ppmd_rust/
encoder_7.rs

1use std::io::Write;
2
3use crate::{
4    internal::ppmd7::{PPMd7, RangeEncoder},
5    Error, PPMD7_MAX_MEM_SIZE, PPMD7_MAX_ORDER, PPMD7_MIN_MEM_SIZE, PPMD7_MIN_ORDER, SYM_END,
6};
7
8/// An encoder to compress data using PPMd7 (PPMdH) with the 7z range coder.
9pub struct Ppmd7Encoder<W: Write> {
10    ppmd: PPMd7<RangeEncoder<W>>,
11}
12
13unsafe impl<W: Write> Send for Ppmd7Encoder<W> {}
14unsafe impl<W: Write> Sync for Ppmd7Encoder<W> {}
15
16impl<W: Write> Ppmd7Encoder<W> {
17    /// Creates a new [`Ppmd7Encoder`] which provides a writer over the compressed data.
18    ///
19    /// The given `order` must be between [`PPMD7_MIN_ORDER`] and [`PPMD7_MAX_ORDER`] (inclusive).
20    /// The given `mem_size` must be between [`PPMD7_MIN_MEM_SIZE`] and [`PPMD7_MAX_MEM_SIZE`] (inclusive).
21    pub fn new(writer: W, order: u32, mem_size: u32) -> crate::Result<Self> {
22        if !(PPMD7_MIN_ORDER..=PPMD7_MAX_ORDER).contains(&order)
23            || !(PPMD7_MIN_MEM_SIZE..=PPMD7_MAX_MEM_SIZE).contains(&mem_size)
24        {
25            return Err(Error::InvalidParameter);
26        }
27
28        let ppmd = PPMd7::new_encoder(writer, order, mem_size)?;
29
30        Ok(Self { ppmd })
31    }
32
33    /// Returns the inner writer.
34    pub fn into_inner(self) -> W {
35        self.ppmd.into_inner()
36    }
37
38    /// Finishes the encoding process.
39    ///
40    /// Adds an end marker to the data if `with_end_marker` is set to `true`.
41    pub fn finish(mut self, with_end_marker: bool) -> std::io::Result<W> {
42        if with_end_marker {
43            self.ppmd.encode_symbol(SYM_END)?;
44        }
45        self.flush()?;
46        Ok(self.into_inner())
47    }
48}
49
50impl<W: Write> Write for Ppmd7Encoder<W> {
51    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
52        if buf.is_empty() {
53            return Ok(0);
54        }
55
56        for &byte in buf.iter() {
57            self.ppmd.encode_symbol(byte as i32)?;
58        }
59
60        Ok(buf.len())
61    }
62
63    fn flush(&mut self) -> std::io::Result<()> {
64        self.ppmd.flush_range_encoder()
65    }
66}
67
68#[cfg(test)]
69mod test {
70    use std::io::{Read, Write};
71
72    use super::{super::decoder_7::Ppmd7Decoder, Ppmd7Encoder};
73
74    const ORDER: u32 = 8;
75    const MEM_SIZE: u32 = 262144;
76
77    #[test]
78    fn ppmd7encoder_without_end_marker() {
79        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
80
81        let mut data = Vec::new();
82        {
83            let mut encoder = Ppmd7Encoder::new(&mut data, ORDER, MEM_SIZE).unwrap();
84            encoder.write_all(test_data.as_bytes()).unwrap();
85            encoder.finish(false).unwrap();
86        }
87
88        let mut decoder = Ppmd7Decoder::new(data.as_slice(), ORDER, MEM_SIZE).unwrap();
89
90        let mut decoded = vec![0; test_data.len()];
91        decoder.read_exact(&mut decoded).unwrap();
92
93        let decoded_data = String::from_utf8(decoded).unwrap();
94        assert_eq!(decoded_data, test_data);
95    }
96
97    #[test]
98    fn ppmd7encoder_with_end_marker() {
99        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
100
101        let mut data = Vec::new();
102        {
103            let mut encoder = Ppmd7Encoder::new(&mut data, ORDER, MEM_SIZE).unwrap();
104            encoder.write_all(test_data.as_bytes()).unwrap();
105            encoder.finish(true).unwrap();
106        }
107
108        let mut decoder = Ppmd7Decoder::new(data.as_slice(), ORDER, MEM_SIZE).unwrap();
109
110        let mut decoded = Vec::new();
111        decoder.read_to_end(&mut decoded).unwrap();
112
113        let decoded_data = String::from_utf8(decoded).unwrap();
114        assert_eq!(decoded_data, test_data);
115    }
116}
ppmd_rust/encoder_7.rs

ppmd_rust/
encoder_7.rs
