Implement io.ReaderFrom
Aliaksandr Valialkin
7 years ago
| 15 | 15 |
B []byte
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}
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// WriteTo implements io.WriterTo
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// Len returns the size of the byte buffer.
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func (b *ByteBuffer) Len() int {
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return len(b.B)
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}
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// ReadFrom implements io.ReaderFrom.
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//
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// The function appends all the data read from r to b.
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func (b *ByteBuffer) ReadFrom(r io.Reader) (int64, error) {
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p := b.B
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nStart := int64(len(p))
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nMax := int64(cap(p))
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n := nStart
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if nMax == 0 {
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nMax = 64
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p = make([]byte, nMax)
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} else {
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p = p[:nMax]
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}
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for {
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if n == nMax {
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nMax *= 2
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bNew := make([]byte, nMax)
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copy(bNew, p)
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p = bNew
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}
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nn, err := r.Read(p[n:])
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n += int64(nn)
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if err != nil {
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b.B = p[:n]
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n -= nStart
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if err == io.EOF {
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return n, nil
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}
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return n, err
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}
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}
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}
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// WriteTo implements io.WriterTo.
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func (b *ByteBuffer) WriteTo(w io.Writer) (int64, error) {
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| 20 | 59 |
n, err := w.Write(b.B)
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return int64(n), err
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| 6 | 6 |
"testing"
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"time"
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)
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func TestByteBufferReadFrom(t *testing.T) {
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prefix := "foobar"
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expectedS := "asadfsdafsadfasdfisdsdfa"
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prefixLen := int64(len(prefix))
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expectedN := int64(len(expectedS))
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var bb ByteBuffer
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bb.WriteString(prefix)
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rf := (io.ReaderFrom)(&bb)
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for i := 0; i < 20; i++ {
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r := bytes.NewBufferString(expectedS)
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n, err := rf.ReadFrom(r)
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if n != expectedN {
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t.Fatalf("unexpected n=%d. Expecting %d. iteration %d", n, expectedN, i)
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}
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if err != nil {
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t.Fatalf("unexpected error: %s", err)
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}
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bbLen := int64(bb.Len())
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expectedLen := prefixLen + int64(i+1)*expectedN
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if bbLen != expectedLen {
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t.Fatalf("unexpected byteBuffer length: %d. Expecting %d", bbLen, expectedLen)
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}
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for j := 0; j < i; j++ {
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start := prefixLen + int64(j)*expectedN
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b := bb.B[start : start+expectedN]
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if string(b) != expectedS {
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t.Fatalf("unexpected byteBuffer contents: %q. Expecting %q", b, expectedS)
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}
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}
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}
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}
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func TestByteBufferWriteTo(t *testing.T) {
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expectedS := "foobarbaz"
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