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//! Expression parsing (`WHERE`/`HAVING`): the `AND`/`OR`/`NOT` precedence
//! chain down to comparisons, `IS [NOT] NULL`, `LIKE`, `IN`, `BETWEEN`,
//! `EXISTS`, and subquery comparisons.
use alloc::boxed::Box;
use alloc::string::ToString;
use alloc::vec::Vec;
use super::ast::{AggregateFunc, CmpOp, DateTimeField, Expr, Literal, ParseError};
use super::lexer::{
eq_ignore_case, expect_ident, expect_int, expect_kw, expect_tok, is_kw, Tok, TokenStream,
};
use super::select::parse_select_inner;
pub(super) fn parse_expr(ts: &mut TokenStream) -> Result<Expr, ParseError> {
// Depth is guarded once per recursive-descent level in `parse_primary_expr`
// (the only caller of which is, transitively, this function) — guarding
// here too would double-count every paren/subquery nesting level.
parse_or(ts)
}
fn parse_or(ts: &mut TokenStream) -> Result<Expr, ParseError> {
let mut left = parse_and(ts)?;
loop {
if let Tok::Ident(kw) = ts.peek() {
if eq_ignore_case(&kw, "or") {
ts.next();
let right = parse_and(ts)?;
left = Expr::Or(Box::new(left), Box::new(right));
continue;
}
}
break;
}
Ok(left)
}
fn parse_and(ts: &mut TokenStream) -> Result<Expr, ParseError> {
let mut left = parse_not(ts)?;
loop {
if let Tok::Ident(kw) = ts.peek() {
if eq_ignore_case(&kw, "and") {
ts.next();
let right = parse_not(ts)?;
left = Expr::And(Box::new(left), Box::new(right));
continue;
}
}
break;
}
Ok(left)
}
fn parse_not(ts: &mut TokenStream) -> Result<Expr, ParseError> {
if let Tok::Ident(kw) = ts.peek() {
if eq_ignore_case(&kw, "not") {
ts.next();
ts.enter_depth()?;
let inner = parse_not(ts);
ts.exit_depth();
return Ok(Expr::Not(Box::new(inner?)));
}
}
parse_primary_expr(ts)
}
fn parse_primary_expr(ts: &mut TokenStream) -> Result<Expr, ParseError> {
ts.enter_depth()?;
let result = match ts.peek() {
Tok::Ident(kw) if eq_ignore_case(&kw, "exists") => {
ts.next();
expect_tok(ts, Tok::LParen, "'(' after EXISTS")?;
expect_kw(ts, "select")?;
let query = parse_select_inner(ts)?;
expect_tok(ts, Tok::RParen, "')' after EXISTS subquery")?;
Ok(Expr::Exists {
query: Box::new(query),
})
}
Tok::Ident(kw)
if matches!(
kw.to_ascii_lowercase().as_str(),
"count" | "sum" | "avg" | "min" | "max"
) =>
{
let func = match kw.to_ascii_lowercase().as_str() {
"count" => AggregateFunc::Count,
"sum" => AggregateFunc::Sum,
"avg" => AggregateFunc::Avg,
"min" => AggregateFunc::Min,
"max" => AggregateFunc::Max,
_ => unreachable!(),
};
ts.next();
expect_tok(ts, Tok::LParen, "'(' after aggregate function")?;
let col = if let Tok::Star = ts.peek() {
ts.next();
expect_tok(ts, Tok::RParen, "')'")?;
"*".to_string()
} else {
let c = expect_ident(ts, "column in aggregate")?;
expect_tok(ts, Tok::RParen, "')'")?;
c
};
match ts.peek() {
Tok::Op(op) => {
ts.next();
let value = parse_literal(ts)?;
Ok(Expr::AggCmp {
func,
column: col,
op,
value,
})
}
_ => Ok(Expr::Agg { func, column: col }),
}
}
Tok::Ident(kw) if eq_ignore_case(&kw, "extract") => {
ts.next();
expect_tok(ts, Tok::LParen, "'(' after EXTRACT")?;
let field = match ts.next() {
Tok::Ident(f) if eq_ignore_case(&f, "year") => DateTimeField::Year,
Tok::Ident(f) if eq_ignore_case(&f, "month") => DateTimeField::Month,
Tok::Ident(f) if eq_ignore_case(&f, "day") => DateTimeField::Day,
Tok::Ident(f) if eq_ignore_case(&f, "hour") => DateTimeField::Hour,
Tok::Ident(f) if eq_ignore_case(&f, "minute") => DateTimeField::Minute,
Tok::Ident(f) if eq_ignore_case(&f, "second") => DateTimeField::Second,
other => {
return Err(ParseError(alloc::format!(
"expected date/time field (YEAR/MONTH/DAY/HOUR/MINUTE/SECOND) in EXTRACT, \
got '{other:?}'"
)));
}
};
expect_kw(ts, "from")?;
let source = expect_ident(ts, "column name in EXTRACT")?;
expect_tok(ts, Tok::RParen, "')' after EXTRACT")?;
match ts.peek() {
Tok::Ident(kw) if eq_ignore_case(&kw, "is") => {
ts.next();
let negated = match ts.next() {
Tok::Ident(kw) if eq_ignore_case(&kw, "not") => {
expect_kw(ts, "null")?;
true
}
Tok::Ident(kw) if eq_ignore_case(&kw, "null") => false,
_ => {
return Err(ParseError(
"expected NULL or NOT NULL after IS".to_string(),
))
}
};
Ok(Expr::IsNull {
column: source,
negated,
})
}
Tok::Op(op) => {
ts.next();
let value = parse_literal(ts)?;
Ok(Expr::ExtractCmp {
field,
source,
op,
value,
})
}
_ => Err(ParseError(
"expected comparison operator or IS NULL after EXTRACT(...)".to_string(),
)),
}
}
Tok::Ident(col) => {
ts.next();
if is_kw(&col) {
return Err(ParseError(alloc::format!(
"unexpected keyword '{col}' in expression"
)));
}
let mut col_name = col.to_string();
if let Tok::Dot = ts.peek() {
ts.next();
let field = expect_ident(ts, "field name after '.'")?;
col_name = alloc::format!("{col_name}.{field}");
}
match ts.peek() {
Tok::Ident(kw) if eq_ignore_case(&kw, "is") => {
ts.next();
let negated = match ts.next() {
Tok::Ident(kw) if eq_ignore_case(&kw, "not") => {
expect_kw(ts, "null")?;
true
}
Tok::Ident(kw) if eq_ignore_case(&kw, "null") => false,
_ => {
return Err(ParseError(
"expected NULL or NOT NULL after IS".to_string(),
))
}
};
Ok(Expr::IsNull {
column: col_name,
negated,
})
}
Tok::Ident(kw) if eq_ignore_case(&kw, "like") => {
ts.next();
let pattern = match ts.next() {
Tok::Text(s) => s.to_string(),
_ => {
return Err(ParseError(
"expected pattern string after LIKE".to_string(),
))
}
};
Ok(Expr::Like {
column: col_name,
pattern,
})
}
Tok::Ident(kw) if eq_ignore_case(&kw, "between") => {
ts.next();
let low = expect_int(ts, "BETWEEN low")?;
expect_kw(ts, "and")?;
let high = expect_int(ts, "BETWEEN high")?;
Ok(Expr::BetweenInt {
column: col_name,
low,
high,
})
}
Tok::Ident(kw) if eq_ignore_case(&kw, "in") => {
ts.next();
expect_tok(ts, Tok::LParen, "'(' after IN")?;
let is_subquery = if let Tok::Ident(k2) = ts.peek() {
eq_ignore_case(&k2, "select")
} else {
false
};
if is_subquery {
ts.next();
let query = parse_select_inner(ts)?;
expect_tok(ts, Tok::RParen, "')' after IN subquery")?;
Ok(Expr::InSubquery {
column: col_name,
query: Box::new(query),
})
} else {
let mut values = Vec::new();
loop {
values.push(expect_int(ts, "value in IN list")?);
match ts.next() {
Tok::Comma => continue,
Tok::RParen => break,
_ => {
return Err(ParseError(
"expected ',' or ')' in IN list".to_string(),
))
}
}
}
Ok(Expr::InInt {
column: col_name,
values,
})
}
}
Tok::Op(op) => {
ts.next();
match ts.peek() {
Tok::Ident(kw) if eq_ignore_case(&kw, "null") => {
ts.next();
match op {
CmpOp::Eq => Ok(Expr::IsNull {
column: col_name,
negated: false,
}),
CmpOp::Ne => Ok(Expr::IsNull {
column: col_name,
negated: true,
}),
_ => Err(ParseError(
"comparison with NULL requires IS / IS NOT".to_string(),
)),
}
}
Tok::Int(v) => {
ts.next();
Ok(Expr::Cmp {
column: col_name,
op,
value: Literal::Int(v),
})
}
Tok::Float(v) => {
ts.next();
Ok(Expr::Cmp {
column: col_name,
op,
value: Literal::Float(v),
})
}
Tok::Text(s) => {
ts.next();
Ok(Expr::Cmp {
column: col_name,
op,
value: Literal::Text(s.to_string()),
})
}
Tok::Ident(right) => {
ts.next();
let mut right = right.to_string();
if let Tok::Dot = ts.peek() {
ts.next();
let field = expect_ident(ts, "field name after '.'")?;
right = alloc::format!("{right}.{field}");
}
Ok(Expr::CmpColumn {
left: col_name,
op,
right,
})
}
Tok::LParen => {
ts.next();
expect_kw(ts, "select")?;
let query = parse_select_inner(ts)?;
expect_tok(ts, Tok::RParen, "')' after scalar subquery")?;
Ok(Expr::ScalarCmp {
column: col_name,
op,
query: Box::new(query),
})
}
_ => Err(ParseError("expected value after operator".to_string())),
}
}
_ => Err(ParseError(
"expected operator or IS after column name".to_string(),
)),
}
}
Tok::LParen => {
ts.next();
let inner = parse_expr(ts)?;
expect_tok(ts, Tok::RParen, "')'")?;
Ok(inner)
}
_ => Err(ParseError(
"expected column name or '(' in expression".to_string(),
)),
};
ts.exit_depth();
result
}
fn parse_vector_literal(ts: &mut TokenStream) -> Result<Literal, ParseError> {
let mut vals = Vec::new();
loop {
match ts.peek() {
Tok::Float(v) => {
vals.push(v);
ts.next();
}
Tok::Int(v) => {
vals.push(v as f32);
ts.next();
}
Tok::RBracket => {
ts.next();
break;
}
_ => {
return Err(ParseError(
"expected number or ']' in vector literal".to_string(),
))
}
}
if let Tok::Comma = ts.peek() {
ts.next();
}
}
Ok(Literal::Vector(vals))
}
pub(super) fn parse_literal(ts: &mut TokenStream) -> Result<Literal, ParseError> {
match ts.next() {
Tok::Int(v) => Ok(Literal::Int(v)),
Tok::Float(v) => Ok(Literal::Float(v)),
Tok::Text(s) => Ok(Literal::Text(s.to_string())),
Tok::LBracket => parse_vector_literal(ts),
Tok::Ident(kw) if eq_ignore_case(&kw, "null") => Ok(Literal::Null),
_ => Err(ParseError("expected a value".to_string())),
}
}