lavina/src/util/xml.rs

use quick_xml::events::Event;
use quick_xml::name::ResolveResult;

use crate::prelude::Result;

mod ignore;
pub use ignore::Ignore;

pub trait FromXml: Sized {
    type P: Parser<Output = Result<Self>>;

    fn parse() -> Self::P;
}

pub trait ToXml: Sized {
    fn serialize(&self, events: &mut Vec<Event<'static>>);
}

pub trait FromXmlTag: FromXml {
    const NAME: &'static str;
    const NS: &'static str;
}

pub trait Parser: Sized {
    type Output;

    fn consume<'a>(
        self: Self,
        namespace: ResolveResult,
        event: &Event<'a>,
    ) -> Continuation<Self, Self::Output>;
}

pub enum Continuation<Parser, Res> {
    Final(Res),
    Continue(Parser),
}

macro_rules! fail_fast {
    ($errorable: expr) => {
        match $errorable {
            Ok(i) => i,
            Err(e) => return Continuation::Final(Err(e.into())),
        }
    };
}

macro_rules! delegate_parsing {
    ($parser: ident, $intermediate: ident, $namespace: expr, $event: expr) => {
        match $parser.consume($namespace, $event) {
            Continuation::Final(Ok(r)) => Continuation::Final(Ok(r.into())),
            Continuation::Final(Err(e)) => Continuation::Final(Err(e)),
            Continuation::Continue(s) => {
                let inner: $intermediate = s.into();
                Continuation::Continue(inner.into())
            }
        }
    };
}

macro_rules! match_parser {
    ($outer: ident, $name: expr, $ns: expr, $event: expr; $subtype: ty) => {
        if $name.0 == <$subtype as FromXmlTag>::NAME.as_bytes() && $ns == ResolveResult::Bound(Namespace(<$subtype as FromXmlTag>::NS.as_bytes())) {
            $outer(<$subtype as FromXml>::parse().into()).consume($ns, $event)
        } else {
            Continuation::Final(Err(ffail!("Unexpected XML event of name {:?} in namespace {:?}", $name, $ns)))
        }
    };
    ($outer: ident, $name: expr, $ns: expr, $event: expr; $subtype: ty, $($rest: ty),+) => {
        if $name.0 == <$subtype as FromXmlTag>::NAME.as_bytes() && $ns == ResolveResult::Bound(Namespace(<$subtype as FromXmlTag>::NS.as_bytes())) {
            $outer(<$subtype as FromXml>::parse().into()).consume($ns, $event)
        } else {
            match_parser!($outer, $name, $ns, $event; $($rest),*)
        }
    };
}

pub(crate) use delegate_parsing;
pub(crate) use fail_fast;
pub(crate) use match_parser;