1 files changed, 69 insertions, 0 deletions

diff --git a/crates/proc_macro_srv/src/lib.rs b/crates/proc_macro_srv/src/lib.rs
new file mode 100644
index 000000000..7e4e4ad50
--- /dev/null
+++ b/crates/proc_macro_srv/src/lib.rs
@@ -0,0 +1,69 @@
+//! RA Proc Macro Server
+//!
+//! This library is able to call compiled Rust custom derive dynamic libraries on arbitrary code.
+//! The general idea here is based on https://github.com/fedochet/rust-proc-macro-expander.
+//!
+//! But we adapt it to better fit RA needs:
+//!
+//! * We use `tt` for proc-macro `TokenStream` server, it is easier to manipulate and interact with
+//!   RA than `proc-macro2` token stream.
+//! * By **copying** the whole rustc `lib_proc_macro` code, we are able to build this with `stable`
+//!   rustc rather than `unstable`. (Although in general ABI compatibility is still an issue)…
+
+#[allow(dead_code)]
+#[doc(hidden)]
+mod proc_macro;
+
+#[doc(hidden)]
+mod rustc_server;
+
+mod dylib;
+
+use proc_macro::bridge::client::TokenStream;
+use proc_macro_api::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask};
+use std::{
+    collections::{hash_map::Entry, HashMap},
+    fs,
+    path::{Path, PathBuf},
+    time::SystemTime,
+};
+
+#[derive(Default)]
+pub(crate) struct ProcMacroSrv {
+    expanders: HashMap<(PathBuf, SystemTime), dylib::Expander>,
+}
+
+impl ProcMacroSrv {
+    pub fn expand(&mut self, task: &ExpansionTask) -> Result<ExpansionResult, String> {
+        let expander = self.expander(&task.lib)?;
+        match expander.expand(&task.macro_name, &task.macro_body, task.attributes.as_ref()) {
+            Ok(expansion) => Ok(ExpansionResult { expansion }),
+            Err(msg) => {
+                Err(format!("Cannot perform expansion for {}: error {:?}", &task.macro_name, msg))
+            }
+        }
+    }
+
+    pub fn list_macros(&mut self, task: &ListMacrosTask) -> Result<ListMacrosResult, String> {
+        let expander = self.expander(&task.lib)?;
+        Ok(ListMacrosResult { macros: expander.list_macros() })
+    }
+
+    fn expander(&mut self, path: &Path) -> Result<&dylib::Expander, String> {
+        let time = fs::metadata(path).and_then(|it| it.modified()).map_err(|err| {
+            format!("Failed to get file metadata for {}: {:?}", path.display(), err)
+        })?;
+
+        Ok(match self.expanders.entry((path.to_path_buf(), time)) {
+            Entry::Vacant(v) => v.insert(dylib::Expander::new(path).map_err(|err| {
+                format!("Cannot create expander for {}: {:?}", path.display(), err)
+            })?),
+            Entry::Occupied(e) => e.into_mut(),
+        })
+    }
+}
+
+pub mod cli;
+
+#[cfg(test)]
+mod tests;