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use std::rc::Rc;
/// A location in the source text
#[derive(Debug, Clone)]
pub struct ParsedSpan {
input: Rc<str>,
/// # Safety
///
/// Must be a valid character boundary index into `input`.
start: usize,
/// # Safety
///
/// Must be a valid character boundary index into `input`.
end: usize,
}
#[derive(Debug, Clone)]
pub enum Span {
/// A location in the source text
Parsed(ParsedSpan),
/// For expressions obtained from decoding binary
Decoded,
/// For expressions constructed during normalization/typecheck
Artificial,
}
impl Span {
pub(crate) fn make(input: Rc<str>, sp: pest::Span) -> Self {
Span::Parsed(ParsedSpan {
input,
start: sp.start(),
end: sp.end(),
})
}
/// Takes the union of the two spans, i.e. the range of input covered by the two spans plus any
/// input between them. Assumes that the spans come from the same input. Fails if one of the
/// spans does not point to an input location.
pub fn union(&self, other: &Span) -> Self {
use std::cmp::{max, min};
use Span::*;
match (self, other) {
(Parsed(x), Parsed(y)) if Rc::ptr_eq(&x.input, &y.input) => {
Parsed(ParsedSpan {
input: x.input.clone(),
start: min(x.start, y.start),
end: max(x.end, y.end),
})
}
_ => panic!(
"Tried to union incompatible spans: {:?} and {:?}",
self, other
),
}
}
/// Merges two spans assumed to point to a similar thing. If only one of them points to an
/// input location, use that one.
pub fn merge(&self, other: &Span) -> Self {
use Span::*;
match (self, other) {
(Parsed(x), _) | (_, Parsed(x)) => Parsed(x.clone()),
(Artificial, _) | (_, Artificial) => Artificial,
(Decoded, Decoded) => Decoded,
}
}
pub fn error(&self, message: impl Into<String>) -> String {
use pest::error::{Error, ErrorVariant};
use pest::Span;
let message: String = message.into();
let span = match self {
self::Span::Parsed(span) => span,
_ => return format!("[unknown location] {}", message),
};
let span = Span::new(&*span.input, span.start, span.end).unwrap();
let err: ErrorVariant<!> = ErrorVariant::CustomError { message };
let err = Error::new_from_span(err, span);
format!("{}", err)
}
}
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