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    /// Gets a reference to the underlying writer.
34    pub fn get_ref(&self) -> &W {
35        self.ppmd.get_ref()
36    }
37
38    /// Gets a mutable reference to the underlying writer.
39    ///
40    /// Note that mutating the output/input state of the stream may corrupt
41    /// this object, so care must be taken when using this method.
42    pub fn get_mut(&mut self) -> &mut W {
43        self.ppmd.get_mut()
44    }
45
46    /// Returns the inner writer.
47    pub fn into_inner(self) -> W {
48        self.ppmd.into_inner()
49    }
50
51    /// Finishes the encoding process.
52    ///
53    /// Adds an end marker to the data if `with_end_marker` is set to `true`.
54    pub fn finish(mut self, with_end_marker: bool) -> std::io::Result<W> {
55        if with_end_marker {
56            self.ppmd.encode_symbol(SYM_END)?;
57        }
58        self.flush()?;
59        Ok(self.into_inner())
60    }
61}
62
63impl<W: Write> Write for Ppmd7Encoder<W> {
64    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
65        if buf.is_empty() {
66            return Ok(0);
67        }
68
69        for &byte in buf.iter() {
70            self.ppmd.encode_symbol(byte as i32)?;
71        }
72
73        Ok(buf.len())
74    }
75
76    fn flush(&mut self) -> std::io::Result<()> {
77        self.ppmd.flush_range_encoder()
78    }
79}
80
81#[cfg(test)]
82mod test {
83    use std::io::{Read, Write};
84
85    use super::{super::decoder_7::Ppmd7Decoder, Ppmd7Encoder};
86
87    const ORDER: u32 = 8;
88    const MEM_SIZE: u32 = 262144;
89
90    #[test]
91    fn ppmd7encoder_without_end_marker() {
92        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
93
94        let mut data = Vec::new();
95        {
96            let mut encoder = Ppmd7Encoder::new(&mut data, ORDER, MEM_SIZE).unwrap();
97            encoder.write_all(test_data.as_bytes()).unwrap();
98            encoder.finish(false).unwrap();
99        }
100
101        let mut decoder = Ppmd7Decoder::new(data.as_slice(), ORDER, MEM_SIZE).unwrap();
102
103        let mut decoded = vec![0; test_data.len()];
104        decoder.read_exact(&mut decoded).unwrap();
105
106        let decoded_data = String::from_utf8(decoded).unwrap();
107        assert_eq!(decoded_data, test_data);
108    }
109
110    #[test]
111    fn ppmd7encoder_with_end_marker() {
112        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
113
114        let mut data = Vec::new();
115        {
116            let mut encoder = Ppmd7Encoder::new(&mut data, ORDER, MEM_SIZE).unwrap();
117            encoder.write_all(test_data.as_bytes()).unwrap();
118            encoder.finish(true).unwrap();
119        }
120
121        let mut decoder = Ppmd7Decoder::new(data.as_slice(), ORDER, MEM_SIZE).unwrap();
122
123        let mut decoded = Vec::new();
124        decoder.read_to_end(&mut decoded).unwrap();
125
126        let decoded_data = String::from_utf8(decoded).unwrap();
127        assert_eq!(decoded_data, test_data);
128    }
129}
ppmd_rust/encoder_7.rs

ppmd_rust/
encoder_7.rs
