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//! Spans map elements to the part of source code they originate from.
use std::fmt::{self, Display, Formatter};
/// Annotates a value with the part of the source code it corresponds to.
#[derive(Copy, Clone, Eq, PartialEq)]
pub struct Spanned<T> {
pub v: T,
pub span: Span,
}
impl<T> Spanned<T> {
pub fn new(v: T, span: Span) -> Spanned<T> {
Spanned { v, span }
}
pub fn value(self) -> T {
self.v
}
pub fn map<F, U>(self, f: F) -> Spanned<U> where F: FnOnce(T) -> U {
Spanned::new(f(self.v), self.span)
}
}
impl<T> Display for Spanned<T> where T: std::fmt::Debug {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "({:?}:{})", self.v, self.span)
}
}
debug_display!(Spanned; T where T: std::fmt::Debug);
/// Describes a slice of source code.
#[derive(Copy, Clone, Eq, PartialEq)]
pub struct Span {
pub start: usize,
pub end: usize,
}
impl Span {
pub fn new(start: usize, end: usize) -> Span {
Span { start, end }
}
pub fn merge(a: Span, b: Span) -> Span {
Span {
start: a.start.min(b.start),
end: a.end.max(b.end),
}
}
pub fn at(index: usize) -> Span {
Span { start: index, end: index + 1 }
}
pub fn pair(&self) -> (usize, usize) {
(self.start, self.end)
}
pub fn expand(&mut self, other: Span) {
*self = Span::merge(*self, other)
}
}
impl Display for Span {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "[{}, {}]", self.start, self.end)
}
}
debug_display!(Span);
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