2 files changed, 47 insertions, 11 deletions

diff --git a/crates/ra_hir_expand/src/hygiene.rs b/crates/ra_hir_expand/src/hygiene.rs
new file mode 100644
index 000000000..77428ec99
--- /dev/null
+++ b/crates/ra_hir_expand/src/hygiene.rs
@@ -0,0 +1,46 @@
+//! This modules handles hygiene information.
+//!
+//! Specifically, `ast` + `Hygiene` allows you to create a `Name`. Note that, at
+//! this moment, this is horribly incomplete and handles only `$crate`.
+use ra_db::CrateId;
+use ra_syntax::ast;
+
+use crate::{
+    db::AstDatabase,
+    either::Either,
+    name::{AsName, Name},
+    HirFileId, HirFileIdRepr,
+};
+
+#[derive(Debug)]
+pub struct Hygiene {
+    // This is what `$crate` expands to
+    def_crate: Option<CrateId>,
+}
+
+impl Hygiene {
+    pub fn new(db: &impl AstDatabase, file_id: HirFileId) -> Hygiene {
+        let def_crate = match file_id.0 {
+            HirFileIdRepr::FileId(_) => None,
+            HirFileIdRepr::MacroFile(macro_file) => {
+                let loc = db.lookup_intern_macro(macro_file.macro_call_id);
+                Some(loc.def.krate)
+            }
+        };
+        Hygiene { def_crate }
+    }
+
+    pub fn new_unhygienic() -> Hygiene {
+        Hygiene { def_crate: None }
+    }
+
+    // FIXME: this should just return name
+    pub fn name_ref_to_name(&self, name_ref: ast::NameRef) -> Either<Name, CrateId> {
+        if let Some(def_crate) = self.def_crate {
+            if name_ref.text() == "$crate" {
+                return Either::B(def_crate);
+            }
+        }
+        Either::A(name_ref.as_name())
+    }
+}
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index cf28de3d8..5a0e5a19c 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -8,6 +8,7 @@ pub mod db;
 pub mod ast_id_map;
 pub mod either;
 pub mod name;
+pub mod hygiene;
 
 use std::hash::{Hash, Hasher};
 
@@ -61,17 +62,6 @@ impl HirFileId {
             }
         }
     }
-
-    /// Get the crate which the macro lives in, if it is a macro file.
-    pub fn macro_crate(self, db: &dyn db::AstDatabase) -> Option<CrateId> {
-        match self.0 {
-            HirFileIdRepr::FileId(_) => None,
-            HirFileIdRepr::MacroFile(macro_file) => {
-                let loc = db.lookup_intern_macro(macro_file.macro_call_id);
-                Some(loc.def.krate)
-            }
-        }
-    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]