diff options
Diffstat (limited to 'askama_parser/src/expr.rs')
| -rw-r--r-- | askama_parser/src/expr.rs | 114 |
1 files changed, 81 insertions, 33 deletions
diff --git a/askama_parser/src/expr.rs b/askama_parser/src/expr.rs index 7f82266..ad0c19e 100644 --- a/askama_parser/src/expr.rs +++ b/askama_parser/src/expr.rs @@ -15,11 +15,12 @@ use super::{ macro_rules! expr_prec_layer { ( $name:ident, $inner:ident, $op:expr ) => { - fn $name(i: &'a str) -> IResult<&'a str, Self> { - let (i, left) = Self::$inner(i)?; + fn $name(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; + let (i, left) = Self::$inner(i, level)?; let (i, right) = many0(pair( ws(tag($op)), - Self::$inner, + |i| Self::$inner(i, level), ))(i)?; Ok(( i, @@ -30,11 +31,12 @@ macro_rules! expr_prec_layer { } }; ( $name:ident, $inner:ident, $( $op:expr ),+ ) => { - fn $name(i: &'a str) -> IResult<&'a str, Self> { - let (i, left) = Self::$inner(i)?; + fn $name(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; + let (i, left) = Self::$inner(i, level)?; let (i, right) = many0(pair( ws(alt(($( tag($op) ),+,))), - Self::$inner, + |i| Self::$inner(i, level), ))(i)?; Ok(( i, @@ -69,24 +71,35 @@ pub enum Expr<'a> { } impl<'a> Expr<'a> { - pub(super) fn arguments(i: &'a str) -> IResult<&'a str, Vec<Self>> { + pub(super) fn arguments(i: &'a str, level: Level) -> IResult<&'a str, Vec<Self>> { + let level = level.nest(i)?; preceded( ws(char('(')), cut(terminated( - separated_list0(char(','), ws(Self::parse)), + separated_list0(char(','), ws(move |i| Self::nested(i, level))), char(')'), )), )(i) } pub(super) fn parse(i: &'a str) -> IResult<&'a str, Self> { - let range_right = |i| pair(ws(alt((tag("..="), tag("..")))), opt(Self::or))(i); + Self::nested(i, Level::default()) + } + + fn nested(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; + let range_right = move |i| { + pair( + ws(alt((tag("..="), tag("..")))), + opt(move |i| Self::or(i, level)), + )(i) + }; alt(( map(range_right, |(op, right)| { Self::Range(op, None, right.map(Box::new)) }), map( - pair(Self::or, opt(range_right)), + pair(move |i| Self::or(i, level), opt(range_right)), |(left, right)| match right { Some((op, right)) => Self::Range(op, Some(Box::new(left)), right.map(Box::new)), None => left, @@ -105,14 +118,19 @@ impl<'a> Expr<'a> { expr_prec_layer!(addsub, muldivmod, "+", "-"); expr_prec_layer!(muldivmod, filtered, "*", "/", "%"); - fn filtered(i: &'a str) -> IResult<&'a str, Self> { - fn filter(i: &str) -> IResult<&str, (&str, Option<Vec<Expr<'_>>>)> { - let (i, (_, fname, args)) = - tuple((char('|'), ws(identifier), opt(Expr::arguments)))(i)?; + fn filtered(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; + fn filter(i: &str, level: Level) -> IResult<&str, (&str, Option<Vec<Expr<'_>>>)> { + let (i, (_, fname, args)) = tuple(( + char('|'), + ws(identifier), + opt(|i| Expr::arguments(i, level)), + ))(i)?; Ok((i, (fname, args))) } - let (i, (obj, filters)) = tuple((Self::prefix, many0(filter)))(i)?; + let (i, (obj, filters)) = + tuple((|i| Self::prefix(i, level), many0(|i| filter(i, level))))(i)?; let mut res = obj; for (fname, args) in filters { @@ -129,27 +147,32 @@ impl<'a> Expr<'a> { Ok((i, res)) } - fn prefix(i: &'a str) -> IResult<&'a str, Self> { - let (i, (ops, mut expr)) = pair(many0(ws(alt((tag("!"), tag("-"))))), Suffix::parse)(i)?; + fn prefix(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; + let (i, (ops, mut expr)) = pair(many0(ws(alt((tag("!"), tag("-"))))), |i| { + Suffix::parse(i, level) + })(i)?; for op in ops.iter().rev() { expr = Self::Unary(op, Box::new(expr)); } Ok((i, expr)) } - fn single(i: &'a str) -> IResult<&'a str, Self> { + fn single(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; alt(( Self::num, Self::str, Self::char, Self::path_var_bool, - Self::array, - Self::group, + move |i| Self::array(i, level), + move |i| Self::group(i, level), ))(i) } - fn group(i: &'a str) -> IResult<&'a str, Self> { - let (i, expr) = preceded(ws(char('(')), opt(Self::parse))(i)?; + fn group(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; + let (i, expr) = preceded(ws(char('(')), opt(|i| Self::nested(i, level)))(i)?; let expr = match expr { Some(expr) => expr, None => { @@ -166,7 +189,7 @@ impl<'a> Expr<'a> { let mut exprs = vec![expr]; let (i, _) = fold_many0( - preceded(char(','), ws(Self::parse)), + preceded(char(','), ws(|i| Self::nested(i, level))), || (), |_, expr| { exprs.push(expr); @@ -176,11 +199,15 @@ impl<'a> Expr<'a> { Ok((i, Self::Tuple(exprs))) } - fn array(i: &'a str) -> IResult<&'a str, Self> { + fn array(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; preceded( ws(char('[')), cut(terminated( - map(separated_list0(char(','), ws(Self::parse)), Self::Array), + map( + separated_list0(char(','), ws(move |i| Self::nested(i, level))), + Self::Array, + ), char(']'), )), )(i) @@ -218,13 +245,14 @@ enum Suffix<'a> { } impl<'a> Suffix<'a> { - fn parse(i: &'a str) -> IResult<&'a str, Expr<'a>> { - let (mut i, mut expr) = Expr::single(i)?; + fn parse(i: &'a str, level: Level) -> IResult<&'a str, Expr<'a>> { + let level = level.nest(i)?; + let (mut i, mut expr) = Expr::single(i, level)?; loop { let (j, suffix) = opt(alt(( Self::attr, - Self::index, - Self::call, + |i| Self::index(i, level), + |i| Self::call(i, level), Self::r#try, Self::r#macro, )))(i)?; @@ -315,18 +343,38 @@ impl<'a> Suffix<'a> { )(i) } - fn index(i: &'a str) -> IResult<&'a str, Self> { + fn index(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; map( - preceded(ws(char('[')), cut(terminated(ws(Expr::parse), char(']')))), + preceded( + ws(char('[')), + cut(terminated(ws(move |i| Expr::nested(i, level)), char(']'))), + ), Self::Index, )(i) } - fn call(i: &'a str) -> IResult<&'a str, Self> { - map(Expr::arguments, Self::Call)(i) + fn call(i: &'a str, level: Level) -> IResult<&'a str, Self> { + let level = level.nest(i)?; + map(move |i| Expr::arguments(i, level), Self::Call)(i) } fn r#try(i: &'a str) -> IResult<&'a str, Self> { map(preceded(take_till(not_ws), char('?')), |_| Self::Try)(i) } } + +#[derive(Clone, Copy, Default)] +pub(crate) struct Level(u8); + +impl Level { + fn nest(self, i: &str) -> Result<Level, nom::Err<nom::error::Error<&str>>> { + if self.0 >= Self::MAX_EXPR_DEPTH { + return Err(nom::Err::Failure(error_position!(i, ErrorKind::TooLarge))); + } + + Ok(Level(self.0 + 1)) + } + + const MAX_EXPR_DEPTH: u8 = 64; +} |