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bytes: add Next method to Buffer, simplify Read.
R=r CC=golang-dev https://golang.org/cl/980043
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78551a9b43
@ -196,17 +196,23 @@ func (b *Buffer) Read(p []byte) (n int, err os.Error) {
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b.Truncate(0)
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return 0, os.EOF
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}
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m := b.Len()
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n = len(p)
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n = copy(p, b.buf[b.off:])
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b.off += n
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return
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}
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// Next returns a slice containing the next n bytes from the buffer,
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// advancing the buffer as if the bytes had been returned by Read.
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// If there are fewer than n bytes in the buffer, Next returns the entire buffer.
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// The slice is only valid until the next call to a read or write method.
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func (b *Buffer) Next(n int) []byte {
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m := b.Len()
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if n > m {
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// more bytes requested than available
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n = m
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}
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copy(p, b.buf[b.off:b.off+n])
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data := b.buf[b.off : b.off+n]
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b.off += n
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return n, err
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return data
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}
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// ReadByte reads and returns the next byte from the buffer.
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@ -264,6 +264,7 @@ func TestWriteTo(t *testing.T) {
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}
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}
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func TestRuneIO(t *testing.T) {
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const NRune = 1000
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// Built a test array while we write the data
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@ -297,3 +298,37 @@ func TestRuneIO(t *testing.T) {
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}
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}
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}
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func TestNext(t *testing.T) {
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b := []byte{0, 1, 2, 3, 4}
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tmp := make([]byte, 5)
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for i := 0; i <= 5; i++ {
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for j := i; j <= 5; j++ {
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for k := 0; k <= 6; k++ {
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// 0 <= i <= j <= 5; 0 <= k <= 6
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// Check that if we start with a buffer
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// of length j at offset i and ask for
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// Next(k), we get the right bytes.
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buf := NewBuffer(b[0:j])
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n, _ := buf.Read(tmp[0:i])
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if n != i {
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t.Fatalf("Read %d returned %d", i, n)
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}
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bb := buf.Next(k)
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want := k
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if want > j-i {
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want = j - i
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}
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if len(bb) != want {
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t.Fatalf("in %d,%d: len(Next(%d)) == %d", i, j, k, len(bb))
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}
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for l, v := range bb {
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if v != byte(l+i) {
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t.Fatalf("in %d,%d: Next(%d)[%d] = %d, want %d", i, j, k, l, v, l+i)
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}
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}
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}
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}
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}
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}
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