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// Copyright 2014-2019 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"
"unicode"
)
// operation represents an operation on the dictionary during encoding or
// decoding.
type operation interface {
Len() int
}
// rep represents a repetition at the given distance and the given length
type match struct {
// supports all possible distance values, including the eos marker
distance int64
// length
n int
}
// verify checks whether the match is valid. If that is not the case an
// error is returned.
func (m match) verify() error {
if !(minDistance <= m.distance && m.distance <= maxDistance) {
return errors.New("distance out of range")
}
if !(1 <= m.n && m.n <= maxMatchLen) {
return errors.New("length out of range")
}
return nil
}
// l return the l-value for the match, which is the difference of length
// n and 2.
func (m match) l() uint32 {
return uint32(m.n - minMatchLen)
}
// dist returns the dist value for the match, which is one less of the
// distance stored in the match.
func (m match) dist() uint32 {
return uint32(m.distance - minDistance)
}
// Len returns the number of bytes matched.
func (m match) Len() int {
return m.n
}
// String returns a string representation for the repetition.
func (m match) String() string {
return fmt.Sprintf("M{%d,%d}", m.distance, m.n)
}
// lit represents a single byte literal.
type lit struct {
b byte
}
// Len returns 1 for the single byte literal.
func (l lit) Len() int {
return 1
}
// String returns a string representation for the literal.
func (l lit) String() string {
var c byte
if unicode.IsPrint(rune(l.b)) {
c = l.b
} else {
c = '.'
}
return fmt.Sprintf("L{%c/%02x}", c, l.b)
}
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