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Snowflake: preserve reluctant MATCH_RECOGNIZE quantifiers #2510

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Snowflake: preserve reluctant MATCH_RECOGNIZE quantifiers #2510

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3 changes: 3 additions & 0 deletions src/ast/query.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2194,6 +2194,8 @@ pub enum RepetitionQuantifier {
AtMost(u32),
/// `{n,m}
Range(u32, u32),
/// A reluctant (non-greedy) quantifier, for example `*?` or `{n,m}?`.
Reluctant(Box<RepetitionQuantifier>),
}

impl fmt::Display for RepetitionQuantifier {
Expand All @@ -2207,6 +2209,7 @@ impl fmt::Display for RepetitionQuantifier {
AtLeast(n) => write!(f, "{{{n},}}"),
AtMost(n) => write!(f, "{{,{n}}}"),
Range(n, m) => write!(f, "{{{n},{m}}}"),
Reluctant(quantifier) => write!(f, "{quantifier}?"),
}
}
}
Expand Down
99 changes: 51 additions & 48 deletions src/parser/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17322,58 +17322,61 @@ impl<'a> Parser<'a> {
}

fn parse_repetition_pattern(&mut self) -> Result<MatchRecognizePattern, ParserError> {
let mut pattern = self.parse_base_pattern()?;
loop {
let token = self.next_token();
let quantifier = match token.token {
Token::Mul => RepetitionQuantifier::ZeroOrMore,
Token::Plus => RepetitionQuantifier::OneOrMore,
Token::Placeholder(s) if s == "?" => RepetitionQuantifier::AtMostOne,
Token::LBrace => {
// quantifier is a range like {n} or {n,} or {,m} or {n,m}
let token = self.next_token();
match token.token {
Token::Comma => {
let next_token = self.next_token();
let Token::Number(n, _) = next_token.token else {
return self.expected("literal number", next_token);
};
self.expect_token(&Token::RBrace)?;
RepetitionQuantifier::AtMost(Self::parse(n, token.span.start)?)
}
Token::Number(n, _) if self.consume_token(&Token::Comma) => {
let next_token = self.next_token();
match next_token.token {
Token::Number(m, _) => {
self.expect_token(&Token::RBrace)?;
RepetitionQuantifier::Range(
Self::parse(n, token.span.start)?,
Self::parse(m, token.span.start)?,
)
}
Token::RBrace => {
RepetitionQuantifier::AtLeast(Self::parse(n, token.span.start)?)
}
_ => {
return self.expected("} or upper bound", next_token);
}
let pattern = self.parse_base_pattern()?;
let token = self.next_token();
let quantifier = match token.token {
Token::Mul => RepetitionQuantifier::ZeroOrMore,
Token::Plus => RepetitionQuantifier::OneOrMore,
Token::Placeholder(s) if s == "?" => RepetitionQuantifier::AtMostOne,
Token::LBrace => {
// quantifier is a range like {n} or {n,} or {,m} or {n,m}
let token = self.next_token();
match token.token {
Token::Comma => {
let next_token = self.next_token();
let Token::Number(n, _) = next_token.token else {
return self.expected("literal number", next_token);
};
self.expect_token(&Token::RBrace)?;
RepetitionQuantifier::AtMost(Self::parse(n, token.span.start)?)
}
Token::Number(n, _) if self.consume_token(&Token::Comma) => {
let next_token = self.next_token();
match next_token.token {
Token::Number(m, _) => {
self.expect_token(&Token::RBrace)?;
RepetitionQuantifier::Range(
Self::parse(n, token.span.start)?,
Self::parse(m, token.span.start)?,
)
}
Token::RBrace => {
RepetitionQuantifier::AtLeast(Self::parse(n, token.span.start)?)
}
_ => return self.expected("} or upper bound", next_token),
}
Token::Number(n, _) => {
self.expect_token(&Token::RBrace)?;
RepetitionQuantifier::Exactly(Self::parse(n, token.span.start)?)
}
_ => return self.expected("quantifier range", token),
}
Token::Number(n, _) => {
self.expect_token(&Token::RBrace)?;
RepetitionQuantifier::Exactly(Self::parse(n, token.span.start)?)
}
_ => return self.expected("quantifier range", token),
}
_ => {
self.prev_token();
break;
}
};
pattern = MatchRecognizePattern::Repetition(Box::new(pattern), quantifier);
}
Ok(pattern)
}
_ => {
self.prev_token();
return Ok(pattern);
}
};
let quantifier = if self.consume_token(&Token::Placeholder("?".into())) {
RepetitionQuantifier::Reluctant(Box::new(quantifier))
} else {
quantifier
};
Ok(MatchRecognizePattern::Repetition(
Box::new(pattern),
quantifier,
))
}

fn parse_concat_pattern(&mut self) -> Result<MatchRecognizePattern, ParserError> {
Expand Down
46 changes: 35 additions & 11 deletions tests/sqlparser_common.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13948,18 +13948,45 @@ fn test_match_recognize_patterns() {
]),
);

// double repetition
// reluctant repetition
check(
"S2*?",
Repetition(
Box::new(Repetition(
Box::new(Symbol(Named(Ident::new("S2")))),
ZeroOrMore,
)),
AtMostOne,
Box::new(Symbol(Named(Ident::new("S2")))),
Reluctant(Box::new(ZeroOrMore)),
),
);

check(
"S1+? S2?? S3{2,4}?",
Concat(vec![
Repetition(
Box::new(Symbol(Named(Ident::new("S1")))),
Reluctant(Box::new(OneOrMore)),
),
Repetition(
Box::new(Symbol(Named(Ident::new("S2")))),
Reluctant(Box::new(AtMostOne)),
),
Repetition(
Box::new(Symbol(Named(Ident::new("S3")))),
Reluctant(Box::new(Range(2, 4))),
),
]),
);

for pattern in ["S1**", "S1+++", "S1???", "S1{2,4}+"] {
let sql = format!(
"SELECT * FROM my_table MATCH_RECOGNIZE(PATTERN ({pattern}) DEFINE DUMMY AS 1 = 1)"
);
assert!(
all_dialects_where(|d| d.supports_match_recognize())
.parse_sql_statements(&sql)
.is_err(),
"stacked quantifier should fail: {pattern}"
);
}

// range quantifiers in an alternation
check(
"S1{1} | S2{2,3} | S3{4,} | S4{,5}",
Expand Down Expand Up @@ -14000,11 +14027,8 @@ fn test_match_recognize_patterns() {
Symbol(Start),
Symbol(Named(Ident::new("S1"))),
Repetition(
Box::new(Repetition(
Box::new(Symbol(Named(Ident::new("S2")))),
ZeroOrMore,
)),
AtMostOne,
Box::new(Symbol(Named(Ident::new("S2")))),
Reluctant(Box::new(ZeroOrMore)),
),
Repetition(
Box::new(Group(Box::new(Concat(vec![
Expand Down
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