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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),
/// Desugarings
DuplicateRecordFieldsSugar,
DottedFieldSugar,
RecordPunSugar,
/// For expressions obtained from decoding binary
Decoded,
/// For expressions constructed during normalization/typecheck
Artificial,
}
impl ParsedSpan {
pub fn to_input(&self) -> String {
self.input.to_string()
}
/// Convert to a char range for consumption by annotate_snippets.
/// This compensates for https://github.com/rust-lang/annotate-snippets-rs/issues/24
pub fn as_char_range(&self) -> (usize, usize) {
(
char_idx_from_byte_idx(&self.input, self.start),
char_idx_from_byte_idx(&self.input, self.end),
)
}
}
impl Span {
pub 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),
})
}
(Parsed(_), Parsed(_)) => panic!(
"Tried to union incompatible spans: {:?} and {:?}",
self, other
),
(Parsed(x), _) => Parsed(x.clone()),
(_, Parsed(x)) => Parsed(x.clone()),
_ => panic!(
"Tried to union incompatible spans: {:?} and {:?}",
self, other
),
}
}
}
/// Convert a byte idx into a string into a char idx for consumption by annotate_snippets.
/// The byte idx must be at a char boundary.
fn char_idx_from_byte_idx(input: &str, idx: usize) -> usize {
use std::iter::once;
input
.char_indices()
.map(|(byte_i, _)| byte_i) // We don't care about the char
.chain(once(input.len())) // In case the idx points to the end of the string
.enumerate()
.find(|(_, byte_i)| *byte_i == idx)
.map(|(char_i, _)| char_i)
.unwrap()
}
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