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//! Spans map elements to the part of source code they originate from.
use std::fmt::{self, Debug, Display, Formatter};
use std::ops::{Add, Sub};
use serde::Serialize;
/// A line-column position in source code.
#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Serialize)]
pub struct Position {
/// The 0-indexed line (inclusive).
pub line: usize,
/// The 0-indexed column (inclusive).
pub column: usize,
}
impl Position {
pub const ZERO: Position = Position { line: 0, column: 0 };
pub fn new(line: usize, column: usize) -> Position {
Position { line, column }
}
}
impl Add for Position {
type Output = Position;
fn add(self, rhs: Position) -> Position {
if rhs.line == 0 {
Position {
line: self.line,
column: self.column + rhs.column
}
} else {
Position {
line: self.line + rhs.line,
column: rhs.column,
}
}
}
}
impl Sub for Position {
type Output = Position;
fn sub(self, rhs: Position) -> Position {
if self.line == rhs.line {
Position {
line: 0,
column: self.column - rhs.column
}
} else {
Position {
line: self.line - rhs.line,
column: self.column,
}
}
}
}
/// Describes a slice of source code.
#[derive(Copy, Clone, Eq, PartialEq, Hash, Serialize)]
pub struct Span {
pub start: Position,
pub end: Position,
}
impl Span {
pub const ZERO: Span = Span { start: Position::ZERO, end: Position::ZERO };
pub fn new(start: Position, end: Position) -> 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(pos: Position) -> Span {
Span { start: pos, end: pos }
}
pub fn expand(&mut self, other: Span) {
*self = Span::merge(*self, other)
}
pub fn offset(self, start: Position) -> Span {
Span {
start: start + self.start,
end: start + self.end,
}
}
}
/// Annotates a value with the part of the source code it corresponds to.
#[derive(Copy, Clone, Eq, PartialEq, Hash, Serialize)]
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<V, F>(self, f: F) -> Spanned<V> where F: FnOnce(T) -> V {
Spanned { v: f(self.v), span: self.span }
}
pub fn map_span<F>(mut self, f: F) -> Spanned<T> where F: FnOnce(Span) -> Span {
self.span = f(self.span);
self
}
}
/// A vector of spanned things.
pub type SpanVec<T> = Vec<Spanned<T>>;
pub fn offset_spans<T>(vec: SpanVec<T>, start: Position) -> impl Iterator<Item=Spanned<T>> {
vec.into_iter().map(move |s| s.map_span(|span| span.offset(start)))
}
impl Display for Position {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}:{}", self.line, self.column)
}
}
impl Display for Span {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "({}, {})", self.start, self.end)
}
}
impl<T> Display for Spanned<T> where T: std::fmt::Display {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "({}, {}, ", self.span.start, self.span.end)?;
self.v.fmt(f)?;
write!(f, ")")
}
}
impl<T> Debug for Spanned<T> where T: std::fmt::Debug {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "({}, {}, ", self.span.start, self.span.end)?;
self.v.fmt(f)?;
write!(f, ")")
}
}
debug_display!(Position);
debug_display!(Span);
|
