Implement ra_proc_macro client logic

1 files changed, 202 insertions, 0 deletions

diff --git a/crates/ra_proc_macro/src/process.rs b/crates/ra_proc_macro/src/process.rs
new file mode 100644
index 000000000..a9095af11
--- /dev/null
+++ b/crates/ra_proc_macro/src/process.rs
@@ -0,0 +1,202 @@
+use crossbeam_channel::{bounded, Receiver, Sender};
+use ra_tt::Subtree;
+
+use crate::msg::{ErrorCode, Message, Request, Response, ResponseError};
+use crate::rpc::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask, ProcMacroKind};
+
+use io::{BufRead, BufReader};
+use std::{
+    io::{self, Write},
+    path::{Path, PathBuf},
+    process::{Child, Command, Stdio},
+    thread::spawn,
+};
+
+#[derive(Debug, Default)]
+pub(crate) struct ProcMacroProcessSrv {
+    inner: Option<Handle>,
+}
+
+struct Task {
+    req: Message,
+    result_tx: Sender<Message>,
+}
+
+#[derive(Debug)]
+struct Handle {
+    sender: Sender<Task>,
+}
+
+struct Process {
+    path: PathBuf,
+    child: Child,
+}
+
+impl Process {
+    fn run(process_path: &Path) -> Result<Process, io::Error> {
+        let child = Command::new(process_path.clone())
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .spawn()?;
+
+        Ok(Process { path: process_path.into(), child })
+    }
+
+    fn restart(&mut self) -> Result<(), io::Error> {
+        let _ = self.child.kill();
+        self.child =
+            Command::new(self.path.clone()).stdin(Stdio::piped()).stdout(Stdio::piped()).spawn()?;
+        Ok(())
+    }
+
+    fn stdio(&mut self) -> Option<(impl Write, impl BufRead)> {
+        let stdin = self.child.stdin.take()?;
+        let stdout = self.child.stdout.take()?;
+        let read = BufReader::new(stdout);
+
+        Some((stdin, read))
+    }
+}
+
+impl ProcMacroProcessSrv {
+    pub fn run(process_path: &Path) -> Result<ProcMacroProcessSrv, io::Error> {
+        let process = Process::run(process_path)?;
+
+        let (task_tx, task_rx) = bounded(0);
+
+        let _ = spawn(move || {
+            client_loop(task_rx, process);
+        });
+        Ok(ProcMacroProcessSrv { inner: Some(Handle { sender: task_tx }) })
+    }
+
+    pub fn find_proc_macros(
+        &self,
+        dylib_path: &Path,
+    ) -> Result<Vec<(String, ProcMacroKind)>, ra_tt::ExpansionError> {
+        let task = ListMacrosTask { lib: dylib_path.to_path_buf() };
+
+        let result: ListMacrosResult = self.send_task("list_macros", task)?;
+        Ok(result.macros)
+    }
+
+    pub fn custom_derive(
+        &self,
+        dylib_path: &Path,
+        subtree: &Subtree,
+        derive_name: &str,
+    ) -> Result<Subtree, ra_tt::ExpansionError> {
+        let task = ExpansionTask {
+            macro_body: subtree.clone(),
+            macro_name: derive_name.to_string(),
+            attributes: None,
+            lib: dylib_path.to_path_buf(),
+        };
+
+        let result: ExpansionResult = self.send_task("custom_derive", task)?;
+        Ok(result.expansion)
+    }
+
+    pub fn send_task<'a, T, R>(&self, method: &str, task: T) -> Result<R, ra_tt::ExpansionError>
+    where
+        T: serde::Serialize,
+        R: serde::de::DeserializeOwned + Default,
+    {
+        let handle = match &self.inner {
+            None => return Err(ra_tt::ExpansionError::Unknown("No handle is found.".to_string())),
+            Some(it) => it,
+        };
+
+        let msg = serde_json::to_value(task).unwrap();
+
+        // FIXME: use a proper request id
+        let id = 0;
+        let req = Request { id: id.into(), method: method.into(), params: msg };
+
+        let (result_tx, result_rx) = bounded(0);
+
+        handle.sender.send(Task { req: req.into(), result_tx }).unwrap();
+        let response = result_rx.recv().unwrap();
+
+        match response {
+            Message::Request(_) => {
+                return Err(ra_tt::ExpansionError::Unknown(
+                    "Return request from ra_proc_srv".into(),
+                ))
+            }
+            Message::Response(res) => {
+                if let Some(err) = res.error {
+                    return Err(ra_tt::ExpansionError::ExpansionError(err.message));
+                }
+                match res.result {
+                    None => Ok(R::default()),
+                    Some(res) => {
+                        let result: R = serde_json::from_value(res)
+                            .map_err(|err| ra_tt::ExpansionError::JsonError(err.to_string()))?;
+                        Ok(result)
+                    }
+                }
+            }
+        }
+    }
+}
+
+fn client_loop(task_rx: Receiver<Task>, mut process: Process) {
+    let (mut stdin, mut stdout) = match process.stdio() {
+        None => return,
+        Some(it) => it,
+    };
+
+    loop {
+        let task = match task_rx.recv() {
+            Ok(task) => task,
+            Err(_) => break,
+        };
+
+        let res = match send_message(&mut stdin, &mut stdout, task.req) {
+            Ok(res) => res,
+            Err(_err) => {
+                let res = Response {
+                    id: 0.into(),
+                    result: None,
+                    error: Some(ResponseError {
+                        code: ErrorCode::ServerErrorEnd as i32,
+                        message: "Server closed".into(),
+                        data: None,
+                    }),
+                };
+                if task.result_tx.send(res.into()).is_err() {
+                    break;
+                }
+                // Restart the process
+                if process.restart().is_err() {
+                    break;
+                }
+                let stdio = match process.stdio() {
+                    None => break,
+                    Some(it) => it,
+                };
+                stdin = stdio.0;
+                stdout = stdio.1;
+                continue;
+            }
+        };
+
+        if let Some(res) = res {
+            if task.result_tx.send(res).is_err() {
+                break;
+            }
+        }
+    }
+
+    let _ = process.child.kill();
+}
+
+fn send_message(
+    mut writer: &mut impl Write,
+    mut reader: &mut impl BufRead,
+    msg: Message,
+) -> Result<Option<Message>, io::Error> {
+    msg.write(&mut writer)?;
+    Ok(Message::read(&mut reader)?)
+}