Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / IO / StreamReader.cs / 1305376 / StreamReader.cs
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*============================================================
**
** Class: StreamReader
**
** [....]
**
**
** Purpose: For reading text from streams in a particular
** encoding.
**
**
===========================================================*/
using System;
using System.Text;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Diagnostics.Contracts;
namespace System.IO {
// This class implements a TextReader for reading characters to a Stream.
// This is designed for character input in a particular Encoding,
// whereas the Stream class is designed for byte input and output.
//
[Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public class StreamReader : TextReader
{
// StreamReader.Null is threadsafe.
public new static readonly StreamReader Null = new NullStreamReader();
// Using a 1K byte buffer and a 4K FileStream buffer works out pretty well
// perf-wise. On even a 40 MB text file, any perf loss by using a 4K
// buffer is negated by the win of allocating a smaller byte[], which
// saves construction time. This does break adaptive buffering,
// but this is slightly faster.
internal const int DefaultBufferSize = 1024; // Byte buffer size
private const int DefaultFileStreamBufferSize = 4096;
private const int MinBufferSize = 128;
private bool _closable; // For Console.In. We should consider exposing a Closable bit perhaps on stream at some point.
private Stream stream;
private Encoding encoding;
private Decoder decoder;
private byte[] byteBuffer;
private char[] charBuffer;
private byte[] _preamble; // Encoding's preamble, which identifies this encoding.
private int charPos;
private int charLen;
// Record the number of valid bytes in the byteBuffer, for a few checks.
private int byteLen;
// This is used only for preamble detection
private int bytePos;
// This is the maximum number of chars we can get from one call to
// ReadBuffer. Used so ReadBuffer can tell when to copy data into
// a user's char[] directly, instead of our internal char[].
private int _maxCharsPerBuffer;
// We will support looking for byte order marks in the stream and trying
// to decide what the encoding might be from the byte order marks, IF they
// exist. But that's all we'll do.
private bool _detectEncoding;
// Whether we must still check for the encoding's given preamble at the
// beginning of this file.
private bool _checkPreamble;
// Whether the stream is most likely not going to give us back as much
// data as we want the next time we call it. We must do the computation
// before we do any byte order mark handling and save the result. Note
// that we need this to allow users to handle streams used for an
// interactive protocol, where they block waiting for the remote end
// to send a response, like logging in on a Unix machine.
private bool _isBlocked;
// StreamReader by default will ignore illegal UTF8 characters. We don't want to
// throw here because we want to be able to read ill-formed data without choking.
// The high level goal is to be tolerant of encoding errors when we read and very strict
// when we write. Hence, default StreamWriter encoding will throw on error.
internal StreamReader() {
}
public StreamReader(Stream stream)
: this(stream, true) {
}
public StreamReader(Stream stream, bool detectEncodingFromByteOrderMarks)
: this(stream, Encoding.UTF8, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
public StreamReader(Stream stream, Encoding encoding)
: this(stream, encoding, true, DefaultBufferSize) {
}
public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks)
: this(stream, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
// Creates a new StreamReader 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.
//
// Note that detectEncodingFromByteOrderMarks is a very
// loose attempt at detecting the encoding by looking at the first
// 3 bytes of the stream. It will recognize UTF-8, little endian
// unicode, and big endian unicode text, but that's it. If neither
// of those three match, it will use the Encoding you provided.
//
public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
{
if (stream==null || encoding==null)
throw new ArgumentNullException((stream==null ? "stream" : "encoding"));
if (!stream.CanRead)
throw new ArgumentException(Environment.GetResourceString("Argument_StreamNotReadable"));
if (bufferSize <= 0)
throw new ArgumentOutOfRangeException("bufferSize", Environment.GetResourceString("ArgumentOutOfRange_NeedPosNum"));
Contract.EndContractBlock();
Init(stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);
}
// For non closable streams such as Console.In
internal StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize, bool closable)
: this(stream, encoding, detectEncodingFromByteOrderMarks, bufferSize) {
_closable = closable;
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path)
: this(path, true) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, bool detectEncodingFromByteOrderMarks)
: this(path, Encoding.UTF8, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, Encoding encoding)
: this(path, encoding, true, DefaultBufferSize) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, Encoding encoding, bool detectEncodingFromByteOrderMarks)
: this(path, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
{
// Don't open a Stream before checking for invalid arguments,
// or we'll create a FileStream on disk and we won't close it until
// the finalizer runs, causing problems for applications.
if (path==null || encoding==null)
throw new ArgumentNullException((path==null ? "path" : "encoding"));
if (path.Length==0)
throw new ArgumentException(Environment.GetResourceString("Argument_EmptyPath"));
if (bufferSize <= 0)
throw new ArgumentOutOfRangeException("bufferSize", Environment.GetResourceString("ArgumentOutOfRange_NeedPosNum"));
Contract.EndContractBlock();
Stream stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read, DefaultFileStreamBufferSize, FileOptions.SequentialScan);
Init(stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);
}
private void Init(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize) {
this.stream = stream;
this.encoding = encoding;
decoder = encoding.GetDecoder();
if (bufferSize < MinBufferSize) bufferSize = MinBufferSize;
byteBuffer = new byte[bufferSize];
_maxCharsPerBuffer = encoding.GetMaxCharCount(bufferSize);
charBuffer = new char[_maxCharsPerBuffer];
byteLen = 0;
bytePos = 0;
_detectEncoding = detectEncodingFromByteOrderMarks;
_preamble = encoding.GetPreamble();
_checkPreamble = (_preamble.Length > 0);
_isBlocked = false;
_closable = true; // ByDefault all streams are closable unless explicitly told otherwise
}
// Init used by NullStreamReader, to delay load encoding
internal void Init(Stream stream)
{
this.stream = stream;
_closable = true;
}
public override void Close()
{
Dispose(true);
}
protected override void Dispose(bool disposing)
{
// Dispose of our resources if this StreamReader is closable.
// Note that Console.In should not be closable.
try {
// Note that Stream.Close() can potentially throw here. So we need to
// ensure cleaning up internal resources, inside the finally block.
if (Closable && disposing && (stream != null))
stream.Close();
}
finally {
if (Closable && (stream != null)) {
stream = null;
encoding = null;
decoder = null;
byteBuffer = null;
charBuffer = null;
charPos = 0;
charLen = 0;
base.Dispose(disposing);
}
}
}
public virtual Encoding CurrentEncoding {
get { return encoding; }
}
public virtual Stream BaseStream {
get { return stream; }
}
internal bool Closable {
get { return _closable; }
//set { _closable = value; }
}
// DiscardBufferedData tells StreamReader to throw away its internal
// buffer contents. This is useful if the user needs to seek on the
// underlying stream to a known location then wants the StreamReader
// to start reading from this new point. This method should be called
// very sparingly, if ever, since it can lead to very poor performance.
// However, it may be the only way of handling some scenarios where
// users need to re-read the contents of a StreamReader a second time.
public void DiscardBufferedData() {
byteLen = 0;
charLen = 0;
charPos = 0;
// in general we'd like to have an invariant that encoding isn't null. However,
// for startup improvements for NullStreamReader, we want to delay load encoding.
if (encoding != null) {
decoder = encoding.GetDecoder();
}
_isBlocked = false;
}
public bool EndOfStream {
[System.Security.SecuritySafeCritical] // auto-generated
get {
if (stream == null)
__Error.ReaderClosed();
if (charPos < charLen)
return false;
// This may block on pipes!
int numRead = ReadBuffer();
return numRead == 0;
}
}
[Pure]
[System.Security.SecuritySafeCritical] // auto-generated
public override int Peek() {
if (stream == null)
__Error.ReaderClosed();
if (charPos == charLen) {
if (_isBlocked || ReadBuffer() == 0) return -1;
}
return charBuffer[charPos];
}
[System.Security.SecuritySafeCritical] // auto-generated
public override int Read() {
if (stream == null)
__Error.ReaderClosed();
if (charPos == charLen) {
if (ReadBuffer() == 0) return -1;
}
int result = charBuffer[charPos];
charPos++;
return result;
}
[System.Security.SecuritySafeCritical] // auto-generated
public override int Read([In, Out] char[] buffer, int index, int count) {
if (buffer==null)
throw new ArgumentNullException("buffer", Environment.GetResourceString("ArgumentNull_Buffer"));
if (index < 0 || count < 0)
throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
if (buffer.Length - index < count)
throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
Contract.EndContractBlock();
if (stream == null)
__Error.ReaderClosed();
int charsRead = 0;
// As a perf optimization, if we had exactly one buffer's worth of
// data read in, let's try writing directly to the user's buffer.
bool readToUserBuffer = false;
while (count > 0) {
int n = charLen - charPos;
if (n == 0) n = ReadBuffer(buffer, index + charsRead, count, out readToUserBuffer);
if (n == 0) break; // We're at EOF
if (n > count) n = count;
if (!readToUserBuffer) {
Buffer.InternalBlockCopy(charBuffer, charPos * 2, buffer, (index + charsRead) * 2, n*2);
charPos += n;
}
charsRead += n;
count -= n;
// This function shouldn't block for an indefinite amount of time,
// or reading from a network stream won't work right. If we got
// fewer bytes than we requested, then we want to break right here.
if (_isBlocked)
break;
}
return charsRead;
}
[System.Security.SecuritySafeCritical] // auto-generated
public override String ReadToEnd()
{
if (stream == null)
__Error.ReaderClosed();
// Call ReadBuffer, then pull data out of charBuffer.
StringBuilder sb = new StringBuilder(charLen - charPos);
do {
sb.Append(charBuffer, charPos, charLen - charPos);
charPos = charLen; // Note we consumed these characters
ReadBuffer();
} while (charLen > 0);
return sb.ToString();
}
// Trims n bytes from the front of the buffer.
private void CompressBuffer(int n)
{
Contract.Assert(byteLen >= n, "CompressBuffer was called with a number of bytes greater than the current buffer length. Are two threads using this StreamReader at the same time?");
Buffer.InternalBlockCopy(byteBuffer, n, byteBuffer, 0, byteLen - n);
byteLen -= n;
}
private void DetectEncoding()
{
if (byteLen < 2)
return;
_detectEncoding = false;
bool changedEncoding = false;
if (byteBuffer[0]==0xFE && byteBuffer[1]==0xFF) {
// Big Endian Unicode
encoding = new UnicodeEncoding(true, true);
CompressBuffer(2);
changedEncoding = true;
}
else if (byteBuffer[0]==0xFF && byteBuffer[1]==0xFE) {
// Little Endian Unicode, or possibly little endian UTF32
if (byteLen < 4 || byteBuffer[2] != 0 || byteBuffer[3] != 0) {
encoding = new UnicodeEncoding(false, true);
CompressBuffer(2);
changedEncoding = true;
}
#if FEATURE_UTF32
else {
encoding = new UTF32Encoding(false, true);
CompressBuffer(4);
changedEncoding = true;
}
#endif
}
else if (byteLen >= 3 && byteBuffer[0]==0xEF && byteBuffer[1]==0xBB && byteBuffer[2]==0xBF) {
// UTF-8
encoding = Encoding.UTF8;
CompressBuffer(3);
changedEncoding = true;
}
#if FEATURE_UTF32
else if (byteLen >= 4 && byteBuffer[0] == 0 && byteBuffer[1] == 0 &&
byteBuffer[2] == 0xFE && byteBuffer[3] == 0xFF) {
// Big Endian UTF32
encoding = new UTF32Encoding(true, true);
CompressBuffer(4);
changedEncoding = true;
}
#endif
else if (byteLen == 2)
_detectEncoding = true;
// Note: in the future, if we change this algorithm significantly,
// we can support checking for the preamble of the given encoding.
if (changedEncoding) {
decoder = encoding.GetDecoder();
_maxCharsPerBuffer = encoding.GetMaxCharCount(byteBuffer.Length);
charBuffer = new char[_maxCharsPerBuffer];
}
}
// Trims the preamble bytes from the byteBuffer. This routine can be called multiple times
// and we will buffer the bytes read until the preamble is matched or we determine that
// there is no match. If there is no match, every byte read previously will be available
// for further consumption. If there is a match, we will compress the buffer for the
// leading preamble bytes
private bool IsPreamble()
{
if (!_checkPreamble)
return _checkPreamble;
Contract.Assert(bytePos <= _preamble.Length, "_compressPreamble was called with the current bytePos greater than the preamble buffer length. Are two threads using this StreamReader at the same time?");
int len = (byteLen >= (_preamble.Length))? (_preamble.Length - bytePos) : (byteLen - bytePos);
for(int i=0; i= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (len == 0) {
// EOF but we might have buffered bytes from previous
// attempts to detecting preamble that needs to decoded now
if (byteLen > 0)
charLen += decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charLen);
return charLen;
}
byteLen += len;
}
else {
Contract.Assert(bytePos == 0, "bytePos can be non zero only when we are trying to _checkPreamble. Are two threads using this StreamReader at the same time?");
byteLen = stream.Read(byteBuffer, 0, byteBuffer.Length);
Contract.Assert(byteLen >= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (byteLen == 0) // We're at EOF
return charLen;
}
// _isBlocked == whether we read fewer bytes than we asked for.
// Note we must check it here because CompressBuffer or
// DetectEncoding will change byteLen.
_isBlocked = (byteLen < byteBuffer.Length);
// Check for preamble before detect encoding. This is not to override the
// user suppplied Encoding for the one we implicitly detect. The user could
// customize the encoding which we will loose, such as ThrowOnError on UTF8
if (IsPreamble())
continue;
// If we're supposed to detect the encoding and haven't done so yet,
// do it. Note this may need to be called more than once.
if (_detectEncoding && byteLen >= 2)
DetectEncoding();
charLen += decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charLen);
} while (charLen == 0);
//Console.WriteLine("ReadBuffer called. chars: "+charLen);
return charLen;
}
// This version has a perf optimization to decode data DIRECTLY into the
// user's buffer, bypassing StreamWriter's own buffer.
// This gives a > 20% perf improvement for our encodings across the board,
// but only when asking for at least the number of characters that one
// buffer's worth of bytes could produce.
// This optimization, if run, will break SwitchEncoding, so we must not do
// this on the first call to ReadBuffer.
private int ReadBuffer(char[] userBuffer, int userOffset, int desiredChars, out bool readToUserBuffer) {
charLen = 0;
charPos = 0;
if (!_checkPreamble)
byteLen = 0;
int charsRead = 0;
// As a perf optimization, we can decode characters DIRECTLY into a
// user's char[]. We absolutely must not write more characters
// into the user's buffer than they asked for. Calculating
// encoding.GetMaxCharCount(byteLen) each time is potentially very
// expensive - instead, cache the number of chars a full buffer's
// worth of data may produce. Yes, this makes the perf optimization
// less aggressive, in that all reads that asked for fewer than AND
// returned fewer than _maxCharsPerBuffer chars won't get the user
// buffer optimization. This affects reads where the end of the
// Stream comes in the middle somewhere, and when you ask for
// fewer chars than than your buffer could produce.
readToUserBuffer = desiredChars >= _maxCharsPerBuffer;
do {
if (_checkPreamble) {
Contract.Assert(bytePos <= _preamble.Length, "possible bug in _compressPreamble. Are two threads using this StreamReader at the same time?");
int len = stream.Read(byteBuffer, bytePos, byteBuffer.Length - bytePos);
Contract.Assert(len >= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (len == 0) {
// EOF but we might have buffered bytes from previous
// attempts to detecting preamble that needs to decoded now
if (byteLen > 0) {
if (readToUserBuffer) {
charsRead += decoder.GetChars(byteBuffer, 0, byteLen, userBuffer, userOffset + charsRead);
charLen = 0; // StreamReader's buffer is empty.
}
else {
charsRead = decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charsRead);
charLen += charsRead; // Number of chars in StreamReader's buffer.
}
}
return charsRead;
}
byteLen += len;
}
else {
Contract.Assert(bytePos == 0, "bytePos can be non zero only when we are trying to _checkPreamble. Are two threads using this StreamReader at the same time?");
byteLen = stream.Read(byteBuffer, 0, byteBuffer.Length);
Contract.Assert(byteLen >= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (byteLen == 0) // EOF
return charsRead;
}
// _isBlocked == whether we read fewer bytes than we asked for.
// Note we must check it here because CompressBuffer or
// DetectEncoding will change byteLen.
_isBlocked = (byteLen < byteBuffer.Length);
// Check for preamble before detect encoding. This is not to override the
// user suppplied Encoding for the one we implicitly detect. The user could
// customize the encoding which we will loose, such as ThrowOnError on UTF8
// Note: we don't need to recompute readToUserBuffer optimization as IsPreamble
// doesn't change the encoding or affect _maxCharsPerBuffer
if (IsPreamble())
continue;
// On the first call to ReadBuffer, if we're supposed to detect the encoding, do it.
if (_detectEncoding && byteLen >= 2) {
DetectEncoding();
// DetectEncoding changes some buffer state. Recompute this.
readToUserBuffer = desiredChars >= _maxCharsPerBuffer;
}
charPos = 0;
if (readToUserBuffer) {
charsRead += decoder.GetChars(byteBuffer, 0, byteLen, userBuffer, userOffset + charsRead);
charLen = 0; // StreamReader's buffer is empty.
}
else {
charsRead = decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charsRead);
charLen += charsRead; // Number of chars in StreamReader's buffer.
}
} while (charsRead == 0);
_isBlocked &= charsRead < desiredChars;
//Console.WriteLine("ReadBuffer: charsRead: "+charsRead+" readToUserBuffer: "+readToUserBuffer);
return charsRead;
}
// Reads a line. A line is defined as a sequence of characters followed by
// a carriage return ('\r'), a line feed ('\n'), or a carriage return
// immediately followed by a line feed. The resulting string does not
// contain the terminating carriage return and/or line feed. The returned
// value is null if the end of the input stream has been reached.
//
[System.Security.SecuritySafeCritical] // auto-generated
public override String ReadLine() {
if (stream == null)
__Error.ReaderClosed();
if (charPos == charLen) {
if (ReadBuffer() == 0) return null;
}
StringBuilder sb = null;
do {
int i = charPos;
do {
char ch = charBuffer[i];
// Note the following common line feed chars:
// \n - UNIX \r\n - DOS \r - Mac
if (ch == '\r' || ch == '\n') {
String s;
if (sb != null) {
sb.Append(charBuffer, charPos, i - charPos);
s = sb.ToString();
}
else {
s = new String(charBuffer, charPos, i - charPos);
}
charPos = i + 1;
if (ch == '\r' && (charPos < charLen || ReadBuffer() > 0)) {
if (charBuffer[charPos] == '\n') charPos++;
}
return s;
}
i++;
} while (i < charLen);
i = charLen - charPos;
if (sb == null) sb = new StringBuilder(i + 80);
sb.Append(charBuffer, charPos, i);
} while (ReadBuffer() > 0);
return sb.ToString();
}
// No data, class doesn't need to be serializable.
// Note this class is threadsafe.
private class NullStreamReader : StreamReader
{
// Instantiating Encoding causes unnecessary perf hit.
internal NullStreamReader() {
Init(Stream.Null);
}
public override Stream BaseStream {
get { return Stream.Null; }
}
public override Encoding CurrentEncoding {
get { return Encoding.Unicode; }
}
protected override void Dispose(bool disposing)
{
// Do nothing - this is essentially unclosable.
}
public override int Peek()
{
return -1;
}
public override int Read()
{
return -1;
}
public override int Read(char[] buffer, int index, int count) {
return 0;
}
public override String ReadLine() {
return null;
}
public override String ReadToEnd()
{
return String.Empty;
}
internal override int ReadBuffer()
{
return 0;
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
/*============================================================
**
** Class: StreamReader
**
** [....]
**
**
** Purpose: For reading text from streams in a particular
** encoding.
**
**
===========================================================*/
using System;
using System.Text;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Diagnostics.Contracts;
namespace System.IO {
// This class implements a TextReader for reading characters to a Stream.
// This is designed for character input in a particular Encoding,
// whereas the Stream class is designed for byte input and output.
//
[Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public class StreamReader : TextReader
{
// StreamReader.Null is threadsafe.
public new static readonly StreamReader Null = new NullStreamReader();
// Using a 1K byte buffer and a 4K FileStream buffer works out pretty well
// perf-wise. On even a 40 MB text file, any perf loss by using a 4K
// buffer is negated by the win of allocating a smaller byte[], which
// saves construction time. This does break adaptive buffering,
// but this is slightly faster.
internal const int DefaultBufferSize = 1024; // Byte buffer size
private const int DefaultFileStreamBufferSize = 4096;
private const int MinBufferSize = 128;
private bool _closable; // For Console.In. We should consider exposing a Closable bit perhaps on stream at some point.
private Stream stream;
private Encoding encoding;
private Decoder decoder;
private byte[] byteBuffer;
private char[] charBuffer;
private byte[] _preamble; // Encoding's preamble, which identifies this encoding.
private int charPos;
private int charLen;
// Record the number of valid bytes in the byteBuffer, for a few checks.
private int byteLen;
// This is used only for preamble detection
private int bytePos;
// This is the maximum number of chars we can get from one call to
// ReadBuffer. Used so ReadBuffer can tell when to copy data into
// a user's char[] directly, instead of our internal char[].
private int _maxCharsPerBuffer;
// We will support looking for byte order marks in the stream and trying
// to decide what the encoding might be from the byte order marks, IF they
// exist. But that's all we'll do.
private bool _detectEncoding;
// Whether we must still check for the encoding's given preamble at the
// beginning of this file.
private bool _checkPreamble;
// Whether the stream is most likely not going to give us back as much
// data as we want the next time we call it. We must do the computation
// before we do any byte order mark handling and save the result. Note
// that we need this to allow users to handle streams used for an
// interactive protocol, where they block waiting for the remote end
// to send a response, like logging in on a Unix machine.
private bool _isBlocked;
// StreamReader by default will ignore illegal UTF8 characters. We don't want to
// throw here because we want to be able to read ill-formed data without choking.
// The high level goal is to be tolerant of encoding errors when we read and very strict
// when we write. Hence, default StreamWriter encoding will throw on error.
internal StreamReader() {
}
public StreamReader(Stream stream)
: this(stream, true) {
}
public StreamReader(Stream stream, bool detectEncodingFromByteOrderMarks)
: this(stream, Encoding.UTF8, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
public StreamReader(Stream stream, Encoding encoding)
: this(stream, encoding, true, DefaultBufferSize) {
}
public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks)
: this(stream, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
// Creates a new StreamReader 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.
//
// Note that detectEncodingFromByteOrderMarks is a very
// loose attempt at detecting the encoding by looking at the first
// 3 bytes of the stream. It will recognize UTF-8, little endian
// unicode, and big endian unicode text, but that's it. If neither
// of those three match, it will use the Encoding you provided.
//
public StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
{
if (stream==null || encoding==null)
throw new ArgumentNullException((stream==null ? "stream" : "encoding"));
if (!stream.CanRead)
throw new ArgumentException(Environment.GetResourceString("Argument_StreamNotReadable"));
if (bufferSize <= 0)
throw new ArgumentOutOfRangeException("bufferSize", Environment.GetResourceString("ArgumentOutOfRange_NeedPosNum"));
Contract.EndContractBlock();
Init(stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);
}
// For non closable streams such as Console.In
internal StreamReader(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize, bool closable)
: this(stream, encoding, detectEncodingFromByteOrderMarks, bufferSize) {
_closable = closable;
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path)
: this(path, true) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, bool detectEncodingFromByteOrderMarks)
: this(path, Encoding.UTF8, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, Encoding encoding)
: this(path, encoding, true, DefaultBufferSize) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, Encoding encoding, bool detectEncodingFromByteOrderMarks)
: this(path, encoding, detectEncodingFromByteOrderMarks, DefaultBufferSize) {
}
[System.Security.SecuritySafeCritical] // auto-generated
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public StreamReader(String path, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize)
{
// Don't open a Stream before checking for invalid arguments,
// or we'll create a FileStream on disk and we won't close it until
// the finalizer runs, causing problems for applications.
if (path==null || encoding==null)
throw new ArgumentNullException((path==null ? "path" : "encoding"));
if (path.Length==0)
throw new ArgumentException(Environment.GetResourceString("Argument_EmptyPath"));
if (bufferSize <= 0)
throw new ArgumentOutOfRangeException("bufferSize", Environment.GetResourceString("ArgumentOutOfRange_NeedPosNum"));
Contract.EndContractBlock();
Stream stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read, DefaultFileStreamBufferSize, FileOptions.SequentialScan);
Init(stream, encoding, detectEncodingFromByteOrderMarks, bufferSize);
}
private void Init(Stream stream, Encoding encoding, bool detectEncodingFromByteOrderMarks, int bufferSize) {
this.stream = stream;
this.encoding = encoding;
decoder = encoding.GetDecoder();
if (bufferSize < MinBufferSize) bufferSize = MinBufferSize;
byteBuffer = new byte[bufferSize];
_maxCharsPerBuffer = encoding.GetMaxCharCount(bufferSize);
charBuffer = new char[_maxCharsPerBuffer];
byteLen = 0;
bytePos = 0;
_detectEncoding = detectEncodingFromByteOrderMarks;
_preamble = encoding.GetPreamble();
_checkPreamble = (_preamble.Length > 0);
_isBlocked = false;
_closable = true; // ByDefault all streams are closable unless explicitly told otherwise
}
// Init used by NullStreamReader, to delay load encoding
internal void Init(Stream stream)
{
this.stream = stream;
_closable = true;
}
public override void Close()
{
Dispose(true);
}
protected override void Dispose(bool disposing)
{
// Dispose of our resources if this StreamReader is closable.
// Note that Console.In should not be closable.
try {
// Note that Stream.Close() can potentially throw here. So we need to
// ensure cleaning up internal resources, inside the finally block.
if (Closable && disposing && (stream != null))
stream.Close();
}
finally {
if (Closable && (stream != null)) {
stream = null;
encoding = null;
decoder = null;
byteBuffer = null;
charBuffer = null;
charPos = 0;
charLen = 0;
base.Dispose(disposing);
}
}
}
public virtual Encoding CurrentEncoding {
get { return encoding; }
}
public virtual Stream BaseStream {
get { return stream; }
}
internal bool Closable {
get { return _closable; }
//set { _closable = value; }
}
// DiscardBufferedData tells StreamReader to throw away its internal
// buffer contents. This is useful if the user needs to seek on the
// underlying stream to a known location then wants the StreamReader
// to start reading from this new point. This method should be called
// very sparingly, if ever, since it can lead to very poor performance.
// However, it may be the only way of handling some scenarios where
// users need to re-read the contents of a StreamReader a second time.
public void DiscardBufferedData() {
byteLen = 0;
charLen = 0;
charPos = 0;
// in general we'd like to have an invariant that encoding isn't null. However,
// for startup improvements for NullStreamReader, we want to delay load encoding.
if (encoding != null) {
decoder = encoding.GetDecoder();
}
_isBlocked = false;
}
public bool EndOfStream {
[System.Security.SecuritySafeCritical] // auto-generated
get {
if (stream == null)
__Error.ReaderClosed();
if (charPos < charLen)
return false;
// This may block on pipes!
int numRead = ReadBuffer();
return numRead == 0;
}
}
[Pure]
[System.Security.SecuritySafeCritical] // auto-generated
public override int Peek() {
if (stream == null)
__Error.ReaderClosed();
if (charPos == charLen) {
if (_isBlocked || ReadBuffer() == 0) return -1;
}
return charBuffer[charPos];
}
[System.Security.SecuritySafeCritical] // auto-generated
public override int Read() {
if (stream == null)
__Error.ReaderClosed();
if (charPos == charLen) {
if (ReadBuffer() == 0) return -1;
}
int result = charBuffer[charPos];
charPos++;
return result;
}
[System.Security.SecuritySafeCritical] // auto-generated
public override int Read([In, Out] char[] buffer, int index, int count) {
if (buffer==null)
throw new ArgumentNullException("buffer", Environment.GetResourceString("ArgumentNull_Buffer"));
if (index < 0 || count < 0)
throw new ArgumentOutOfRangeException((index < 0 ? "index" : "count"), Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum"));
if (buffer.Length - index < count)
throw new ArgumentException(Environment.GetResourceString("Argument_InvalidOffLen"));
Contract.EndContractBlock();
if (stream == null)
__Error.ReaderClosed();
int charsRead = 0;
// As a perf optimization, if we had exactly one buffer's worth of
// data read in, let's try writing directly to the user's buffer.
bool readToUserBuffer = false;
while (count > 0) {
int n = charLen - charPos;
if (n == 0) n = ReadBuffer(buffer, index + charsRead, count, out readToUserBuffer);
if (n == 0) break; // We're at EOF
if (n > count) n = count;
if (!readToUserBuffer) {
Buffer.InternalBlockCopy(charBuffer, charPos * 2, buffer, (index + charsRead) * 2, n*2);
charPos += n;
}
charsRead += n;
count -= n;
// This function shouldn't block for an indefinite amount of time,
// or reading from a network stream won't work right. If we got
// fewer bytes than we requested, then we want to break right here.
if (_isBlocked)
break;
}
return charsRead;
}
[System.Security.SecuritySafeCritical] // auto-generated
public override String ReadToEnd()
{
if (stream == null)
__Error.ReaderClosed();
// Call ReadBuffer, then pull data out of charBuffer.
StringBuilder sb = new StringBuilder(charLen - charPos);
do {
sb.Append(charBuffer, charPos, charLen - charPos);
charPos = charLen; // Note we consumed these characters
ReadBuffer();
} while (charLen > 0);
return sb.ToString();
}
// Trims n bytes from the front of the buffer.
private void CompressBuffer(int n)
{
Contract.Assert(byteLen >= n, "CompressBuffer was called with a number of bytes greater than the current buffer length. Are two threads using this StreamReader at the same time?");
Buffer.InternalBlockCopy(byteBuffer, n, byteBuffer, 0, byteLen - n);
byteLen -= n;
}
private void DetectEncoding()
{
if (byteLen < 2)
return;
_detectEncoding = false;
bool changedEncoding = false;
if (byteBuffer[0]==0xFE && byteBuffer[1]==0xFF) {
// Big Endian Unicode
encoding = new UnicodeEncoding(true, true);
CompressBuffer(2);
changedEncoding = true;
}
else if (byteBuffer[0]==0xFF && byteBuffer[1]==0xFE) {
// Little Endian Unicode, or possibly little endian UTF32
if (byteLen < 4 || byteBuffer[2] != 0 || byteBuffer[3] != 0) {
encoding = new UnicodeEncoding(false, true);
CompressBuffer(2);
changedEncoding = true;
}
#if FEATURE_UTF32
else {
encoding = new UTF32Encoding(false, true);
CompressBuffer(4);
changedEncoding = true;
}
#endif
}
else if (byteLen >= 3 && byteBuffer[0]==0xEF && byteBuffer[1]==0xBB && byteBuffer[2]==0xBF) {
// UTF-8
encoding = Encoding.UTF8;
CompressBuffer(3);
changedEncoding = true;
}
#if FEATURE_UTF32
else if (byteLen >= 4 && byteBuffer[0] == 0 && byteBuffer[1] == 0 &&
byteBuffer[2] == 0xFE && byteBuffer[3] == 0xFF) {
// Big Endian UTF32
encoding = new UTF32Encoding(true, true);
CompressBuffer(4);
changedEncoding = true;
}
#endif
else if (byteLen == 2)
_detectEncoding = true;
// Note: in the future, if we change this algorithm significantly,
// we can support checking for the preamble of the given encoding.
if (changedEncoding) {
decoder = encoding.GetDecoder();
_maxCharsPerBuffer = encoding.GetMaxCharCount(byteBuffer.Length);
charBuffer = new char[_maxCharsPerBuffer];
}
}
// Trims the preamble bytes from the byteBuffer. This routine can be called multiple times
// and we will buffer the bytes read until the preamble is matched or we determine that
// there is no match. If there is no match, every byte read previously will be available
// for further consumption. If there is a match, we will compress the buffer for the
// leading preamble bytes
private bool IsPreamble()
{
if (!_checkPreamble)
return _checkPreamble;
Contract.Assert(bytePos <= _preamble.Length, "_compressPreamble was called with the current bytePos greater than the preamble buffer length. Are two threads using this StreamReader at the same time?");
int len = (byteLen >= (_preamble.Length))? (_preamble.Length - bytePos) : (byteLen - bytePos);
for(int i=0; i= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (len == 0) {
// EOF but we might have buffered bytes from previous
// attempts to detecting preamble that needs to decoded now
if (byteLen > 0)
charLen += decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charLen);
return charLen;
}
byteLen += len;
}
else {
Contract.Assert(bytePos == 0, "bytePos can be non zero only when we are trying to _checkPreamble. Are two threads using this StreamReader at the same time?");
byteLen = stream.Read(byteBuffer, 0, byteBuffer.Length);
Contract.Assert(byteLen >= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (byteLen == 0) // We're at EOF
return charLen;
}
// _isBlocked == whether we read fewer bytes than we asked for.
// Note we must check it here because CompressBuffer or
// DetectEncoding will change byteLen.
_isBlocked = (byteLen < byteBuffer.Length);
// Check for preamble before detect encoding. This is not to override the
// user suppplied Encoding for the one we implicitly detect. The user could
// customize the encoding which we will loose, such as ThrowOnError on UTF8
if (IsPreamble())
continue;
// If we're supposed to detect the encoding and haven't done so yet,
// do it. Note this may need to be called more than once.
if (_detectEncoding && byteLen >= 2)
DetectEncoding();
charLen += decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charLen);
} while (charLen == 0);
//Console.WriteLine("ReadBuffer called. chars: "+charLen);
return charLen;
}
// This version has a perf optimization to decode data DIRECTLY into the
// user's buffer, bypassing StreamWriter's own buffer.
// This gives a > 20% perf improvement for our encodings across the board,
// but only when asking for at least the number of characters that one
// buffer's worth of bytes could produce.
// This optimization, if run, will break SwitchEncoding, so we must not do
// this on the first call to ReadBuffer.
private int ReadBuffer(char[] userBuffer, int userOffset, int desiredChars, out bool readToUserBuffer) {
charLen = 0;
charPos = 0;
if (!_checkPreamble)
byteLen = 0;
int charsRead = 0;
// As a perf optimization, we can decode characters DIRECTLY into a
// user's char[]. We absolutely must not write more characters
// into the user's buffer than they asked for. Calculating
// encoding.GetMaxCharCount(byteLen) each time is potentially very
// expensive - instead, cache the number of chars a full buffer's
// worth of data may produce. Yes, this makes the perf optimization
// less aggressive, in that all reads that asked for fewer than AND
// returned fewer than _maxCharsPerBuffer chars won't get the user
// buffer optimization. This affects reads where the end of the
// Stream comes in the middle somewhere, and when you ask for
// fewer chars than than your buffer could produce.
readToUserBuffer = desiredChars >= _maxCharsPerBuffer;
do {
if (_checkPreamble) {
Contract.Assert(bytePos <= _preamble.Length, "possible bug in _compressPreamble. Are two threads using this StreamReader at the same time?");
int len = stream.Read(byteBuffer, bytePos, byteBuffer.Length - bytePos);
Contract.Assert(len >= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (len == 0) {
// EOF but we might have buffered bytes from previous
// attempts to detecting preamble that needs to decoded now
if (byteLen > 0) {
if (readToUserBuffer) {
charsRead += decoder.GetChars(byteBuffer, 0, byteLen, userBuffer, userOffset + charsRead);
charLen = 0; // StreamReader's buffer is empty.
}
else {
charsRead = decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charsRead);
charLen += charsRead; // Number of chars in StreamReader's buffer.
}
}
return charsRead;
}
byteLen += len;
}
else {
Contract.Assert(bytePos == 0, "bytePos can be non zero only when we are trying to _checkPreamble. Are two threads using this StreamReader at the same time?");
byteLen = stream.Read(byteBuffer, 0, byteBuffer.Length);
Contract.Assert(byteLen >= 0, "Stream.Read returned a negative number! This is a bug in your stream class.");
if (byteLen == 0) // EOF
return charsRead;
}
// _isBlocked == whether we read fewer bytes than we asked for.
// Note we must check it here because CompressBuffer or
// DetectEncoding will change byteLen.
_isBlocked = (byteLen < byteBuffer.Length);
// Check for preamble before detect encoding. This is not to override the
// user suppplied Encoding for the one we implicitly detect. The user could
// customize the encoding which we will loose, such as ThrowOnError on UTF8
// Note: we don't need to recompute readToUserBuffer optimization as IsPreamble
// doesn't change the encoding or affect _maxCharsPerBuffer
if (IsPreamble())
continue;
// On the first call to ReadBuffer, if we're supposed to detect the encoding, do it.
if (_detectEncoding && byteLen >= 2) {
DetectEncoding();
// DetectEncoding changes some buffer state. Recompute this.
readToUserBuffer = desiredChars >= _maxCharsPerBuffer;
}
charPos = 0;
if (readToUserBuffer) {
charsRead += decoder.GetChars(byteBuffer, 0, byteLen, userBuffer, userOffset + charsRead);
charLen = 0; // StreamReader's buffer is empty.
}
else {
charsRead = decoder.GetChars(byteBuffer, 0, byteLen, charBuffer, charsRead);
charLen += charsRead; // Number of chars in StreamReader's buffer.
}
} while (charsRead == 0);
_isBlocked &= charsRead < desiredChars;
//Console.WriteLine("ReadBuffer: charsRead: "+charsRead+" readToUserBuffer: "+readToUserBuffer);
return charsRead;
}
// Reads a line. A line is defined as a sequence of characters followed by
// a carriage return ('\r'), a line feed ('\n'), or a carriage return
// immediately followed by a line feed. The resulting string does not
// contain the terminating carriage return and/or line feed. The returned
// value is null if the end of the input stream has been reached.
//
[System.Security.SecuritySafeCritical] // auto-generated
public override String ReadLine() {
if (stream == null)
__Error.ReaderClosed();
if (charPos == charLen) {
if (ReadBuffer() == 0) return null;
}
StringBuilder sb = null;
do {
int i = charPos;
do {
char ch = charBuffer[i];
// Note the following common line feed chars:
// \n - UNIX \r\n - DOS \r - Mac
if (ch == '\r' || ch == '\n') {
String s;
if (sb != null) {
sb.Append(charBuffer, charPos, i - charPos);
s = sb.ToString();
}
else {
s = new String(charBuffer, charPos, i - charPos);
}
charPos = i + 1;
if (ch == '\r' && (charPos < charLen || ReadBuffer() > 0)) {
if (charBuffer[charPos] == '\n') charPos++;
}
return s;
}
i++;
} while (i < charLen);
i = charLen - charPos;
if (sb == null) sb = new StringBuilder(i + 80);
sb.Append(charBuffer, charPos, i);
} while (ReadBuffer() > 0);
return sb.ToString();
}
// No data, class doesn't need to be serializable.
// Note this class is threadsafe.
private class NullStreamReader : StreamReader
{
// Instantiating Encoding causes unnecessary perf hit.
internal NullStreamReader() {
Init(Stream.Null);
}
public override Stream BaseStream {
get { return Stream.Null; }
}
public override Encoding CurrentEncoding {
get { return Encoding.Unicode; }
}
protected override void Dispose(bool disposing)
{
// Do nothing - this is essentially unclosable.
}
public override int Peek()
{
return -1;
}
public override int Read()
{
return -1;
}
public override int Read(char[] buffer, int index, int count) {
return 0;
}
public override String ReadLine() {
return null;
}
public override String ReadToEnd()
{
return String.Empty;
}
internal override int ReadBuffer()
{
return 0;
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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