Split parse and expand errors

crates/ra_mbe/src/lib.rs

@@ -25,14 +25,17 @@ use ra_syntax::SmolStr;
 pub use tt::{Delimiter, Punct};
 
 #[derive(Debug, PartialEq, Eq)]
-pub enum MacroRulesError {
-    NoMatchingRule,
-    UnexpectedToken,
-    BindingError(String),
+pub enum ParseError {
     ParseError,
 }
 
-pub type Result<T> = ::std::result::Result<T, MacroRulesError>;
+#[derive(Debug, PartialEq, Eq)]
+pub enum ExpandError {
+    NoMatchingRule,
+    UnexpectedToken,
+    BindingError(String),
+}
+
 pub use crate::syntax_bridge::{ast_to_token_tree, token_tree_to_ast_item_list};
 
 /// This struct contains AST for a single `macro_rules` definition. What might
@@ -45,10 +48,10 @@ pub struct MacroRules {
 }
 
 impl MacroRules {
-    pub fn parse(tt: &tt::Subtree) -> Result<MacroRules> {
+    pub fn parse(tt: &tt::Subtree) -> Result<MacroRules, ParseError> {
         mbe_parser::parse(tt)
     }
-    pub fn expand(&self, tt: &tt::Subtree) -> Result<tt::Subtree> {
+    pub fn expand(&self, tt: &tt::Subtree) -> Result<tt::Subtree, ExpandError> {
         mbe_expander::expand(self, tt)
     }
 }