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Change initial_matcher_pos() into MatcherPos::new().

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This commit is contained in:
Nicholas Nethercote 2022-03-03 12:14:27 +11:00
parent e5f3fd6250
commit 97eb1b4669
1 changed files with 29 additions and 29 deletions
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58
compiler/rustc_expand/src/mbe/macro_parser.rs
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@ -154,7 +154,7 @@ type NamedMatchVec = SmallVec<[NamedMatch; 4]>;
/// lifetime. By separating `'tt` from `'root`, we can show that.
#[derive(Clone)]
struct MatcherPos<'root, 'tt> {
/// The token or sequence of tokens that make up the matcher
/// The token or sequence of tokens that make up the matcher. `elts` is short for "elements".
top_elts: TokenTreeOrTokenTreeSlice<'tt>,
/// The position of the "dot" in this matcher
@ -203,6 +203,33 @@ struct MatcherPos<'root, 'tt> {
rustc_data_structures::static_assert_size!(MatcherPos<'_, '_>, 192);
impl<'root, 'tt> MatcherPos<'root, 'tt> {
/// Generates the top-level matcher position in which the "dot" is before the first token of
/// the matcher `ms`.
fn new(ms: &'tt [TokenTree]) -> Self {
let match_idx_hi = count_names(ms);
MatcherPos {
// Start with the top level matcher given to us.
top_elts: TtSeq(ms),
// The "dot" is before the first token of the matcher.
idx: 0,
// Initialize `matches` to a bunch of empty `Vec`s -- one for each metavar in
// `top_elts`. `match_lo` for `top_elts` is 0 and `match_hi` is `match_idx_hi`.
// `match_cur` is 0 since we haven't actually matched anything yet.
matches: create_matches(match_idx_hi),
match_lo: 0,
match_cur: 0,
match_hi: match_idx_hi,
// Haven't descended into any delimiters, so this is empty.
stack: smallvec![],
// Haven't descended into any sequences, so this is `None`.
repetition: None,
}
}
/// Adds `m` as a named match for the `idx`-th metavar.
fn push_match(&mut self, idx: usize, m: NamedMatch) {
let matches = Lrc::make_mut(&mut self.matches[idx]);
@ -314,33 +341,6 @@ fn create_matches(len: usize) -> Box<[Lrc<NamedMatchVec>]> {
.into_boxed_slice()
}
/// Generates the top-level matcher position in which the "dot" is before the first token of the
/// matcher `ms`.
fn initial_matcher_pos<'root, 'tt>(ms: &'tt [TokenTree]) -> MatcherPos<'root, 'tt> {
let match_idx_hi = count_names(ms);
let matches = create_matches(match_idx_hi);
MatcherPos {
// Start with the top level matcher given to us
top_elts: TtSeq(ms), // "elts" is an abbr. for "elements"
// The "dot" is before the first token of the matcher
idx: 0,
// Initialize `matches` to a bunch of empty `Vec`s -- one for each metavar in `top_elts`.
// `match_lo` for `top_elts` is 0 and `match_hi` is `matches.len()`. `match_cur` is 0 since
// we haven't actually matched anything yet.
matches,
match_lo: 0,
match_cur: 0,
match_hi: match_idx_hi,
// Haven't descended into any delimiters, so empty stack
stack: smallvec![],
// Haven't descended into any sequences, so this is `None`.
repetition: None,
}
}
/// `NamedMatch` is a pattern-match result for a single `token::MATCH_NONTERMINAL`:
/// so it is associated with a single ident in a parse, and all
/// `MatchedNonterminal`s in the `NamedMatch` have the same non-terminal type
@ -642,7 +642,7 @@ pub(super) fn parse_tt(
//
// This MatcherPos instance is allocated on the stack. All others -- and
// there are frequently *no* others! -- are allocated on the heap.
let mut initial = initial_matcher_pos(ms);
let mut initial = MatcherPos::new(ms);
let mut cur_items = smallvec![MatcherPosHandle::Ref(&mut initial)];
let mut next_items = Vec::new();