bytes: Add Buffer.ReadBytes, Buffer.ReadString

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/4000046

2 files changed, 55 insertions, 1 deletions

diff --git a/src/pkg/bytes/buffer.go b/src/pkg/bytes/buffer.go
index 62cf82810e..4aa74371f1 100644
--- a/src/pkg/bytes/buffer.go
+++ b/src/pkg/bytes/buffer.go
@@ -301,6 +301,35 @@ func (b *Buffer) UnreadByte() os.Error {
 	return nil
 }
 
+// ReadBytes reads until the first occurrence of delim in the input,
+// returning a slice containing the data up to and including the delimiter.
+// If ReadBytes encounters an error before finding a delimiter,
+// it returns the data read before the error and the error itself (often os.EOF).
+// ReadBytes returns err != nil if and only if the returned data does not end in
+// delim.
+func (b *Buffer) ReadBytes(delim byte) (line []byte, err os.Error) {
+	i := IndexByte(b.buf[b.off:], delim)
+	size := i + 1 - b.off
+	if i < 0 {
+		size = len(b.buf) - b.off
+		err = os.EOF
+	}
+	line = make([]byte, size)
+	copy(line, b.buf[b.off:])
+	return
+}
+
+// ReadString reads until the first occurrence of delim in the input,
+// returning a string containing the data up to and including the delimiter.
+// If ReadString encounters an error before finding a delimiter,
+// it returns the data read before the error and the error itself (often os.EOF).
+// ReadString returns err != nil if and only if the returned data does not end
+// in delim.
+func (b *Buffer) ReadString(delim byte) (line string, err os.Error) {
+	bytes, err := b.ReadBytes(delim)
+	return string(bytes), err
+}
+
 // 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 size the internal buffer for writing.  To do that,
diff --git a/src/pkg/bytes/buffer_test.go b/src/pkg/bytes/buffer_test.go
index 509793d24a..2af9ffdefa 100644
--- a/src/pkg/bytes/buffer_test.go
+++ b/src/pkg/bytes/buffer_test.go
@@ -6,6 +6,7 @@ package bytes_test
 
 import (
 	. "bytes"
+	"os"
 	"rand"
 	"testing"
 	"utf8"
@@ -238,7 +239,7 @@ func TestMixedReadsAndWrites(t *testing.T) {
 func TestNil(t *testing.T) {
 	var b *Buffer
 	if b.String() != "<nil>" {
-		t.Errorf("expcted <nil>; got %q", b.String())
+		t.Errorf("expected <nil>; got %q", b.String())
 	}
 }
 
@@ -347,3 +348,27 @@ func TestNext(t *testing.T) {
 		}
 	}
 }
+
+var readBytesTests = []struct {
+	buffer   []byte
+	delim    byte
+	expected []byte
+	err      os.Error
+}{
+	{err: os.EOF},
+	{[]byte{}, 0, []byte{}, os.EOF},
+	{[]byte("a\x00"), 0, []byte("a\x00"), nil},
+	{[]byte("hello\x01world"), 1, []byte("hello\x01"), nil},
+	{[]byte("foo\nbar"), 0, []byte("foo\nbar"), os.EOF},
+	{[]byte("alpha beta gamma"), ' ', []byte("alpha "), nil},
+}
+
+func TestReadBytes(t *testing.T) {
+	for _, test := range readBytesTests {
+		buf := NewBuffer(test.buffer)
+		bytes, err := buf.ReadBytes(test.delim)
+		if !Equal(bytes, test.expected) || err != test.err {
+			t.Errorf("expected %q, %v got %q, %v", test.expected, test.err, bytes, err)
+		}
+	}
+}