Struct pest_meta::parser::ParserNode

source ·

pub struct ParserNode<'i> {
    pub expr: ParserExpr<'i>,
    pub span: Span<'i>,
}

Expand description

The pest grammar node

Fields§

§expr: ParserExpr<'i>

The node’s expression

§span: Span<'i>

The node’s span

Implementations§

source §

impl<'i> ParserNode<'i>

source

pub fn filter_map_top_down<F, T>(self, f: F) -> Vec<T>where
F: FnMut(ParserNode<'i>) -> Option<T>,

will remove nodes that do not match f

Examples found in repository ?

src/validator.rs (lines 307-336)

fn validate_repetition<'a, 'i: 'a>(rules: &'a [ParserRule<'i>]) -> Vec<Error<Rule>> {
    let mut result = vec![];
    let map = to_hash_map(rules);

    for rule in rules {
        let mut errors = rule.node
            .clone()
            .filter_map_top_down(|node| match node.expr {
                ParserExpr::Rep(ref other)
                | ParserExpr::RepOnce(ref other)
                | ParserExpr::RepMin(ref other, _) => {
                    if is_non_failing(&other.expr, &map, &mut vec![]) {
                        Some(Error::new_from_span(
                            ErrorVariant::CustomError {
                                message:
                                    "expression inside repetition cannot fail and will repeat \
                                     infinitely"
                                        .to_owned()
                            },
                            node.span
                        ))
                    } else if is_non_progressing(&other.expr, &map, &mut vec![]) {
                        Some(Error::new_from_span(
                            ErrorVariant::CustomError {
                                message:
                                    "expression inside repetition is non-progressing and will repeat \
                                     infinitely"
                                        .to_owned(),
                            },
                            node.span
                        ))
                    } else {
                        None
                    }
                }
                _ => None
            });

        result.append(&mut errors);
    }

    result
}

fn validate_choices<'a, 'i: 'a>(rules: &'a [ParserRule<'i>]) -> Vec<Error<Rule>> {
    let mut result = vec![];
    let map = to_hash_map(rules);

    for rule in rules {
        let mut errors = rule
            .node
            .clone()
            .filter_map_top_down(|node| match node.expr {
                ParserExpr::Choice(ref lhs, _) => {
                    let node = match lhs.expr {
                        ParserExpr::Choice(_, ref rhs) => rhs,
                        _ => lhs,
                    };

                    if is_non_failing(&node.expr, &map, &mut vec![]) {
                        Some(Error::new_from_span(
                            ErrorVariant::CustomError {
                                message:
                                    "expression cannot fail; following choices cannot be reached"
                                        .to_owned(),
                            },
                            node.span,
                        ))
                    } else {
                        None
                    }
                }
                _ => None,
            });

        result.append(&mut errors);
    }

    result
}