cleanup dollar handling in expressions

crates/ra_parser/src/grammar/expressions.rs

@@ -14,20 +14,17 @@ const EXPR_FIRST: TokenSet = LHS_FIRST;
 
 pub(super) fn expr(p: &mut Parser) -> BlockLike {
     let r = Restrictions { forbid_structs: false, prefer_stmt: false };
-    let mut dollar_lvl = 0;
+    expr_bp(p, r, 1).1
-    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 };
-    let mut dollar_lvl = 0;
+    expr_bp(p, r, 1)
-    expr_bp(p, r, 1, &mut dollar_lvl)
 }
 
 fn expr_no_struct(p: &mut Parser) {
     let r = Restrictions { forbid_structs: true, prefer_stmt: false };
-    let mut dollar_lvl = 0;
+    expr_bp(p, r, 1);
-    expr_bp(p, r, 1, &mut dollar_lvl);
 }
 
 // test block
@@ -257,23 +254,8 @@ fn current_op(p: &Parser) -> (u8, SyntaxKind) {
 }
 
 // Parses expression with binding power of at least bp.
-fn expr_bp(
+fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>, BlockLike) {
-    p: &mut Parser,
+    let mut lhs = match lhs(p, r) {
-    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 = if p.at_l_dollar() {
-        *dollar_lvl += p.eat_l_dollars();
-        true
-    } else {
-        false
-    };
-
-    let mut lhs = match lhs(p, r, dollar_lvl) {
         Some((lhs, blocklike)) => {
             // test stmt_bin_expr_ambiguity
             // fn foo() {
@@ -289,15 +271,6 @@ fn expr_bp(
     };
 
     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.at(T![..]) || p.at(T![..=]);
         let (op_bp, op) = current_op(p);
         if op_bp < bp {
@@ -306,7 +279,7 @@ fn expr_bp(
         let m = lhs.precede(p);
         p.bump(op);
 
-        expr_bp(p, r, op_bp + 1, dollar_lvl);
+        expr_bp(p, r, op_bp + 1);
         lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
     }
     (Some(lhs), BlockLike::NotBlock)
@@ -314,11 +287,7 @@ fn expr_bp(
 
 const LHS_FIRST: TokenSet = atom::ATOM_EXPR_FIRST.union(token_set![AMP, STAR, EXCL, DOT, MINUS]);
 
-fn lhs(
+fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)> {
-    p: &mut Parser,
-    r: Restrictions,
-    dollar_lvl: &mut usize,
-) -> Option<(CompletedMarker, BlockLike)> {
     let m;
     let kind = match p.current() {
         // test ref_expr
@@ -351,7 +320,7 @@ fn lhs(
                     m = p.start();
                     p.bump(op);
                     if p.at_ts(EXPR_FIRST) {
-                        expr_bp(p, r, 2, dollar_lvl);
+                        expr_bp(p, r, 2);
                     }
                     return Some((m.complete(p, RANGE_EXPR), BlockLike::NotBlock));
                 }
@@ -367,7 +336,7 @@ fn lhs(
             return Some(postfix_expr(p, lhs, blocklike, !(r.prefer_stmt && blocklike.is_block())));
         }
     };
-    expr_bp(p, r, 255, dollar_lvl);
+    expr_bp(p, r, 255);
     Some((m.complete(p, kind), BlockLike::NotBlock))
 }
 

crates/ra_parser/src/grammar/expressions/atom.rs

@@ -69,6 +69,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
     let done = match p.current() {
         T!['('] => tuple_expr(p),
         T!['['] => array_expr(p),
+        L_DOLLAR => meta_var_expr(p),
         T![|] => lambda_expr(p),
         T![move] if la == T![|] => lambda_expr(p),
         T![async] if la == T![|] || (la == T![move] && p.nth(2) == T![|]) => lambda_expr(p),
@@ -554,3 +555,27 @@ fn box_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
     }
     m.complete(p, BOX_EXPR)
 }
+
+/// Expression from `$var` macro expansion, wrapped in dollars
+fn meta_var_expr(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(L_DOLLAR));
+    let m = p.start();
+    p.bump(L_DOLLAR);
+    let (completed, _is_block) =
+        expr_bp(p, Restrictions { forbid_structs: false, prefer_stmt: false }, 1);
+
+    match (completed, p.current()) {
+        (Some(it), R_DOLLAR) => {
+            p.bump(R_DOLLAR);
+            m.abandon(p);
+            it
+        }
+        _ => {
+            while !p.at(R_DOLLAR) {
+                p.bump_any()
+            }
+            p.bump(R_DOLLAR);
+            m.complete(p, ERROR)
+        }
+    }
+}

crates/ra_parser/src/parser.rs

@@ -5,7 +5,7 @@ use drop_bomb::DropBomb;
 use crate::{
     event::Event,
     ParseError,
-    SyntaxKind::{self, EOF, ERROR, TOMBSTONE},
+    SyntaxKind::{self, EOF, ERROR, L_DOLLAR, R_DOLLAR, TOMBSTONE},
     TokenSet, TokenSource, T,
 };
 
@@ -211,19 +211,26 @@ impl<'t> Parser<'t> {
 
     /// Create an error node and consume the next token.
     pub(crate) fn err_recover(&mut self, message: &str, recovery: TokenSet) {
-        if self.at(T!['{']) || self.at(T!['}']) || self.at_ts(recovery) {
+        match self.current() {
+            T!['{'] | T!['}'] | L_DOLLAR | R_DOLLAR => {
                 self.error(message);
-        } else {
+                return;
+            }
+            _ => (),
+        }
+
+        if self.at_ts(recovery) {
+            self.error(message);
+            return;
+        }
+
         let m = self.start();
         self.error(message);
         self.bump_any();
         m.complete(self, ERROR);
-        };
     }
 
     fn do_bump(&mut self, kind: SyntaxKind, n_raw_tokens: u8) {
-        // self.eat_dollars();
-
         for _ in 0..n_raw_tokens {
             self.token_source.bump();
         }
@@ -234,52 +241,6 @@ impl<'t> Parser<'t> {
     fn push_event(&mut self, event: Event) {
         self.events.push(event)
     }
-
-    pub(crate) fn eat_l_dollars(&mut self) -> usize {
-        let mut ate_count = 0;
-        loop {
-            match self.token_source.current().kind {
-                k @ SyntaxKind::L_DOLLAR => {
-                    self.token_source.bump();
-                    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.current().kind {
-                k @ SyntaxKind::R_DOLLAR => {
-                    self.token_source.bump();
-                    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.current().kind;
-        (kind == SyntaxKind::L_DOLLAR)
-    }
-
-    pub(crate) fn at_r_dollar(&self) -> bool {
-        let kind = self.token_source.current().kind;
-        (kind == SyntaxKind::R_DOLLAR)
-    }
 }
 
 /// See `Parser::start`.