singrdk/base/Libraries/System.IO/StreamWriter.cs

360 lines
15 KiB
C#

// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*============================================================
**
** Class: StreamWriter
**
**
** Purpose: For writing text to streams in a particular
** encoding.
**
** Date: February 21, 2000
**
===========================================================*/
using System;
using System.Diagnostics;
using System.Text;
namespace System.IO {
// This class implements a TextWriter for writing characters to a Stream.
// This is designed for character output in a particular Encoding,
// whereas the Stream class is designed for byte input and output.
//
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter"]/*' />
public class StreamWriter : TextWriter
{
// For UTF-8, the values of 1K for the default buffer size and 4K for the
// file stream buffer size are reasonable & give very reasonable
// performance for in terms of construction time for the StreamWriter and
// write perf. Note that for UTF-8, we end up allocating a 4K byte buffer,
// which means we take advantage of Anders' adaptive buffering code.
// The performance using UnicodeEncoding is acceptable. -- Brian 7/9/2001
private const int DefaultBufferSize = 1024; // char[]
private const int DefaultFileStreamBufferSize = 4096;
private const int MinBufferSize = 128;
#if DONT
// Bit bucket - Null has no backing store.
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Null"]/*' />
public new static readonly StreamWriter Null = new StreamWriter(Stream.Null, new UTF8Encoding(false, true), 128);
#endif
internal Stream stream;
private Encoding encoding;
private Encoder encoder;
internal byte[] byteBuffer;
internal char[] charBuffer;
internal int charPos;
internal int charLen;
internal bool autoFlush;
private bool haveWrittenPreamble;
private bool closable; // For Console.Out - should Finalize call Dispose?
#if _DEBUG
private String allocatedFrom = String.Empty;
#endif
[Microsoft.Contracts.NotDelayed]
internal StreamWriter() {
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.StreamWriter"]/*' />
[Microsoft.Contracts.NotDelayed]
public StreamWriter(Stream stream)
: this(stream, new UTF8Encoding(false, true), DefaultBufferSize) {
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.StreamWriter1"]/*' />
[Microsoft.Contracts.NotDelayed]
public StreamWriter(Stream stream, Encoding encoding)
: this(stream, encoding, DefaultBufferSize) {
}
// Creates a new StreamWriter for the given stream. The
// character encoding is set by encoding and the buffer size,
// in number of 16-bit characters, is set by bufferSize.
//
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.StreamWriter2"]/*' />
[Microsoft.Contracts.NotDelayed]
public StreamWriter(Stream stream, Encoding encoding, int bufferSize) {
if (stream==null || encoding==null)
throw new ArgumentNullException((stream==null ? "stream" : "encoding"));
if (!stream.CanWrite)
throw new ArgumentException("Argument_StreamNotWritable");
if (bufferSize <= 0) throw new ArgumentOutOfRangeException("ArgumentOutOfRange_NeedPosNum");
Init(stream, encoding, bufferSize);
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.StreamWriter3"]/*' />
[Microsoft.Contracts.NotDelayed]
public StreamWriter(String path)
: this(path, false, new UTF8Encoding(false, true), DefaultBufferSize) {
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.StreamWriter4"]/*' />
[Microsoft.Contracts.NotDelayed]
public StreamWriter(String path, bool append)
: this(path, append, new UTF8Encoding(false, true), DefaultBufferSize) {
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.StreamWriter5"]/*' />
[Microsoft.Contracts.NotDelayed]
public StreamWriter(String path, bool append, Encoding encoding)
: this(path, append, encoding, DefaultBufferSize) {
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.StreamWriter6"]/*' />
[Microsoft.Contracts.NotDelayed]
public StreamWriter(String path, bool append, Encoding encoding, int bufferSize) {
if (path==null || encoding==null)
throw new ArgumentNullException((path==null ? "path" : "encoding"));
if (bufferSize <= 0) throw new ArgumentOutOfRangeException("ArgumentOutOfRange_NeedPosNum");
Stream stream = CreateFile(path, append);
Init(stream, encoding, bufferSize);
}
private void Init(Stream! stream, Encoding! encoding, int bufferSize)
{
this.stream = stream;
this.encoding = encoding;
this.encoder = encoding.GetEncoder();
if (bufferSize < MinBufferSize) bufferSize = MinBufferSize;
charBuffer = new char[bufferSize];
byteBuffer = new byte[encoding.GetMaxByteCount(bufferSize)];
charLen = bufferSize;
// If we're appending to a Stream that already has data, don't write
// the preamble junk.
if (stream.CanSeek && stream.Position > 0)
haveWrittenPreamble = true;
closable = true;
}
private static Stream! CreateFile(String path, bool append) {
FileMode mode = append? FileMode.Append: FileMode.Create;
FileStream f = new FileStream(path, mode, FileAccess.Write, FileShare.Read, DefaultFileStreamBufferSize);
return f;
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Close"]/*' />
public override void Close() {
Dispose(true);
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Dispose"]/*' />
protected override void Dispose(bool disposing) {
// Dispose of our resources if this StreamWriter is closable.
// Note that Console.Out should not be closable.
if (disposing) {
if (stream != null) {
Flush(true, true);
if (Closable)
stream.Close();
}
}
if (Closable && stream != null) {
stream = null;
byteBuffer = null;
charBuffer = null;
encoding = null;
encoder = null;
charLen = 0;
base.Dispose(disposing);
}
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Finalize"]/*' />
~StreamWriter()
{
// Make sure people closed this StreamWriter, but of course, make
// allowances for BufferedStream (used by Console.Out & Error) and
// StreamWriter::Null.
#if _DEBUG
Debug.Correctness(charPos == 0, "You didn't close a StreamWriter, and you lost data!\r\nStream type: "+(stream==null ? "<null>" : stream.GetType().FullName)+((stream != null && stream is FileStream) ? " File name: "+((FileStream)stream).NameInternal : "")+"\r\nAllocated from:\r\n"+allocatedFrom);
#endif
Dispose(false);
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Flush"]/*' />
public override void Flush() {
Flush(true, true);
}
private void Flush(bool flushStream, bool flushEncoder) {
// flushEncoder should be true at the end of the file and if
// the user explicitly calls Flush (though not if AutoFlush is true).
// This is required to flush any dangling characters from our UTF-7
// and UTF-8 encoders.
if (stream == null)
__Error.WriterClosed();
// Perf boost for Flush on non-dirty writers.
if (charPos==0 && !flushStream && !flushEncoder)
return;
if (!haveWrittenPreamble) {
haveWrittenPreamble = true;
byte[] preamble = encoding.GetPreamble();
if (preamble.Length > 0)
stream.Write(preamble, 0, preamble.Length);
}
int count = encoder.GetBytes(charBuffer, 0, charPos, byteBuffer, 0, flushEncoder);
charPos = 0;
if (count > 0)
stream.Write(byteBuffer, 0, count);
// By definition, calling Flush should flush the stream, but this is
// only necessary if we passed in true for flushStream. The Web
// Services guys have some perf tests where flushing needlessly hurts.
if (flushStream)
stream.Flush();
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.AutoFlush"]/*' />
public virtual bool AutoFlush {
get { return autoFlush; }
set {
autoFlush = value;
if (value) Flush(true, false);
}
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.BaseStream"]/*' />
public virtual Stream BaseStream {
get { return stream; }
}
internal bool Closable {
get { return closable; }
set { closable = value; }
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Encoding"]/*' />
public override Encoding Encoding {
get { return encoding; }
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Write"]/*' />
public override void Write(char value) {
if (charPos == charLen) Flush(false, false);
charBuffer[charPos++] = value;
if (autoFlush) Flush(true, false);
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Write1"]/*' />
public override void Write(char[] buffer) {
if (buffer == null) {
return;
}
int index = 0;
int count = buffer.Length;
while (count > 0) {
int limit = this.charLen - this.charPos;
if (limit <= 0) {
this.Flush(false, false);
limit = this.charLen - this.charPos;
}
if (limit > count) {
limit = count;
}
Buffer.BlockCopy(buffer, index*2,
charBuffer, charPos*2,
limit*2);
this.charPos += limit;
index += limit;
count -= limit;
}
if (this.autoFlush) {
this.Flush(true, false);
}
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Write2"]/*' />
public override void Write(char[] buffer, int index, int count) {
if (buffer == null) {
throw new ArgumentNullException("buffer", "Buffer is null");
}
if (index < 0) {
throw new ArgumentOutOfRangeException("index", "index is negative");
}
if (count < 0) {
throw new ArgumentOutOfRangeException("count", "count is negative");
}
if (buffer.Length < index + count) {
throw new ArgumentException("index + count greater than buffer length");
}
while (count > 0) {
int limit = this.charLen - this.charPos;
if (limit <= 0) {
this.Flush(false, false);
limit = this.charLen - this.charPos;
}
if (limit > count) {
limit = count;
}
for (int i = 0; i < limit; i++) {
charBuffer[this.charPos + i] = buffer[index + i];
}
this.charPos += limit;
index += limit;
count -= limit;
}
if (this.autoFlush) {
this.Flush(true, false);
}
}
//| <include file='doc\StreamWriter.uex' path='docs/doc[@for="StreamWriter.Write3"]/*' />
public override void Write(String value) {
if (value != null) {
int count = value.Length;
int index = 0;
while (count > 0) {
if (charPos == charLen) Flush(false, false);
int n = charLen - charPos;
if (n > count) n = count;
Debug.Assert(n > 0, "StreamWriter::Write(String) isn't making progress! This is most likely a race condition in user code.");
value.CopyTo(index, charBuffer, charPos, n);
charPos += n;
index += n;
count -= n;
}
if (autoFlush) Flush(true, false);
}
}
/*
// This method is more efficient for long strings outputted to streams
// than the one on TextWriter, and won't cause any problems in terms of
// hiding methods on TextWriter as long as languages respect the
// hide-by-name-and-sig metadata flag.
public override void WriteLine(String value) {
if (value != null) {
int count = value.Length;
int index = 0;
while (count > 0) {
if (charPos == charLen) Flush(false);
int n = charLen - charPos;
if (n > count) n = count;
Debug.Assert(n > 0, "StreamWriter::WriteLine(String) isn't making progress! This is most likely a race condition in user code.");
value.CopyTo(index, charBuffer, charPos, n);
charPos += n;
index += n;
count -= n;
}
}
if (charPos >= charLen - 2) Flush(false);
Buffer.BlockCopy(CoreNewLine, 0, charBuffer, charPos*2, CoreNewLine.Length * 2);
charPos += CoreNewLine.Length;
if (autoFlush) Flush(true, false);
}
*/
}
}