Commit 0ac5ef70 authored by Rob Pike's avatar Rob Pike

Add ReadRune and WriteRune to bytes.Buffer

The comments mention bufio's WriteRune, which should come next.

R=rsc
CC=golang-dev
https://golang.org/cl/245041
parent 4b22e1bd
......@@ -9,6 +9,7 @@ package bytes
import (
"io"
"os"
"utf8"
)
// Copy from string to byte array at offset doff. Assume there's room.
......@@ -22,10 +23,10 @@ func copyString(dst []byte, doff int, str string) {
// A Buffer is a variable-sized buffer of bytes with Read and Write methods.
// The zero value for Buffer is an empty buffer ready to use.
type Buffer struct {
buf []byte // contents are the bytes buf[off : len(buf)]
off int // read at &buf[off], write at &buf[len(buf)]
oneByte [1]byte // avoid allocation of slice on each WriteByte
bootstrap [64]byte // memory to hold first slice; helps small buffers (Printf) avoid allocation.
buf []byte // contents are the bytes buf[off : len(buf)]
off int // read at &buf[off], write at &buf[len(buf)]
runeBytes [utf8.UTFMax]byte // avoid allocation of slice on each WriteByte or Rune
bootstrap [64]byte // memory to hold first slice; helps small buffers (Printf) avoid allocation.
}
// Bytes returns a slice of the contents of the unread portion of the buffer;
......@@ -176,11 +177,25 @@ func (b *Buffer) WriteTo(w io.Writer) (n int64, err os.Error) {
// The returned error is always nil, but is included
// to match bufio.Writer's WriteByte.
func (b *Buffer) WriteByte(c byte) os.Error {
b.oneByte[0] = c
b.Write(&b.oneByte)
b.runeBytes[0] = c
b.Write(b.runeBytes[0:1])
return nil
}
// WriteRune appends the UTF-8 encoding of Unicode
// code point r to the buffer, returning its length and
// an error, which is always nil but is included
// to match bufio.Writer's WriteRune.
func (b *Buffer) WriteRune(r int) (n int, err os.Error) {
if r < utf8.RuneSelf {
b.WriteByte(byte(r))
return 1, nil
}
n = utf8.EncodeRune(r, &b.runeBytes)
b.Write(b.runeBytes[0:n])
return n, nil
}
// Read reads the next len(p) bytes from the buffer or until the buffer
// is drained. The return value n is the number of bytes read. If the
// buffer has no data to return, err is os.EOF even if len(p) is zero;
......@@ -217,6 +232,27 @@ func (b *Buffer) ReadByte() (c byte, err os.Error) {
return c, nil
}
// ReadRune reads and returns the next UTF-8-encoded
// Unicode code point from the buffer.
// If no bytes are available, the error returned is os.EOF.
// If the bytes are an erroneous UTF-8 encoding, it
// consumes one byte and returns U+FFFD, 1.
func (b *Buffer) ReadRune() (r int, size int, err os.Error) {
if b.off >= len(b.buf) {
// Buffer is empty, reset to recover space.
b.Truncate(0)
return 0, 0, os.EOF
}
c := b.buf[b.off]
if c < utf8.RuneSelf {
b.off++
return int(c), 1, nil
}
r, n := utf8.DecodeRune(b.buf[b.off:])
b.off += n
return r, n, nil
}
// NewBuffer creates and initializes a new Buffer using buf as its initial
// contents. It is intended to prepare a Buffer to read existing data. It
// can also be used to to size the internal buffer for writing. To do that,
......
......@@ -8,6 +8,7 @@ import (
. "bytes"
"rand"
"testing"
"utf8"
)
......@@ -262,3 +263,37 @@ func TestWriteTo(t *testing.T) {
empty(t, "TestReadFrom (2)", &b, s, make([]byte, len(data)))
}
}
func TestRuneIO(t *testing.T) {
const NRune = 1000
// Built a test array while we write the data
b := make([]byte, utf8.UTFMax*NRune)
var buf Buffer
n := 0
for r := 0; r < NRune; r++ {
size := utf8.EncodeRune(r, b[n:])
nbytes, err := buf.WriteRune(r)
if err != nil {
t.Fatalf("WriteRune(0x%x) error: %s", r, err)
}
if nbytes != size {
t.Fatalf("WriteRune(0x%x) expected %d, got %d", size, nbytes)
}
n += size
}
b = b[0:n]
// Check the resulting bytes
if !Equal(buf.Bytes(), b) {
t.Fatalf("incorrect result from WriteRune: %q not %q", buf.Bytes(), b)
}
// Read it back with ReadRune
for r := 0; r < NRune; r++ {
size := utf8.EncodeRune(r, b)
nr, nbytes, err := buf.ReadRune()
if nr != r || nbytes != size || err != nil {
t.Fatalf("ReadRune(0x%x) got 0x%x,%d not 0x%x,%d (err=%s)", r, nr, nbytes, r, size, err)
}
}
}
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