deko 0.6.0

A decoder that automatically detects compression format (gzip, bzip2, xz, zstd) via external crates. Includes an encoder for the same formats as well.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237

macro_rules! define_decoder {
    ($trait: ident) => {
        #[cfg(feature = "nightly")]
        use std::io::BorrowedCursor;
        use std::io::Empty;
        use std::io::Error;
        use std::io::ErrorKind;
        use std::io::IoSliceMut;
        use std::io::Read;

        #[cfg(feature = "nightly")]
        use crate::dispatch;
        use crate::dispatch_mut;
        use crate::Format;

        /// A decoder that decompresses the supplied input stream using any of the supported formats.
        ///
        /// The format is detected using the _magic bytes_ at the start of the stream.
        /// By default, if the format is not supported, the data is read verbatim.
        /// Use [fail_on_unknown_format](AnyDecoder::fail_on_unknown_format) to change this behaviour.
        pub struct AnyDecoder<R: $trait> {
            reader: Option<MagicReader<R>>,
            inner: InnerDecoder<MagicReader<R>>,
            fail_on_unknown_format: bool,
        }

        impl<R: $trait> AnyDecoder<R> {
            /// Create new decoder from the supplied `reader`.
            pub fn new(reader: R) -> Self {
                Self {
                    reader: Some(MagicReader::new(reader)),
                    inner: InnerDecoder::Empty(std::io::empty()),
                    fail_on_unknown_format: false,
                }
            }

            /// Throw an error when the decoder fails to detect compression format.
            ///
            /// By default no error is thrown, and the data is read verbatim.
            pub fn fail_on_unknown_format(&mut self, value: bool) {
                self.fail_on_unknown_format = value;
            }

            #[inline]
            fn get_kind(&self) -> Format {
                match self.inner {
                    InnerDecoder::Reader(..) => Format::Verbatim,
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Gz(..) => Format::Gz,
                    #[cfg(feature = "bzip2")]
                    InnerDecoder::Bz(..) => Format::Bz,
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Zlib(..) => Format::Zlib,
                    #[cfg(feature = "xz")]
                    InnerDecoder::Xz(..) => Format::Xz,
                    #[cfg(feature = "zstd")]
                    InnerDecoder::Zstd(..) => Format::Zstd,
                    InnerDecoder::Empty(..) => unreachable!(),
                }
            }

            /// Get the input stream format.
            ///
            /// The format is detected automatically when the data is read from the decoder.
            /// If nothing was read before calling this method, a small amount of data is read from the
            /// stream to detect the format.
            /// If the format has already been detected, this method merely returns it.
            pub fn kind(&mut self) -> Result<Format, Error> {
                self.detect()?;
                Ok(self.get_kind())
            }

            /// Get immutable reference to the underlying reader.
            pub fn get_ref(&self) -> &R {
                if let Some(r) = self.reader.as_ref() {
                    return r.get_ref();
                }
                match self.inner {
                    InnerDecoder::Reader(ref r) => r.get_ref(),
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Gz(ref r) => r.get_ref().get_ref(),
                    #[cfg(feature = "bzip2")]
                    InnerDecoder::Bz(ref r) => r.get_ref().get_ref(),
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Zlib(ref r) => r.get_ref().get_ref(),
                    #[cfg(feature = "xz")]
                    InnerDecoder::Xz(ref r) => r.get_ref().get_ref(),
                    #[cfg(feature = "zstd")]
                    InnerDecoder::Zstd(ref r) => crate::zstd_get_ref!($trait, r),
                    InnerDecoder::Empty(..) => unreachable!(),
                }
            }

            /// Get mutable reference to the underlying reader.
            pub fn get_mut(&mut self) -> &mut R {
                if let Some(r) = self.reader.as_mut() {
                    return r.get_mut();
                }
                match self.inner {
                    InnerDecoder::Reader(ref mut r) => r.get_mut(),
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Gz(ref mut r) => r.get_mut().get_mut(),
                    #[cfg(feature = "bzip2")]
                    InnerDecoder::Bz(ref mut r) => r.get_mut().get_mut(),
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Zlib(ref mut r) => r.get_mut().get_mut(),
                    #[cfg(feature = "xz")]
                    InnerDecoder::Xz(ref mut r) => r.get_mut().get_mut(),
                    #[cfg(feature = "zstd")]
                    InnerDecoder::Zstd(ref mut r) => crate::zstd_get_mut!($trait, r),
                    InnerDecoder::Empty(..) => unreachable!(),
                }
            }

            /// Return the underlying reader.
            pub fn into_inner(mut self) -> R {
                if let Some(r) = self.reader.take() {
                    return r.into_inner();
                }
                match self.inner {
                    InnerDecoder::Reader(r) => r.into_inner(),
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Gz(r) => r.into_inner().into_inner(),
                    #[cfg(feature = "bzip2")]
                    InnerDecoder::Bz(r) => r.into_inner().into_inner(),
                    #[cfg(feature = "flate2")]
                    InnerDecoder::Zlib(r) => r.into_inner().into_inner(),
                    #[cfg(feature = "xz")]
                    InnerDecoder::Xz(r) => r.into_inner().into_inner(),
                    #[cfg(feature = "zstd")]
                    InnerDecoder::Zstd(r) => crate::zstd_into_inner!($trait, r),
                    InnerDecoder::Empty(..) => unreachable!(),
                }
            }

            #[inline]
            fn detect(&mut self) -> Result<(), Error> {
                if let Some(r) = self.reader.take() {
                    self.inner = InnerDecoder::new(r, self.fail_on_unknown_format)?;
                }
                Ok(())
            }
        }

        impl<R: $trait> Read for AnyDecoder<R> {
            fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error> {
                self.detect()?;
                dispatch_mut!(self.inner, Read::read, buf)
            }

            fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error> {
                self.detect()?;
                dispatch_mut!(self.inner, Read::read_vectored, bufs)
            }

            #[cfg(feature = "nightly")]
            fn is_read_vectored(&self) -> bool {
                dispatch!(self.inner, Read::is_read_vectored)
            }

            fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error> {
                self.detect()?;
                dispatch_mut!(self.inner, Read::read_to_end, buf)
            }

            fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error> {
                self.detect()?;
                dispatch_mut!(self.inner, Read::read_to_string, buf)
            }

            fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error> {
                self.detect()?;
                dispatch_mut!(self.inner, Read::read_exact, buf)
            }

            #[cfg(feature = "nightly")]
            fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error> {
                self.detect()?;
                dispatch_mut!(self.inner, Read::read_buf, buf)
            }

            #[cfg(feature = "nightly")]
            fn read_buf_exact(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error> {
                self.detect()?;
                dispatch_mut!(self.inner, Read::read_buf_exact, buf)
            }
        }

        crate::define_inner_decoder!($trait);
    };
}

pub(crate) use define_decoder;

macro_rules! dispatch_mut {
    ($inner:expr, $method:expr $(,$args:ident)*) => {
        match $inner {
            InnerDecoder::Reader(ref mut r) => $method(r, $($args),*),
            #[cfg(feature = "flate2")]
            InnerDecoder::Gz(ref mut r) => $method(r, $($args),*),
            #[cfg(feature = "bzip2")]
            InnerDecoder::Bz(ref mut r) => $method(r, $($args),*),
            #[cfg(feature = "flate2")]
            InnerDecoder::Zlib(ref mut r) => $method(r, $($args),*),
            #[cfg(feature = "xz")]
            InnerDecoder::Xz(ref mut r) => $method(r, $($args),*),
            #[cfg(feature = "zstd")]
            InnerDecoder::Zstd(ref mut r) => $method(r, $($args),*),
            InnerDecoder::Empty(ref mut r) => $method(r, $($args),*),
        }
    }
}

pub(crate) use dispatch_mut;

#[cfg(feature = "nightly")]
macro_rules! dispatch {
    ($inner:expr, $method:expr $(,$args:ident)*) => {
        match $inner {
            InnerDecoder::Reader(ref r) => $method(r, $($args),*),
            #[cfg(feature = "flate2")]
            InnerDecoder::Gz(ref r) => $method(r, $($args),*),
            #[cfg(feature = "bzip2")]
            InnerDecoder::Bz(ref r) => $method(r, $($args),*),
            #[cfg(feature = "flate2")]
            InnerDecoder::Zlib(ref r) => $method(r, $($args),*),
            #[cfg(feature = "xz")]
            InnerDecoder::Xz(ref r) => $method(r, $($args),*),
            #[cfg(feature = "zstd")]
            InnerDecoder::Zstd(ref r) => $method(r, $($args),*),
            InnerDecoder::Empty(ref r) => $method(r, $($args),*),
        }
    }
}

#[cfg(feature = "nightly")]
pub(crate) use dispatch;