1 files changed, 76 insertions, 5 deletions

diff --git a/crates/ra_proc_macro/src/lib.rs b/crates/ra_proc_macro/src/lib.rs
index 31e1bb209..a7a84249f 100644
--- a/crates/ra_proc_macro/src/lib.rs
+++ b/crates/ra_proc_macro/src/lib.rs
@@ -1,7 +1,78 @@
-#[cfg(test)]
-mod tests {
-    #[test]
-    fn it_works() {
-        assert_eq!(2 + 2, 4);
+//! Client-side Proc-Macro crate
+//!
+//! We separate proc-macro expanding logic to an extern program to allow
+//! different implementations (e.g. wasm or dylib loading). And this crate
+//! is used for provide basic infra-structure for commnicate between two
+//! process: Client (RA itself), Server (the external program)
+
+use ra_mbe::ExpandError;
+use ra_tt::Subtree;
+use std::{
+    path::{Path, PathBuf},
+    sync::Arc,
+};
+
+trait ProcMacroExpander: std::fmt::Debug + Send + Sync + std::panic::RefUnwindSafe {
+    fn custom_derive(&self, subtree: &Subtree, derive_name: &str) -> Result<Subtree, ExpandError>;
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ProcMacroProcessExpander {
+    process_path: PathBuf,
+}
+
+impl ProcMacroExpander for ProcMacroProcessExpander {
+    fn custom_derive(
+        &self,
+        _subtree: &Subtree,
+        _derive_name: &str,
+    ) -> Result<Subtree, ExpandError> {
+        // FIXME: do nothing for now
+        Ok(Subtree::default())
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ProcMacro {
+    expander: Arc<Box<dyn ProcMacroExpander>>,
+    name: String,
+}
+
+impl Eq for ProcMacro {}
+impl PartialEq for ProcMacro {
+    fn eq(&self, other: &ProcMacro) -> bool {
+        self.name == other.name && Arc::ptr_eq(&self.expander, &other.expander)
+    }
+}
+
+impl ProcMacro {
+    pub fn name(&self) -> String {
+        self.name.clone()
+    }
+
+    pub fn custom_derive(&self, subtree: &Subtree) -> Result<Subtree, ExpandError> {
+        self.expander.custom_derive(subtree, &self.name)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ProcMacroClient {
+    Process { expander: Arc<ProcMacroProcessExpander> },
+    Dummy,
+}
+
+impl ProcMacroClient {
+    pub fn extern_process(process_path: &Path) -> ProcMacroClient {
+        let expander = ProcMacroProcessExpander { process_path: process_path.into() };
+        ProcMacroClient::Process { expander: Arc::new(expander) }
+    }
+
+    pub fn dummy() -> ProcMacroClient {
+        ProcMacroClient::Dummy
+    }
+
+    pub fn by_dylib_path(&self, _dylib_path: &Path) -> Vec<ProcMacro> {
+        // FIXME: return empty for now
+        vec![]
     }
 }