bufio: drop error return for NewReaderSize and NewWriterSize
It complicates the interface unnecessarily.
Document this in go1.html.
Also update the go/doc Makefile.
Fixes #2836.
R=golang-dev, gri, bradfitz
CC=golang-dev
https://golang.org/cl/5642054
diff --git a/src/pkg/bufio/bufio.go b/src/pkg/bufio/bufio.go
index d421152..156dddf 100644
--- a/src/pkg/bufio/bufio.go
+++ b/src/pkg/bufio/bufio.go
@@ -11,7 +11,6 @@
"bytes"
"errors"
"io"
- "strconv"
"unicode/utf8"
)
@@ -27,13 +26,6 @@
errInternal = errors.New("bufio: internal error")
)
-// BufSizeError is the error representing an invalid buffer size.
-type BufSizeError int
-
-func (b BufSizeError) Error() string {
- return "bufio: bad buffer size " + strconv.Itoa(int(b))
-}
-
// Buffered input.
// Reader implements buffering for an io.Reader object.
@@ -48,35 +40,29 @@
const minReadBufferSize = 16
-// NewReaderSize creates a new Reader whose buffer has the specified size,
-// which must be at least 16 bytes. If the argument io.Reader is already a
-// Reader with large enough size, it returns the underlying Reader.
-// It returns the Reader and any error.
-func NewReaderSize(rd io.Reader, size int) (*Reader, error) {
- if size < minReadBufferSize {
- return nil, BufSizeError(size)
- }
+// NewReaderSize returns a new Reader whose buffer has at least the specified
+// size. If the argument io.Reader is already a Reader with large enough
+// size, it returns the underlying Reader.
+func NewReaderSize(rd io.Reader, size int) *Reader {
// Is it already a Reader?
b, ok := rd.(*Reader)
if ok && len(b.buf) >= size {
- return b, nil
+ return b
}
- b = new(Reader)
- b.buf = make([]byte, size)
- b.rd = rd
- b.lastByte = -1
- b.lastRuneSize = -1
- return b, nil
+ if size < minReadBufferSize {
+ size = minReadBufferSize
+ }
+ return &Reader{
+ buf: make([]byte, size),
+ rd: rd,
+ lastByte: -1,
+ lastRuneSize: -1,
+ }
}
// NewReader returns a new Reader whose buffer has the default size.
func NewReader(rd io.Reader) *Reader {
- b, err := NewReaderSize(rd, defaultBufSize)
- if err != nil {
- // cannot happen - defaultBufSize is a valid size
- panic(err)
- }
- return b
+ return NewReaderSize(rd, defaultBufSize)
}
// fill reads a new chunk into the buffer.
@@ -396,33 +382,27 @@
wr io.Writer
}
-// NewWriterSize creates a new Writer whose buffer has the specified size,
-// which must be greater than zero. If the argument io.Writer is already a
-// Writer with large enough size, it returns the underlying Writer.
-// It returns the Writer and any error.
-func NewWriterSize(wr io.Writer, size int) (*Writer, error) {
- if size <= 0 {
- return nil, BufSizeError(size)
- }
+// NewWriterSize returns a new Writer whose buffer has at least the specified
+// size. If the argument io.Writer is already a Writer with large enough
+// size, it returns the underlying Writer.
+func NewWriterSize(wr io.Writer, size int) *Writer {
// Is it already a Writer?
b, ok := wr.(*Writer)
if ok && len(b.buf) >= size {
- return b, nil
+ return b
+ }
+ if size <= 0 {
+ size = defaultBufSize
}
b = new(Writer)
b.buf = make([]byte, size)
b.wr = wr
- return b, nil
+ return b
}
// NewWriter returns a new Writer whose buffer has the default size.
func NewWriter(wr io.Writer) *Writer {
- b, err := NewWriterSize(wr, defaultBufSize)
- if err != nil {
- // cannot happen - defaultBufSize is valid size
- panic(err)
- }
- return b
+ return NewWriterSize(wr, defaultBufSize)
}
// Flush writes any buffered data to the underlying io.Writer.
diff --git a/src/pkg/bufio/bufio_test.go b/src/pkg/bufio/bufio_test.go
index a2ee849..9aec61e 100644
--- a/src/pkg/bufio/bufio_test.go
+++ b/src/pkg/bufio/bufio_test.go
@@ -161,7 +161,7 @@
bufreader := bufreaders[j]
bufsize := bufsizes[k]
read := readmaker.fn(bytes.NewBufferString(text))
- buf, _ := NewReaderSize(read, bufsize)
+ buf := NewReaderSize(read, bufsize)
s := bufreader.fn(buf)
if s != text {
t.Errorf("reader=%s fn=%s bufsize=%d want=%q got=%q",
@@ -379,18 +379,14 @@
// and that the data is correct.
w.Reset()
- buf, e := NewWriterSize(w, bs)
+ buf := NewWriterSize(w, bs)
context := fmt.Sprintf("nwrite=%d bufsize=%d", nwrite, bs)
- if e != nil {
- t.Errorf("%s: NewWriterSize %d: %v", context, bs, e)
- continue
- }
n, e1 := buf.Write(data[0:nwrite])
if e1 != nil || n != nwrite {
t.Errorf("%s: buf.Write %d = %d, %v", context, nwrite, n, e1)
continue
}
- if e = buf.Flush(); e != nil {
+ if e := buf.Flush(); e != nil {
t.Errorf("%s: buf.Flush = %v", context, e)
}
@@ -447,23 +443,14 @@
func TestNewReaderSizeIdempotent(t *testing.T) {
const BufSize = 1000
- b, err := NewReaderSize(bytes.NewBufferString("hello world"), BufSize)
- if err != nil {
- t.Error("NewReaderSize create fail", err)
- }
+ b := NewReaderSize(bytes.NewBufferString("hello world"), BufSize)
// Does it recognize itself?
- b1, err2 := NewReaderSize(b, BufSize)
- if err2 != nil {
- t.Error("NewReaderSize #2 create fail", err2)
- }
+ b1 := NewReaderSize(b, BufSize)
if b1 != b {
t.Error("NewReaderSize did not detect underlying Reader")
}
// Does it wrap if existing buffer is too small?
- b2, err3 := NewReaderSize(b, 2*BufSize)
- if err3 != nil {
- t.Error("NewReaderSize #3 create fail", err3)
- }
+ b2 := NewReaderSize(b, 2*BufSize)
if b2 == b {
t.Error("NewReaderSize did not enlarge buffer")
}
@@ -471,23 +458,14 @@
func TestNewWriterSizeIdempotent(t *testing.T) {
const BufSize = 1000
- b, err := NewWriterSize(new(bytes.Buffer), BufSize)
- if err != nil {
- t.Error("NewWriterSize create fail", err)
- }
+ b := NewWriterSize(new(bytes.Buffer), BufSize)
// Does it recognize itself?
- b1, err2 := NewWriterSize(b, BufSize)
- if err2 != nil {
- t.Error("NewWriterSize #2 create fail", err2)
- }
+ b1 := NewWriterSize(b, BufSize)
if b1 != b {
t.Error("NewWriterSize did not detect underlying Writer")
}
// Does it wrap if existing buffer is too small?
- b2, err3 := NewWriterSize(b, 2*BufSize)
- if err3 != nil {
- t.Error("NewWriterSize #3 create fail", err3)
- }
+ b2 := NewWriterSize(b, 2*BufSize)
if b2 == b {
t.Error("NewWriterSize did not enlarge buffer")
}
@@ -496,10 +474,7 @@
func TestWriteString(t *testing.T) {
const BufSize = 8
buf := new(bytes.Buffer)
- b, err := NewWriterSize(buf, BufSize)
- if err != nil {
- t.Error("NewWriterSize create fail", err)
- }
+ b := NewWriterSize(buf, BufSize)
b.WriteString("0") // easy
b.WriteString("123456") // still easy
b.WriteString("7890") // easy after flush
@@ -516,10 +491,7 @@
func TestBufferFull(t *testing.T) {
const longString = "And now, hello, world! It is the time for all good men to come to the aid of their party"
- buf, err := NewReaderSize(strings.NewReader(longString), minReadBufferSize)
- if err != nil {
- t.Fatal("NewReaderSize:", err)
- }
+ buf := NewReaderSize(strings.NewReader(longString), minReadBufferSize)
line, err := buf.ReadSlice('!')
if string(line) != "And now, hello, " || err != ErrBufferFull {
t.Errorf("first ReadSlice(,) = %q, %v", line, err)
@@ -533,7 +505,7 @@
func TestPeek(t *testing.T) {
p := make([]byte, 10)
// string is 16 (minReadBufferSize) long.
- buf, _ := NewReaderSize(strings.NewReader("abcdefghijklmnop"), minReadBufferSize)
+ buf := NewReaderSize(strings.NewReader("abcdefghijklmnop"), minReadBufferSize)
if s, err := buf.Peek(1); string(s) != "a" || err != nil {
t.Fatalf("want %q got %q, err=%v", "a", string(s), err)
}
@@ -609,7 +581,7 @@
for stride := 1; stride < 2; stride++ {
done := 0
reader := testReader{input, stride}
- l, _ := NewReaderSize(&reader, len(input)+1)
+ l := NewReaderSize(&reader, len(input)+1)
for {
line, isPrefix, err := l.ReadLine()
if len(line) > 0 && err != nil {
@@ -646,7 +618,7 @@
data = append(data, '0'+byte(i%10))
}
buf := bytes.NewBuffer(data)
- l, _ := NewReaderSize(buf, minReadBufferSize)
+ l := NewReaderSize(buf, minReadBufferSize)
line, isPrefix, err := l.ReadLine()
if !isPrefix || !bytes.Equal(line, data[:minReadBufferSize]) || err != nil {
t.Errorf("bad result for first line: got %q want %q %v", line, data[:minReadBufferSize], err)
@@ -673,7 +645,7 @@
inbuf := bytes.NewBuffer([]byte(line1 + "\n" + restData))
outbuf := new(bytes.Buffer)
maxLineLength := len(line1) + len(restData)/2
- l, _ := NewReaderSize(inbuf, maxLineLength)
+ l := NewReaderSize(inbuf, maxLineLength)
line, isPrefix, err := l.ReadLine()
if isPrefix || err != nil || string(line) != line1 {
t.Errorf("bad result for first line: isPrefix=%v err=%v line=%q", isPrefix, err, string(line))
@@ -688,7 +660,7 @@
}
func TestReadEmptyBuffer(t *testing.T) {
- l, _ := NewReaderSize(new(bytes.Buffer), minReadBufferSize)
+ l := NewReaderSize(new(bytes.Buffer), minReadBufferSize)
line, isPrefix, err := l.ReadLine()
if err != io.EOF {
t.Errorf("expected EOF from ReadLine, got '%s' %t %s", line, isPrefix, err)
@@ -696,7 +668,7 @@
}
func TestLinesAfterRead(t *testing.T) {
- l, _ := NewReaderSize(bytes.NewBuffer([]byte("foo")), minReadBufferSize)
+ l := NewReaderSize(bytes.NewBuffer([]byte("foo")), minReadBufferSize)
_, err := ioutil.ReadAll(l)
if err != nil {
t.Error(err)
@@ -752,10 +724,7 @@
}
func testReadLineNewlines(t *testing.T, input string, expect []readLineResult) {
- b, err := NewReaderSize(strings.NewReader(input), minReadBufferSize)
- if err != nil {
- t.Fatal(err)
- }
+ b := NewReaderSize(strings.NewReader(input), minReadBufferSize)
for i, e := range expect {
line, isPrefix, err := b.ReadLine()
if bytes.Compare(line, e.line) != 0 {
