parses simple macro

crates/ra_hir/src/macros.rs

@@ -260,7 +260,7 @@ fn convert_tt(tt: &SyntaxNode) -> Option<tt::Subtree> {
 fn test_convert_tt() {
     let text = r#"
 macro_rules! impl_froms {
-    ($e:ident: $($v:ident), *) => {
+    ($e:ident: $($v:ident),*) => {
         $(
             impl From<$v> for $e {
                 fn from(it: $v) -> $e {
@@ -279,5 +279,5 @@ macro_rules! impl_froms {
         .unwrap();
     let tt = macro_call_to_tt(maco_call).unwrap();
     let tt = mbe::parse(&tt);
-    dbg!(tt);
+    assert!(tt.is_some());
 }

crates/ra_hir/src/macros/mbe.rs

@@ -1,6 +1,6 @@
 use ra_syntax::SmolStr;
 
-use crate::macros::tt;
+use crate::macros::tt::{self, Delimiter};
 
 #[derive(Debug)]
 pub(crate) struct MacroRules {
@@ -19,6 +19,7 @@ enum TokenTree {
     Subtree(Subtree),
     Repeat(Repeat),
 }
+impl_froms!(TokenTree: Leaf, Subtree, Repeat);
 
 #[derive(Debug)]
 enum Leaf {
@@ -27,6 +28,7 @@ enum Leaf {
     Ident(Ident),
     Var(Var),
 }
+impl_froms!(Leaf: Literal, Punct, Ident, Var);
 
 #[derive(Debug)]
 struct Subtree {
@@ -34,18 +36,11 @@ struct Subtree {
     token_trees: Vec<TokenTree>,
 }
 
-#[derive(Debug)]
-enum Delimiter {
-    Parenthesis,
-    Brace,
-    Bracket,
-    None,
-}
-
 #[derive(Debug)]
 struct Repeat {
     subtree: Subtree,
     kind: RepeatKind,
+    separator: Option<Punct>,
 }
 
 #[derive(Debug)]
@@ -73,6 +68,7 @@ struct Ident {
 #[derive(Debug)]
 struct Var {
     text: SmolStr,
+    kind: Option<SmolStr>,
 }
 
 pub(crate) fn parse(tt: &tt::Subtree) -> Option<MacroRules> {
@@ -86,16 +82,81 @@ pub(crate) fn parse(tt: &tt::Subtree) -> Option<MacroRules> {
 
 fn parse_rule(p: &mut RulesParser) -> Option<Rule> {
     let lhs = parse_subtree(p.eat_subtree()?)?;
-    p.eat_punct('=')?;
-    p.eat_punct('>')?;
+    p.expect_char('=')?;
+    p.expect_char('>')?;
     let rhs = parse_subtree(p.eat_subtree()?)?;
     Some(Rule { lhs, rhs })
 }
 
 fn parse_subtree(tt: &tt::Subtree) -> Option<Subtree> {
+    let mut token_trees = Vec::new();
+    let mut p = RulesParser::new(tt);
+    while let Some(tt) = p.eat() {
+        let child: TokenTree = match tt {
+            tt::TokenTree::Leaf(leaf) => match leaf {
+                tt::Leaf::Punct(tt::Punct { char: '$' }) => {
+                    if p.at_ident().is_some() {
+                        Leaf::from(parse_var(&mut p)?).into()
+                    } else {
+                        parse_repeat(&mut p)?.into()
+                    }
+                }
+                tt::Leaf::Punct(tt::Punct { char }) => Leaf::from(Punct { char: *char }).into(),
+                tt::Leaf::Ident(tt::Ident { text }) => {
+                    Leaf::from(Ident { text: text.clone() }).into()
+                }
+                tt::Leaf::Literal(tt::Literal { text }) => {
+                    Leaf::from(Literal { text: text.clone() }).into()
+                }
+            },
+            tt::TokenTree::Subtree(subtree) => parse_subtree(subtree)?.into(),
+        };
+        token_trees.push(child);
+    }
     Some(Subtree {
-        token_trees: Vec::new(),
-        delimiter: Delimiter::None,
+        token_trees,
+        delimiter: tt.delimiter,
+    })
+}
+
+fn parse_var(p: &mut RulesParser) -> Option<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() {
+            Some(ident.text.clone())
+        } else {
+            // ugly as hell :(
+            p.pos -= 1;
+            None
+        }
+    } else {
+        None
+    };
+    Some(Var { text, kind })
+}
+
+fn parse_repeat(p: &mut RulesParser) -> Option<Repeat> {
+    let subtree = p.eat_subtree().unwrap();
+    let subtree = parse_subtree(subtree)?;
+    let mut sep = p.eat_punct()?;
+    let (separator, rep) = match sep.char {
+        '*' | '+' | '?' => (None, sep.char),
+        char => (Some(Punct { char }), p.eat_punct()?.char),
+    };
+
+    let kind = match rep {
+        '*' => RepeatKind::ZeroOrMore,
+        '+' => RepeatKind::OneOrMore,
+        '?' => RepeatKind::ZeroOrMore,
+        _ => return None,
+    };
+    p.bump();
+    Some(Repeat {
+        subtree,
+        kind,
+        separator,
     })
 }
 
@@ -117,9 +178,41 @@ impl<'a> RulesParser<'a> {
         self.subtree.token_trees.get(self.pos)
     }
 
+    fn at_punct(&self) -> Option<&'a tt::Punct> {
+        match self.current() {
+            Some(tt::TokenTree::Leaf(tt::Leaf::Punct(it))) => Some(it),
+            _ => None,
+        }
+    }
+
+    fn at_char(&self, char: char) -> bool {
+        match self.at_punct() {
+            Some(tt::Punct { char: c }) if *c == char => true,
+            _ => false,
+        }
+    }
+
+    fn at_ident(&mut self) -> Option<&'a tt::Ident> {
+        match self.current() {
+            Some(tt::TokenTree::Leaf(tt::Leaf::Ident(i))) => Some(i),
+            _ => None,
+        }
+    }
+
     fn bump(&mut self) {
         self.pos += 1;
     }
+
+    fn eat(&mut self) -> Option<&'a tt::TokenTree> {
+        match self.current() {
+            Some(it) => {
+                self.bump();
+                Some(it)
+            }
+            None => None,
+        }
+    }
+
     fn eat_subtree(&mut self) -> Option<&'a tt::Subtree> {
         match self.current()? {
             tt::TokenTree::Subtree(sub) => {
@@ -129,13 +222,28 @@ impl<'a> RulesParser<'a> {
             _ => return None,
         }
     }
-    fn eat_punct(&mut self, char: char) -> Option<()> {
-        match self.current()? {
-            tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: c })) if *c == char => {
-                self.bump();
-                Some(())
-            }
-            _ => None,
+
+    fn eat_punct(&mut self) -> Option<&'a tt::Punct> {
+        if let Some(it) = self.at_punct() {
+            self.bump();
+            return Some(it);
         }
+        None
+    }
+
+    fn eat_ident(&mut self) -> Option<&'a tt::Ident> {
+        if let Some(i) = self.at_ident() {
+            self.bump();
+            return Some(i);
+        }
+        None
+    }
+
+    fn expect_char(&mut self, char: char) -> Option<()> {
+        if self.at_char(char) {
+            self.bump();
+            return Some(());
+        }
+        None
     }
 }

crates/ra_hir/src/macros/tt.rs

@@ -21,7 +21,7 @@ pub(crate) struct Subtree {
     pub(crate) token_trees: Vec<TokenTree>,
 }
 
-#[derive(Debug)]
+#[derive(Clone, Copy, Debug)]
 pub(crate) enum Delimiter {
     Parenthesis,
     Brace,