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//! Spans map elements to the part of source code they originate from.
use std::fmt::{self, Debug, Formatter};
use std::ops::{Add, Sub};
use serde::Serialize;
/// Span offsetting.
pub trait Offset {
/// Offset all spans contained in `Self` by the given position.
fn offset(self, by: Pos) -> Self;
}
/// A vector of spanned values of type `T`.
pub type SpanVec<T> = Vec<Spanned<T>>;
impl<T> Offset for SpanVec<T> {
fn offset(mut self, by: Pos) -> Self {
for spanned in &mut self {
spanned.span = spanned.span.offset(by);
}
self
}
}
/// A value with the span it corresponds to in the source code.
#[derive(Copy, Clone, Eq, PartialEq, Hash, Serialize)]
pub struct Spanned<T> {
/// The value.
pub v: T,
/// The corresponding span.
pub span: Span,
}
impl<T> Spanned<T> {
/// Create a new instance from a value and its span.
pub fn new(v: T, span: Span) -> Spanned<T> {
Spanned { v, span }
}
/// Create a new instance from a value with the zero span.
pub fn zero(v: T) -> Spanned<T> {
Spanned { v, span: Span::ZERO }
}
/// Access the value.
pub fn value(self) -> T {
self.v
}
/// Map the value using a function while keeping the span.
pub fn map<V, F>(self, f: F) -> Spanned<V> where F: FnOnce(T) -> V {
Spanned { v: f(self.v), span: self.span }
}
/// Maps the span while keeping the value.
pub fn map_span<F>(mut self, f: F) -> Spanned<T> where F: FnOnce(Span) -> Span {
self.span = f(self.span);
self
}
}
impl<T> Offset for Spanned<T> {
fn offset(self, by: Pos) -> Self {
self.map_span(|span| span.offset(by))
}
}
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)?;
}
Ok(())
}
}
/// Locates a slice of source code.
#[derive(Copy, Clone, Eq, PartialEq, Hash, Serialize)]
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: Span = Span { start: Pos::ZERO, end: Pos::ZERO };
/// Create a new span from start and end positions.
pub fn new(start: Pos, end: Pos) -> Span {
Span { start, end }
}
/// Create a span including just a single position.
pub fn at(pos: Pos) -> Span {
Span { start: pos, end: pos }
}
/// Create a new span with the earlier start and later end position.
pub fn merge(a: Span, b: Span) -> Span {
Span {
start: a.start.min(b.start),
end: a.end.max(b.end),
}
}
/// Expand a span by merging it with another span.
pub fn expand(&mut self, other: Span) {
*self = Span::merge(*self, other)
}
}
impl Offset for Span {
fn offset(self, by: Pos) -> Self {
Span {
start: self.start.offset(by),
end: self.end.offset(by),
}
}
}
impl Debug for Span {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "<{:?}-{:?}>", self.start, self.end)
}
}
/// Zero-indexed line-column position in source code.
#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Serialize)]
pub struct Pos {
/// The zero-indexed line.
pub line: usize,
/// The zero-indexed column.
pub column: usize,
}
impl Pos {
/// The line 0, column 0 position.
pub const ZERO: Pos = Pos { line: 0, column: 0 };
/// Create a new position from line and column.
pub fn new(line: usize, column: usize) -> Pos {
Pos { line, column }
}
}
impl Offset for Pos {
fn offset(self, by: Pos) -> Self {
by + self
}
}
impl Add for Pos {
type Output = Pos;
fn add(self, rhs: Pos) -> Pos {
if rhs.line == 0 {
Pos {
line: self.line,
column: self.column + rhs.column
}
} else {
Pos {
line: self.line + rhs.line,
column: rhs.column,
}
}
}
}
impl Sub for Pos {
type Output = Pos;
fn sub(self, rhs: Pos) -> Pos {
if self.line == rhs.line {
Pos {
line: 0,
column: self.column - rhs.column
}
} else {
Pos {
line: self.line - rhs.line,
column: self.column,
}
}
}
}
impl Debug for Pos {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}:{}", self.line, self.column)
}
}
|
