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

use array::array;
use enumset::{enum_set, EnumSet};
use pawarser::parser::ParserBuilder;

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

use self::object::object;

mod array;
mod 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()
    }
}

#[cfg(test)]
mod tests {
    use super::{
        test_utils::{check_parser, gen_checks},
        value,
    };

    #[test]
    fn value_lit() {
        gen_checks! {value;
            r#""helo world""# => r#"ROOT { STRING "\"helo world\""; }"#,
            "42" => r#"ROOT { NUMBER "42"; }"#,
            "null" => r#"ROOT { NULL "null"; }"#,
            "true" => r#"ROOT { BOOL "true"; }"#,
            "false" => r#"ROOT { BOOL "false"; }"#
        };
    }
}

#[cfg(test)]
mod test_utils {
    use pawarser::parser::ParserBuilder;

    use crate::syntax_kind::{lex, SyntaxKind};

    use super::Parser;

    macro_rules! gen_checks {
        ($fn_to_test:ident; $($in:literal => $out:literal),+) => {
            $(crate::grammar::test_utils::check_parser($in, |p| { $fn_to_test(p); }, $out);)+
        }
    }

    pub(super) use gen_checks;

    pub(super) fn check_parser(input: &str, parser_fn: fn(&mut Parser), expected_output: &str) {
        let toks = lex(input);
        let mut p: Parser = ParserBuilder::new(toks)
            .add_meaningless(SyntaxKind::WHITESPACE)
            .add_meaningless(SyntaxKind::NEWLINE)
            .build();

        parser_fn(&mut p);

        let out = p.finish();

        assert_eq!(format!("{out:?}").trim_end(), expected_output);
    }
}