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//! Conversion of byte positions to line/column locations.
use std::fmt::{self, Debug, Display, Formatter};
use super::Pos;
use crate::parse::is_newline_char;
/// Enables conversion of byte position to locations.
pub struct LineMap<'s> {
src: &'s str,
line_starts: Vec<Pos>,
}
impl<'s> LineMap<'s> {
/// Create a new line map for a source string.
pub fn new(src: &'s str) -> Self {
let mut line_starts = vec![Pos::ZERO];
let mut iter = src.char_indices().peekable();
while let Some((mut i, c)) = iter.next() {
if is_newline_char(c) {
i += c.len_utf8();
if c == '\r' && matches!(iter.peek(), Some((_, '\n'))) {
i += '\n'.len_utf8();
iter.next();
}
line_starts.push(Pos(i as u32));
}
}
Self { src, line_starts }
}
/// Convert a byte position to a location.
///
/// # Panics
/// This panics if the position is out of bounds.
pub fn location(&self, pos: Pos) -> Location {
let line_index = match self.line_starts.binary_search(&pos) {
Ok(i) => i,
Err(i) => i - 1,
};
let line_start = self.line_starts[line_index];
let head = &self.src[line_start.to_usize() .. pos.to_usize()];
let column_index = head.chars().count();
Location {
line: 1 + line_index as u32,
column: 1 + column_index as u32,
}
}
}
/// One-indexed line-column position in source code.
#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[cfg_attr(feature = "serialize", derive(serde::Serialize))]
pub struct Location {
/// The one-indexed line.
pub line: u32,
/// The one-indexed column.
pub column: u32,
}
impl Location {
/// Create a new location from line and column.
pub fn new(line: u32, column: u32) -> Self {
Self { line, column }
}
}
impl Debug for Location {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
Display::fmt(self, f)
}
}
impl Display for Location {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}:{}", self.line, self.column)
}
}
#[cfg(test)]
mod tests {
use super::*;
const TEST: &str = "äbcde\nf💛g\r\nhi\rjkl";
#[test]
fn test_line_map_new() {
let map = LineMap::new(TEST);
assert_eq!(map.line_starts, vec![Pos(0), Pos(7), Pos(15), Pos(18)]);
}
#[test]
fn test_line_map_location() {
let map = LineMap::new(TEST);
assert_eq!(map.location(Pos(0)), Location::new(1, 1));
assert_eq!(map.location(Pos(2)), Location::new(1, 2));
assert_eq!(map.location(Pos(6)), Location::new(1, 6));
assert_eq!(map.location(Pos(7)), Location::new(2, 1));
assert_eq!(map.location(Pos(8)), Location::new(2, 2));
assert_eq!(map.location(Pos(12)), Location::new(2, 3));
assert_eq!(map.location(Pos(21)), Location::new(4, 4));
}
#[test]
#[should_panic]
fn test_line_map_panics_out_of_bounds() {
LineMap::new(TEST).location(Pos(22));
}
}
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