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Markdown parser fork with extended syntax for personal use.
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6.5 kB · 210 lines
Rust
at hack
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211//! Deal with positions in a file.//!//! * Convert between byte indices and unist points.//! * Convert between byte indices into a string which is built up of several//! slices in a whole document, and byte indices into that whole document.
use crate::unist::Point;use alloc::{vec, vec::Vec};
/// Each stop represents a new slice, which contains the byte index into the/// corresponding string where the slice starts (`0`), and the byte index into/// the whole document where that slice starts (`1`).pub type Stop = (usize, usize);
#[derive(Debug)]pub struct Location { /// List, where each index is a line number (0-based), and each value is /// the byte index *after* where the line ends. indices: Vec<usize>,}
impl Location { /// Get an index for the given `bytes`. /// /// Port of <https://github.com/vfile/vfile-location/blob/main/index.js> #[must_use] pub fn new(bytes: &[u8]) -> Self { let mut index = 0; let mut location_index = Self { indices: vec![] };
while index < bytes.len() { if bytes[index] == b'\r' { if index + 1 < bytes.len() && bytes[index + 1] == b'\n' { location_index.indices.push(index + 2); index += 1; } else { location_index.indices.push(index + 1); } } else if bytes[index] == b'\n' { location_index.indices.push(index + 1); }
index += 1; }
location_index.indices.push(index + 1); location_index }
/// Get the line and column-based `point` for `offset` in the bound indices. /// /// Returns `None` when given out of bounds input. /// /// Port of <https://github.com/vfile/vfile-location/blob/main/index.js> #[must_use] pub fn to_point(&self, offset: usize) -> Option<Point> { let mut index = 0;
if let Some(end) = self.indices.last() { if offset < *end { while index < self.indices.len() { if self.indices[index] > offset { break; }
index += 1; }
let previous = if index > 0 { self.indices[index - 1] } else { 0 }; return Some(Point::new(index + 1, offset + 1 - previous, offset)); } }
None }
/// Like `to_point`, but takes a relative offset from a certain string /// instead of an absolute offset into the whole document. /// /// The relative offset is made absolute based on `stops`, which represent /// where that certain string is in the whole document. #[must_use] pub fn relative_to_point(&self, stops: &[Stop], relative: usize) -> Option<Point> { Location::relative_to_absolute(stops, relative).and_then(|absolute| self.to_point(absolute)) }
/// Turn a relative offset into an absolute offset. #[must_use] pub fn relative_to_absolute(stops: &[Stop], relative: usize) -> Option<usize> { let mut index = 0;
while index < stops.len() && stops[index].0 <= relative { index += 1; }
// There are no points: that only occurs if there was an empty string. if index == 0 { None } else { let (stop_relative, stop_absolute) = &stops[index - 1]; Some(stop_absolute + (relative - stop_relative)) } }}
#[cfg(test)]mod tests { use super::*;
#[test] fn test_location_lf() { let location = Location::new("ab\nc".as_bytes()); assert_eq!( location.to_point(0), // `a` Some(Point::new(1, 1, 0)), "should support some points (1)" ); assert_eq!( location.to_point(1), // `b` Some(Point::new(1, 2, 1)), "should support some points (2)" ); assert_eq!( location.to_point(2), // `\n` Some(Point::new(1, 3, 2)), "should support some points (3)" ); assert_eq!( location.to_point(3), // `c` Some(Point::new(2, 1, 3)), "should support some points (4)" ); assert_eq!( location.to_point(4), // EOF // Still gets a point, so that we can represent positions of things // that end at the last character, the `c` end at `2:2`. Some(Point::new(2, 2, 4)), "should support some points (5)" ); assert_eq!( location.to_point(5), // Out of bounds None, "should support some points (6)" ); }
#[test] fn test_location_cr() { let location = Location::new("a\rb".as_bytes()); assert_eq!( location.to_point(0), // `a` Some(Point::new(1, 1, 0)), "should support some points (1)" ); assert_eq!( location.to_point(1), // `\r` Some(Point::new(1, 2, 1)), "should support some points (2)" ); assert_eq!( location.to_point(2), // `b` Some(Point::new(2, 1, 2)), "should support some points (3)" ); }
#[test] fn test_location_cr_lf() { let location = Location::new("a\r\nb".as_bytes()); assert_eq!( location.to_point(0), // `a` Some(Point::new(1, 1, 0)), "should support some points (1)" ); assert_eq!( location.to_point(1), // `\r` Some(Point::new(1, 2, 1)), "should support some points (2)" ); assert_eq!( location.to_point(2), // `\n` Some(Point::new(1, 3, 2)), "should support some points (3)" ); assert_eq!( location.to_point(3), // `b` Some(Point::new(2, 1, 3)), "should support some points (4)" ); } #[test] fn test_empty() { let location = Location::new("".as_bytes()); assert_eq!(location.to_point(0), Some(Point::new(1, 1, 0)), "to_point"); assert_eq!( location.relative_to_point(&[], 0), None, "relative_to_point" ); assert_eq!( Location::relative_to_absolute(&[], 0), None, "relative_to_absolute" ); }}