1 files changed, 69 insertions, 0 deletions

diff --git a/crates/ra_hir_def/src/per_ns.rs b/crates/ra_hir_def/src/per_ns.rs
new file mode 100644
index 000000000..00e866bf9
--- /dev/null
+++ b/crates/ra_hir_def/src/per_ns.rs
@@ -0,0 +1,69 @@
+//! In rust, it is possible to have a value, a type and a macro with the same
+//! name without conflicts.
+//!
+//! `PerNs` (per namespace) captures this.
+
+use hir_expand::MacroDefId;
+
+use crate::ModuleDefId;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub struct PerNs {
+    pub types: Option<ModuleDefId>,
+    pub values: Option<ModuleDefId>,
+    /// Since macros has different type, many methods simply ignore it.
+    /// We can only use special method like `get_macros` to access it.
+    pub macros: Option<MacroDefId>,
+}
+
+impl Default for PerNs {
+    fn default() -> Self {
+        PerNs { types: None, values: None, macros: None }
+    }
+}
+
+impl PerNs {
+    pub fn none() -> PerNs {
+        PerNs { types: None, values: None, macros: None }
+    }
+
+    pub fn values(t: ModuleDefId) -> PerNs {
+        PerNs { types: None, values: Some(t), macros: None }
+    }
+
+    pub fn types(t: ModuleDefId) -> PerNs {
+        PerNs { types: Some(t), values: None, macros: None }
+    }
+
+    pub fn both(types: ModuleDefId, values: ModuleDefId) -> PerNs {
+        PerNs { types: Some(types), values: Some(values), macros: None }
+    }
+
+    pub fn macros(macro_: MacroDefId) -> PerNs {
+        PerNs { types: None, values: None, macros: Some(macro_) }
+    }
+
+    pub fn is_none(&self) -> bool {
+        self.types.is_none() && self.values.is_none() && self.macros.is_none()
+    }
+
+    pub fn take_types(self) -> Option<ModuleDefId> {
+        self.types
+    }
+
+    pub fn take_values(self) -> Option<ModuleDefId> {
+        self.values
+    }
+
+    pub fn take_macros(self) -> Option<MacroDefId> {
+        self.macros
+    }
+
+    pub fn or(self, other: PerNs) -> PerNs {
+        PerNs {
+            types: self.types.or(other.types),
+            values: self.values.or(other.values),
+            macros: self.macros.or(other.macros),
+        }
+    }
+}