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Fix performance problem

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This commit is contained in:
Florian Diebold 2020-03-15 14:37:30 +01:00
parent e6ec4a329f
commit 0660dd10d2
2 changed files with 40 additions and 35 deletions
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73
crates/ra_mbe/src/mbe_expander.rs
View file

@ -11,40 +11,45 @@ use rustc_hash::FxHashMap;
use crate::{ExpandError, ExpandResult};
pub(crate) fn expand(rules: &crate::MacroRules, input: &tt::Subtree) -> ExpandResult<tt::Subtree> {
let (mut result, mut unmatched_tokens, mut unmatched_patterns, mut err) = (
tt::Subtree::default(),
usize::max_value(),
usize::max_value(),
Some(ExpandError::NoMatchingRule),
);
for rule in &rules.rules {
let ((res, tokens, patterns), e) = expand_rule(rule, input);
if e.is_none() {
// if we find a rule that applies without errors, we're done
return (res, None);
}
// use the rule if we matched more tokens, or had fewer patterns left
if tokens < unmatched_tokens || tokens == unmatched_tokens && patterns < unmatched_patterns
{
result = res;
err = e;
unmatched_tokens = tokens;
unmatched_patterns = patterns;
}
}
(result, err)
expand_rules(&rules.rules, input)
}
fn expand_rule(
rule: &crate::Rule,
input: &tt::Subtree,
) -> ExpandResult<(tt::Subtree, usize, usize)> {
let (match_result, bindings_err) = matcher::match_(&rule.lhs, input);
let (res, transcribe_err) = transcriber::transcribe(&rule.rhs, &match_result.bindings);
(
(res, match_result.unmatched_tokens, match_result.unmatched_patterns),
bindings_err.or(transcribe_err),
)
fn expand_rules(rules: &[crate::Rule], input: &tt::Subtree) -> ExpandResult<tt::Subtree> {
let mut match_: Option<(matcher::Match, &crate::Rule)> = None;
let mut err = Some(ExpandError::NoMatchingRule);
for rule in rules {
let (new_match, bindings_err) = matcher::match_(&rule.lhs, input);
if bindings_err.is_none() {
// if we find a rule that applies without errors, we're done
eprintln!("match without errors: {:?}", new_match);
let (res, transcribe_err) = transcriber::transcribe(&rule.rhs, &new_match.bindings);
eprintln!("transcribe_err = {:?}", transcribe_err);
if transcribe_err.is_none() {
return (res, None);
}
}
// use the rule if we matched more tokens, or had fewer patterns left
if let Some((prev_match, _)) = &match_ {
if new_match.unmatched_tokens < prev_match.unmatched_tokens
|| new_match.unmatched_tokens == prev_match.unmatched_tokens
&& new_match.unmatched_patterns < prev_match.unmatched_patterns
|| err.is_some() && bindings_err.is_none()
{
match_ = Some((new_match, rule));
err = bindings_err;
}
} else {
match_ = Some((new_match, rule));
err = bindings_err;
}
}
if let Some((match_, rule)) = match_ {
// if we got here, there was no match without errors
let (result, transcribe_err) = transcriber::transcribe(&rule.rhs, &match_.bindings);
(result, err.or(transcribe_err))
} else {
(tt::Subtree::default(), err)
}
}
/// The actual algorithm for expansion is not too hard, but is pretty tricky.
@ -167,7 +172,7 @@ mod tests {
let (invocation_tt, _) =
ast_to_token_tree(&macro_invocation.token_tree().unwrap()).unwrap();
let expanded = expand_rule(&rules.rules[0], &invocation_tt);
((expanded.0).0, expanded.1)
let expanded = expand_rules(&rules.rules, &invocation_tt);
(expanded.0, expanded.1)
}
}

2
crates/ra_mbe/src/tests.rs
View file

@ -1663,5 +1663,5 @@ fn test_expand_bad_literal() {
macro_rules! foo { ($i:literal) => {}; }
"#,
)
.assert_expand_err(r#"foo!(&k");"#, &ExpandError::NoMatchingRule);
.assert_expand_err(r#"foo!(&k");"#, &ExpandError::BindingError("".to_string()));
}