1 files changed, 107 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/proc-macro-api/src/process.rs b/src/tools/rust-analyzer/crates/proc-macro-api/src/process.rs
new file mode 100644
index 000000000..c4018d3b3
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/proc-macro-api/src/process.rs
@@ -0,0 +1,107 @@
+//! Handle process life-time and message passing for proc-macro client
+
+use std::{
+    ffi::{OsStr, OsString},
+    io::{self, BufRead, BufReader, Write},
+    process::{Child, ChildStdin, ChildStdout, Command, Stdio},
+};
+
+use paths::{AbsPath, AbsPathBuf};
+use stdx::JodChild;
+
+use crate::{
+    msg::{Message, Request, Response},
+    ProcMacroKind, ServerError,
+};
+
+#[derive(Debug)]
+pub(crate) struct ProcMacroProcessSrv {
+    _process: Process,
+    stdin: ChildStdin,
+    stdout: BufReader<ChildStdout>,
+}
+
+impl ProcMacroProcessSrv {
+    pub(crate) fn run(
+        process_path: AbsPathBuf,
+        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
+    ) -> io::Result<ProcMacroProcessSrv> {
+        let mut process = Process::run(process_path, args)?;
+        let (stdin, stdout) = process.stdio().expect("couldn't access child stdio");
+
+        let srv = ProcMacroProcessSrv { _process: process, stdin, stdout };
+
+        Ok(srv)
+    }
+
+    pub(crate) fn find_proc_macros(
+        &mut self,
+        dylib_path: &AbsPath,
+    ) -> Result<Result<Vec<(String, ProcMacroKind)>, String>, ServerError> {
+        let request = Request::ListMacros { dylib_path: dylib_path.to_path_buf().into() };
+
+        let response = self.send_task(request)?;
+
+        match response {
+            Response::ListMacros(it) => Ok(it),
+            Response::ExpandMacro { .. } => {
+                Err(ServerError { message: "unexpected response".to_string(), io: None })
+            }
+        }
+    }
+
+    pub(crate) fn send_task(&mut self, req: Request) -> Result<Response, ServerError> {
+        let mut buf = String::new();
+        send_request(&mut self.stdin, &mut self.stdout, req, &mut buf)
+    }
+}
+
+#[derive(Debug)]
+struct Process {
+    child: JodChild,
+}
+
+impl Process {
+    fn run(
+        path: AbsPathBuf,
+        args: impl IntoIterator<Item = impl AsRef<OsStr>>,
+    ) -> io::Result<Process> {
+        let args: Vec<OsString> = args.into_iter().map(|s| s.as_ref().into()).collect();
+        let child = JodChild(mk_child(&path, &args)?);
+        Ok(Process { child })
+    }
+
+    fn stdio(&mut self) -> Option<(ChildStdin, BufReader<ChildStdout>)> {
+        let stdin = self.child.stdin.take()?;
+        let stdout = self.child.stdout.take()?;
+        let read = BufReader::new(stdout);
+
+        Some((stdin, read))
+    }
+}
+
+fn mk_child(
+    path: &AbsPath,
+    args: impl IntoIterator<Item = impl AsRef<OsStr>>,
+) -> io::Result<Child> {
+    Command::new(path.as_os_str())
+        .args(args)
+        .env("RUST_ANALYZER_INTERNALS_DO_NOT_USE", "this is unstable")
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::inherit())
+        .spawn()
+}
+
+fn send_request(
+    mut writer: &mut impl Write,
+    mut reader: &mut impl BufRead,
+    req: Request,
+    buf: &mut String,
+) -> Result<Response, ServerError> {
+    req.write(&mut writer)
+        .map_err(|err| ServerError { message: "failed to write request".into(), io: Some(err) })?;
+    let res = Response::read(&mut reader, buf)
+        .map_err(|err| ServerError { message: "failed to read response".into(), io: Some(err) })?;
+    res.ok_or_else(|| ServerError { message: "server exited".into(), io: None })
+}