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use std::cmp::Ordering;
use std::{cmp, fmt};
use index::{ByteIndex, Index};
/// A region of code in a source file
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Ord, PartialOrd)]
#[cfg_attr(feature = "serialization", derive(Deserialize, Serialize))]
pub struct Span<I> {
start: I,
end: I,
}
impl<I: Ord> Span<I> {
/// Create a new span
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let span = Span::new(ByteIndex(3), ByteIndex(6));
/// assert_eq!(span.start(), ByteIndex(3));
/// assert_eq!(span.end(), ByteIndex(6));
/// ```
///
/// `start` and `end` are reordered to maintain the invariant that `start <= end`
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let span = Span::new(ByteIndex(6), ByteIndex(3));
/// assert_eq!(span.start(), ByteIndex(3));
/// assert_eq!(span.end(), ByteIndex(6));
/// ```
pub fn new(start: I, end: I) -> Span<I> {
if start <= end {
Span { start, end }
} else {
Span {
start: end,
end: start,
}
}
}
pub fn map<F, J>(self, mut f: F) -> Span<J>
where
F: FnMut(I) -> J,
J: Ord,
{
Span::new(f(self.start), f(self.end))
}
}
impl<I> Span<I> {
/// Get the start index
pub fn start(self) -> I {
self.start
}
/// Get the end index
pub fn end(self) -> I {
self.end
}
}
impl<I: Index> Span<I> {
/// Makes a span from offsets relative to the start of this span.
pub fn subspan(&self, begin: I::Offset, end: I::Offset) -> Span<I> {
assert!(end >= begin);
assert!(self.start() + end <= self.end());
Span {
start: self.start() + begin,
end: self.start() + end,
}
}
/// Create a new span from a byte start and an offset
pub fn from_offset(start: I, off: I::Offset) -> Span<I> {
Span::new(start, start + off)
}
/// Return a new span with the low byte position replaced with the supplied byte position
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let span = Span::new(ByteIndex(3), ByteIndex(6));
/// assert_eq!(span.with_start(ByteIndex(2)), Span::new(ByteIndex(2), ByteIndex(6)));
/// assert_eq!(span.with_start(ByteIndex(5)), Span::new(ByteIndex(5), ByteIndex(6)));
/// assert_eq!(span.with_start(ByteIndex(7)), Span::new(ByteIndex(6), ByteIndex(7)));
/// ```
pub fn with_start(self, start: I) -> Span<I> {
Span::new(start, self.end())
}
/// Return a new span with the high byte position replaced with the supplied byte position
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let span = Span::new(ByteIndex(3), ByteIndex(6));
/// assert_eq!(span.with_end(ByteIndex(7)), Span::new(ByteIndex(3), ByteIndex(7)));
/// assert_eq!(span.with_end(ByteIndex(5)), Span::new(ByteIndex(3), ByteIndex(5)));
/// assert_eq!(span.with_end(ByteIndex(2)), Span::new(ByteIndex(2), ByteIndex(3)));
/// ```
pub fn with_end(self, end: I) -> Span<I> {
Span::new(self.start(), end)
}
/// Return true if `self` fully encloses `other`.
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let a = Span::new(ByteIndex(5), ByteIndex(8));
///
/// assert_eq!(a.contains(a), true);
/// assert_eq!(a.contains(Span::new(ByteIndex(6), ByteIndex(7))), true);
/// assert_eq!(a.contains(Span::new(ByteIndex(6), ByteIndex(10))), false);
/// assert_eq!(a.contains(Span::new(ByteIndex(3), ByteIndex(6))), false);
/// ```
pub fn contains(self, other: Span<I>) -> bool {
self.start() <= other.start() && other.end() <= self.end()
}
/// Return `Equal` if `self` contains `pos`, otherwise it returns `Less` if `pos` is before
/// `start` or `Greater` if `pos` is after or at `end`.
///
/// ```rust
/// use codespan::{ByteIndex, Span};
/// use std::cmp::Ordering::*;
///
/// let a = Span::new(ByteIndex(5), ByteIndex(8));
///
/// assert_eq!(a.containment(ByteIndex(4)), Less);
/// assert_eq!(a.containment(ByteIndex(5)), Equal);
/// assert_eq!(a.containment(ByteIndex(6)), Equal);
/// assert_eq!(a.containment(ByteIndex(8)), Equal);
/// assert_eq!(a.containment(ByteIndex(9)), Greater);
/// ```
pub fn containment(self, pos: I) -> Ordering {
use std::cmp::Ordering::*;
match (pos.cmp(&self.start), pos.cmp(&self.end)) {
(Equal, _) | (_, Equal) | (Greater, Less) => Equal,
(Less, _) => Less,
(_, Greater) => Greater,
}
}
/// Return `Equal` if `self` contains `pos`, otherwise it returns `Less` if `pos` is before
/// `start` or `Greater` if `pos` is *strictly* after `end`.
///
/// ```rust
/// use codespan::{ByteIndex, Span};
/// use std::cmp::Ordering::*;
///
/// let a = Span::new(ByteIndex(5), ByteIndex(8));
///
/// assert_eq!(a.containment_exclusive(ByteIndex(4)), Less);
/// assert_eq!(a.containment_exclusive(ByteIndex(5)), Equal);
/// assert_eq!(a.containment_exclusive(ByteIndex(6)), Equal);
/// assert_eq!(a.containment_exclusive(ByteIndex(8)), Greater);
/// assert_eq!(a.containment_exclusive(ByteIndex(9)), Greater);
/// ```
pub fn containment_exclusive(self, pos: I) -> Ordering {
if self.end == pos {
Ordering::Greater
} else {
self.containment(pos)
}
}
/// Return a `Span` that would enclose both `self` and `end`.
///
/// ```plain
/// self ~~~~~~~
/// end ~~~~~~~~
/// returns ~~~~~~~~~~~~~~~~~~~~~~~
/// ```
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let a = Span::new(ByteIndex(2), ByteIndex(5));
/// let b = Span::new(ByteIndex(10), ByteIndex(14));
///
/// assert_eq!(a.to(b), Span::new(ByteIndex(2), ByteIndex(14)));
/// ```
pub fn to(self, end: Span<I>) -> Span<I> {
Span::new(
cmp::min(self.start(), end.start()),
cmp::max(self.end(), end.end()),
)
}
/// Return a `Span` between the end of `self` to the beginning of `end`.
///
/// ```plain
/// self ~~~~~~~
/// end ~~~~~~~~
/// returns ~~~~~~~~~
/// ```
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let a = Span::new(ByteIndex(2), ByteIndex(5));
/// let b = Span::new(ByteIndex(10), ByteIndex(14));
///
/// assert_eq!(a.between(b), Span::new(ByteIndex(5), ByteIndex(10)));
/// ```
pub fn between(self, end: Span<I>) -> Span<I> {
Span::new(self.end(), end.start())
}
/// Return a `Span` between the beginning of `self` to the beginning of `end`.
///
/// ```plain
/// self ~~~~~~~
/// end ~~~~~~~~
/// returns ~~~~~~~~~~~~~~~~
/// ```
///
/// ```rust
/// use codespan::{ByteIndex, Span};
///
/// let a = Span::new(ByteIndex(2), ByteIndex(5));
/// let b = Span::new(ByteIndex(10), ByteIndex(14));
///
/// assert_eq!(a.until(b), Span::new(ByteIndex(2), ByteIndex(10)));
/// ```
pub fn until(self, end: Span<I>) -> Span<I> {
Span::new(self.start(), end.start())
}
}
impl<I: fmt::Display> fmt::Display for Span<I> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.start.fmt(f)?;
write!(f, "..")?;
self.end.fmt(f)?;
Ok(())
}
}
/// A span of byte indices
pub type ByteSpan = Span<ByteIndex>;