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50 lines
1.4 KiB
Go
50 lines
1.4 KiB
Go
package io
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import (
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"bytes"
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"errors"
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)
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// ErrDrained is returned on an attempt to use an already drained write buffer.
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var ErrDrained = errors.New("buffer already drained")
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// BufBinWriter is an additional layer on top of BinWriter that
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// automatically creates a buffer to write into that you can get after all
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// writes via Bytes().
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type BufBinWriter struct {
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*BinWriter
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buf bytes.Buffer
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}
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// NewBufBinWriter makes a BufBinWriter with an empty byte buffer.
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func NewBufBinWriter() *BufBinWriter {
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b := new(BufBinWriter)
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b.BinWriter = NewBinWriterFromIO(&b.buf)
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return b
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}
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// Len returns the number of bytes of the unread portion of the buffer.
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func (bw *BufBinWriter) Len() int {
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return bw.buf.Len()
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}
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// Bytes returns the resulting buffer and makes future writes return an error.
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// Subsequent calls to it will return nil. You can reuse this instance of
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// [BufBinWriter] after [BufBinWriter.Reset].
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func (bw *BufBinWriter) Bytes() []byte {
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if bw.Err != nil {
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return nil
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}
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bw.Err = ErrDrained
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return bw.buf.Bytes()
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}
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// Reset resets the state of the buffer, making it usable again. It can
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// make buffer usage somewhat more efficient because you don't need to
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// create it again. But beware, the buffer is gonna be the same as the one
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// returned by Bytes(), so if you need that data after Reset() you have to copy
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// it yourself.
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func (bw *BufBinWriter) Reset() {
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bw.Err = nil
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bw.buf.Reset()
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}
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