use crate::*;

/// Show one item if a condition is true and another if the condition is false
pub struct Either<A, B>(pub bool, pub A, pub B);
impl<A, B> Either<A, B> {
    /// Create a ternary condition.
    pub const fn new (c: bool, a: A, b: B) -> Self {
        Self(c, a, b)
    }
}
#[cfg(feature = "dsl")] take!(Either<A, B>, A, B|state, words|Ok(
if let Some(Token { value: Value::Key("either"), .. }) = words.peek() {
    let base = words.clone();
    let _ = words.next().unwrap();
    return Ok(Some(Self(
        state.give_or_fail(words, ||"either: no condition")?,
        state.give_or_fail(words, ||"either: no content 1")?,
        state.give_or_fail(words, ||"either: no content 2")?,
    )))
} else {
    None
}));
impl<E: Output, A: Render<E>, B: Render<E>> Content<E> for Either<A, B> {
    fn layout (&self, to: E::Area) -> E::Area {
        let Self(cond, a, b) = self;
        if *cond { a.layout(to) } else { b.layout(to) }
    }
    fn render (&self, to: &mut E) {
        let Self(cond, a, b) = self;
        if *cond { a.render(to) } else { b.render(to) }
    }
}