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Some more refactoring

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This commit is contained in:
Florian Diebold 2020-03-16 18:38:10 +01:00
parent d6b622cdef
commit 32dce75747
2 changed files with 76 additions and 58 deletions
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22
crates/ra_mbe/src/mbe_expander.rs
View file

@ -16,10 +16,15 @@ pub(crate) fn expand(rules: &crate::MacroRules, input: &tt::Subtree) -> ExpandRe
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 ExpandResult(new_match, bindings_err) = matcher::match_(&rule.lhs, input);
if bindings_err.is_none() {
let new_match = match matcher::match_(&rule.lhs, input) {
Ok(m) => m,
Err(_e) => {
// error in pattern parsing
continue;
}
};
if new_match.err.is_none() {
// If we find a rule that applies without errors, we're done.
// Unconditionally returning the transcription here makes the
// `test_repeat_bad_var` test fail.
@ -32,25 +37,22 @@ fn expand_rules(rules: &[crate::Rule], input: &tt::Subtree) -> ExpandResult<tt::
// Use the rule if we matched more tokens, or had fewer patterns left,
// or had no error
if let Some((prev_match, _)) = &match_ {
if (new_match.unmatched_tokens, new_match.unmatched_patterns)
< (prev_match.unmatched_tokens, prev_match.unmatched_patterns)
|| err.is_some() && bindings_err.is_none()
if (new_match.unmatched_tts, new_match.err_count)
< (prev_match.unmatched_tts, prev_match.err_count)
{
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 ExpandResult(result, transcribe_err) =
transcriber::transcribe(&rule.rhs, &match_.bindings);
ExpandResult(result, err.or(transcribe_err))
ExpandResult(result, match_.err.or(transcribe_err))
} else {
ExpandResult(tt::Subtree::default(), err)
ExpandResult(tt::Subtree::default(), Some(ExpandError::NoMatchingRule))
}
}

112
crates/ra_mbe/src/mbe_expander/matcher.rs
View file

@ -62,24 +62,41 @@ macro_rules! err {
#[derive(Debug, Default)]
pub(super) struct Match {
pub bindings: Bindings,
pub unmatched_tokens: usize,
pub unmatched_patterns: usize,
/// We currently just keep the first error and count the rest to compare matches.
pub err: Option<ExpandError>,
pub err_count: usize,
/// How many top-level token trees were left to match.
pub unmatched_tts: usize,
}
pub(super) fn match_(pattern: &tt::Subtree, src: &tt::Subtree) -> ExpandResult<Match> {
impl Match {
pub fn add_err(&mut self, err: ExpandError) {
let prev_err = self.err.take();
self.err = prev_err.or(Some(err));
self.err_count += 1;
}
}
// General note: These functions have two channels to return errors, a `Result`
// return value and the `&mut Match`. The returned Result is for pattern parsing
// errors; if a branch of the macro definition doesn't parse, it doesn't make
// sense to try using it. Matching errors are added to the `Match`. It might
// make sense to make pattern parsing a separate step?
pub(super) fn match_(pattern: &tt::Subtree, src: &tt::Subtree) -> Result<Match, ExpandError> {
assert!(pattern.delimiter == None);
let mut res = Match::default();
let mut src = TtIter::new(src);
let mut err = match_subtree(&mut res, pattern, &mut src).err();
match_subtree(&mut res, pattern, &mut src)?;
res.unmatched_tokens += src.len();
if src.len() > 0 && err.is_none() {
err = Some(err!("leftover tokens"));
if src.len() > 0 {
res.unmatched_tts += src.len();
res.add_err(err!("leftover tokens"));
}
ExpandResult(res, err)
Ok(res)
}
fn match_subtree(
@ -87,19 +104,13 @@ fn match_subtree(
pattern: &tt::Subtree,
src: &mut TtIter,
) -> Result<(), ExpandError> {
let mut result = Ok(());
for op in parse_pattern(pattern) {
if result.is_err() {
// We're just going through the patterns to count how many we missed
res.unmatched_patterns += 1;
continue;
}
match op? {
Op::TokenTree(tt::TokenTree::Leaf(lhs)) => {
let rhs = match src.expect_leaf() {
Ok(l) => l,
Err(()) => {
result = Err(err!("expected leaf: `{}`", lhs));
res.add_err(err!("expected leaf: `{}`", lhs));
continue;
}
};
@ -117,7 +128,7 @@ fn match_subtree(
tt::Leaf::Literal(tt::Literal { text: rhs, .. }),
) if lhs == rhs => (),
_ => {
result = Err(ExpandError::UnexpectedToken);
res.add_err(ExpandError::UnexpectedToken);
}
}
}
@ -125,26 +136,25 @@ fn match_subtree(
let rhs = match src.expect_subtree() {
Ok(s) => s,
Err(()) => {
result = Err(err!("expected subtree"));
res.add_err(err!("expected subtree"));
continue;
}
};
if lhs.delimiter_kind() != rhs.delimiter_kind() {
result = Err(err!("mismatched delimiter"));
res.add_err(err!("mismatched delimiter"));
continue;
}
let mut src = TtIter::new(rhs);
result = match_subtree(res, lhs, &mut src);
res.unmatched_tokens += src.len();
if src.len() > 0 && result.is_ok() {
result = Err(err!("leftover tokens"));
match_subtree(res, lhs, &mut src)?;
if src.len() > 0 {
res.add_err(err!("leftover tokens"));
}
}
Op::Var { name, kind } => {
let kind = match kind {
Some(k) => k,
None => {
result = Err(ExpandError::UnexpectedToken);
res.add_err(ExpandError::UnexpectedToken);
continue;
}
};
@ -156,14 +166,16 @@ fn match_subtree(
None if match_err.is_none() => res.bindings.push_optional(name),
_ => {}
}
result = match_err.map_or(Ok(()), Err);
if let Some(err) = match_err {
res.add_err(err);
}
}
Op::Repeat { subtree, kind, separator } => {
result = match_repeat(res, subtree, kind, separator, src);
match_repeat(res, subtree, kind, separator, src)?;
}
}
}
result
Ok(())
}
impl<'a> TtIter<'a> {
@ -345,35 +357,39 @@ pub(super) fn match_repeat(
}
let mut nested = Match::default();
match match_subtree(&mut nested, pattern, &mut fork) {
Ok(()) => {
limit -= 1;
if limit == 0 {
log::warn!(
"match_lhs exceeded repeat pattern limit => {:#?}\n{:#?}\n{:#?}\n{:#?}",
pattern,
src,
kind,
separator
);
match_subtree(&mut nested, pattern, &mut fork)?;
if nested.err.is_none() {
limit -= 1;
if limit == 0 {
log::warn!(
"match_lhs exceeded repeat pattern limit => {:#?}\n{:#?}\n{:#?}\n{:#?}",
pattern,
src,
kind,
separator
);
break;
}
*src = fork;
if let Err(err) = res.bindings.push_nested(counter, nested.bindings) {
res.add_err(err);
}
counter += 1;
if counter == 1 {
if let RepeatKind::ZeroOrOne = kind {
break;
}
*src = fork;
res.bindings.push_nested(counter, nested.bindings)?;
counter += 1;
if counter == 1 {
if let RepeatKind::ZeroOrOne = kind {
break;
}
}
}
Err(_) => break,
} else {
break;
}
}
match (kind, counter) {
(RepeatKind::OneOrMore, 0) => return Err(ExpandError::UnexpectedToken),
(RepeatKind::OneOrMore, 0) => {
res.add_err(ExpandError::UnexpectedToken);
}
(_, 0) => {
// Collect all empty variables in subtrees
let mut vars = Vec::new();