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//! # Line ending normalization module
//!
//! This crate provides a `normalize` method that takes a char iterator and returns
//! a new one with `\n` for all line endings
//!
//! Based on https://github.com/derekdreery/normalize-line-endings.
use crate::line_writer::LineBreak;
use std::iter::Peekable;
/// This struct wraps a `std::io::Chars` to normalize line endings.
///
/// Implements `Iterator<Item=char>` so can be used in place
pub struct Normalized<I>
where
I: Iterator<Item = char>,
{
line_break: LineBreak,
iter: Peekable<I>,
prev_was_cr: bool,
}
impl<I: Iterator<Item = char>> Normalized<I> {
/// Take a Chars and return similar struct with normalized line endings
///
/// # Example
/// ```
/// use std::iter::FromIterator;
/// use pgp::normalize_lines::Normalized;
/// use pgp::line_writer::LineBreak;
///
/// let input = "This is a string \n with \r some \n\r\n random newlines\r\r\n\n";
/// assert_eq!(
/// &String::from_iter(Normalized::new(input.chars(), LineBreak::Lf)),
/// "This is a string \n with \n some \n\n random newlines\n\n\n"
/// );
/// ```
pub fn new(iter: I, line_break: LineBreak) -> Normalized<I> {
Normalized {
iter: iter.peekable(),
prev_was_cr: false,
line_break,
}
}
}
impl<I: Iterator<Item = char>> Iterator for Normalized<I> {
type Item = char;
fn next(&mut self) -> Option<char> {
match self.iter.peek() {
Some('\n') => {
match self.line_break {
LineBreak::Lf => {
if self.prev_was_cr {
// we already inserted a \n
let _ = self.iter.next();
}
self.iter.next()
}
LineBreak::Cr => {
// skip \n
let _ = self.iter.next();
if self.prev_was_cr {
self.prev_was_cr = false;
self.next()
} else {
Some('\r')
}
}
LineBreak::Crlf => {
if self.prev_was_cr {
self.prev_was_cr = false;
self.iter.next()
} else {
self.prev_was_cr = true;
Some('\r')
}
}
}
}
Some('\r') => match self.line_break {
LineBreak::Lf => {
self.prev_was_cr = true;
let _ = self.iter.next();
Some('\n')
}
LineBreak::Cr => {
self.prev_was_cr = true;
self.iter.next()
}
LineBreak::Crlf => {
if self.prev_was_cr {
self.prev_was_cr = false;
Some('\n')
} else {
self.prev_was_cr = true;
self.iter.next()
}
}
},
_ => match self.line_break {
LineBreak::Lf | LineBreak::Cr => {
self.prev_was_cr = false;
self.iter.next()
}
LineBreak::Crlf => {
if self.prev_was_cr {
self.prev_was_cr = false;
Some('\n')
} else {
self.prev_was_cr = false;
self.iter.next()
}
}
},
}
}
}
// tests
#[cfg(test)]
mod tests {
use super::*;
use std::iter::FromIterator;
use crate::line_writer::LineBreak;
#[test]
fn normalized_lf() {
let input = "This is a string \n with \r some \n\r\n random newlines\r\r\n\n";
assert_eq!(
&String::from_iter(Normalized::new(input.chars(), LineBreak::Lf)),
"This is a string \n with \n some \n\n random newlines\n\n\n"
);
}
#[test]
fn normalized_cr() {
let input = "This is a string \n with \r some \n\r\n random newlines\r\r\n\n";
assert_eq!(
&String::from_iter(Normalized::new(input.chars(), LineBreak::Cr)),
"This is a string \r with \r some \r\r random newlines\r\r\r"
);
}
#[test]
fn normalized_crlf() {
let input = "This is a string \n with \r some \n\r\n random newlines\r\r\n\n";
assert_eq!(
&String::from_iter(Normalized::new(input.chars(), LineBreak::Crlf)),
"This is a string \r\n with \r\n some \r\n\r\n random newlines\r\n\r\n\r\n"
);
}
}