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use crate::io;
pub struct LineColIterator<I> {
iter: I,
/// Index of the current line. Characters in the first line of the input
/// (before the first newline character) are in line 1.
line: usize,
/// Index of the current column. The first character in the input and any
/// characters immediately following a newline character are in column 1.
/// The column is 0 immediately after a newline character has been read.
col: usize,
/// Byte offset of the start of the current line. This is the sum of lengths
/// of all previous lines. Keeping track of things this way allows efficient
/// computation of the current line, column, and byte offset while only
/// updating one of the counters in `next()` in the common case.
start_of_line: usize,
}
impl<I> LineColIterator<I>
where
I: Iterator<Item = io::Result<u8>>,
{
pub fn new(iter: I) -> LineColIterator<I> {
LineColIterator {
iter,
line: 1,
col: 0,
start_of_line: 0,
}
}
pub fn line(&self) -> usize {
self.line
}
pub fn col(&self) -> usize {
self.col
}
pub fn byte_offset(&self) -> usize {
self.start_of_line + self.col
}
}
impl<I> Iterator for LineColIterator<I>
where
I: Iterator<Item = io::Result<u8>>,
{
type Item = io::Result<u8>;
fn next(&mut self) -> Option<io::Result<u8>> {
match self.iter.next() {
None => None,
Some(Ok(b'\n')) => {
self.start_of_line += self.col + 1;
self.line += 1;
self.col = 0;
Some(Ok(b'\n'))
}
Some(Ok(c)) => {
self.col += 1;
Some(Ok(c))
}
Some(Err(e)) => Some(Err(e)),
}
}
}
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