ppmd_rust/
encoder_8.rs

1use std::io::Write;
2
3use crate::{
4    internal::ppmd8::{PPMd8, RangeEncoder},
5    Error, RestoreMethod, PPMD8_MAX_MEM_SIZE, PPMD8_MAX_ORDER, PPMD8_MIN_MEM_SIZE, PPMD8_MIN_ORDER,
6    SYM_END,
7};
8
9/// A encoder to compress data using PPMd8 (PPMdI rev.1).
10pub struct Ppmd8Encoder<W: Write> {
11    ppmd: PPMd8<RangeEncoder<W>>,
12}
13
14unsafe impl<W: Write> Send for Ppmd8Encoder<W> {}
15unsafe impl<W: Write> Sync for Ppmd8Encoder<W> {}
16
17impl<W: Write> Ppmd8Encoder<W> {
18    /// Creates a new [`Ppmd8Encoder`] which provides a writer over the compressed data.
19    ///
20    /// The given `order` must be between [`PPMD8_MIN_ORDER`] and [`PPMD8_MAX_ORDER`] (inclusive).
21    /// The given `mem_size` must be between [`PPMD8_MIN_MEM_SIZE`] and [`PPMD8_MAX_MEM_SIZE`] (inclusive).
22    pub fn new(
23        writer: W,
24        order: u32,
25        mem_size: u32,
26        restore_method: RestoreMethod,
27    ) -> crate::Result<Self> {
28        if !(PPMD8_MIN_ORDER..=PPMD8_MAX_ORDER).contains(&order)
29            || !(PPMD8_MIN_MEM_SIZE..=PPMD8_MAX_MEM_SIZE).contains(&mem_size)
30        {
31            return Err(Error::InvalidParameter);
32        }
33
34        let ppmd = PPMd8::new_encoder(writer, order, mem_size, restore_method)?;
35
36        Ok(Self { ppmd })
37    }
38
39    /// Gets a reference to the underlying writer.
40    pub fn get_ref(&self) -> &W {
41        self.ppmd.get_ref()
42    }
43
44    /// Gets a mutable reference to the underlying writer.
45    ///
46    /// Note that mutating the output/input state of the stream may corrupt
47    /// this object, so care must be taken when using this method.
48    pub fn get_mut(&mut self) -> &mut W {
49        self.ppmd.get_mut()
50    }
51
52    /// Returns the inner writer.
53    pub fn into_inner(self) -> W {
54        self.ppmd.into_inner()
55    }
56
57    /// Finishes the encoding process.
58    ///
59    /// Adds an end marker to the data if `with_end_marker` is set to `true`.
60    pub fn finish(mut self, with_end_marker: bool) -> std::io::Result<W> {
61        if with_end_marker {
62            unsafe { self.ppmd.encode_symbol(SYM_END)? };
63        }
64        self.flush()?;
65        Ok(self.into_inner())
66    }
67}
68
69impl<W: Write> Write for Ppmd8Encoder<W> {
70    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
71        if buf.is_empty() {
72            return Ok(0);
73        }
74
75        for &byte in buf.iter() {
76            unsafe { self.ppmd.encode_symbol(byte as i32)? };
77        }
78
79        Ok(buf.len())
80    }
81
82    fn flush(&mut self) -> std::io::Result<()> {
83        self.ppmd.flush_range_encoder()
84    }
85}
86
87#[cfg(test)]
88mod test {
89    use std::io::{Read, Write};
90
91    use super::{super::decoder_8::Ppmd8Decoder, Ppmd8Encoder, RestoreMethod};
92
93    const ORDER: u32 = 8;
94    const MEM_SIZE: u32 = 262144;
95    const RESTORE_METHOD: RestoreMethod = RestoreMethod::Restart;
96
97    #[test]
98    fn ppmd8encoder_without_end_marker() {
99        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
100
101        let mut writer = Vec::new();
102        {
103            let mut encoder =
104                Ppmd8Encoder::new(&mut writer, ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
105            encoder.write_all(test_data.as_bytes()).unwrap();
106            encoder.finish(false).unwrap();
107        }
108
109        let mut decoder =
110            Ppmd8Decoder::new(writer.as_slice(), ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
111
112        let mut decoded = vec![0; test_data.len()];
113        decoder.read_exact(&mut decoded).unwrap();
114
115        let decoded_data = String::from_utf8(decoded).unwrap();
116        assert_eq!(decoded_data, test_data);
117    }
118
119    #[test]
120    fn ppmd8encoder_with_end_marker() {
121        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
122
123        let mut writer = Vec::new();
124        {
125            let mut encoder =
126                Ppmd8Encoder::new(&mut writer, ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
127            encoder.write_all(test_data.as_bytes()).unwrap();
128            encoder.finish(true).unwrap();
129        }
130
131        let mut decoder =
132            Ppmd8Decoder::new(writer.as_slice(), ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
133
134        let mut decoded = Vec::new();
135        decoder.read_to_end(&mut decoded).unwrap();
136
137        let decoded_data = String::from_utf8(decoded).unwrap();
138        assert_eq!(decoded_data, test_data);
139    }
140}
ppmd_rust/encoder_8.rs

ppmd_rust/
encoder_8.rs
