Struct LineIndex 

pub struct LineIndex { /* private fields */ }

a table of line-start byte offsets, built once from the source, used to map a byte offset to a 1-based line and column.

line_starts[0] is always 0 (the first line starts at the first byte); an entry offset + 1 is pushed after each \n byte. \r\n needs no special case: the \n ends the line and a lone \r is just whitespace inside the preceding line.

Implementations

impl LineIndex

pub fn new(src: &str) -> Self

scan the source once and record where each line starts.

pub fn location(&self, src: &str, byte_offset: usize) -> (usize, usize)

the 1-based line and 1-based column of byte_offset in src.

the column is a count of characters from the start of the line, so a tab counts as one column, not eight. this is deliberate: the logical column is character-based, and any tab-expanded display column is the renderer’s job later. an offset at end of file returns a valid pair and never panics. an offset beyond src.len() is clamped to src.len() rather than panicking; this keeps WASM alive when a downstream caller (e.g. the diagnostics layer) passes a span-derived offset that is slightly wrong.