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
diff --git a/src/pkg/bytes/buffer.go b/src/pkg/bytes/buffer.go
index 7612695..acd4523 100644
--- a/src/pkg/bytes/buffer.go
+++ b/src/pkg/bytes/buffer.go
@@ -9,6 +9,7 @@
import (
"io"
"os"
+ "utf8"
)
// Copy from string to byte array at offset doff. Assume there's room.
@@ -22,10 +23,10 @@
// 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 @@
// 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 @@
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,
