wisp/src/syntax/ast.rs

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use ordered_float::OrderedFloat;
use std::{
fmt::{Display, Write},
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hash::Hash,
};
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pub type Span = std::ops::Range<usize>;
/// A spanned item
#[derive(Clone, Debug)]
pub struct Spanned<T> {
pub item: T,
pub span: Span,
}
impl<T> Spanned<T> {
pub fn new(item: T, span: Span) -> Self {
Self { item, span }
}
}
impl<T: Display> Display for Spanned<T> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{} \x1B[2m@ {:?}\x1B[22m", self.item, self.span)
}
}
impl<T: PartialEq> PartialEq for Spanned<T> {
fn eq(&self, other: &Self) -> bool {
self.item == other.item
}
}
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impl<T: Hash> Hash for Spanned<T> {
fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
self.item.hash(state);
}
}
/// A Wisp AST
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#[derive(Debug, Clone, Hash, PartialEq)]
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pub enum Expr<'s> {
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List(Vec<Spanned<Self>>),
Vector(Vec<Spanned<Self>>),
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Pair((Box<Spanned<Self>>, Box<Spanned<Self>>)),
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Quote(Box<Spanned<Self>>),
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Symbol(&'s str),
Keyword(&'s str),
Number(OrderedFloat<f64>),
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String(&'s str),
}
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impl<'s> Display for Expr<'s> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
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Self::List(list) => fmt_list(f, list),
Self::Vector(vec) => {
write!(f, "#")?;
fmt_list(f, vec)
}
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Self::Pair((l, r)) => write!(f, "{l} . {r}"),
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Self::Quote(expr) => write!(f, "'{expr}"),
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 fmt_list(f: &mut impl Write, iterable: &[Spanned<Expr>]) -> std::fmt::Result {
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let mut iter = iterable.iter();
write!(f, "(")?;
if let Some(i) = iter.next() {
write!(f, "{i}")?;
}
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for i in iter {
write!(f, " {i}")?;
}
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write!(f, ")")
}