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

use std::io;
use std::io::prelude::BufRead;
use std::iter::Iterator;

use error::*;
use types::*;

pub struct Reader<R> {
    reader: io::BufReader<R>,
}

macro_rules! parse_line {
    ($reader:ident) => {{
        let mut buffer = String::new();
        $reader.read_line(&mut buffer)?;
        buffer
    }};
    ($reader:ident, $t:ty) => {{
        let mut buffer = String::new();
        $reader.read_line(&mut buffer)?;
        buffer.trim().parse::<$t>()?
    }}
}

impl<R: io::Read> Reader<R> {
    pub fn new(inner: R) -> Self {
        Reader {
            reader: io::BufReader::new(inner)
        }
    }

    pub fn read_snapshot(&mut self) -> Result<Snapshot> {
        let reader = &mut self.reader;

        let num_atoms = parse_line!(reader, i32);
        let comment = parse_line!(reader);

        let mut atoms: Vec<Atom> = Vec::new();
        for _ in 0..num_atoms {
            atoms.push(parse_line!(reader, Atom));
        }

        Ok(Snapshot {
            comment: comment,
            atoms: atoms
        })
    }
}

impl<R: io::Read> Iterator for Reader<R> {
    type Item = Snapshot;

    fn next(&mut self) -> Option<Self::Item> {
        self.read_snapshot().ok()
    }
}

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

    #[test]
    fn test_reader() {
        let data: &[u8] = b"\
            3
            comment
            C 1.0 2.0 3.0
            O 4.0 3.0 6.0
            H 5.0 1.5 4.0";
        let mut reader = Reader::new(data);
        let success = reader.read_snapshot();
        assert!(success.is_ok());

        let snapshot = success.unwrap();
        assert_eq!(3, snapshot.size());
    }

    #[test]
    fn test_iterator() {
        let data: &[u8] = b"\
            3
            1st snapshot
            C 1.0 2.0 3.0
            O 4.0 3.0 6.0
            H 5.0 1.5 4.0
            3
            2nd snapshot
            C 1.1 1.9 2.8
            O 4.2 3.0 5.9
            H 5.0 1.6 4.0";
        let mut reader = Reader::new(data);
        assert!(reader.next().is_some());
        assert!(reader.next().is_some());
        assert!(reader.next().is_none());
    }
}