mirror of https://bitbucket.org/ausocean/av.git
84 lines
1.9 KiB
Go
84 lines
1.9 KiB
Go
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/*
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NAME
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lex.go
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AUTHOR
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Trek Hopton <trek@ausocean.org>
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LICENSE
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This file is Copyright (C) 2019 the Australian Ocean Lab (AusOcean)
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It is free software: you can redistribute it and/or modify them
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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It is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License in gpl.txt.
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If not, see [GNU licenses](http://www.gnu.org/licenses).
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*/
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package codecutil
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import (
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"fmt"
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"io"
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"time"
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)
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// ByteLexer is used to lex bytes using a buffer size which is configured upon construction.
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type ByteLexer struct {
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bufSize int
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}
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// NewByteLexer returns a pointer to a ByteLexer with the given buffer size.
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func NewByteLexer(s int) (*ByteLexer, error) {
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if s <= 0 {
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return nil, fmt.Errorf("invalid buffer size: %v", s)
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}
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return &ByteLexer{bufSize: s}, nil
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}
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// zeroTicks can be used to create an instant ticker.
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var zeroTicks chan time.Time
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func init() {
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zeroTicks = make(chan time.Time)
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close(zeroTicks)
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}
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// Lex reads l.bufSize bytes from src and writes them to dst every d seconds.
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func (l *ByteLexer) Lex(dst io.Writer, src io.Reader, d time.Duration) error {
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if d < 0 {
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return fmt.Errorf("invalid delay: %v", d)
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}
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var ticker *time.Ticker
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if d == 0 {
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ticker = &time.Ticker{C: zeroTicks}
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} else {
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ticker = time.NewTicker(d)
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defer ticker.Stop()
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}
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buf := make([]byte, l.bufSize)
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for {
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<-ticker.C
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off, err := src.Read(buf)
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// The only error that will stop the lexer is an EOF.
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if err == io.EOF {
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return err
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} else if err != nil {
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continue
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}
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_, err = dst.Write(buf[:off])
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if err != nil {
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return err
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}
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}
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}
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