diff options
Diffstat (limited to 'vendor/github.com/ulikunitz/xz/lzma/encoderdict.go')
-rw-r--r-- | vendor/github.com/ulikunitz/xz/lzma/encoderdict.go | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/vendor/github.com/ulikunitz/xz/lzma/encoderdict.go b/vendor/github.com/ulikunitz/xz/lzma/encoderdict.go new file mode 100644 index 000000000..9d0fbc703 --- /dev/null +++ b/vendor/github.com/ulikunitz/xz/lzma/encoderdict.go @@ -0,0 +1,149 @@ +// Copyright 2014-2017 Ulrich Kunitz. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package lzma + +import ( + "errors" + "fmt" + "io" +) + +// matcher is an interface that supports the identification of the next +// operation. +type matcher interface { + io.Writer + SetDict(d *encoderDict) + NextOp(rep [4]uint32) operation +} + +// encoderDict provides the dictionary of the encoder. It includes an +// addtional buffer atop of the actual dictionary. +type encoderDict struct { + buf buffer + m matcher + head int64 + capacity int + // preallocated array + data [maxMatchLen]byte +} + +// newEncoderDict creates the encoder dictionary. The argument bufSize +// defines the size of the additional buffer. +func newEncoderDict(dictCap, bufSize int, m matcher) (d *encoderDict, err error) { + if !(1 <= dictCap && int64(dictCap) <= MaxDictCap) { + return nil, errors.New( + "lzma: dictionary capacity out of range") + } + if bufSize < 1 { + return nil, errors.New( + "lzma: buffer size must be larger than zero") + } + d = &encoderDict{ + buf: *newBuffer(dictCap + bufSize), + capacity: dictCap, + m: m, + } + m.SetDict(d) + return d, nil +} + +// Discard discards n bytes. Note that n must not be larger than +// MaxMatchLen. +func (d *encoderDict) Discard(n int) { + p := d.data[:n] + k, _ := d.buf.Read(p) + if k < n { + panic(fmt.Errorf("lzma: can't discard %d bytes", n)) + } + d.head += int64(n) + d.m.Write(p) +} + +// Len returns the data available in the encoder dictionary. +func (d *encoderDict) Len() int { + n := d.buf.Available() + if int64(n) > d.head { + return int(d.head) + } + return n +} + +// DictLen returns the actual length of data in the dictionary. +func (d *encoderDict) DictLen() int { + if d.head < int64(d.capacity) { + return int(d.head) + } + return d.capacity +} + +// Available returns the number of bytes that can be written by a +// following Write call. +func (d *encoderDict) Available() int { + return d.buf.Available() - d.DictLen() +} + +// Write writes data into the dictionary buffer. Note that the position +// of the dictionary head will not be moved. If there is not enough +// space in the buffer ErrNoSpace will be returned. +func (d *encoderDict) Write(p []byte) (n int, err error) { + m := d.Available() + if len(p) > m { + p = p[:m] + err = ErrNoSpace + } + var e error + if n, e = d.buf.Write(p); e != nil { + err = e + } + return n, err +} + +// Pos returns the position of the head. +func (d *encoderDict) Pos() int64 { return d.head } + +// ByteAt returns the byte at the given distance. +func (d *encoderDict) ByteAt(distance int) byte { + if !(0 < distance && distance <= d.Len()) { + return 0 + } + i := d.buf.rear - distance + if i < 0 { + i += len(d.buf.data) + } + return d.buf.data[i] +} + +// CopyN copies the last n bytes from the dictionary into the provided +// writer. This is used for copying uncompressed data into an +// uncompressed segment. +func (d *encoderDict) CopyN(w io.Writer, n int) (written int, err error) { + if n <= 0 { + return 0, nil + } + m := d.Len() + if n > m { + n = m + err = ErrNoSpace + } + i := d.buf.rear - n + var e error + if i < 0 { + i += len(d.buf.data) + if written, e = w.Write(d.buf.data[i:]); e != nil { + return written, e + } + i = 0 + } + var k int + k, e = w.Write(d.buf.data[i:d.buf.rear]) + written += k + if e != nil { + err = e + } + return written, err +} + +// Buffered returns the number of bytes in the buffer. +func (d *encoderDict) Buffered() int { return d.buf.Buffered() } |