Merge #1138

1138: Add L_DOLLAR and R_DOLLAR r=matklad a=edwin0cheng

As discussion in issue https://github.com/rust-analyzer/rust-analyzer/issues/1132 and PR #1125 , this PR add 2 `Syntax::Kind` : `L_DOLLAR` and `R_DOLLAR` for representing `Delimiter::None` in mbe and proc_marco. By design, It should not affect the final syntax tree, and will be discard in `TreeSink`.

My original idea is handling these 2 tokens case by case, but i found that they will appear in every place in the parser (imagine `tt` matcher). So this PR only handle it in `Parser::do_bump` and `Parser::start`, although It will not fix the `expr` matcher executing order problem in original idea.


Co-authored-by: Edwin Cheng <[email protected]>

2 files changed, 42 insertions, 10 deletions

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 `|`