From bcd6754f1266ef3f4ce42f76974e379815234494 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Tue, 7 Aug 2018 16:32:09 +0300
Subject: semis after blcoks

---
 src/grammar/expressions/atom.rs | 24 +++++++++++++++++-------
 src/grammar/expressions/mod.rs  | 33 ++++++++++++++++++++++++++++-----
 src/grammar/mod.rs              |  5 +++++
 3 files changed, 50 insertions(+), 12 deletions(-)

(limited to 'src/grammar')

diff --git a/src/grammar/expressions/atom.rs b/src/grammar/expressions/atom.rs
index e4f681c17..524a69a8c 100644
--- a/src/grammar/expressions/atom.rs
+++ b/src/grammar/expressions/atom.rs
@@ -133,7 +133,7 @@ fn lambda_expr(p: &mut Parser) -> CompletedMarker {
     if fn_ret_type(p) {
         block(p);
     } else {
-        expr(p)
+        expr(p);
     }
     m.complete(p, LAMBDA_EXPR)
 }
@@ -225,8 +225,17 @@ fn match_expr(p: &mut Parser) -> CompletedMarker {
     expr_no_struct(p);
     p.eat(L_CURLY);
     while !p.at(EOF) && !p.at(R_CURLY) {
-        match_arm(p);
-        if !p.at(R_CURLY) {
+        // test match_arms_commas
+        // fn foo() {
+        //     match () {
+        //         _ => (),
+        //         _ => {}
+        //         _ => ()
+        //     }
+        // }
+        if match_arm(p).is_block() {
+            p.eat(COMMA);
+        } else if !p.at(R_CURLY) {
             p.expect(COMMA);
         }
     }
@@ -241,7 +250,7 @@ fn match_expr(p: &mut Parser) -> CompletedMarker {
 //         X | Y if Z => (),
 //     };
 // }
-fn match_arm(p: &mut Parser) {
+fn match_arm(p: &mut Parser) -> BlockLike {
     let m = p.start();
     loop {
         patterns::pattern(p);
@@ -253,8 +262,9 @@ fn match_arm(p: &mut Parser) {
         expr_no_struct(p);
     }
     p.expect(FAT_ARROW);
-    expr(p);
+    let ret = expr(p);
     m.complete(p, MATCH_ARM);
+    ret
 }
 
 // test block_expr
@@ -285,8 +295,8 @@ pub(super) fn block_expr(p: &mut Parser) -> CompletedMarker {
                     // test pub_expr
                     // fn foo() { pub 92; } //FIXME
                     items::MaybeItem::None => {
-                        expressions::expr(p);
-                        if p.eat(SEMI) {
+                        let is_blocklike = expressions::expr(p) == BlockLike::Block;
+                        if p.eat(SEMI) || (is_blocklike && !p.at(R_CURLY)) {
                             m.complete(p, EXPR_STMT);
                         } else {
                             m.abandon(p);
diff --git a/src/grammar/expressions/mod.rs b/src/grammar/expressions/mod.rs
index 55e965ff4..ce709dbb2 100644
--- a/src/grammar/expressions/mod.rs
+++ b/src/grammar/expressions/mod.rs
@@ -5,14 +5,14 @@ pub(super) use self::atom::literal;
 
 const EXPR_FIRST: TokenSet = LHS_FIRST;
 
-pub(super) fn expr(p: &mut Parser) {
+pub(super) fn expr(p: &mut Parser) -> BlockLike {
     let r = Restrictions { forbid_structs: false };
     expr_bp(p, r, 1)
 }
 
 fn expr_no_struct(p: &mut Parser) {
     let r = Restrictions { forbid_structs: true };
-    expr_bp(p, r, 1)
+    expr_bp(p, r, 1);
 }
 
 // test block
@@ -85,10 +85,14 @@ 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) {
+fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> BlockLike {
+    let mut block: bool;
     let mut lhs = match lhs(p, r) {
-        Some(lhs) => lhs,
-        None => return,
+        Some(lhs) => {
+            block = is_block(lhs.kind());
+            lhs
+        },
+        None => return BlockLike::NotBlock,
     };
 
     loop {
@@ -97,6 +101,7 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) {
         if op_bp < bp {
             break;
         }
+        block = false;
         let m = lhs.precede(p);
         match op {
             Op::Simple => p.bump(),
@@ -107,6 +112,24 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) {
         expr_bp(p, r, op_bp + 1);
         lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
     }
+    if block { BlockLike::Block } else { BlockLike::NotBlock }
+}
+
+// test no_semi_after_block
+// fn foo() {
+//     if true {}
+//     loop {}
+//     match () {}
+//     while true {}
+//     for _ in () {}
+//     {}
+//     {}
+// }
+fn is_block(kind: SyntaxKind) -> bool {
+    match kind {
+        IF_EXPR | WHILE_EXPR | FOR_EXPR | LOOP_EXPR | MATCH_EXPR | BLOCK_EXPR => true,
+        _ => false,
+    }
 }
 
 const LHS_FIRST: TokenSet =
diff --git a/src/grammar/mod.rs b/src/grammar/mod.rs
index 1b997d861..b6da0d013 100644
--- a/src/grammar/mod.rs
+++ b/src/grammar/mod.rs
@@ -44,11 +44,16 @@ pub(crate) fn file(p: &mut Parser) {
 }
 
 
+#[derive(Clone, Copy, PartialEq, Eq)]
 enum BlockLike {
     Block,
     NotBlock,
 }
 
+impl BlockLike {
+    fn is_block(self) -> bool { self == BlockLike::Block }
+}
+
 fn visibility(p: &mut Parser) {
     if p.at(PUB_KW) {
         let vis = p.start();
-- 
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