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    /// Returns the inner writer.
40    pub fn into_inner(self) -> W {
41        self.ppmd.into_inner()
42    }
43
44    /// Finishes the encoding process.
45    ///
46    /// Adds an end marker to the data if `with_end_marker` is set to `true`.
47    pub fn finish(mut self, with_end_marker: bool) -> std::io::Result<W> {
48        if with_end_marker {
49            unsafe { self.ppmd.encode_symbol(SYM_END)? };
50        }
51        self.flush()?;
52        Ok(self.into_inner())
53    }
54}
55
56impl<W: Write> Write for Ppmd8Encoder<W> {
57    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
58        if buf.is_empty() {
59            return Ok(0);
60        }
61
62        for &byte in buf.iter() {
63            unsafe { self.ppmd.encode_symbol(byte as i32)? };
64        }
65
66        Ok(buf.len())
67    }
68
69    fn flush(&mut self) -> std::io::Result<()> {
70        self.ppmd.flush_range_encoder()
71    }
72}
73
74#[cfg(test)]
75mod test {
76    use std::io::{Read, Write};
77
78    use super::{super::decoder_8::Ppmd8Decoder, Ppmd8Encoder, RestoreMethod};
79
80    const ORDER: u32 = 8;
81    const MEM_SIZE: u32 = 262144;
82    const RESTORE_METHOD: RestoreMethod = RestoreMethod::Restart;
83
84    #[test]
85    fn ppmd8encoder_without_end_marker() {
86        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
87
88        let mut writer = Vec::new();
89        {
90            let mut encoder =
91                Ppmd8Encoder::new(&mut writer, ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
92            encoder.write_all(test_data.as_bytes()).unwrap();
93            encoder.finish(false).unwrap();
94        }
95
96        let mut decoder =
97            Ppmd8Decoder::new(writer.as_slice(), ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
98
99        let mut decoded = vec![0; test_data.len()];
100        decoder.read_exact(&mut decoded).unwrap();
101
102        let decoded_data = String::from_utf8(decoded).unwrap();
103        assert_eq!(decoded_data, test_data);
104    }
105
106    #[test]
107    fn ppmd8encoder_with_end_marker() {
108        let test_data = include_str!("../tests/fixtures/text/apache2.txt");
109
110        let mut writer = Vec::new();
111        {
112            let mut encoder =
113                Ppmd8Encoder::new(&mut writer, ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
114            encoder.write_all(test_data.as_bytes()).unwrap();
115            encoder.finish(true).unwrap();
116        }
117
118        let mut decoder =
119            Ppmd8Decoder::new(writer.as_slice(), ORDER, MEM_SIZE, RESTORE_METHOD).unwrap();
120
121        let mut decoded = Vec::new();
122        decoder.read_to_end(&mut decoded).unwrap();
123
124        let decoded_data = String::from_utf8(decoded).unwrap();
125        assert_eq!(decoded_data, test_data);
126    }
127}
ppmd_rust/encoder_8.rs

ppmd_rust/
encoder_8.rs
