Replace option with result in mbe

1 files changed, 17 insertions, 16 deletions

diff --git a/crates/ra_mbe/src/mbe_parser.rs b/crates/ra_mbe/src/mbe_parser.rs
index 58e2533f1..ee1b11091 100644
--- a/crates/ra_mbe/src/mbe_parser.rs
+++ b/crates/ra_mbe/src/mbe_parser.rs
@@ -1,40 +1,41 @@
 /// This module parses a raw `tt::TokenStream` into macro-by-example token
 /// stream. This is a *mostly* identify function, expect for handling of
 /// `$var:tt_kind` and `$(repeat),*` constructs.
+use crate::{MacroRulesError, Result};
 use crate::tt_cursor::TtCursor;
 
-pub(crate) fn parse(tt: &tt::Subtree) -> Option<crate::MacroRules> {
+pub(crate) fn parse(tt: &tt::Subtree) -> Result<crate::MacroRules> {
     let mut parser = TtCursor::new(tt);
     let mut rules = Vec::new();
     while !parser.is_eof() {
         rules.push(parse_rule(&mut parser)?);
-        if parser.expect_char(';') == None {
+        if let Err(e) = parser.expect_char(';') {
             if !parser.is_eof() {
-                return None;
+                return Err(e);
             }
             break;
         }
     }
-    Some(crate::MacroRules { rules })
+    Ok(crate::MacroRules { rules })
 }
 
-fn parse_rule(p: &mut TtCursor) -> Option<crate::Rule> {
+fn parse_rule(p: &mut TtCursor) -> Result<crate::Rule> {
     let lhs = parse_subtree(p.eat_subtree()?)?;
     p.expect_char('=')?;
     p.expect_char('>')?;
     let mut rhs = parse_subtree(p.eat_subtree()?)?;
     rhs.delimiter = crate::Delimiter::None;
-    Some(crate::Rule { lhs, rhs })
+    Ok(crate::Rule { lhs, rhs })
 }
 
-fn parse_subtree(tt: &tt::Subtree) -> Option<crate::Subtree> {
+fn parse_subtree(tt: &tt::Subtree) -> Result<crate::Subtree> {
     let mut token_trees = Vec::new();
     let mut p = TtCursor::new(tt);
-    while let Some(tt) = p.eat() {
+    while let Ok(tt) = p.eat() {
         let child: crate::TokenTree = match tt {
             tt::TokenTree::Leaf(leaf) => match leaf {
                 tt::Leaf::Punct(tt::Punct { char: '$', .. }) => {
-                    if p.at_ident().is_some() {
+                    if p.at_ident().is_ok() {
                         crate::Leaf::from(parse_var(&mut p)?).into()
                     } else {
                         parse_repeat(&mut p)?.into()
@@ -52,15 +53,15 @@ fn parse_subtree(tt: &tt::Subtree) -> Option<crate::Subtree> {
         };
         token_trees.push(child);
     }
-    Some(crate::Subtree { token_trees, delimiter: tt.delimiter })
+    Ok(crate::Subtree { token_trees, delimiter: tt.delimiter })
 }
 
-fn parse_var(p: &mut TtCursor) -> Option<crate::Var> {
+fn parse_var(p: &mut TtCursor) -> Result<crate::Var> {
     let ident = p.eat_ident().unwrap();
     let text = ident.text.clone();
     let kind = if p.at_char(':') {
         p.bump();
-        if let Some(ident) = p.eat_ident() {
+        if let Ok(ident) = p.eat_ident() {
             Some(ident.text.clone())
         } else {
             p.rev_bump();
@@ -69,10 +70,10 @@ fn parse_var(p: &mut TtCursor) -> Option<crate::Var> {
     } else {
         None
     };
-    Some(crate::Var { text, kind })
+    Ok(crate::Var { text, kind })
 }
 
-fn parse_repeat(p: &mut TtCursor) -> Option<crate::Repeat> {
+fn parse_repeat(p: &mut TtCursor) -> Result<crate::Repeat> {
     let subtree = p.eat_subtree().unwrap();
     let mut subtree = parse_subtree(subtree)?;
     subtree.delimiter = crate::Delimiter::None;
@@ -86,8 +87,8 @@ fn parse_repeat(p: &mut TtCursor) -> Option<crate::Repeat> {
         '*' => crate::RepeatKind::ZeroOrMore,
         '+' => crate::RepeatKind::OneOrMore,
         '?' => crate::RepeatKind::ZeroOrOne,
-        _ => return None,
+        _ => return Err(MacroRulesError::ParseError),
     };
     p.bump();
-    Some(crate::Repeat { subtree, kind, separator })
+    Ok(crate::Repeat { subtree, kind, separator })
 }