1 files changed, 172 insertions, 0 deletions

diff --git a/crates/gen_lsp_server/src/msg.rs b/crates/gen_lsp_server/src/msg.rs
new file mode 100644
index 000000000..9426e98ec
--- /dev/null
+++ b/crates/gen_lsp_server/src/msg.rs
@@ -0,0 +1,172 @@
+use std::io::{BufRead, Write};
+
+use serde_json::{Value, from_str, to_string, from_value, to_value};
+use serde::{Serialize, de::DeserializeOwned};
+use languageserver_types::{
+    request::Request,
+    notification::Notification,
+};
+
+use Result;
+
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum RawMessage {
+    Request(RawRequest),
+    Notification(RawNotification),
+    Response(RawResponse),
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct RawRequest {
+    pub id: u64,
+    pub method: String,
+    pub params: Value,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct RawResponse {
+    // JSON RPC allows this to be null if it was impossible
+    // to decode the request's id. Ignore this special case
+    // and just die horribly.
+    pub id: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub result: Option<Value>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub error: Option<RawResponseError>,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct RawResponseError {
+    pub code: i32,
+    pub message: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub data: Option<Value>,
+}
+
+#[allow(unused)]
+pub enum ErrorCode {
+    ParseError = -32700,
+    InvalidRequest = -32600,
+    MethodNotFound = -32601,
+    InvalidParams = -32602,
+    InternalError = -32603,
+    ServerErrorStart = -32099,
+    ServerErrorEnd = -32000,
+    ServerNotInitialized = -32002,
+    UnknownErrorCode = -32001,
+    RequestCancelled = -32800,
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+pub struct RawNotification {
+    pub method: String,
+    pub params: Value,
+}
+
+impl RawMessage {
+    pub fn read(r: &mut impl BufRead) -> Result<Option<RawMessage>> {
+        let text = match read_msg_text(r)? {
+            None => return Ok(None),
+            Some(text) => text,
+        };
+        let msg = from_str(&text)?;
+        Ok(Some(msg))
+    }
+    pub fn write(self, w: &mut impl Write) -> Result<()> {
+        #[derive(Serialize)]
+        struct JsonRpc {
+            jsonrpc: &'static str,
+            #[serde(flatten)]
+            msg: RawMessage,
+        }
+        let text = to_string(&JsonRpc { jsonrpc: "2.0", msg: self })?;
+        write_msg_text(w, &text)?;
+        Ok(())
+    }
+}
+
+impl RawRequest {
+    pub fn cast<R>(self) -> ::std::result::Result<(u64, R::Params), RawRequest>
+    where
+        R: Request,
+        R::Params: DeserializeOwned,
+    {
+        if self.method != R::METHOD {
+            return Err(self);
+        }
+        let id = self.id;
+        let params: R::Params = from_value(self.params).unwrap();
+        Ok((id, params))
+    }
+}
+
+impl RawResponse {
+    pub fn ok(id: u64, result: impl Serialize) -> RawResponse {
+        RawResponse {
+            id,
+            result: Some(to_value(&result).unwrap()),
+            error: None,
+        }
+    }
+    pub fn err(id: u64, code: i32, message: String) -> RawResponse {
+        let error = RawResponseError { code, message, data: None };
+        RawResponse {
+            id,
+            result: None,
+            error: Some(error),
+        }
+    }
+}
+
+impl RawNotification {
+    pub fn cast<N>(self) -> ::std::result::Result<N::Params, RawNotification>
+    where
+        N: Notification,
+        N::Params: DeserializeOwned,
+    {
+        if self.method != N::METHOD {
+            return Err(self);
+        }
+        Ok(from_value(self.params).unwrap())
+    }
+}
+
+fn read_msg_text(inp: &mut impl BufRead) -> Result<Option<String>> {
+    let mut size = None;
+    let mut buf = String::new();
+    loop {
+        buf.clear();
+        if inp.read_line(&mut buf)? == 0 {
+            return Ok(None);
+        }
+        if !buf.ends_with("\r\n") {
+            bail!("malformed header: {:?}", buf);
+        }
+        let buf = &buf[..buf.len() - 2];
+        if buf.is_empty() {
+            break;
+        }
+        let mut parts = buf.splitn(2, ": ");
+        let header_name = parts.next().unwrap();
+        let header_value = parts.next().ok_or_else(|| format_err!("malformed header: {:?}", buf))?;
+        if header_name == "Content-Length" {
+            size = Some(header_value.parse::<usize>()?);
+        }
+    }
+    let size = size.ok_or_else(|| format_err!("no Content-Length"))?;
+    let mut buf = buf.into_bytes();
+    buf.resize(size, 0);
+    inp.read_exact(&mut buf)?;
+    let buf = String::from_utf8(buf)?;
+    debug!("< {}", buf);
+    Ok(Some(buf))
+}
+
+fn write_msg_text(out: &mut impl Write, msg: &str) -> Result<()> {
+    debug!("> {}", msg);
+    write!(out, "Content-Length: {}\r\n\r\n", msg.len())?;
+    out.write_all(msg.as_bytes())?;
+    out.flush()?;
+    Ok(())
+}