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internal: more reasonable grammar for blocks

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Consider these expples

        { 92 }
  async { 92 }
    'a: { 92 }
   #[a] { 92 }

Previously the tree for them were

  BLOCK_EXPR
    { ... }

  EFFECT_EXPR
    async
    BLOCK_EXPR
      { ... }

  EFFECT_EXPR
    'a:
    BLOCK_EXPR
      { ... }

  BLOCK_EXPR
    #[a]
    { ... }

As you see, it gets progressively worse :) The last two items are
especially odd. The last one even violates the balanced curleys
invariant we have (#10357) The new approach is to say that the stuff in
`{}` is stmt_list, and the block is stmt_list + optional modifiers

  BLOCK_EXPR
    STMT_LIST
      { ... }

  BLOCK_EXPR
    async
    STMT_LIST
      { ... }

  BLOCK_EXPR
    'a:
    STMT_LIST
      { ... }

  BLOCK_EXPR
    #[a]
    STMT_LIST
      { ... }
This commit is contained in:
Aleksey Kladov 2021-09-26 12:12:57 +03:00
parent c51a3c78cf
commit 2bf81922f7
233 changed files with 11762 additions and 11343 deletions
Download patch file Download diff file Expand all files Collapse all files

40
crates/parser/src/grammar/expressions/atom.rs
View file

@ -93,8 +93,8 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
// test labeled_block
// fn f() { 'label: {}; }
T!['{'] => {
block_expr(p);
m.complete(p, EFFECT_EXPR)
stmt_list(p);
m.complete(p, BLOCK_EXPR)
}
_ => {
// test_err misplaced_label_err
@ -111,8 +111,8 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
let m = p.start();
p.bump(T![async]);
p.eat(T![move]);
block_expr(p);
m.complete(p, EFFECT_EXPR)
stmt_list(p);
m.complete(p, BLOCK_EXPR)
}
T![match] => match_expr(p),
// test unsafe_block
@ -120,16 +120,16 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
T![unsafe] if la == T!['{'] => {
let m = p.start();
p.bump(T![unsafe]);
block_expr(p);
m.complete(p, EFFECT_EXPR)
stmt_list(p);
m.complete(p, BLOCK_EXPR)
}
// test const_block
// fn f() { const { } }
T![const] if la == T!['{'] => {
let m = p.start();
p.bump(T![const]);
block_expr(p);
m.complete(p, EFFECT_EXPR)
stmt_list(p);
m.complete(p, BLOCK_EXPR)
}
T!['{'] => {
// test for_range_from
@ -138,7 +138,9 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
// break;
// }
// }
block_expr_unchecked(p)
let m = p.start();
stmt_list(p);
m.complete(p, BLOCK_EXPR)
}
T![return] => return_expr(p),
T![yield] => yield_expr(p),
@ -150,9 +152,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
}
};
let blocklike = match done.kind() {
IF_EXPR | WHILE_EXPR | FOR_EXPR | LOOP_EXPR | MATCH_EXPR | BLOCK_EXPR | EFFECT_EXPR => {
BlockLike::Block
}
IF_EXPR | WHILE_EXPR | FOR_EXPR | LOOP_EXPR | MATCH_EXPR | BLOCK_EXPR => BlockLike::Block,
_ => BlockLike::NotBlock,
};
Some((done, blocklike))
@ -486,16 +486,18 @@ pub(crate) fn block_expr(p: &mut Parser) {
p.error("expected a block");
return;
}
block_expr_unchecked(p);
let m = p.start();
stmt_list(p);
m.complete(p, BLOCK_EXPR);
}
fn block_expr_unchecked(p: &mut Parser) -> CompletedMarker {
fn stmt_list(p: &mut Parser) -> CompletedMarker {
assert!(p.at(T!['{']));
let m = p.start();
p.bump(T!['{']);
expr_block_contents(p);
p.expect(T!['}']);
m.complete(p, BLOCK_EXPR)
m.complete(p, STMT_LIST)
}
// test return_expr
@ -597,8 +599,12 @@ fn try_block_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
}
p.bump(T![try]);
block_expr(p);
m.complete(p, EFFECT_EXPR)
if p.at(T!['{']) {
stmt_list(p);
} else {
p.error("expected a block")
}
m.complete(p, BLOCK_EXPR)
}
// test box_expr