Merge #3738

3738: Implement ra_proc_macro client logic r=matklad a=edwin0cheng

This PR add the actual client logic for `ra_proc_macro` crate:

1. Define all necessary rpc serialization data structure, which include `ra_tt` related data and some task messages. Although adding `Serialize` and `Deserialize` trait to ra_tt directly seem to be much easier,   we deliberately duplicate the `ra_tt` struct with `#[serde(with = "XXDef")]` for separation of  code responsibility. 
2. Define a simplified version of lsp base protocol for rpc, which basically copy from lsp-server code base. 
3. Implement the actual `IO` for the client side progress spawning and message passing.

Co-authored-by: Edwin Cheng <[email protected]>

1 files changed, 93 insertions, 0 deletions

diff --git a/crates/ra_proc_macro/src/msg.rs b/crates/ra_proc_macro/src/msg.rs
new file mode 100644
index 000000000..aa95bcc8f
--- /dev/null
+++ b/crates/ra_proc_macro/src/msg.rs
@@ -0,0 +1,93 @@
+//! Defines messages for cross-process message based on `ndjson` wire protocol
+
+use std::{
+    convert::TryFrom,
+    io::{self, BufRead, Write},
+};
+
+use crate::{
+    rpc::{ListMacrosResult, ListMacrosTask},
+    ExpansionResult, ExpansionTask,
+};
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub enum Request {
+    ListMacro(ListMacrosTask),
+    ExpansionMacro(ExpansionTask),
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub enum Response {
+    Error(ResponseError),
+    ListMacro(ListMacrosResult),
+    ExpansionMacro(ExpansionResult),
+}
+
+macro_rules! impl_try_from_response {
+    ($ty:ty, $tag:ident) => {
+        impl TryFrom<Response> for $ty {
+            type Error = &'static str;
+            fn try_from(value: Response) -> Result<Self, Self::Error> {
+                match value {
+                    Response::$tag(res) => Ok(res),
+                    _ => Err("Fail to convert from response"),
+                }
+            }
+        }
+    };
+}
+
+impl_try_from_response!(ListMacrosResult, ListMacro);
+impl_try_from_response!(ExpansionResult, ExpansionMacro);
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ResponseError {
+    pub code: ErrorCode,
+    pub message: String,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub enum ErrorCode {
+    ServerErrorEnd,
+    ExpansionError,
+}
+
+pub trait Message: Sized + Serialize + DeserializeOwned {
+    fn read(r: &mut impl BufRead) -> io::Result<Option<Self>> {
+        let text = match read_json(r)? {
+            None => return Ok(None),
+            Some(text) => text,
+        };
+        let msg = serde_json::from_str(&text)?;
+        Ok(Some(msg))
+    }
+    fn write(self, w: &mut impl Write) -> io::Result<()> {
+        let text = serde_json::to_string(&self)?;
+        write_json(w, &text)
+    }
+}
+
+impl Message for Request {}
+impl Message for Response {}
+
+fn read_json(inp: &mut impl BufRead) -> io::Result<Option<String>> {
+    let mut buf = String::new();
+    if inp.read_line(&mut buf)? == 0 {
+        return Ok(None);
+    }
+    // Remove ending '\n'
+    let buf = &buf[..buf.len() - 1];
+    if buf.is_empty() {
+        return Ok(None);
+    }
+    Ok(Some(buf.to_string()))
+}
+
+fn write_json(out: &mut impl Write, msg: &str) -> io::Result<()> {
+    log::debug!("> {}", msg);
+    out.write_all(msg.as_bytes())?;
+    out.write_all(b"\n")?;
+    out.flush()?;
+    Ok(())
+}