iowo/crates/json-pawarser/src/grammar.rs

use array::array;
use enumset::{enum_set, EnumSet};

use crate::{syntax_error::SyntaxError, syntax_kind::SyntaxKind};

use self::object::object;

pub(crate) type Parser<'src> = pawarser::Parser<'src, SyntaxKind, SyntaxError>;
pub(crate) type CompletedMarker = pawarser::CompletedMarker<SyntaxKind, SyntaxError>;

const BASIC_VALUE_TOKENS: EnumSet<SyntaxKind> =
    enum_set!(SyntaxKind::BOOL | SyntaxKind::NULL | SyntaxKind::NUMBER | SyntaxKind::STRING);

pub fn value(p: &mut Parser) -> bool {
    if BASIC_VALUE_TOKENS.contains(p.current()) {
        p.do_bump();
        return true;
    } else {
        object(p).or_else(|| array(p)).is_some()
    }
}

mod object {
    use crate::{grammar::value, syntax_error::SyntaxError, syntax_kind::SyntaxKind};

    use super::{CompletedMarker, Parser, BASIC_VALUE_TOKENS};

    pub(super) fn object(p: &mut Parser) -> Option<CompletedMarker> {
        let obj_start = p.start("object");

        if !p.eat(SyntaxKind::BRACE_OPEN) {
            obj_start.abandon(p);
            return None;
        }

        member(p);
        while p.at(SyntaxKind::COMMA) {
            // not always an error, later configurable
            let potential_trailing_comma = p.start("potential_trailing_comma");
            p.eat(SyntaxKind::COMMA);

            if member(p).is_none() {
                potential_trailing_comma.complete(p, SyntaxKind::TRAILING_COMMA);
            } else {
                potential_trailing_comma.abandon(p);
            }
        }

        Some(if !p.eat(SyntaxKind::BRACE_CLOSE) {
            obj_start.error(p, SyntaxError::UnclosedObject)
        } else {
            obj_start.complete(p, SyntaxKind::OBJECT)
        })
    }

    fn member(p: &mut Parser) -> Option<CompletedMarker> {
        let member_start = p.start("member");

        if p.at(SyntaxKind::BRACE_CLOSE) {
            member_start.abandon(p);
            return None;
        } else if p.at(SyntaxKind::STRING) {
            let member_name_start = p.start("member_name");
            p.eat(SyntaxKind::STRING);
            member_name_start.complete(p, SyntaxKind::MEMBER_NAME);
        } else {
            return todo!("handle other tokens: {:?}", p.current());
        }

        if !p.eat(SyntaxKind::COLON) {
            todo!("handle wrong tokens")
        }

        let member_value_start = p.start("member_value_start");
        if value(p) {
            member_value_start.complete(p, SyntaxKind::MEMBER_VALUE);
            Some(member_start.complete(p, SyntaxKind::MEMBER))
        } else {
            member_value_start.abandon(p);
            let e = member_start.error(p, SyntaxError::MemberMissingValue);
            Some(
                e.precede(p, "member but failed already")
                    .complete(p, SyntaxKind::MEMBER),
            )
        }
    }
}
mod array {
    use crate::{syntax_error::SyntaxError, syntax_kind::SyntaxKind};

    use super::{value, CompletedMarker, Parser};

    pub(super) fn array(p: &mut Parser) -> Option<CompletedMarker> {
        let array_start = p.start("array");

        if !p.eat(SyntaxKind::BRACKET_OPEN) {
            array_start.abandon(p);
            return None;
        }

        let el = p.start("arr_el");
        value(p);
        el.complete(p, SyntaxKind::ELEMENT);

        while p.at(SyntaxKind::COMMA) {
            let potential_trailing_comma = p.start("potential_trailing_comma");

            p.eat(SyntaxKind::COMMA);
            let maybe_el = p.start("arr_el");
            if !value(p) {
                maybe_el.abandon(p);
                potential_trailing_comma.complete(p, SyntaxKind::TRAILING_COMMA);
            } else {
                maybe_el.complete(p, SyntaxKind::ELEMENT);
                potential_trailing_comma.abandon(p);
            }
        }

        Some(if !p.eat(SyntaxKind::BRACKET_CLOSE) {
            array_start.error(p, SyntaxError::UnclosedArray)
        } else {
            array_start.complete(p, SyntaxKind::ARRAY)
        })
    }
}