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30 lines
706 B
30 lines
706 B
// Copyright 2014-2021 Ulrich Kunitz. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package hash
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// Roller provides an interface for rolling hashes. The hash value will become
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// valid after hash has been called Len times.
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type Roller interface {
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Len() int
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RollByte(x byte) uint64
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}
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// Hashes computes all hash values for the array p. Note that the state of the
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// roller is changed.
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func Hashes(r Roller, p []byte) []uint64 {
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n := r.Len()
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if len(p) < n {
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return nil
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}
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h := make([]uint64, len(p)-n+1)
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for i := 0; i < n-1; i++ {
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r.RollByte(p[i])
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}
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for i := range h {
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h[i] = r.RollByte(p[i+n-1])
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}
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return h
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}
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