66 lines
1.4 KiB
Go
66 lines
1.4 KiB
Go
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package buffer
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import (
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"io"
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)
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// Writer implements an io.Writer over a byte slice.
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type Writer struct {
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buf []byte
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err error
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expand bool
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}
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// NewWriter returns a new Writer for a given byte slice.
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func NewWriter(buf []byte) *Writer {
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return &Writer{
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buf: buf,
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expand: true,
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}
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}
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// NewStaticWriter returns a new Writer for a given byte slice. It does not reallocate and expand the byte-slice.
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func NewStaticWriter(buf []byte) *Writer {
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return &Writer{
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buf: buf,
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expand: false,
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}
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}
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// Write writes bytes from the given byte slice and returns the number of bytes written and an error if occurred. When err != nil, n == 0.
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func (w *Writer) Write(b []byte) (int, error) {
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n := len(b)
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end := len(w.buf)
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if end+n > cap(w.buf) {
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if !w.expand {
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w.err = io.EOF
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return 0, io.EOF
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}
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buf := make([]byte, end, 2*cap(w.buf)+n)
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copy(buf, w.buf)
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w.buf = buf
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}
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w.buf = w.buf[:end+n]
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return copy(w.buf[end:], b), nil
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}
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// Len returns the length of the underlying byte slice.
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func (w *Writer) Len() int {
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return len(w.buf)
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}
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// Bytes returns the underlying byte slice.
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func (w *Writer) Bytes() []byte {
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return w.buf
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}
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// Reset empties and reuses the current buffer. Subsequent writes will overwrite the buffer, so any reference to the underlying slice is invalidated after this call.
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func (w *Writer) Reset() {
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w.buf = w.buf[:0]
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}
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// Close returns the last error.
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func (w *Writer) Close() error {
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return w.err
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}
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