10 files changed, 307 insertions, 33 deletions

diff --git a/crates/ra_mbe/src/lib.rs b/crates/ra_mbe/src/lib.rs
index 4126854d1..a530f3b03 100644
--- a/crates/ra_mbe/src/lib.rs
+++ b/crates/ra_mbe/src/lib.rs
@@ -189,6 +189,14 @@ impl_froms!(TokenTree: Leaf, Subtree);
         rules.expand(&invocation_tt).unwrap()
     }
 
+    pub(crate) fn expand_to_syntax(
+        rules: &MacroRules,
+        invocation: &str,
+    ) -> ra_syntax::TreeArc<ast::SourceFile> {
+        let expanded = expand(rules, invocation);
+        token_tree_to_ast_item_list(&expanded)
+    }
+
     pub(crate) fn assert_expansion(rules: &MacroRules, invocation: &str, expansion: &str) {
         let expanded = expand(rules, invocation);
         assert_eq!(expanded.to_string(), expansion);
@@ -485,4 +493,93 @@ SOURCE_FILE@[0; 40)
         );
         assert_expansion(&rules, "foo! { foo }", "fn foo () {let a = foo :: bar ;}");
     }
+
+    #[test]
+    fn test_expr() {
+        let rules = create_rules(
+            r#"
+        macro_rules! foo {
+            ($ i:expr) => {
+                 fn bar() { $ i; } 
+            }
+        }
+"#,
+        );
+
+        assert_expansion(
+            &rules,
+            "foo! { 2 + 2 * baz(3).quux() }",
+            "fn bar () {2 + 2 * baz (3) . quux () ;}",
+        );
+    }
+
+    #[test]
+    fn test_expr_order() {
+        let rules = create_rules(
+            r#"
+        macro_rules! foo {
+            ($ i:expr) => {
+                 fn bar() { $ i * 2; } 
+            }
+        }
+"#,
+        );
+
+        assert_eq!(
+            expand_to_syntax(&rules, "foo! { 1 + 1  }").syntax().debug_dump().trim(),
+            r#"SOURCE_FILE@[0; 15)
+  FN_DEF@[0; 15)
+    FN_KW@[0; 2) "fn"
+    NAME@[2; 5)
+      IDENT@[2; 5) "bar"
+    PARAM_LIST@[5; 7)
+      L_PAREN@[5; 6) "("
+      R_PAREN@[6; 7) ")"
+    BLOCK@[7; 15)
+      L_CURLY@[7; 8) "{"
+      EXPR_STMT@[8; 14)
+        BIN_EXPR@[8; 13)
+          BIN_EXPR@[8; 11)
+            LITERAL@[8; 9)
+              INT_NUMBER@[8; 9) "1"
+            PLUS@[9; 10) "+"
+            LITERAL@[10; 11)
+              INT_NUMBER@[10; 11) "1"
+          STAR@[11; 12) "*"
+          LITERAL@[12; 13)
+            INT_NUMBER@[12; 13) "2"
+        SEMI@[13; 14) ";"
+      R_CURLY@[14; 15) "}""#,
+        );
+    }
+
+    #[test]
+    fn test_ty() {
+        let rules = create_rules(
+            r#"
+        macro_rules! foo {
+            ($ i:ty) => (
+                fn bar() -> $ i { unimplemented!() }
+            )
+        }
+"#,
+        );
+        assert_expansion(
+            &rules,
+            "foo! { Baz<u8> }",
+            "fn bar () -> Baz < u8 > {unimplemented ! ()}",
+        );
+    }
+
+    #[test]
+    fn test_pat_() {
+        let rules = create_rules(
+            r#"
+        macro_rules! foo {
+            ($ i:pat) => { fn foo() { let $ i; } }
+        }
+"#,
+        );
+        assert_expansion(&rules, "foo! { (a, b) }", "fn foo () {let (a , b) ;}");
+    }
 }
diff --git a/crates/ra_mbe/src/mbe_expander.rs b/crates/ra_mbe/src/mbe_expander.rs
index ce41d7225..7a259f338 100644
--- a/crates/ra_mbe/src/mbe_expander.rs
+++ b/crates/ra_mbe/src/mbe_expander.rs
@@ -144,6 +144,19 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings,
                                 input.eat_path().ok_or(ExpandError::UnexpectedToken)?.clone();
                             res.inner.insert(text.clone(), Binding::Simple(path.into()));
                         }
+                        "expr" => {
+                            let expr =
+                                input.eat_expr().ok_or(ExpandError::UnexpectedToken)?.clone();
+                            res.inner.insert(text.clone(), Binding::Simple(expr.into()));
+                        }
+                        "ty" => {
+                            let ty = input.eat_ty().ok_or(ExpandError::UnexpectedToken)?.clone();
+                            res.inner.insert(text.clone(), Binding::Simple(ty.into()));
+                        }
+                        "pat" => {
+                            let pat = input.eat_pat().ok_or(ExpandError::UnexpectedToken)?.clone();
+                            res.inner.insert(text.clone(), Binding::Simple(pat.into()));
+                        }
                         _ => return Err(ExpandError::UnexpectedToken),
                     }
                 }
diff --git a/crates/ra_mbe/src/subtree_parser.rs b/crates/ra_mbe/src/subtree_parser.rs
index 164240d92..13d5d2169 100644
--- a/crates/ra_mbe/src/subtree_parser.rs
+++ b/crates/ra_mbe/src/subtree_parser.rs
@@ -30,6 +30,18 @@ impl<'a> Parser<'a> {
         self.parse(ra_parser::parse_path)
     }
 
+    pub fn parse_expr(self) -> Option<tt::TokenTree> {
+        self.parse(ra_parser::parse_expr)
+    }
+
+    pub fn parse_ty(self) -> Option<tt::TokenTree> {
+        self.parse(ra_parser::parse_ty)
+    }
+
+    pub fn parse_pat(self) -> Option<tt::TokenTree> {
+        self.parse(ra_parser::parse_pat)
+    }
+
     fn parse<F>(self, f: F) -> Option<tt::TokenTree>
     where
         F: FnOnce(&dyn TokenSource, &mut dyn TreeSink),
diff --git a/crates/ra_mbe/src/subtree_source.rs b/crates/ra_mbe/src/subtree_source.rs
index 6aa20057e..0a070b46a 100644
--- a/crates/ra_mbe/src/subtree_source.rs
+++ b/crates/ra_mbe/src/subtree_source.rs
@@ -109,6 +109,8 @@ impl<'a> SubTreeWalker<'a> {
         self.cursor = match self.ts.get(0) {
             DelimToken::Token(token) => match token {
                 tt::TokenTree::Subtree(subtree) => {
+                    let ts = TokenSeq::from(subtree);
+                    self.stack.push((ts, 0));
                     WalkCursor::Token(0, convert_delim(subtree.delimiter, false))
                 }
                 tt::TokenTree::Leaf(leaf) => {
@@ -254,7 +256,7 @@ impl<'a> WalkerOwner<'a> {
                         }
                     }
                 } else if walker.stack.len() == 1 {
-                    if let DelimToken::Delim(_, is_end) = walker.ts.get(*u) {
+                    if let DelimToken::Delim(_, is_end) = walker.top().get(*u) {
                         if !is_end {
                             let (_, last_idx) = &walker.stack[0];
                             if let DelimToken::Token(token) = walker.ts.get(*last_idx) {
@@ -310,10 +312,16 @@ impl<'a> TokenSource for SubtreeTokenSource<'a> {
         }
     }
     fn is_token_joint_to_next(&self, pos: usize) -> bool {
-        self.walker.get(pos).unwrap().is_joint_to_next
+        match self.walker.get(pos) {
+            Some(t) => t.is_joint_to_next,
+            _ => false,
+        }
     }
     fn is_keyword(&self, pos: usize, kw: &str) -> bool {
-        self.walker.get(pos).unwrap().text == *kw
+        match self.walker.get(pos) {
+            Some(t) => t.text == *kw,
+            _ => false,
+        }
     }
 }
 
diff --git a/crates/ra_mbe/src/tt_cursor.rs b/crates/ra_mbe/src/tt_cursor.rs
index d29faa77c..f6cefe087 100644
--- a/crates/ra_mbe/src/tt_cursor.rs
+++ b/crates/ra_mbe/src/tt_cursor.rs
@@ -84,6 +84,21 @@ impl<'a> TtCursor<'a> {
         parser.parse_path()
     }
 
+    pub(crate) fn eat_expr(&mut self) -> Option<tt::TokenTree> {
+        let parser = Parser::new(&mut self.pos, self.subtree);
+        parser.parse_expr()
+    }
+
+    pub(crate) fn eat_ty(&mut self) -> Option<tt::TokenTree> {
+        let parser = Parser::new(&mut self.pos, self.subtree);
+        parser.parse_ty()
+    }
+
+    pub(crate) fn eat_pat(&mut self) -> Option<tt::TokenTree> {
+        let parser = Parser::new(&mut self.pos, self.subtree);
+        parser.parse_pat()
+    }
+
     pub(crate) fn expect_char(&mut self, char: char) -> Result<(), ParseError> {
         if self.at_char(char) {
             self.bump();
diff --git a/crates/ra_parser/src/grammar.rs b/crates/ra_parser/src/grammar.rs
index c5f510e6b..5a7a55141 100644
--- a/crates/ra_parser/src/grammar.rs
+++ b/crates/ra_parser/src/grammar.rs
@@ -53,6 +53,18 @@ pub(crate) fn path(p: &mut Parser) {
     paths::type_path(p);
 }
 
+pub(crate) fn expr(p: &mut Parser) {
+    expressions::expr(p);
+}
+
+pub(crate) fn type_(p: &mut Parser) {
+    types::type_(p)
+}
+
+pub(crate) fn pattern(p: &mut Parser) {
+    patterns::pattern(p)
+}
+
 pub(crate) fn reparser(
     node: SyntaxKind,
     first_child: Option<SyntaxKind>,
diff --git a/crates/ra_parser/src/grammar/expressions.rs b/crates/ra_parser/src/grammar/expressions.rs
index 9b38b0a31..295577325 100644
--- a/crates/ra_parser/src/grammar/expressions.rs
+++ b/crates/ra_parser/src/grammar/expressions.rs
@@ -8,17 +8,20 @@ const EXPR_FIRST: TokenSet = LHS_FIRST;
 
 pub(super) fn expr(p: &mut Parser) -> BlockLike {
     let r = Restrictions { forbid_structs: false, prefer_stmt: false };
-    expr_bp(p, r, 1).1
+    let mut dollar_lvl = 0;
+    expr_bp(p, r, 1, &mut dollar_lvl).1
 }
 
 pub(super) fn expr_stmt(p: &mut Parser) -> (Option<CompletedMarker>, BlockLike) {
     let r = Restrictions { forbid_structs: false, prefer_stmt: true };
-    expr_bp(p, r, 1)
+    let mut dollar_lvl = 0;
+    expr_bp(p, r, 1, &mut dollar_lvl)
 }
 
 fn expr_no_struct(p: &mut Parser) {
     let r = Restrictions { forbid_structs: true, prefer_stmt: false };
-    expr_bp(p, r, 1);
+    let mut dollar_lvl = 0;
+    expr_bp(p, r, 1, &mut dollar_lvl);
 }
 
 // test block
@@ -206,8 +209,23 @@ fn current_op(p: &Parser) -> (u8, Op) {
 }
 
 // Parses expression with binding power of at least bp.
-fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>, BlockLike) {
-    let mut lhs = match lhs(p, r) {
+fn expr_bp(
+    p: &mut Parser,
+    r: Restrictions,
+    mut bp: u8,
+    dollar_lvl: &mut usize,
+) -> (Option<CompletedMarker>, BlockLike) {
+    // `newly_dollar_open` is a flag indicated that dollar is just closed after lhs, e.g.
+    // `$1$ + a`
+    // We use this flag to skip handling it.
+    let mut newly_dollar_open = false;
+
+    if p.at_l_dollar() {
+        *dollar_lvl += p.eat_l_dollars();
+        newly_dollar_open = true;
+    }
+
+    let mut lhs = match lhs(p, r, dollar_lvl) {
         Some((lhs, blocklike)) => {
             // test stmt_bin_expr_ambiguity
             // fn foo() {
@@ -223,6 +241,15 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>,
     };
 
     loop {
+        if *dollar_lvl > 0 && p.at_r_dollar() {
+            *dollar_lvl -= p.eat_r_dollars(*dollar_lvl);
+            if !newly_dollar_open {
+                // We "pump" bp for make it highest priority
+                bp = 255;
+            }
+            newly_dollar_open = false;
+        }
+
         let is_range = p.current() == DOTDOT || p.current() == DOTDOTEQ;
         let (op_bp, op) = current_op(p);
         if op_bp < bp {
@@ -235,7 +262,8 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>,
                 p.bump_compound(kind, n);
             }
         }
-        expr_bp(p, r, op_bp + 1);
+
+        expr_bp(p, r, op_bp + 1, dollar_lvl);
         lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
     }
     (Some(lhs), BlockLike::NotBlock)
@@ -244,7 +272,11 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>,
 const LHS_FIRST: TokenSet =
     atom::ATOM_EXPR_FIRST.union(token_set![AMP, STAR, EXCL, DOTDOT, DOTDOTEQ, MINUS]);
 
-fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)> {
+fn lhs(
+    p: &mut Parser,
+    r: Restrictions,
+    dollar_lvl: &mut usize,
+) -> Option<(CompletedMarker, BlockLike)> {
     let m;
     let kind = match p.current() {
         // test ref_expr
@@ -275,7 +307,7 @@ fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)>
             m = p.start();
             p.bump();
             if p.at_ts(EXPR_FIRST) {
-                expr_bp(p, r, 2);
+                expr_bp(p, r, 2, dollar_lvl);
             }
             return Some((m.complete(p, RANGE_EXPR), BlockLike::NotBlock));
         }
@@ -287,7 +319,7 @@ fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)>
             ));
         }
     };
-    expr_bp(p, r, 255);
+    expr_bp(p, r, 255, dollar_lvl);
     Some((m.complete(p, kind), BlockLike::NotBlock))
 }
 
diff --git a/crates/ra_parser/src/grammar/patterns.rs b/crates/ra_parser/src/grammar/patterns.rs
index 9a307559b..03fa9b71e 100644
--- a/crates/ra_parser/src/grammar/patterns.rs
+++ b/crates/ra_parser/src/grammar/patterns.rs
@@ -5,7 +5,7 @@ pub(super) const PATTERN_FIRST: TokenSet = expressions::LITERAL_FIRST
     .union(token_set![REF_KW, MUT_KW, L_PAREN, L_BRACK, AMP, UNDERSCORE, MINUS]);
 
 pub(super) fn pattern(p: &mut Parser) {
-    pattern_r(p, PAT_RECOVERY_SET)
+    pattern_r(p, PAT_RECOVERY_SET);
 }
 
 /// Parses a pattern list separated by pipes `|`
diff --git a/crates/ra_parser/src/lib.rs b/crates/ra_parser/src/lib.rs
index 3ceeeebd7..56755c394 100644
--- a/crates/ra_parser/src/lib.rs
+++ b/crates/ra_parser/src/lib.rs
@@ -53,20 +53,39 @@ pub trait TreeSink {
     fn error(&mut self, error: ParseError);
 }
 
-/// Parse given tokens into the given sink as a rust file.
-pub fn parse(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
+fn parse_from_tokens<F>(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink, f: F)
+where
+    F: FnOnce(&mut parser::Parser),
+{
     let mut p = parser::Parser::new(token_source);
-    grammar::root(&mut p);
+    f(&mut p);
     let events = p.finish();
     event::process(tree_sink, events);
 }
 
+/// Parse given tokens into the given sink as a rust file.
+pub fn parse(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
+    parse_from_tokens(token_source, tree_sink, grammar::root);
+}
+
 /// Parse given tokens into the given sink as a path
 pub fn parse_path(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
-    let mut p = parser::Parser::new(token_source);
-    grammar::path(&mut p);
-    let events = p.finish();
-    event::process(tree_sink, events);
+    parse_from_tokens(token_source, tree_sink, grammar::path);
+}
+
+/// Parse given tokens into the given sink as a expression
+pub fn parse_expr(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
+    parse_from_tokens(token_source, tree_sink, grammar::expr);
+}
+
+/// Parse given tokens into the given sink as a ty
+pub fn parse_ty(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
+    parse_from_tokens(token_source, tree_sink, grammar::type_);
+}
+
+/// Parse given tokens into the given sink as a pattern
+pub fn parse_pat(token_source: &dyn TokenSource, tree_sink: &mut dyn TreeSink) {
+    parse_from_tokens(token_source, tree_sink, grammar::pattern);
 }
 
 /// A parsing function for a specific braced-block.
diff --git a/crates/ra_parser/src/parser.rs b/crates/ra_parser/src/parser.rs
index 3cb57ed9c..71f1f8b30 100644
--- a/crates/ra_parser/src/parser.rs
+++ b/crates/ra_parser/src/parser.rs
@@ -45,8 +45,9 @@ impl<'t> Parser<'t> {
     ///
     /// Useful for parsing things like `>>`.
     pub(crate) fn current2(&self) -> Option<(SyntaxKind, SyntaxKind)> {
-        let c1 = self.token_source.token_kind(self.token_pos);
-        let c2 = self.token_source.token_kind(self.token_pos + 1);
+        let c1 = self.nth(0);
+        let c2 = self.nth(1);
+
         if self.token_source.is_token_joint_to_next(self.token_pos) {
             Some((c1, c2))
         } else {
@@ -59,9 +60,9 @@ impl<'t> Parser<'t> {
     ///
     /// Useful for parsing things like `=>>`.
     pub(crate) fn current3(&self) -> Option<(SyntaxKind, SyntaxKind, SyntaxKind)> {
-        let c1 = self.token_source.token_kind(self.token_pos);
-        let c2 = self.token_source.token_kind(self.token_pos + 1);
-        let c3 = self.token_source.token_kind(self.token_pos + 2);
+        let c1 = self.nth(0);
+        let c2 = self.nth(1);
+        let c3 = self.nth(2);
         if self.token_source.is_token_joint_to_next(self.token_pos)
             && self.token_source.is_token_joint_to_next(self.token_pos + 1)
         {
@@ -77,7 +78,23 @@ impl<'t> Parser<'t> {
         let steps = self.steps.get();
         assert!(steps <= 10_000_000, "the parser seems stuck");
         self.steps.set(steps + 1);
-        self.token_source.token_kind(self.token_pos + n)
+
+        // It is beecause the Dollar will appear between nth
+        // Following code skips through it
+        let mut non_dollars_count = 0;
+        let mut i = 0;
+
+        loop {
+            let kind = self.token_source.token_kind(self.token_pos + i);
+            i += 1;
+
+            match kind {
+                EOF => return EOF,
+                SyntaxKind::L_DOLLAR | SyntaxKind::R_DOLLAR => {}
+                _ if non_dollars_count == n => return kind,
+                _ => non_dollars_count += 1,
+            }
+        }
     }
 
     /// Checks if the current token is `kind`.
@@ -99,8 +116,6 @@ impl<'t> Parser<'t> {
     /// consumed between the `start` and the corresponding `Marker::complete`
     /// belong to the same node.
     pub(crate) fn start(&mut self) -> Marker {
-        self.eat_dollars();
-
         let pos = self.events.len() as u32;
         self.push_event(Event::tombstone());
         Marker::new(pos)
@@ -185,7 +200,6 @@ impl<'t> Parser<'t> {
         self.eat_dollars();
         self.token_pos += usize::from(n_raw_tokens);
         self.push_event(Event::Token { kind, n_raw_tokens });
-        self.eat_dollars();
     }
 
     fn push_event(&mut self, event: Event) {
@@ -193,12 +207,64 @@ impl<'t> Parser<'t> {
     }
 
     fn eat_dollars(&mut self) {
-        while self.nth(0) == SyntaxKind::L_DOLLAR || self.nth(0) == SyntaxKind::R_DOLLAR {
-            let kind = self.nth(0);
-            self.token_pos += 1;
-            self.push_event(Event::Token { kind, n_raw_tokens: 1 });
+        loop {
+            match self.token_source.token_kind(self.token_pos) {
+                k @ SyntaxKind::L_DOLLAR | k @ SyntaxKind::R_DOLLAR => {
+                    self.token_pos += 1;
+                    self.push_event(Event::Token { kind: k, n_raw_tokens: 1 });
+                }
+                _ => {
+                    return;
+                }
+            }
+        }
+    }
+
+    pub(crate) fn eat_l_dollars(&mut self) -> usize {
+        let mut ate_count = 0;
+        loop {
+            match self.token_source.token_kind(self.token_pos) {
+                k @ SyntaxKind::L_DOLLAR => {
+                    self.token_pos += 1;
+                    self.push_event(Event::Token { kind: k, n_raw_tokens: 1 });
+                    ate_count += 1;
+                }
+                _ => {
+                    return ate_count;
+                }
+            }
         }
     }
+
+    pub(crate) fn eat_r_dollars(&mut self, max_count: usize) -> usize {
+        let mut ate_count = 0;
+        loop {
+            match self.token_source.token_kind(self.token_pos) {
+                k @ SyntaxKind::R_DOLLAR => {
+                    self.token_pos += 1;
+                    self.push_event(Event::Token { kind: k, n_raw_tokens: 1 });
+                    ate_count += 1;
+
+                    if max_count >= ate_count {
+                        return ate_count;
+                    }
+                }
+                _ => {
+                    return ate_count;
+                }
+            }
+        }
+    }
+
+    pub(crate) fn at_l_dollar(&self) -> bool {
+        let kind = self.token_source.token_kind(self.token_pos);
+        (kind == SyntaxKind::L_DOLLAR)
+    }
+
+    pub(crate) fn at_r_dollar(&self) -> bool {
+        let kind = self.token_source.token_kind(self.token_pos);
+        (kind == SyntaxKind::R_DOLLAR)
+    }
 }
 
 /// See `Parser::start`.