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