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//! Parsing code related to processing analytical function calls.
use super::{MetaTracker, ParserInner, Result};
use crate::{
ast::{
Node, OrderBy, PartitionBy, PartitionByExprs, WindowFrame, WindowFrameBoundDirection,
WindowFrameBoundType, WindowFrameBounds, WindowFrameExclude, WindowFrameExcludeSubject,
WindowFrameUnit, WindowSpec, WindowSpecDetails,
},
parser::{Error, parse_comma_separated, parse_parens},
scanner::{Keyword, Reserved, Token, TokenType},
};
/// Defines different [WindowSpec] parsing modes.
#[derive(Copy, Clone)]
pub(super) enum WindowSpecMode {
/// Parsing a window spec as part of a query defintion,
/// i.e. within a `WINDOW <window_name> AS (<window_spec>)` clause
///
/// Syntax: <https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/SELECT.html#GUID-CFA006CA-6FF1-4972-821E-6996142A51C6__GUID-D600493B-4CD7-423A-A851-E12BC37E2904>
Query,
/// Parsing a window spec as part of an analytical function call,
/// e.g. within a `count(*) OVER (<window_spec>)`
///
/// Syntax: <https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Analytic-Functions.html>
Function,
/// Parsing a window spec as part of an analytical function call, without
/// support for an `order_by_clause` (and subsequently no `windowing_clause`.)
///
/// Syntax: <https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Analytic-Functions.html>
FunctionWithoutOrderBy,
/// Parsing a window spec as part of an analytical function call, without
/// support for a `windowing_clause`, ie. a [WindowFrame]
///
/// Syntax: <https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Analytic-Functions.html>
FunctionWithoutWindowFrame,
}
impl<'s, M> ParserInner<'s, M>
where
M: MetaTracker<'s>,
{
/// Parses a window specificiation, e.g. `(PARTITION BY ...)`
pub(super) fn parse_window_spec(
&mut self,
mode: WindowSpecMode,
) -> Result<Node<WindowSpec<'s, M::NodeId>, M::NodeId>> {
/// Unlike the "partition by" for join, this does not allow parentheses
fn parse_partition_by<'s, M: MetaTracker<'s>>(
parser: &mut ParserInner<'s, M>,
) -> Result<Option<PartitionBy<'s, M::NodeId>>> {
let partition_token = if let Some(Token {
ttype: TokenType::Identifier(_, Some(Reserved::PARTITION)),
loc,
}) = parser.peek_token()?
{
let loc = *loc;
parser.consume_token()?;
Node((), parser.meta_tracker.on_node_start(loc))
} else {
return Ok(None);
};
let by_token = expect_token!(|t = parser.next_token()| "the BY keyword" match {
TokenType::Keyword(Keyword::BY) => Node((), parser.meta_tracker.on_node_start(t.loc)),
});
// ~ no parantheses
let expressions = PartitionByExprs::Exprs(parse_comma_separated(parser, |parser| {
parser.parse_expr()
})?);
Ok(Some(PartitionBy {
partition_token,
by_token,
expressions,
}))
}
fn allow_order_by(mode: WindowSpecMode) -> bool {
match mode {
WindowSpecMode::Query => true,
WindowSpecMode::Function => true,
WindowSpecMode::FunctionWithoutOrderBy => false,
WindowSpecMode::FunctionWithoutWindowFrame => true,
}
}
fn allow_frame<ID>(mode: WindowSpecMode, order_by: Option<&OrderBy<'_, ID>>) -> bool {
match mode {
WindowSpecMode::Query => true,
WindowSpecMode::Function => order_by.is_some(),
WindowSpecMode::FunctionWithoutOrderBy => false,
WindowSpecMode::FunctionWithoutWindowFrame => false,
}
}
parse_parens(self, |parser, node_id| {
let window_spec = if let Some(t) = parser.peek_token()? {
match t.ttype {
TokenType::RightParen => {
// ~ we're misusing the closing paren's location for
// an artificial node to track potential comments
// within the empty paren pair
WindowSpec::Empty(Node((), {
let loc = t.loc;
parser.meta_tracker.on_node_start(loc)
}))
}
TokenType::Keyword(Keyword::ORDER) if allow_order_by(mode) => {
let order_by = parser.parse_order_by()?;
let frame =
parser.parse_window_frame_(allow_frame(mode, order_by.as_ref()))?;
WindowSpec::Details(WindowSpecDetails {
window_name: None,
partition_by: None,
order_by,
frame,
})
}
TokenType::Identifier(_, Some(Reserved::PARTITION)) => {
// ~ no need to see if "partition" could be treated as
// a window name; oracle won't allow it anyway
let partition_by = parse_partition_by(parser)?;
let (order_by, frame) = if allow_order_by(mode) {
let order_by = parser.parse_order_by()?;
let frame =
parser.parse_window_frame_(allow_frame(mode, order_by.as_ref()))?;
(order_by, frame)
} else {
(None, None)
};
WindowSpec::Details(WindowSpecDetails {
window_name: None,
partition_by,
order_by,
frame,
})
}
TokenType::Identifier(_, _) => {
let window_name = {
let_next_token!(
parser,
Token {
ttype: TokenType::Identifier(ident, _),
loc
}
);
Some(Node(ident, parser.meta_tracker.on_node_start(loc)))
};
let (order_by, frame) = if allow_order_by(mode) {
let order_by = parser.parse_order_by()?;
let frame =
parser.parse_window_frame_(allow_frame(mode, order_by.as_ref()))?;
(order_by, frame)
} else {
(None, None)
};
WindowSpec::Details(WindowSpecDetails {
window_name,
partition_by: None,
order_by,
frame,
})
}
_ => {
return Err(Error::unexpected_token(
t,
"a window name, a PARTITION BY, an ORDER BY clause, or a closing parethesis",
));
}
}
} else {
// ~ at least the closing parens should have appeared
return unexpected_eof_err!(
parser,
"a window name, a PARTITION BY, an ORDER BY clause, or a closing parethesis"
);
};
Ok(Node(window_spec, node_id))
})
}
fn parse_window_frame_(
&mut self,
// ~ `true` to attempt parsing the frame, `false` not to try at all
allow_frame: bool,
) -> Result<Option<WindowFrame<'s, M::NodeId>>> {
if !allow_frame {
return Ok(None);
}
let unit_token = if let Some(Token {
ttype: TokenType::Identifier(_, Some(reserved)),
loc,
}) = self.peek_token()?
{
let unit = match reserved {
Reserved::ROWS => WindowFrameUnit::Rows,
Reserved::RANGE => WindowFrameUnit::Range,
Reserved::GROUPS => WindowFrameUnit::Groups,
_ => return Ok(None),
};
let loc = *loc;
self.consume_token()?;
Node(unit, self.meta_tracker.on_node_start(loc))
} else {
return Ok(None);
};
enum AllowedDirections {
Both,
Preceding,
Following,
}
fn parse_direction_token<'s, M: MetaTracker<'s>>(
parser: &mut ParserInner<'s, M>,
allow: AllowedDirections,
) -> Result<Node<WindowFrameBoundDirection, M::NodeId>> {
let expected = match allow {
AllowedDirections::Both => "the PRECEDING or FOLLOWING keyword",
AllowedDirections::Preceding => "the PRECEDING keyword",
AllowedDirections::Following => "the FOLLOWING keyword",
};
match parser.next_token()? {
Some(t) => match t.ttype {
TokenType::Identifier(_, Some(Reserved::PRECEDING))
if !matches!(allow, AllowedDirections::Following) =>
{
Ok(Node(
WindowFrameBoundDirection::Preceding,
parser.meta_tracker.on_node_start(t.loc),
))
}
TokenType::Identifier(_, Some(Reserved::FOLLOWING))
if !matches!(allow, AllowedDirections::Preceding) =>
{
Ok(Node(
WindowFrameBoundDirection::Following,
parser.meta_tracker.on_node_start(t.loc),
))
}
_ => Err(Error::unexpected_token(t, expected)),
},
None => unexpected_eof_err!(parser, expected),
}
}
fn parse_bound_type<'s, M: MetaTracker<'s>>(
parser: &mut ParserInner<'s, M>,
unbounded_directions: AllowedDirections,
value_directions: AllowedDirections,
) -> Result<WindowFrameBoundType<'s, M::NodeId>> {
if let Some(t) = parser.peek_token()? {
match t.ttype {
TokenType::Identifier(_, Some(Reserved::UNBOUNDED)) => {
let unbounded_token = {
let loc = t.loc;
parser.consume_token()?;
Node((), parser.meta_tracker.on_node_start(loc))
};
let direction_token = parse_direction_token(parser, unbounded_directions)?;
return Ok(WindowFrameBoundType::Unbounded {
unbounded_token,
direction_token,
});
}
TokenType::Identifier(_, Some(Reserved::CURRENT)) => {
let current_token = {
let loc = t.loc;
parser.consume_token()?;
Node((), parser.meta_tracker.on_node_start(loc))
};
let row_token = expect_reserved!(|t = parser.next_token()| "the ROW keyword" match {
Reserved::ROW => Node((), parser.meta_tracker.on_node_start(t.loc)),
});
return Ok(WindowFrameBoundType::CurrentRow {
current_token,
row_token,
});
}
_ => {
return Ok(WindowFrameBoundType::Value {
expr: parser.parse_expr()?,
direction_token: parse_direction_token(parser, value_directions)?,
});
}
}
}
unexpected_eof_err!(
parser,
"the UNBOUNDED or CURRENT keyword or a value expression"
)
}
let bounds = match self.peek_token()? {
None => {
return unexpected_eof_err!(
self,
"the BETWEEN, UNBOUNDED, CURRENT keyword, or an expression"
);
}
Some(Token {
ttype: TokenType::Keyword(Keyword::BETWEEN),
loc,
}) => {
let between_token = {
let loc = *loc;
self.consume_token()?;
Node((), self.meta_tracker.on_node_start(loc))
};
let start =
parse_bound_type(self, AllowedDirections::Preceding, AllowedDirections::Both)?;
let and_token = expect_token!(|t = self.next_token()| "the AND keyword" match {
TokenType::Keyword(Keyword::AND) => Node((), self.meta_tracker.on_node_start(t.loc)),
});
let end = parse_bound_type(
self,
AllowedDirections::Following,
/*
// https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Analytic-Functions.html#GUID-527832F7-63C0-4445-8C16-307FA5084056__GUID-0A0B25DD-63EC-4C45-A2E5-01123E3E2AFA
For `RANGE` or `ROW`:
- If `value_expr FOLLOWING` is the start point, then the end point must be `value_expr FOLLOWING`.
- If `value_expr PRECEDING` is the end point, then the start point must be `value_expr PRECEDING`.
Personal note: on Oracle 21, this applies to the `GROUPS` unit as well.
Also: `... rows between unbounded preceding and 1 preceding` works fine despite the start bound not being a `<value_expr> preceding`
*/
match &start {
// ~ can only be "preceding", hence, making it work with `<value_expr> [preceding|following]` as an end bound
WindowFrameBoundType::Unbounded { .. } => AllowedDirections::Both,
// ~ effectively enforcing the second rule stated above
WindowFrameBoundType::CurrentRow { .. } => AllowedDirections::Following,
WindowFrameBoundType::Value {
direction_token: Node(direction, _),
..
} => match direction {
WindowFrameBoundDirection::Preceding => AllowedDirections::Both,
WindowFrameBoundDirection::Following => AllowedDirections::Following,
},
},
)?;
WindowFrameBounds::Between {
between_token,
start,
and_token,
end,
}
}
_ => WindowFrameBounds::Start(parse_bound_type(
self,
AllowedDirections::Preceding,
AllowedDirections::Preceding,
)?),
};
let exclude = self.parse_window_frame_exclude_()?;
Ok(Some(WindowFrame {
unit_token,
bounds,
exclude,
}))
}
fn parse_window_frame_exclude_(&mut self) -> Result<Option<WindowFrameExclude<M::NodeId>>> {
if let Some(Token {
ttype: TokenType::Identifier(_, Some(Reserved::EXCLUDE)),
loc,
}) = self.peek_token()?
{
let exclude_token = {
let loc = *loc;
self.consume_token()?;
Node((), self.meta_tracker.on_node_start(loc))
};
let subject = expect_token!(|t = self.next_token()| "the CURRENT [ROW], GROUPS, TIES, or NO [OTHERS] keyword" match {
TokenType::Keyword(Keyword::GROUP) => {
WindowFrameExcludeSubject::Group {
group_token: Node((), self.meta_tracker.on_node_start(t.loc)),
}
}
TokenType::Identifier(_, Some(Reserved::CURRENT)) => {
let current_token = Node((), self.meta_tracker.on_node_start(t.loc));
let row_token = expect_reserved!(|t = self.next_token()| "the ROW keyword" match {
Reserved::ROW => Node((), self.meta_tracker.on_node_start(t.loc)),
});
WindowFrameExcludeSubject::CurrentRow { current_token, row_token }
},
TokenType::Identifier(_, Some(Reserved::TIES)) => {
WindowFrameExcludeSubject::Ties { ties_token: Node((), self.meta_tracker.on_node_start(t.loc)) }
}
TokenType::Identifier(_, Some(Reserved::NO)) => {
let no_token = Node((), self.meta_tracker.on_node_start(t.loc));
let others_token = expect_reserved!(|t = self.next_token()| "the OTHERS keyword" match {
Reserved::OTHERS => Node((), self.meta_tracker.on_node_start(t.loc)),
});
WindowFrameExcludeSubject::NoOthers { no_token, others_token }
}
});
Ok(Some(WindowFrameExclude {
exclude_token,
subject,
}))
} else {
Ok(None)
}
}
}