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Refactor parse_joins, pt.2: implicit/cross/natural joins

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- reduce duplication in the handling of implicit/cross joins and make
  the flow of data slightly clearer by returning the `join` instead of
  pushing it and exiting early.

  (I wanted the block that currently returns `join` to return one of
  JoinOperator::* tags, so that `parse_table_factor` and the construction
  of the `Join` struct could happen after we've parsed the JOIN keywords,
  but that seems impossible.)

- move the check for the NATURAL keyword into the block that deals with 
  INNER/OUTER joins that support constraints (and thus can be preceded
  by "NATURAL")

- add a check for NATURAL not followed by a known join type with a test

- add more tests for NATURAL joins (we didn't have any), and fix
  whitespace bug in `to_string()` that was uncovered (we emitted an
  extra space: `foo NATURAL JOIN bar `)
This commit is contained in:
Nickolay Ponomarev 2019-06-03 02:17:52 +03:00
parent 665b9df729
commit d0f2de06ed
3 changed files with 86 additions and 58 deletions
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12
src/sqlast/query.rs
View file

@ -271,14 +271,14 @@ impl ToString for Join {
}
fn suffix(constraint: &JoinConstraint) -> String {
match constraint {
JoinConstraint::On(expr) => format!("ON {}", expr.to_string()),
JoinConstraint::Using(attrs) => format!("USING({})", attrs.join(", ")),
JoinConstraint::On(expr) => format!(" ON {}", expr.to_string()),
JoinConstraint::Using(attrs) => format!(" USING({})", attrs.join(", ")),
_ => "".to_string(),
}
}
match &self.join_operator {
JoinOperator::Inner(constraint) => format!(
" {}JOIN {} {}",
" {}JOIN {}{}",
prefix(constraint),
self.relation.to_string(),
suffix(constraint)
@ -286,19 +286,19 @@ impl ToString for Join {
JoinOperator::Cross => format!(" CROSS JOIN {}", self.relation.to_string()),
JoinOperator::Implicit => format!(", {}", self.relation.to_string()),
JoinOperator::LeftOuter(constraint) => format!(
" {}LEFT JOIN {} {}",
" {}LEFT JOIN {}{}",
prefix(constraint),
self.relation.to_string(),
suffix(constraint)
),
JoinOperator::RightOuter(constraint) => format!(
" {}RIGHT JOIN {} {}",
" {}RIGHT JOIN {}{}",
prefix(constraint),
self.relation.to_string(),
suffix(constraint)
),
JoinOperator::FullOuter(constraint) => format!(
" {}FULL JOIN {} {}",
" {}FULL JOIN {}{}",
prefix(constraint),
self.relation.to_string(),
suffix(constraint)

95
src/sqlparser.rs
View file

@ -1499,71 +1499,62 @@ impl Parser {
fn parse_joins(&mut self) -> Result<Vec<Join>, ParserError> {
let mut joins = vec![];
loop {
let natural = match &self.peek_token() {
let join = match &self.peek_token() {
Some(Token::Comma) => {
self.next_token();
let relation = self.parse_table_factor()?;
let join = Join {
relation,
Join {
relation: self.parse_table_factor()?,
join_operator: JoinOperator::Implicit,
};
joins.push(join);
continue;
}
}
Some(Token::SQLWord(kw)) if kw.keyword == "CROSS" => {
self.next_token();
self.expect_keyword("JOIN")?;
let relation = self.parse_table_factor()?;
let join = Join {
relation,
Join {
relation: self.parse_table_factor()?,
join_operator: JoinOperator::Cross,
};
joins.push(join);
continue;
}
Some(Token::SQLWord(kw)) if kw.keyword == "NATURAL" => {
self.next_token();
true
}
Some(_) => false,
None => return Ok(joins),
};
let peek_keyword = if let Some(Token::SQLWord(kw)) = self.peek_token() {
kw.keyword
} else {
String::default()
};
let join_operator_type = match peek_keyword.as_ref() {
"INNER" | "JOIN" => {
let _ = self.parse_keyword("INNER");
self.expect_keyword("JOIN")?;
JoinOperator::Inner
}
kw @ "LEFT" | kw @ "RIGHT" | kw @ "FULL" => {
let _ = self.next_token();
let _ = self.parse_keyword("OUTER");
self.expect_keyword("JOIN")?;
match kw {
"LEFT" => JoinOperator::LeftOuter,
"RIGHT" => JoinOperator::RightOuter,
"FULL" => JoinOperator::FullOuter,
_ => unreachable!(),
}
}
_ => break,
};
let relation = self.parse_table_factor()?;
let join_constraint = self.parse_join_constraint(natural)?;
let join = Join {
relation,
join_operator: join_operator_type(join_constraint),
};
_ => {
let natural = self.parse_keyword("NATURAL");
let peek_keyword = if let Some(Token::SQLWord(kw)) = self.peek_token() {
kw.keyword
} else {
String::default()
};
let join_operator_type = match peek_keyword.as_ref() {
"INNER" | "JOIN" => {
let _ = self.parse_keyword("INNER");
self.expect_keyword("JOIN")?;
JoinOperator::Inner
}
kw @ "LEFT" | kw @ "RIGHT" | kw @ "FULL" => {
let _ = self.next_token();
let _ = self.parse_keyword("OUTER");
self.expect_keyword("JOIN")?;
match kw {
"LEFT" => JoinOperator::LeftOuter,
"RIGHT" => JoinOperator::RightOuter,
"FULL" => JoinOperator::FullOuter,
_ => unreachable!(),
}
}
_ if natural => {
return self.expected("a join type after NATURAL", self.peek_token());
}
_ => break,
};
let relation = self.parse_table_factor()?;
let join_constraint = self.parse_join_constraint(natural)?;
Join {
relation,
join_operator: join_operator_type(join_constraint),
}
}
};
joins.push(join);
}
Ok(joins)
}

37
tests/sqlparser_common.rs
View file

@ -1218,6 +1218,43 @@ fn parse_joins_using() {
);
}
#[test]
fn parse_natural_join() {
fn natural_join(f: impl Fn(JoinConstraint) -> JoinOperator) -> Join {
Join {
relation: TableFactor::Table {
name: SQLObjectName(vec!["t2".to_string()]),
alias: None,
args: vec![],
with_hints: vec![],
},
join_operator: f(JoinConstraint::Natural),
}
}
assert_eq!(
verified_only_select("SELECT * FROM t1 NATURAL JOIN t2").joins,
vec![natural_join(JoinOperator::Inner)]
);
assert_eq!(
verified_only_select("SELECT * FROM t1 NATURAL LEFT JOIN t2").joins,
vec![natural_join(JoinOperator::LeftOuter)]
);
assert_eq!(
verified_only_select("SELECT * FROM t1 NATURAL RIGHT JOIN t2").joins,
vec![natural_join(JoinOperator::RightOuter)]
);
assert_eq!(
verified_only_select("SELECT * FROM t1 NATURAL FULL JOIN t2").joins,
vec![natural_join(JoinOperator::FullOuter)]
);
let sql = "SELECT * FROM t1 natural";
assert_eq!(
ParserError::ParserError("Expected a join type after NATURAL, found: EOF".to_string()),
parse_sql_statements(sql).unwrap_err(),
);
}
#[test]
fn parse_complex_join() {
let sql = "SELECT c1, c2 FROM t1, t4 JOIN t2 ON t2.c = t1.c LEFT JOIN t3 USING(q, c) WHERE t4.c = t1.c";