1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154

//! # Line ending normalization module
//!
//! This crate provides a `normalize` method that takes an u8 iterator and returns
//! a new one with newlines normalized to a single style.
//!
//! Based on https://github.com/derekdreery/normalize-line-endings.

use crate::line_writer::LineBreak;
use std::iter::Peekable;

/// This struct wraps an u8 iterator to normalize line endings.
pub struct Normalized<I>
where
    I: Iterator<Item = u8>,
{
    line_break: LineBreak,
    iter: Peekable<I>,
    prev_was_cr: bool,
}

impl<I: Iterator<Item = u8>> Normalized<I> {
    /// Take a u8 iterator and return similar iterator 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_utf8(Normalized::new(input.bytes(), LineBreak::Lf).collect()).unwrap(),
    ///     "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 = u8>> Iterator for Normalized<I> {
    type Item = u8;

    fn next(&mut self) -> Option<u8> {
        match self.iter.peek() {
            Some(b'\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(b'\r')
                        }
                    }
                    LineBreak::Crlf => {
                        if self.prev_was_cr {
                            self.prev_was_cr = false;
                            self.iter.next()
                        } else {
                            self.prev_was_cr = true;
                            Some(b'\r')
                        }
                    }
                }
            }
            Some(b'\r') => match self.line_break {
                LineBreak::Lf => {
                    self.prev_was_cr = true;
                    let _ = self.iter.next();
                    Some(b'\n')
                }
                LineBreak::Cr => {
                    self.prev_was_cr = true;
                    self.iter.next()
                }
                LineBreak::Crlf => {
                    if self.prev_was_cr {
                        self.prev_was_cr = false;
                        Some(b'\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 => {
                    let res = if self.prev_was_cr {
                        Some(b'\n')
                    } else {
                        self.iter.next()
                    };
                    self.prev_was_cr = false;
                    res
                }
            },
        }
    }
}

// tests
#[cfg(test)]
mod tests {
    use super::*;

    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_utf8(Normalized::new(input.bytes(), LineBreak::Lf).collect()).unwrap(),
            "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_utf8(Normalized::new(input.bytes(), LineBreak::Cr).collect()).unwrap(),
            "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_utf8(Normalized::new(input.bytes(), LineBreak::Crlf).collect()).unwrap(),
            "This is a string \r\n with \r\n some \r\n\r\n random newlines\r\n\r\n\r\n"
        );
    }
}