wisp/src/syntax/ast.rs

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1.3 KiB
Rust
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use ordered_float::OrderedFloat;
use std::{
borrow::Cow,
fmt::{Display, Write},
};
/// A Wisp AST
#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
pub enum Expr<'a> {
List(Vec<Self>),
Vector(Vec<Self>),
Map(Vec<(Self, Self)>),
Symbol(Cow<'a, str>),
Keyword(Cow<'a, str>),
Number(OrderedFloat<f64>),
String(Cow<'a, str>),
}
impl<'a> Display for Expr<'a> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::List(list) => write_seq(f, list, "(", ")"),
Self::Vector(vec) => write_seq(f, vec, "[", "]"),
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Self::Map(map) => write_seq(f, map.iter().map(|(k, v)| format!("{k} {v}")), "[", "]"),
Self::Symbol(sym) => write!(f, "{sym}"),
Self::Keyword(kw) => write!(f, ":{kw}"),
Self::Number(n) => write!(f, "{n}"),
Self::String(s) => write!(f, "\"{s}\""),
}
}
}
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fn write_seq(
f: &mut impl Write,
iterable: impl IntoIterator<Item = impl Display>,
delimiter_left: &str,
delimiter_right: &str,
) -> std::fmt::Result {
let mut iter = iterable.into_iter();
write!(f, "{delimiter_left}")?;
if let Some(x) = iter.next() {
write!(f, "{x}")?;
}
for x in iter {
write!(f, " {x}")?;
}
write!(f, "{delimiter_right}")
}