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
13impl<W: Write> Ppmd7Encoder<W> {
14    /// Creates a new [`Ppmd7Encoder`] which provides a writer over the compressed data.
15    ///
16    /// The given `order` must be between [`PPMD7_MIN_ORDER`] and [`PPMD7_MAX_ORDER`] (inclusive).
17    /// The given `mem_size` must be between [`PPMD7_MIN_MEM_SIZE`] and [`PPMD7_MAX_MEM_SIZE`] (inclusive).
18    pub fn new(writer: W, order: u32, mem_size: u32) -> crate::Result<Self> {
19        if !(PPMD7_MIN_ORDER..=PPMD7_MAX_ORDER).contains(&order)
20            || !(PPMD7_MIN_MEM_SIZE..=PPMD7_MAX_MEM_SIZE).contains(&mem_size)
21        {
22            return Err(Error::InvalidParameter);
23        }
24
25        let ppmd = Ppmd7::new_encoder(writer, order, mem_size)?;
26
27        Ok(Self { ppmd })
28    }
29
30    /// Returns the inner writer.
31    pub fn into_inner(self) -> W {
32        self.ppmd.into_inner()
33    }
34
35    /// Finishes the encoding process.
36    ///
37    /// Adds an end marker to the data if `with_end_marker` is set to `true`.
38    pub fn finish(mut self, with_end_marker: bool) -> Result<W, std::io::Error> {
39        if with_end_marker {
40            self.ppmd.encode_symbol(SYM_END)?;
41        }
42        self.flush()?;
43        Ok(self.into_inner())
44    }
45
46    fn inner_flush(&mut self) -> Result<(), std::io::Error> {
47        self.ppmd.flush_range_encoder()
48    }
49}
50
51impl<W: Write> Write for Ppmd7Encoder<W> {
52    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
53        if buf.is_empty() {
54            return Ok(0);
55        }
56
57        for &byte in buf.iter() {
58            self.ppmd.encode_symbol(byte as i32)?;
59        }
60
61        Ok(buf.len())
62    }
63
64    fn flush(&mut self) -> std::io::Result<()> {
65        self.inner_flush()
66    }
67}
68
69#[cfg(test)]
70mod test {
71    use std::io::{Read, Write};
72
73    use super::Ppmd7Encoder;
74    use crate::Ppmd7Decoder;
75
76    const ORDER: u32 = 8;
77    const MEM_SIZE: u32 = 262144;
78
79    #[test]
80    fn ppmd7encoder_without_end_marker() {
81        let test_data = include_str!("../tests/fixtures/apache2.txt");
82
83        let mut data = Vec::new();
84        {
85            let mut encoder = Ppmd7Encoder::new(&mut data, ORDER, MEM_SIZE).unwrap();
86            encoder.write_all(test_data.as_bytes()).unwrap();
87            encoder.finish(false).unwrap();
88        }
89
90        let mut decoder = Ppmd7Decoder::new(data.as_slice(), ORDER, MEM_SIZE).unwrap();
91
92        let mut decoded = vec![0; test_data.len()];
93        decoder.read_exact(&mut decoded).unwrap();
94
95        let decoded_data = String::from_utf8(decoded).unwrap();
96        assert_eq!(decoded_data, test_data);
97    }
98
99    #[test]
100    fn ppmd7encoder_with_end_marker() {
101        let test_data = include_str!("../tests/fixtures/apache2.txt");
102
103        let mut data = Vec::new();
104        {
105            let mut encoder = Ppmd7Encoder::new(&mut data, ORDER, MEM_SIZE).unwrap();
106            encoder.write_all(test_data.as_bytes()).unwrap();
107            encoder.finish(true).unwrap();
108        }
109
110        let mut decoder = Ppmd7Decoder::new(data.as_slice(), ORDER, MEM_SIZE).unwrap();
111
112        let mut decoded = Vec::new();
113        decoder.read_to_end(&mut decoded).unwrap();
114
115        let decoded_data = String::from_utf8(decoded).unwrap();
116        assert_eq!(decoded_data, test_data);
117    }
118}
ppmd_rust/encoder_7.rs

ppmd_rust/
encoder_7.rs
