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use core::fmt;
use core::ops;
use crate::index::Index;
/// A span in the source code, akin to `start..end` so the end of the span is
/// exclusive.
#[derive(Clone, Copy, Eq, PartialOrd, Ord, Hash)]
#[non_exhaustive]
pub struct Span<I> {
/// The start of the span.
pub start: I,
/// The end of the span.
pub end: I,
}
impl<A, B> PartialEq<Span<A>> for Span<B>
where
B: PartialEq<A>,
{
fn eq(&self, other: &Span<A>) -> bool {
self.start == other.start && self.end == other.end
}
}
impl<I> Span<I> {
/// Construct a new span.
///
/// # Examples
///
/// ```
/// use syntree::Span;
///
/// let span = Span::new(4u32, 8u32);
///
/// assert_eq!(span.start, 4);
/// assert_eq!(span.end, 8);
/// ```
#[must_use]
pub const fn new(start: I, end: I) -> Self {
Self { start, end }
}
/// Construct a span corresponding to the given point.
///
/// # Examples
///
/// ```
/// use syntree::Span;
///
/// assert_eq!(Span::point(4u32), Span::new(4u32, 4u32));
/// ```
#[must_use]
pub const fn point(at: I) -> Self
where
I: Copy,
{
Self { start: at, end: at }
}
/// Join the current span with another.
///
/// # Examples
///
/// ```
/// use syntree::Span;
///
/// let a = Span::new(4u32, 8u32);
/// let b = Span::new(5u32, 9u32);
///
/// let span = a.join(&b);
///
/// assert_eq!(span.start, 4);
/// assert_eq!(span.end, 9);
/// assert_eq!(span, b.join(&a));
/// ```
#[must_use]
#[inline]
pub fn join(&self, other: &Self) -> Self
where
I: Copy + Ord,
{
Self {
start: self.start.min(other.start),
end: self.end.max(other.end),
}
}
/// Test if the span is empty.
///
/// # Examples
///
/// ```
/// use syntree::Span;
///
/// assert!(Span::new(0u32, 0u32).is_empty());
/// assert!(!Span::new(0u32, 10u32).is_empty());
/// ```
#[must_use]
#[inline]
pub fn is_empty(&self) -> bool
where
I: Eq,
{
self.end == self.start
}
/// Test if span contains the given index.
///
/// # Examples
///
/// ```
/// use syntree::Span;
///
/// assert!(!Span::new(2u32, 2u32).contains(&2));
/// assert!(Span::new(2u32, 3u32).contains(&2));
/// assert!(!Span::new(2u32, 3u32).contains(&3));
/// ```
#[must_use]
#[inline]
pub fn contains<U>(self, index: &U) -> bool
where
I: PartialOrd<U>,
U: PartialOrd<I> + ?Sized,
{
&self.start <= index && index < &self.end
}
}
impl<I> Span<I>
where
I: Index,
{
/// Coerce into a [`ops::Range`] which is useful for slicing.
///
/// # Examples
///
/// ```
/// use syntree::Span;
///
/// let a = Span::new(4u32, 8u32);
///
/// assert_eq!(a.range(), 4..8);
/// ```
#[must_use]
pub fn range(self) -> ops::Range<usize> {
self.start.as_usize()..self.end.as_usize()
}
/// The length of the span.
///
/// # Examples
///
/// ```
/// use syntree::Span;
///
/// assert_eq!(Span::new(0u32, 0u32).len(), 0);
/// assert_eq!(Span::new(0u32, 10u32).len(), 10);
/// ```
#[must_use]
#[inline]
pub fn len(&self) -> I::Length {
self.start.len_to(self.end)
}
}
impl<I> fmt::Display for Span<I>
where
I: fmt::Display,
{
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}..{}", self.start, self.end)
}
}
impl<I> fmt::Debug for Span<I>
where
I: fmt::Debug,
{
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
(&self.start, &self.end).fmt(f)
}
}
impl<I> PartialEq<&Span<I>> for Span<I>
where
I: PartialEq,
{
#[inline]
fn eq(&self, other: &&Span<I>) -> bool {
*self == **other
}
}
impl<I> PartialEq<Span<I>> for &Span<I>
where
I: PartialEq,
{
#[inline]
fn eq(&self, other: &Span<I>) -> bool {
**self == *other
}
}