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Commit 6efd7e6b authored by Rob Pike's avatar Rob Pike
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move strings.Buffer into bytes 

delete strings.Buffer
add a test for a bug not caught before (mustn't install zero-length blocks)

R=rsc
DELTA=987  (289 added, 587 deleted, 111 changed)
OCL=34850
CL=34850
parent fed47706
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Showing with 370 additions and 669 deletions
src/pkg/Make.deps
View file @ 6efd7e6b
......@@ -31,7 +31,7 @@ fmt.install: io.install os.install reflect.install strconv.install utf8.install
go/ast.install: go/token.install unicode.install utf8.install
go/doc.install: container/vector.install go/ast.install go/token.install io.install once.install regexp.install sort.install strings.install template.install
go/parser.install: bytes.install container/vector.install fmt.install go/ast.install go/scanner.install go/token.install io.install os.install path.install strings.install
go/printer.install: container/vector.install fmt.install go/ast.install go/token.install io.install os.install reflect.install strings.install tabwriter.install
go/printer.install: bytes.install container/vector.install fmt.install go/ast.install go/token.install io.install os.install reflect.install strings.install tabwriter.install
go/scanner.install: bytes.install container/vector.install fmt.install go/token.install io.install os.install sort.install strconv.install unicode.install utf8.install
go/token.install: fmt.install strconv.install
gob.install: bytes.install fmt.install io.install math.install os.install reflect.install sync.install
......@@ -57,7 +57,7 @@ rpc.install: bufio.install fmt.install gob.install http.install io.install log.i
runtime.install:
sort.install:
strconv.install: bytes.install math.install os.install unicode.install utf8.install
strings.install: os.install unicode.install utf8.install
strings.install: unicode.install utf8.install
sync.install:
syscall.install: sync.install
tabwriter.install: bytes.install container/vector.install io.install os.install utf8.install
......
src/pkg/base64/base64_test.go
View file @ 6efd7e6b
......@@ -112,7 +112,7 @@ func TestDecode(t *testing.T) {
func TestDecoder(t *testing.T) {
for _, p := range pairs {
decoder := NewDecoder(StdEncoding, strings.NewBufferString(p.encoded));
decoder := NewDecoder(StdEncoding, bytes.NewBufferString(p.encoded));
dbuf := make([]byte, StdEncoding.DecodedLen(len(p.encoded)));
count, err := decoder.Read(dbuf);
if err != nil && err != os.EOF {
......@@ -129,7 +129,7 @@ func TestDecoder(t *testing.T) {
func TestDecoderBuffering(t *testing.T) {
for bs := 1; bs <= 12; bs++ {
decoder := NewDecoder(StdEncoding, strings.NewBufferString(bigtest.encoded));
decoder := NewDecoder(StdEncoding, bytes.NewBufferString(bigtest.encoded));
buf := make([]byte, len(bigtest.decoded) + 12);
var total int;
for total = 0; total < len(bigtest.decoded); {
......
src/pkg/bufio/bufio_test.go
View file @ 6efd7e6b
......@@ -61,12 +61,12 @@ func readBytes(buf *Reader) string {
func TestReaderSimple(t *testing.T) {
data := "hello world";
b := NewReader(strings.NewBufferString(data));
b := NewReader(bytes.NewBufferString(data));
if s := readBytes(b); s != "hello world" {
t.Errorf("simple hello world test failed: got %q", s);
}
b = NewReader(newRot13Reader(strings.NewBufferString(data)));
b = NewReader(newRot13Reader(bytes.NewBufferString(data)));
if s := readBytes(b); s != "uryyb jbeyq" {
t.Error("rot13 hello world test failed: got %q", s);
}
......@@ -154,7 +154,7 @@ func TestReader(t *testing.T) {
readmaker := readMakers[i];
bufreader := bufreaders[j];
bufsize := bufsizes[k];
read := readmaker.fn(strings.NewBufferString(text));
read := readmaker.fn(bytes.NewBufferString(text));
buf, _ := NewReaderSize(read, bufsize);
s := bufreader.fn(buf);
if s != text {
......@@ -308,7 +308,7 @@ func TestWriteErrors(t *testing.T) {
func TestNewReaderSizeIdempotent(t *testing.T) {
const BufSize = 1000;
b, err := NewReaderSize(strings.NewBufferString("hello world"), BufSize);
b, err := NewReaderSize(bytes.NewBufferString("hello world"), BufSize);
if err != nil {
t.Error("NewReaderSize create fail", err);
}
......
src/pkg/bytes/buffer.go
View file @ 6efd7e6b
......@@ -4,90 +4,276 @@
package bytes
// Simple byte buffer for marshaling data.
import "os"
import (
"os";
)
// Efficient construction of large strings and byte arrays.
// Implements io.Reader and io.Writer.
func bytecopy(dst []byte, doff int, src []byte, soff int, count int) {
for ; count > 0; count-- {
dst[doff] = src[soff];
// A Buffer provides efficient construction of large strings
// and slices of bytes. It implements io.Reader and io.Writer.
// Appends (writes) are efficient.
// The zero value for Buffer is an empty buffer ready to use.
type Buffer struct {
blk []block;
len int;
oneByte [1]byte;
}
// There are two kinds of block: a string or a []byte.
// When the user writes big strings, we add string blocks;
// when the user writes big byte slices, we add []byte blocks.
// Small writes are coalesced onto the end of the last block,
// whatever it is.
// This strategy is intended to reduce unnecessary allocation.
type block interface {
Len() int;
String() string;
appendBytes(s []byte);
appendString(s string);
setSlice(m, n int);
}
// stringBlocks represent strings. We use pointer receivers
// so append and setSlice can overwrite the receiver.
type stringBlock string
func (b *stringBlock) Len() int {
return len(*b)
}
func (b *stringBlock) String() string {
return string(*b)
}
func (b *stringBlock) appendBytes(s []byte) {
*b += stringBlock(s)
}
func (b *stringBlock) appendString(s string) {
*b = stringBlock(s)
}
func (b *stringBlock) setSlice(m, n int) {
*b = (*b)[m:n]
}
// byteBlock represent slices of bytes. We use pointer receivers
// so append and setSlice can overwrite the receiver.
type byteBlock []byte
func (b *byteBlock) Len() int {
return len(*b)
}
func (b *byteBlock) String() string {
return string(*b)
}
func (b *byteBlock) resize(max int) {
by := []byte(*b);
if cap(by) >= max {
by = by[0:max];
} else {
nby := make([]byte, max, 3*(max+10)/2);
copyBytes(nby, 0, by);
by = nby;
}
*b = by;
}
func (b *byteBlock) appendBytes(s []byte) {
curLen := b.Len();
b.resize(curLen + len(s));
copyBytes([]byte(*b), curLen, s);
}
func (b *byteBlock) appendString(s string) {
curLen := b.Len();
b.resize(curLen + len(s));
copyString([]byte(*b), curLen, s);
}
func (b *byteBlock) setSlice(m, n int) {
*b = (*b)[m:n]
}
// Because the user may overwrite the contents of byte slices, we need
// to make a copy. Allocation strategy: leave some space on the end so
// small subsequent writes can avoid another allocation. The input
// is known to be non-empty.
func newByteBlock(s []byte) *byteBlock {
l := len(s);
// Capacity with room to grow. If small, allocate a mininum. If medium,
// double the size. If huge, use the size plus epsilon (room for a newline,
// at least).
c := l;
switch {
case l < 32:
c = 64
case l < 1<<18:
c *= 2;
default:
c += 8
}
b := make([]byte, l, c);
copyBytes(b, 0, s);
return &b;
}
// Copy from block to byte array at offset doff. Assume there's room.
func copy(dst []byte, doff int, src block) {
switch s := src.(type) {
case *stringBlock:
copyString(dst, doff, string(*s));
case *byteBlock:
copyBytes(dst, doff, []byte(*s));
}
}
// Copy from string to byte array at offset doff. Assume there's room.
func copyString(dst []byte, doff int, str string) {
for soff := 0; soff < len(str); soff++ {
dst[doff] = str[soff];
doff++;
soff++;
}
}
// 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)]
// Copy from bytes to byte array at offset doff. Assume there's room.
func copyBytes(dst []byte, doff int, src []byte) {
for soff := 0; soff < len(src); soff++ {
dst[doff] = src[soff];
doff++;
}
}
// Bytes returns the contents of the unread portion of the buffer;
// len(b.Bytes()) == b.Len().
// Bytes returns the contents of the unread portion of the buffer
// as a byte array.
func (b *Buffer) Bytes() []byte {
return b.buf[b.off : len(b.buf)]
n := b.len;
bytes := make([]byte, n);
nbytes := 0;
for _, s := range b.blk {
copy(bytes, nbytes, s);
nbytes += s.Len();
}
return bytes;
}
// String returns the contents of the unread portion of the buffer
// as a string.
func (b *Buffer) String() string {
return string(b.buf[b.off : len(b.buf)])
if len(b.blk) == 1 { // important special case
return b.blk[0].String()
}
return string(b.Bytes())
}
// Len returns the number of bytes of the unread portion of the buffer;
// b.Len() == len(b.Bytes()).
// Len returns the number of bytes in the unread portion of the buffer;
// b.Len() == len(b.Bytes()) == len(b.String()).
func (b *Buffer) Len() int {
return len(b.buf) - b.off
return b.len
}
// Truncate discards all but the first n unread bytes from the buffer.
// It is an error to call b.Truncate(n) with n > b.Len().
func (b *Buffer) Truncate(n int) {
if n == 0 {
// Reuse buffer space.
b.off = 0;
b.len = 0; // recompute during scan.
for i, s := range b.blk {
if n <= 0 {
b.blk = b.blk[0:i];
break;
}
if l := s.Len(); n < l {
b.blk[i].setSlice(0, n);
b.len += n;
n = 0;
} else {
b.len += l;
n -= l;
}
}
b.buf = b.buf[0 : b.off + n];
}
// Reset resets the buffer so it has no content.
// b.Reset() is the same as b.Truncate(0).
func (b *Buffer) Reset() {
b.Truncate(0);
b.blk = b.blk[0:0];
b.len = 0;
}
// Can n bytes be appended efficiently to the end of the final string?
func (b *Buffer) canCombine(n int) bool {
return len(b.blk) > 0 && n+b.blk[len(b.blk)-1].Len() <= 64
}
// WriteString appends string s to the buffer. The return
// value n is the length of s; err is always nil.
func (b *Buffer) WriteString(s string) (n int, err os.Error) {
n = len(s);
if n == 0 {
return
}
b.len += n;
numStr := len(b.blk);
// Special case: If the last piece is short and this one is short,
// combine them and avoid growing the list.
if b.canCombine(n) {
b.blk[numStr-1].appendString(s);
return
}
if cap(b.blk) == numStr {
nstr := make([]block, numStr, 3*(numStr+10)/2);
for i, s := range b.blk {
nstr[i] = s;
}
b.blk = nstr;
}
b.blk = b.blk[0:numStr+1];
// The string is immutable; no need to make a copy.
b.blk[numStr] = (*stringBlock)(&s);
return
}
// Write appends the contents of p to the buffer. The return
// value n is the length of p; err is always nil.
func (b *Buffer) Write(p []byte) (n int, err os.Error) {
m := b.Len();
n = len(p);
if len(b.buf) + n > cap(b.buf) {
// not enough space at end
buf := b.buf;
if m + n > cap(b.buf) {
// not enough space anywhere
buf = make([]byte, 2*cap(b.buf) + n)
if n == 0 {
return
}
bytecopy(buf, 0, b.buf, b.off, m);
b.buf = buf;
b.off = 0
b.len += n;
numStr := len(b.blk);
// Special case: If the last piece is short and this one is short,
// combine them and avoid growing the list.
if b.canCombine(n) {
b.blk[numStr-1].appendBytes(p);
return
}
b.buf = b.buf[0 : b.off + m + n];
bytecopy(b.buf, b.off + m, p, 0, n);
return n, nil
if cap(b.blk) == numStr {
nstr := make([]block, numStr, 3*(numStr+10)/2);
for i, s := range b.blk {
nstr[i] = s;
}
b.blk = nstr;
}
b.blk = b.blk[0:numStr+1];
// Need to copy the data - user might overwrite the data.
b.blk[numStr] = newByteBlock(p);
return
}
// WriteByte appends the byte c to the buffer.
// The returned error is always nil, but is included
// to match bufio.Writer's WriteByte.
func (b *Buffer) WriteByte(c byte) os.Error {
b.Write([]byte{c});
b.oneByte[0] = c;
// For WriteByte, canCombine is almost always true so it's worth
// doing here.
if b.canCombine(1) {
b.blk[len(b.blk)-1].appendBytes(&b.oneByte);
b.len++;
return nil
}
b.Write(&b.oneByte);
return nil;
}
......@@ -96,35 +282,63 @@ func (b *Buffer) WriteByte(c byte) os.Error {
// buffer has no data to return, err is os.EOF even if len(p) is zero;
// otherwise it is nil.
func (b *Buffer) Read(p []byte) (n int, err os.Error) {
if b.off >= len(b.buf) {
if len(b.blk) == 0 {
return 0, os.EOF
}
m := b.Len();
n = len(p);
if n > m {
// more bytes requested than available
n = m
for len(b.blk) > 0 {
blk := b.blk[0];
m := len(p) - n;
if l := blk.Len(); m >= l {
// consume all of this string.
copy(p, n, blk);
n += l;
b.blk = b.blk[1:len(b.blk)];
} else {
// consume some of this block; it's the last piece.
switch b := blk.(type) {
case *stringBlock:
copyString(p, n, string(*b)[0:m]);
case *byteBlock:
copyBytes(p, n, []byte(*b)[0:m]);
}
bytecopy(p, 0, b.buf, b.off, n);
b.off += n;
return n, err
n += m;
b.blk[0].setSlice(m, l);
break;
}
}
b.len -= n;
return
}
// ReadByte reads and returns the next byte from the buffer.
// If no byte is available, it returns error os.EOF.
func (b *Buffer) ReadByte() (c byte, err os.Error) {
if b.off >= len(b.buf) {
return 0, os.EOF;
if _, err := b.Read(&b.oneByte); err != nil {
return 0, err
}
c = b.buf[b.off];
b.off++;
return c, nil;
return b.oneByte[0], nil
}
// NewBufferString creates and initializes a new Buffer
// using a string as its initial contents.
func NewBufferString(str string) *Buffer {
b := new(Buffer);
if len(str) > 0 {
b.blk = make([]block, 1, 10); // room to grow
b.blk[0] = (*stringBlock)(&str);
}
b.len = len(str);
return b;
}
// NewBuffer creates and initializes a new Buffer
// using buf as its initial contents.
func NewBuffer(buf []byte) *Buffer {
return &Buffer{buf, 0};
// using a byte slice as its initial contents.
func NewBuffer(by []byte) *Buffer {
b := new(Buffer);
if len(by) > 0 {
b.blk = make([]block, 1, 10); // room to grow
b.blk[0] = (*byteBlock)(&by);
}
b.len = len(by);
return b;
}
src/pkg/bytes/buffer_test.go
View file @ 6efd7e6b
......@@ -11,38 +11,65 @@ import (
)
const N = 10000; // make this bigger for a larger (and slower) test
var data []byte; // test data for write tests
const N = 10000 // make this bigger for a larger (and slower) test
var data string // test data for write tests
var bytes []byte // test data; same as data but as a slice.
func init() {
data = make([]byte, N);
for i := 0; i < len(data); i++ {
data[i] = 'a' + byte(i % 26)
bytes = make([]byte, N);
for i := 0; i < N; i++ {
bytes[i] = 'a' + byte(i % 26)
}
data = string(bytes);
}
// Verify that contents of buf match the string s.
func check(t *testing.T, testname string, buf *Buffer, s string) {
if buf.Len() != len(buf.Bytes()) {
t.Errorf("%s: buf.Len() == %d, len(buf.Bytes()) == %d\n", testname, buf.Len(), len(buf.Bytes()))
bytes := buf.Bytes();
str := buf.String();
if buf.Len() != len(bytes) {
t.Errorf("%s: buf.Len() == %d, len(buf.Bytes()) == %d\n", testname, buf.Len(), len(bytes))
}
if buf.Len() != len(str) {
t.Errorf("%s: buf.Len() == %d, len(buf.String()) == %d\n", testname, buf.Len(), len(str))
}
if buf.Len() != len(s) {
t.Errorf("%s: buf.Len() == %d, len(s) == %d\n", testname, buf.Len(), len(s))
}
if string(buf.Bytes()) != s {
t.Errorf("%s: string(buf.Bytes()) == %q, s == %q\n", testname, string(buf.Bytes()), s)
if string(bytes) != s {
t.Errorf("%s: string(buf.Bytes()) == %q, s == %q\n", testname, string(bytes), s)
}
}
// Fill buf through n writes of fub.
// Fill buf through n writes of string fus.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fill(t *testing.T, testname string, buf *Buffer, s string, n int, fub []byte) string {
func fillString(t *testing.T, testname string, buf *Buffer, s string, n int, fus string) string {
check(t, testname + " (fill 1)", buf, s);
for ; n > 0; n-- {
m, err := buf.WriteString(fus);
if m != len(fus) {
t.Errorf(testname + " (fill 2): m == %d, expected %d\n", m, len(fus));
}
if err != nil {
t.Errorf(testname + " (fill 3): err should always be nil, found err == %s\n", err);
}
s += fus;
check(t, testname + " (fill 4)", buf, s);
}
return s;
}
// Fill buf through n writes of byte slice fub.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fillBytes(t *testing.T, testname string, buf *Buffer, s string, n int, fub []byte) string {
check(t, testname + " (fill 1)", buf, s);
for ; n > 0; n-- {
m, err := buf.Write(fub);
......@@ -59,6 +86,18 @@ func fill(t *testing.T, testname string, buf *Buffer, s string, n int, fub []byt
}
func TestNewBuffer(t *testing.T) {
buf := NewBuffer(bytes);
check(t, "NewBuffer", buf, data);
}
func TestNewBufferString(t *testing.T) {
buf := NewBufferString(data);
check(t, "NewBufferString", buf, data);
}
// Empty buf through repeated reads into fub.
// The initial contents of buf corresponds to the string s.
func empty(t *testing.T, testname string, buf *Buffer, s string, fub []byte) {
......@@ -92,7 +131,7 @@ func TestBasicOperations(t *testing.T) {
buf.Truncate(0);
check(t, "TestBasicOperations (3)", &buf, "");
n, err := buf.Write(data[0 : 1]);
n, err := buf.Write(Bytes(data[0 : 1]));
if n != 1 {
t.Errorf("wrote 1 byte, but n == %d\n", n);
}
......@@ -104,7 +143,7 @@ func TestBasicOperations(t *testing.T) {
buf.WriteByte(data[1]);
check(t, "TestBasicOperations (5)", &buf, "ab");
n, err = buf.Write(data[2 : 26]);
n, err = buf.Write(Bytes(data[2 : 26]));
if n != 24 {
t.Errorf("wrote 25 bytes, but n == %d\n", n);
}
......@@ -135,23 +174,43 @@ func TestBasicOperations(t *testing.T) {
}
func TestLargeWrites(t *testing.T) {
func TestLargeStringWrites(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fillString(t, "TestLargeWrites (1)", &buf, "", 5, data);
empty(t, "TestLargeStringWrites (2)", &buf, s, make([]byte, len(data)/i));
}
check(t, "TestLargeStringWrites (3)", &buf, "");
}
func TestLargeByteWrites(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fillBytes(t, "TestLargeWrites (1)", &buf, "", 5, bytes);
empty(t, "TestLargeByteWrites (2)", &buf, s, make([]byte, len(data)/i));
}
check(t, "TestLargeByteWrites (3)", &buf, "");
}
func TestLargeStringReads(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fill(t, "TestLargeWrites (1)", &buf, "", 5, data);
empty(t, "TestLargeWrites (2)", &buf, s, make([]byte, len(data)/i));
s := fillString(t, "TestLargeReads (1)", &buf, "", 5, data[0 : len(data)/i]);
empty(t, "TestLargeReads (2)", &buf, s, make([]byte, len(data)));
}
check(t, "TestLargeWrites (3)", &buf, "");
check(t, "TestLargeStringReads (3)", &buf, "");
}
func TestLargeReads(t *testing.T) {
func TestLargeByteReads(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fill(t, "TestLargeReads (1)", &buf, "", 5, data[0 : len(data)/i]);
s := fillBytes(t, "TestLargeReads (1)", &buf, "", 5, bytes[0 : len(bytes)/i]);
empty(t, "TestLargeReads (2)", &buf, s, make([]byte, len(data)));
}
check(t, "TestLargeReads (3)", &buf, "");
check(t, "TestLargeByteReads (3)", &buf, "");
}
......@@ -160,7 +219,11 @@ func TestMixedReadsAndWrites(t *testing.T) {
s := "";
for i := 0; i < 50; i++ {
wlen := rand.Intn(len(data));
s = fill(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, data[0 : wlen]);
if i % 2 == 0 {
s = fillString(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, data[0 : wlen]);
} else {
s = fillBytes(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, bytes[0 : wlen]);
}
rlen := rand.Intn(len(data));
fub := make([]byte, rlen);
......
src/pkg/gob/encoder_test.go
View file @ 6efd7e6b
......@@ -9,7 +9,6 @@ import (
"io";
"os";
"reflect";
"strings";
"testing";
)
......@@ -228,7 +227,7 @@ func TestWrongTypeDecoder(t *testing.T) {
}
func corruptDataCheck(s string, err os.Error, t *testing.T) {
b := strings.NewBufferString(s);
b := bytes.NewBufferString(s);
dec := NewDecoder(b);
dec.Decode(new(ET2));
if dec.state.err != err {
......
src/pkg/strings/Makefile
View file @ 6efd7e6b
......@@ -6,7 +6,6 @@ include $(GOROOT)/src/Make.$(GOARCH)
TARG=strings
GOFILES=\
buffer.go\
strings.go\
include $(GOROOT)/src/Make.pkg
src/pkg/strings/buffer.go deleted 100644 → 0
View file @ fed47706
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package strings
import "os"
// Efficient construction of large strings and byte arrays.
// Implements io.Reader and io.Writer.
// A Buffer provides efficient construction of large strings
// and slices of bytes. It implements io.Reader and io.Writer.
// Appends (writes) are efficient.
// The zero value for Buffer is an empty buffer ready to use.
type Buffer struct {
blk []block;
len int;
oneByte [1]byte;
}
// There are two kinds of block: a string or a []byte.
// When the user writes big strings, we add string blocks;
// when the user writes big byte slices, we add []byte blocks.
// Small writes are coalesced onto the end of the last block,
// whatever it is.
// This strategy is intended to reduce unnecessary allocation.
type block interface {
Len() int;
String() string;
appendBytes(s []byte);
appendString(s string);
setSlice(m, n int);
}
// stringBlocks represent strings. We use pointer receivers
// so append and setSlice can overwrite the receiver.
type stringBlock string
func (b *stringBlock) Len() int {
return len(*b)
}
func (b *stringBlock) String() string {
return string(*b)
}
func (b *stringBlock) appendBytes(s []byte) {
*b += stringBlock(s)
}
func (b *stringBlock) appendString(s string) {
*b = stringBlock(s)
}
func (b *stringBlock) setSlice(m, n int) {
*b = (*b)[m:n]
}
// byteBlock represent slices of bytes. We use pointer receivers
// so append and setSlice can overwrite the receiver.
type byteBlock []byte
func (b *byteBlock) Len() int {
return len(*b)
}
func (b *byteBlock) String() string {
return string(*b)
}
func (b *byteBlock) resize(max int) {
by := []byte(*b);
if cap(by) >= max {
by = by[0:max];
} else {
nby := make([]byte, max, 3*(max+10)/2);
copyBytes(nby, 0, by);
by = nby;
}
*b = by;
}
func (b *byteBlock) appendBytes(s []byte) {
curLen := b.Len();
b.resize(curLen + len(s));
copyBytes([]byte(*b), curLen, s);
}
func (b *byteBlock) appendString(s string) {
curLen := b.Len();
b.resize(curLen + len(s));
copyString([]byte(*b), curLen, s);
}
func (b *byteBlock) setSlice(m, n int) {
*b = (*b)[m:n]
}
// Because the user may overwrite the contents of byte slices, we need
// to make a copy. Allocation strategy: leave some space on the end so
// small subsequent writes can avoid another allocation. The input
// is known to be non-empty.
func newByteBlock(s []byte) *byteBlock {
l := len(s);
// Capacity with room to grow. If small, allocate a mininum. If medium,
// double the size. If huge, use the size plus epsilon (room for a newline,
// at least).
c := l;
switch {
case l < 32:
c = 64
case l < 1<<18:
c *= 2;
default:
c += 8
}
b := make([]byte, l, c);
copyBytes(b, 0, s);
return &b;
}
// Copy from block to byte array at offset doff. Assume there's room.
func copy(dst []byte, doff int, src block) {
switch s := src.(type) {
case *stringBlock:
copyString(dst, doff, string(*s));
case *byteBlock:
copyBytes(dst, doff, []byte(*s));
}
}
// Copy from string to byte array at offset doff. Assume there's room.
func copyString(dst []byte, doff int, str string) {
for soff := 0; soff < len(str); soff++ {
dst[doff] = str[soff];
doff++;
}
}
// Copy from bytes to byte array at offset doff. Assume there's room.
func copyBytes(dst []byte, doff int, src []byte) {
for soff := 0; soff < len(src); soff++ {
dst[doff] = src[soff];
doff++;
}
}
// Bytes returns the contents of the unread portion of the buffer
// as a byte array.
func (b *Buffer) Bytes() []byte {
n := b.len;
bytes := make([]byte, n);
nbytes := 0;
for _, s := range b.blk {
copy(bytes, nbytes, s);
nbytes += s.Len();
}
return bytes;
}
// String returns the contents of the unread portion of the buffer
// as a string.
func (b *Buffer) String() string {
if len(b.blk) == 1 { // important special case
return b.blk[0].String()
}
return string(b.Bytes())
}
// Len returns the number of bytes in the unread portion of the buffer;
// b.Len() == len(b.Bytes()) == len(b.String()).
func (b *Buffer) Len() int {
return b.len
}
// Truncate discards all but the first n unread bytes from the buffer.
func (b *Buffer) Truncate(n int) {
b.len = 0; // recompute during scan.
for i, s := range b.blk {
if n <= 0 {
b.blk = b.blk[0:i];
break;
}
if l := s.Len(); n < l {
b.blk[i].setSlice(0, n);
b.len += n;
n = 0;
} else {
b.len += l;
n -= l;
}
}
}
// Reset resets the buffer so it has no content.
// b.Reset() is the same as b.Truncate(0).
func (b *Buffer) Reset() {
b.blk = b.blk[0:0];
b.len = 0;
}
// Can n bytes be appended efficiently to the end of the final string?
func (b *Buffer) canCombine(n int) bool {
return len(b.blk) > 0 && n+b.blk[len(b.blk)-1].Len() <= 64
}
// WriteString appends string s to the buffer. The return
// value n is the length of s; err is always nil.
func (b *Buffer) WriteString(s string) (n int, err os.Error) {
n = len(s);
if n == 0 {
return
}
b.len += n;
numStr := len(b.blk);
// Special case: If the last piece is short and this one is short,
// combine them and avoid growing the list.
if b.canCombine(n) {
b.blk[numStr-1].appendString(s);
return
}
if cap(b.blk) == numStr {
nstr := make([]block, numStr, 3*(numStr+10)/2);
for i, s := range b.blk {
nstr[i] = s;
}
b.blk = nstr;
}
b.blk = b.blk[0:numStr+1];
// The string is immutable; no need to make a copy.
b.blk[numStr] = (*stringBlock)(&s);
return
}
// Write appends the contents of p to the buffer. The return
// value n is the length of p; err is always nil.
func (b *Buffer) Write(p []byte) (n int, err os.Error) {
n = len(p);
if n == 0 {
return
}
b.len += n;
numStr := len(b.blk);
// Special case: If the last piece is short and this one is short,
// combine them and avoid growing the list.
if b.canCombine(n) {
b.blk[numStr-1].appendBytes(p);
return
}
if cap(b.blk) == numStr {
nstr := make([]block, numStr, 3*(numStr+10)/2);
for i, s := range b.blk {
nstr[i] = s;
}
b.blk = nstr;
}
b.blk = b.blk[0:numStr+1];
// Need to copy the data - user might overwrite the data.
b.blk[numStr] = newByteBlock(p);
return
}
// WriteByte appends the byte c to the buffer.
// 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;
// For WriteByte, canCombine is almost always true so it's worth
// doing here.
if b.canCombine(1) {
b.blk[len(b.blk)-1].appendBytes(&b.oneByte);
b.len++;
return nil
}
b.Write(&b.oneByte);
return 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;
// otherwise it is nil.
func (b *Buffer) Read(p []byte) (n int, err os.Error) {
if len(b.blk) == 0 {
return 0, os.EOF
}
for len(b.blk) > 0 {
blk := b.blk[0];
m := len(p) - n;
if l := blk.Len(); m >= l {
// consume all of this string.
copy(p, n, blk);
n += l;
b.blk = b.blk[1:len(b.blk)];
} else {
// consume some of this block; it's the last piece.
switch b := blk.(type) {
case *stringBlock:
copyString(p, n, string(*b)[0:m]);
case *byteBlock:
copyBytes(p, n, []byte(*b)[0:m]);
}
n += m;
b.blk[0].setSlice(m, l);
break;
}
}
b.len -= n;
return
}
// ReadByte reads and returns the next byte from the buffer.
// If no byte is available, it returns error os.EOF.
func (b *Buffer) ReadByte() (c byte, err os.Error) {
if _, err := b.Read(&b.oneByte); err != nil {
return 0, err
}
return b.oneByte[0], nil
}
// NewBufferString creates and initializes a new Buffer
// using a string as its initial contents.
func NewBufferString(str string) *Buffer {
b := new(Buffer);
b.blk = make([]block, 1, 10); // room to grow
b.blk[0] = (*stringBlock)(&str);
b.len = len(str);
return b;
}
// NewBuffer creates and initializes a new Buffer
// using a byte slice as its initial contents.
func NewBuffer(by []byte) *Buffer {
b := new(Buffer);
b.blk = make([]block, 1, 10); // room to grow
b.blk[0] = (*byteBlock)(&by);
b.len = len(by);
return b;
}
src/pkg/strings/buffer_test.go deleted 100644 → 0
View file @ fed47706
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package strings_test
import (
. "strings";
"rand";
"testing";
)
const N = 10000 // make this bigger for a larger (and slower) test
var data string // test data for write tests
var bytes []byte // test data; same as data but as a slice.
func init() {
bytes = make([]byte, N);
for i := 0; i < N; i++ {
bytes[i] = 'a' + byte(i % 26)
}
data = string(bytes);
}
// Verify that contents of buf match the string s.
func check(t *testing.T, testname string, buf *Buffer, s string) {
bytes := buf.Bytes();
str := buf.String();
if buf.Len() != len(bytes) {
t.Errorf("%s: buf.Len() == %d, len(buf.Bytes()) == %d\n", testname, buf.Len(), len(bytes))
}
if buf.Len() != len(str) {
t.Errorf("%s: buf.Len() == %d, len(buf.String()) == %d\n", testname, buf.Len(), len(str))
}
if buf.Len() != len(s) {
t.Errorf("%s: buf.Len() == %d, len(s) == %d\n", testname, buf.Len(), len(s))
}
if string(bytes) != s {
t.Errorf("%s: string(buf.Bytes()) == %q, s == %q\n", testname, string(bytes), s)
}
}
// Fill buf through n writes of string fus.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fillString(t *testing.T, testname string, buf *Buffer, s string, n int, fus string) string {
check(t, testname + " (fill 1)", buf, s);
for ; n > 0; n-- {
m, err := buf.WriteString(fus);
if m != len(fus) {
t.Errorf(testname + " (fill 2): m == %d, expected %d\n", m, len(fus));
}
if err != nil {
t.Errorf(testname + " (fill 3): err should always be nil, found err == %s\n", err);
}
s += fus;
check(t, testname + " (fill 4)", buf, s);
}
return s;
}
// Fill buf through n writes of byte slice fub.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fillBytes(t *testing.T, testname string, buf *Buffer, s string, n int, fub []byte) string {
check(t, testname + " (fill 1)", buf, s);
for ; n > 0; n-- {
m, err := buf.Write(fub);
if m != len(fub) {
t.Errorf(testname + " (fill 2): m == %d, expected %d\n", m, len(fub));
}
if err != nil {
t.Errorf(testname + " (fill 3): err should always be nil, found err == %s\n", err);
}
s += string(fub);
check(t, testname + " (fill 4)", buf, s);
}
return s;
}
func TestNewBuffer(t *testing.T) {
buf := NewBuffer(bytes);
check(t, "NewBuffer", buf, data);
}
func TestNewBufferString(t *testing.T) {
buf := NewBufferString(data);
check(t, "NewBufferString", buf, data);
}
// Empty buf through repeated reads into fub.
// The initial contents of buf corresponds to the string s.
func empty(t *testing.T, testname string, buf *Buffer, s string, fub []byte) {
check(t, testname + " (empty 1)", buf, s);
for {
n, err := buf.Read(fub);
if n == 0 {
break;
}
if err != nil {
t.Errorf(testname + " (empty 2): err should always be nil, found err == %s\n", err);
}
s = s[n : len(s)];
check(t, testname + " (empty 3)", buf, s);
}
check(t, testname + " (empty 4)", buf, "");
}
func TestBasicOperations(t *testing.T) {
var buf Buffer;
for i := 0; i < 5; i++ {
check(t, "TestBasicOperations (1)", &buf, "");
buf.Reset();
check(t, "TestBasicOperations (2)", &buf, "");
buf.Truncate(0);
check(t, "TestBasicOperations (3)", &buf, "");
n, err := buf.Write(Bytes(data[0 : 1]));
if n != 1 {
t.Errorf("wrote 1 byte, but n == %d\n", n);
}
if err != nil {
t.Errorf("err should always be nil, but err == %s\n", err);
}
check(t, "TestBasicOperations (4)", &buf, "a");
buf.WriteByte(data[1]);
check(t, "TestBasicOperations (5)", &buf, "ab");
n, err = buf.Write(Bytes(data[2 : 26]));
if n != 24 {
t.Errorf("wrote 25 bytes, but n == %d\n", n);
}
check(t, "TestBasicOperations (6)", &buf, string(data[0 : 26]));
buf.Truncate(26);
check(t, "TestBasicOperations (7)", &buf, string(data[0 : 26]));
buf.Truncate(20);
check(t, "TestBasicOperations (8)", &buf, string(data[0 : 20]));
empty(t, "TestBasicOperations (9)", &buf, string(data[0 : 20]), make([]byte, 5));
empty(t, "TestBasicOperations (10)", &buf, "", make([]byte, 100));
buf.WriteByte(data[1]);
c, err := buf.ReadByte();
if err != nil {
t.Errorf("ReadByte unexpected eof\n");
}
if c != data[1] {
t.Errorf("ReadByte wrong value c=%v\n", c);
}
c, err = buf.ReadByte();
if err == nil {
t.Errorf("ReadByte unexpected not eof\n");
}
}
}
func TestLargeStringWrites(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fillString(t, "TestLargeWrites (1)", &buf, "", 5, data);
empty(t, "TestLargeStringWrites (2)", &buf, s, make([]byte, len(data)/i));
}
check(t, "TestLargeStringWrites (3)", &buf, "");
}
func TestLargeByteWrites(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fillBytes(t, "TestLargeWrites (1)", &buf, "", 5, bytes);
empty(t, "TestLargeByteWrites (2)", &buf, s, make([]byte, len(data)/i));
}
check(t, "TestLargeByteWrites (3)", &buf, "");
}
func TestLargeStringReads(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fillString(t, "TestLargeReads (1)", &buf, "", 5, data[0 : len(data)/i]);
empty(t, "TestLargeReads (2)", &buf, s, make([]byte, len(data)));
}
check(t, "TestLargeStringReads (3)", &buf, "");
}
func TestLargeByteReads(t *testing.T) {
var buf Buffer;
for i := 3; i < 30; i += 3 {
s := fillBytes(t, "TestLargeReads (1)", &buf, "", 5, bytes[0 : len(bytes)/i]);
empty(t, "TestLargeReads (2)", &buf, s, make([]byte, len(data)));
}
check(t, "TestLargeByteReads (3)", &buf, "");
}
func TestMixedReadsAndWrites(t *testing.T) {
var buf Buffer;
s := "";
for i := 0; i < 50; i++ {
wlen := rand.Intn(len(data));
if i % 2 == 0 {
s = fillString(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, data[0 : wlen]);
} else {
s = fillBytes(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, bytes[0 : wlen]);
}
rlen := rand.Intn(len(data));
fub := make([]byte, rlen);
n, _ := buf.Read(fub);
s = s[n : len(s)];
}
empty(t, "TestMixedReadsAndWrites (2)", &buf, s, make([]byte, buf.Len()));
}
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