libgo: Update to October 24 version of master library.

From-SVN: r204466

4 files changed, 168 insertions, 29 deletions

diff --git a/libgo/go/bufio/bufio.go b/libgo/go/bufio/bufio.go
index df3501f..d1ff3c9 100644
--- a/libgo/go/bufio/bufio.go
+++ b/libgo/go/bufio/bufio.go
@@ -51,12 +51,9 @@ func NewReaderSize(rd io.Reader, size int) *Reader {
 	if size < minReadBufferSize {
 		size = minReadBufferSize
 	}
-	return &Reader{
-		buf:          make([]byte, size),
-		rd:           rd,
-		lastByte:     -1,
-		lastRuneSize: -1,
-	}
+	r := new(Reader)
+	r.reset(make([]byte, size), rd)
+	return r
 }
 
 // NewReader returns a new Reader whose buffer has the default size.
@@ -64,6 +61,21 @@ func NewReader(rd io.Reader) *Reader {
 	return NewReaderSize(rd, defaultBufSize)
 }
 
+// Reset discards any buffered data, resets all state, and switches
+// the buffered reader to read from r.
+func (b *Reader) Reset(r io.Reader) {
+	b.reset(b.buf, r)
+}
+
+func (b *Reader) reset(buf []byte, r io.Reader) {
+	*b = Reader{
+		buf:          buf,
+		rd:           r,
+		lastByte:     -1,
+		lastRuneSize: -1,
+	}
+}
+
 var errNegativeRead = errors.New("bufio: reader returned negative count from Read")
 
 // fill reads a new chunk into the buffer.
@@ -234,7 +246,7 @@ func (b *Reader) Buffered() int { return b.w - b.r }
 
 // ReadSlice reads until the first occurrence of delim in the input,
 // returning a slice pointing at the bytes in the buffer.
-// The bytes stop being valid at the next read call.
+// The bytes stop being valid at the next read.
 // If ReadSlice encounters an error before finding a delimiter,
 // it returns all the data in the buffer and the error itself (often io.EOF).
 // ReadSlice fails with error ErrBufferFull if the buffer fills without a delim.
@@ -381,7 +393,8 @@ func (b *Reader) ReadBytes(delim byte) (line []byte, err error) {
 // For simple uses, a Scanner may be more convenient.
 func (b *Reader) ReadString(delim byte) (line string, err error) {
 	bytes, err := b.ReadBytes(delim)
-	return string(bytes), err
+	line = string(bytes)
+	return line, err
 }
 
 // WriteTo implements io.WriterTo.
@@ -424,6 +437,9 @@ func (b *Reader) writeBuf(w io.Writer) (int64, error) {
 // Writer implements buffering for an io.Writer object.
 // If an error occurs writing to a Writer, no more data will be
 // accepted and all subsequent writes will return the error.
+// After all data has been written, the client should call the
+// Flush method to guarantee all data has been forwarded to
+// the underlying io.Writer.
 type Writer struct {
 	err error
 	buf []byte
@@ -434,28 +450,41 @@ type Writer struct {
 // 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 {
+func NewWriterSize(w io.Writer, size int) *Writer {
 	// Is it already a Writer?
-	b, ok := wr.(*Writer)
+	b, ok := w.(*Writer)
 	if ok && len(b.buf) >= size {
 		return b
 	}
 	if size <= 0 {
 		size = defaultBufSize
 	}
-	b = new(Writer)
-	b.buf = make([]byte, size)
-	b.wr = wr
-	return b
+	return &Writer{
+		buf: make([]byte, size),
+		wr:  w,
+	}
 }
 
 // NewWriter returns a new Writer whose buffer has the default size.
-func NewWriter(wr io.Writer) *Writer {
-	return NewWriterSize(wr, defaultBufSize)
+func NewWriter(w io.Writer) *Writer {
+	return NewWriterSize(w, defaultBufSize)
+}
+
+// Reset discards any unflushed buffered data, clears any error, and
+// resets b to write its output to w.
+func (b *Writer) Reset(w io.Writer) {
+	b.err = nil
+	b.n = 0
+	b.wr = w
 }
 
 // Flush writes any buffered data to the underlying io.Writer.
 func (b *Writer) Flush() error {
+	err := b.flush()
+	return err
+}
+
+func (b *Writer) flush() error {
 	if b.err != nil {
 		return b.err
 	}
@@ -498,7 +527,7 @@ func (b *Writer) Write(p []byte) (nn int, err error) {
 		} else {
 			n = copy(b.buf[b.n:], p)
 			b.n += n
-			b.Flush()
+			b.flush()
 		}
 		nn += n
 		p = p[n:]
@@ -517,7 +546,7 @@ func (b *Writer) WriteByte(c byte) error {
 	if b.err != nil {
 		return b.err
 	}
-	if b.Available() <= 0 && b.Flush() != nil {
+	if b.Available() <= 0 && b.flush() != nil {
 		return b.err
 	}
 	b.buf[b.n] = c
@@ -540,7 +569,7 @@ func (b *Writer) WriteRune(r rune) (size int, err error) {
 	}
 	n := b.Available()
 	if n < utf8.UTFMax {
-		if b.Flush(); b.err != nil {
+		if b.flush(); b.err != nil {
 			return 0, b.err
 		}
 		n = b.Available()
@@ -565,7 +594,7 @@ func (b *Writer) WriteString(s string) (int, error) {
 		b.n += n
 		nn += n
 		s = s[n:]
-		b.Flush()
+		b.flush()
 	}
 	if b.err != nil {
 		return nn, b.err
@@ -585,23 +614,28 @@ func (b *Writer) ReadFrom(r io.Reader) (n int64, err error) {
 	}
 	var m int
 	for {
+		if b.Available() == 0 {
+			if err1 := b.flush(); err1 != nil {
+				return n, err1
+			}
+		}
 		m, err = r.Read(b.buf[b.n:])
 		if m == 0 {
 			break
 		}
 		b.n += m
 		n += int64(m)
-		if b.Available() == 0 {
-			if err1 := b.Flush(); err1 != nil {
-				return n, err1
-			}
-		}
 		if err != nil {
 			break
 		}
 	}
 	if err == io.EOF {
-		err = nil
+		// If we filled the buffer exactly, flush pre-emptively.
+		if b.Available() == 0 {
+			err = b.flush()
+		} else {
+			err = nil
+		}
 	}
 	return n, err
 }
diff --git a/libgo/go/bufio/bufio_test.go b/libgo/go/bufio/bufio_test.go
index 79ed0f1..41bd3d45 100644
--- a/libgo/go/bufio/bufio_test.go
+++ b/libgo/go/bufio/bufio_test.go
@@ -847,6 +847,10 @@ func TestWriterReadFrom(t *testing.T) {
 				t.Errorf("ws[%d],rs[%d]: w.ReadFrom(r) = %d, %v, want %d, nil", wi, ri, n, err, len(input))
 				continue
 			}
+			if err := w.Flush(); err != nil {
+				t.Errorf("Flush returned %v", err)
+				continue
+			}
 			if got, want := b.String(), string(input); got != want {
 				t.Errorf("ws[%d], rs[%d]:\ngot  %q\nwant %q\n", wi, ri, got, want)
 			}
@@ -1003,6 +1007,56 @@ func TestReaderClearError(t *testing.T) {
 	}
 }
 
+// Test for golang.org/issue/5947
+func TestWriterReadFromWhileFull(t *testing.T) {
+	buf := new(bytes.Buffer)
+	w := NewWriterSize(buf, 10)
+
+	// Fill buffer exactly.
+	n, err := w.Write([]byte("0123456789"))
+	if n != 10 || err != nil {
+		t.Fatalf("Write returned (%v, %v), want (10, nil)", n, err)
+	}
+
+	// Use ReadFrom to read in some data.
+	n2, err := w.ReadFrom(strings.NewReader("abcdef"))
+	if n2 != 6 || err != nil {
+		t.Fatalf("ReadFrom returned (%v, %v), want (6, nil)", n, err)
+	}
+}
+
+func TestReaderReset(t *testing.T) {
+	r := NewReader(strings.NewReader("foo foo"))
+	buf := make([]byte, 3)
+	r.Read(buf)
+	if string(buf) != "foo" {
+		t.Errorf("buf = %q; want foo", buf)
+	}
+	r.Reset(strings.NewReader("bar bar"))
+	all, err := ioutil.ReadAll(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(all) != "bar bar" {
+		t.Errorf("ReadAll = %q; want bar bar", all)
+	}
+}
+
+func TestWriterReset(t *testing.T) {
+	var buf1, buf2 bytes.Buffer
+	w := NewWriter(&buf1)
+	w.WriteString("foo")
+	w.Reset(&buf2) // and not flushed
+	w.WriteString("bar")
+	w.Flush()
+	if buf1.String() != "" {
+		t.Errorf("buf1 = %q; want empty", buf1.String())
+	}
+	if buf2.String() != "bar" {
+		t.Errorf("buf2 = %q; want bar", buf2.String())
+	}
+}
+
 // An onlyReader only implements io.Reader, no matter what other methods the underlying implementation may have.
 type onlyReader struct {
 	r io.Reader
@@ -1083,3 +1137,46 @@ func BenchmarkWriterCopyNoReadFrom(b *testing.B) {
 		io.Copy(dst, src)
 	}
 }
+
+func BenchmarkReaderEmpty(b *testing.B) {
+	b.ReportAllocs()
+	str := strings.Repeat("x", 16<<10)
+	for i := 0; i < b.N; i++ {
+		br := NewReader(strings.NewReader(str))
+		n, err := io.Copy(ioutil.Discard, br)
+		if err != nil {
+			b.Fatal(err)
+		}
+		if n != int64(len(str)) {
+			b.Fatal("wrong length")
+		}
+	}
+}
+
+func BenchmarkWriterEmpty(b *testing.B) {
+	b.ReportAllocs()
+	str := strings.Repeat("x", 1<<10)
+	bs := []byte(str)
+	for i := 0; i < b.N; i++ {
+		bw := NewWriter(ioutil.Discard)
+		bw.Flush()
+		bw.WriteByte('a')
+		bw.Flush()
+		bw.WriteRune('B')
+		bw.Flush()
+		bw.Write(bs)
+		bw.Flush()
+		bw.WriteString(str)
+		bw.Flush()
+	}
+}
+
+func BenchmarkWriterFlush(b *testing.B) {
+	b.ReportAllocs()
+	bw := NewWriter(ioutil.Discard)
+	str := strings.Repeat("x", 50)
+	for i := 0; i < b.N; i++ {
+		bw.WriteString(str)
+		bw.Flush()
+	}
+}
diff --git a/libgo/go/bufio/example_test.go b/libgo/go/bufio/example_test.go
index 08a3944..3da9141 100644
--- a/libgo/go/bufio/example_test.go
+++ b/libgo/go/bufio/example_test.go
@@ -12,6 +12,14 @@ import (
 	"strings"
 )
 
+func ExampleWriter() {
+	w := bufio.NewWriter(os.Stdout)
+	fmt.Fprint(w, "Hello, ")
+	fmt.Fprint(w, "world!")
+	w.Flush() // Don't forget to flush!
+	// Output: Hello, world!
+}
+
 // The simplest use of a Scanner, to read standard input as a set of lines.
 func ExampleScanner_lines() {
 	scanner := bufio.NewScanner(os.Stdin)
diff --git a/libgo/go/bufio/scan.go b/libgo/go/bufio/scan.go
index 2e1a2e9..423505f 100644
--- a/libgo/go/bufio/scan.go
+++ b/libgo/go/bufio/scan.go
@@ -44,8 +44,8 @@ type Scanner struct {
 // to give. The return values are the number of bytes to advance the input
 // and the next token to return to the user, plus an error, if any. If the
 // data does not yet hold a complete token, for instance if it has no newline
-// while scanning lines, SplitFunc can return (0, nil) to signal the Scanner
-// to read more data into the slice and try again with a longer slice
+// while scanning lines, SplitFunc can return (0, nil, nil) to signal the
+// Scanner to read more data into the slice and try again with a longer slice
 // starting at the same point in the input.
 //
 // If the returned error is non-nil, scanning stops and the error
@@ -287,7 +287,7 @@ func ScanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
 	return 0, nil, nil
 }
 
-// isSpace returns whether the character is a Unicode white space character.
+// isSpace reports whether the character is a Unicode white space character.
 // We avoid dependency on the unicode package, but check validity of the implementation
 // in the tests.
 func isSpace(r rune) bool {