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use std::fmt::{self, Debug, Formatter};
use std::ops::{Add, Range};
use serde::{Deserialize, Serialize};
/// A value with the span it corresponds to in the source code.
#[derive(Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
#[derive(Serialize, Deserialize)]
pub struct Spanned<T> {
/// The spanned value.
pub v: T,
/// The location in source code of the value.
pub span: Span,
}
impl<T> Spanned<T> {
/// Create a new instance from a value and its span.
pub fn new(v: T, span: impl Into<Span>) -> Self {
Self { v, span: span.into() }
}
/// Create a new instance from a value with the zero span.
pub fn zero(v: T) -> Self {
Self { v, span: Span::ZERO }
}
/// Convert from `&Spanned<T>` to `Spanned<&T>`
pub fn as_ref(&self) -> Spanned<&T> {
Spanned { v: &self.v, span: self.span }
}
/// Map the value using a function keeping the span.
pub fn map<F, U>(self, f: F) -> Spanned<U>
where
F: FnOnce(T) -> U,
{
Spanned { v: f(self.v), span: self.span }
}
}
impl<T: Debug> Debug for Spanned<T> {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
self.v.fmt(f)?;
if f.alternate() {
f.write_str(" <")?;
self.span.fmt(f)?;
f.write_str(">")?;
}
Ok(())
}
}
/// Bounds of a slice of source code.
#[derive(Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
#[derive(Serialize, Deserialize)]
pub struct Span {
/// The inclusive start position.
pub start: Pos,
/// The inclusive end position.
pub end: Pos,
}
impl Span {
/// The zero span.
pub const ZERO: Self = Self { start: Pos::ZERO, end: Pos::ZERO };
/// Create a new span from start and end positions.
pub fn new(start: impl Into<Pos>, end: impl Into<Pos>) -> Self {
Self { start: start.into(), end: end.into() }
}
/// Create a span including just a single position.
pub fn at(pos: impl Into<Pos> + Copy) -> Self {
Self::new(pos, pos)
}
/// Create a new span with the earlier start and later end position.
pub fn join(self, other: Self) -> Self {
Self {
start: self.start.min(other.start),
end: self.end.max(other.end),
}
}
/// Expand a span by merging it with another span.
pub fn expand(&mut self, other: Self) {
*self = self.join(other)
}
/// Test whether one span complete contains the other span.
pub fn contains(self, other: Self) -> bool {
self.start <= other.start && self.end >= other.end
}
/// Convert to a `Range<usize>` for indexing.
pub fn to_range(self) -> Range<usize> {
self.start.to_usize() .. self.end.to_usize()
}
}
impl<T> From<T> for Span
where
T: Into<Pos> + Copy,
{
fn from(pos: T) -> Self {
Self::at(pos)
}
}
impl<T> From<Range<T>> for Span
where
T: Into<Pos>,
{
fn from(range: Range<T>) -> Self {
Self::new(range.start, range.end)
}
}
impl Debug for Span {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{:?}-{:?}", self.start, self.end)
}
}
/// A byte position in source code.
#[derive(Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
#[derive(Serialize, Deserialize)]
pub struct Pos(pub u32);
impl Pos {
/// The zero position.
pub const ZERO: Self = Self(0);
/// Convert to a usize for indexing.
pub fn to_usize(self) -> usize {
self.0 as usize
}
}
impl From<u32> for Pos {
fn from(index: u32) -> Self {
Self(index)
}
}
impl From<usize> for Pos {
fn from(index: usize) -> Self {
Self(index as u32)
}
}
impl Debug for Pos {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
Debug::fmt(&self.0, f)
}
}
impl<T> Add<T> for Pos
where
T: Into<Pos>,
{
type Output = Self;
fn add(self, rhs: T) -> Self {
Pos(self.0 + rhs.into().0)
}
}
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