctx: DesktopContext, js: String) -> GenerationalBox<Box<dyn Evaluator>> {
        let ctx = desktop_ctx.clone();
        let query = desktop_ctx.query.new_query(&js, ctx);

        // We create a generational box that is owned by the query slot so that when we drop the query slot, the generational box is also dropped.
        let owner = UnsyncStorage::owner();
        let query_id = query.id;
        let query = owner.insert(Box::new(DesktopEvaluator { query }) as Box<dyn Evaluator>);
        desktop_ctx.query.active_requests.slab.borrow_mut()[query_id].owner = Some(owner);

        query
    }
}

impl Evaluator for DesktopEvaluator {
    fn poll_join(
        &mut self,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
        self.query
            .poll_result(cx)
            .map_err(|e| EvalError::Communication(e.to_string()))
    }

    /// Sends a message to the evaluated JavaScript.
    fn send(&self, data: serde_json::Value) -> Result<(), EvalError> {
        if let Err(e) = self.query.send(data) {
            return Err(EvalError::Communication(e.to_string()));
        }
        Ok(())
    }

    /// Gets an UnboundedReceiver to receive messages from the evaluated JavaScript.
    fn poll_recv(
        &mut self,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Result<serde_json::Value, EvalError>> {
        self.query
            .poll_recv(cx)
            .map_err(|e| EvalError::Communication(e.to_string()))
    }
}