209 lines
6.7 KiB
C#
209 lines
6.7 KiB
C#
// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
|
|
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
|
|
|
|
using System;
|
|
using System.IO;
|
|
using System.Text;
|
|
|
|
namespace ICSharpCode.AvalonEdit.Utils
|
|
{
|
|
/// <summary>
|
|
/// Class that can open text files with auto-detection of the encoding.
|
|
/// </summary>
|
|
public static class FileReader
|
|
{
|
|
/// <summary>
|
|
/// Gets if the given encoding is a Unicode encoding (UTF).
|
|
/// </summary>
|
|
/// <remarks>
|
|
/// Returns true for UTF-7, UTF-8, UTF-16 LE, UTF-16 BE, UTF-32 LE and UTF-32 BE.
|
|
/// Returns false for all other encodings.
|
|
/// </remarks>
|
|
public static bool IsUnicode(Encoding encoding)
|
|
{
|
|
if (encoding == null)
|
|
throw new ArgumentNullException("encoding");
|
|
switch (encoding.CodePage) {
|
|
case 65000: // UTF-7
|
|
case 65001: // UTF-8
|
|
case 1200: // UTF-16 LE
|
|
case 1201: // UTF-16 BE
|
|
case 12000: // UTF-32 LE
|
|
case 12001: // UTF-32 BE
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the content of the given stream.
|
|
/// </summary>
|
|
/// <param name="stream">The stream to read.
|
|
/// The stream must support seeking and must be positioned at its beginning.</param>
|
|
/// <param name="defaultEncoding">The encoding to use if the encoding cannot be auto-detected.</param>
|
|
/// <returns>The file content as string.</returns>
|
|
public static string ReadFileContent(Stream stream, Encoding defaultEncoding)
|
|
{
|
|
using (StreamReader reader = OpenStream(stream, defaultEncoding)) {
|
|
return reader.ReadToEnd();
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the content of the file.
|
|
/// </summary>
|
|
/// <param name="fileName">The file name.</param>
|
|
/// <param name="defaultEncoding">The encoding to use if the encoding cannot be auto-detected.</param>
|
|
/// <returns>The file content as string.</returns>
|
|
public static string ReadFileContent(string fileName, Encoding defaultEncoding)
|
|
{
|
|
using (FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read)) {
|
|
return ReadFileContent(fs, defaultEncoding);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Opens the specified file for reading.
|
|
/// </summary>
|
|
/// <param name="fileName">The file to open.</param>
|
|
/// <param name="defaultEncoding">The encoding to use if the encoding cannot be auto-detected.</param>
|
|
/// <returns>Returns a StreamReader that reads from the stream. Use
|
|
/// <see cref="StreamReader.CurrentEncoding"/> to get the encoding that was used.</returns>
|
|
public static StreamReader OpenFile(string fileName, Encoding defaultEncoding)
|
|
{
|
|
if (fileName == null)
|
|
throw new ArgumentNullException("fileName");
|
|
FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
|
|
try {
|
|
return OpenStream(fs, defaultEncoding);
|
|
// don't use finally: the stream must be kept open until the StreamReader closes it
|
|
} catch {
|
|
fs.Dispose();
|
|
throw;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Opens the specified stream for reading.
|
|
/// </summary>
|
|
/// <param name="stream">The stream to open.</param>
|
|
/// <param name="defaultEncoding">The encoding to use if the encoding cannot be auto-detected.</param>
|
|
/// <returns>Returns a StreamReader that reads from the stream. Use
|
|
/// <see cref="StreamReader.CurrentEncoding"/> to get the encoding that was used.</returns>
|
|
public static StreamReader OpenStream(Stream stream, Encoding defaultEncoding)
|
|
{
|
|
if (stream == null)
|
|
throw new ArgumentNullException("stream");
|
|
if (stream.Position != 0)
|
|
throw new ArgumentException("stream is not positioned at beginning.", "stream");
|
|
if (defaultEncoding == null)
|
|
throw new ArgumentNullException("defaultEncoding");
|
|
|
|
if (stream.Length >= 2) {
|
|
// the autodetection of StreamReader is not capable of detecting the difference
|
|
// between ISO-8859-1 and UTF-8 without BOM.
|
|
int firstByte = stream.ReadByte();
|
|
int secondByte = stream.ReadByte();
|
|
switch ((firstByte << 8) | secondByte) {
|
|
case 0x0000: // either UTF-32 Big Endian or a binary file; use StreamReader
|
|
case 0xfffe: // Unicode BOM (UTF-16 LE or UTF-32 LE)
|
|
case 0xfeff: // UTF-16 BE BOM
|
|
case 0xefbb: // start of UTF-8 BOM
|
|
// StreamReader autodetection works
|
|
stream.Position = 0;
|
|
return new StreamReader(stream);
|
|
default:
|
|
return AutoDetect(stream, (byte)firstByte, (byte)secondByte, defaultEncoding);
|
|
}
|
|
} else {
|
|
if (defaultEncoding != null) {
|
|
return new StreamReader(stream, defaultEncoding);
|
|
} else {
|
|
return new StreamReader(stream);
|
|
}
|
|
}
|
|
}
|
|
|
|
static StreamReader AutoDetect(Stream fs, byte firstByte, byte secondByte, Encoding defaultEncoding)
|
|
{
|
|
int max = (int)Math.Min(fs.Length, 500000); // look at max. 500 KB
|
|
const int ASCII = 0;
|
|
const int Error = 1;
|
|
const int UTF8 = 2;
|
|
const int UTF8Sequence = 3;
|
|
int state = ASCII;
|
|
int sequenceLength = 0;
|
|
byte b;
|
|
for (int i = 0; i < max; i++) {
|
|
if (i == 0) {
|
|
b = firstByte;
|
|
} else if (i == 1) {
|
|
b = secondByte;
|
|
} else {
|
|
b = (byte)fs.ReadByte();
|
|
}
|
|
if (b < 0x80) {
|
|
// normal ASCII character
|
|
if (state == UTF8Sequence) {
|
|
state = Error;
|
|
break;
|
|
}
|
|
} else if (b < 0xc0) {
|
|
// 10xxxxxx : continues UTF8 byte sequence
|
|
if (state == UTF8Sequence) {
|
|
--sequenceLength;
|
|
if (sequenceLength < 0) {
|
|
state = Error;
|
|
break;
|
|
} else if (sequenceLength == 0) {
|
|
state = UTF8;
|
|
}
|
|
} else {
|
|
state = Error;
|
|
break;
|
|
}
|
|
} else if (b >= 0xc2 && b < 0xf5) {
|
|
// beginning of byte sequence
|
|
if (state == UTF8 || state == ASCII) {
|
|
state = UTF8Sequence;
|
|
if (b < 0xe0) {
|
|
sequenceLength = 1; // one more byte following
|
|
} else if (b < 0xf0) {
|
|
sequenceLength = 2; // two more bytes following
|
|
} else {
|
|
sequenceLength = 3; // three more bytes following
|
|
}
|
|
} else {
|
|
state = Error;
|
|
break;
|
|
}
|
|
} else {
|
|
// 0xc0, 0xc1, 0xf5 to 0xff are invalid in UTF-8 (see RFC 3629)
|
|
state = Error;
|
|
break;
|
|
}
|
|
}
|
|
fs.Position = 0;
|
|
switch (state) {
|
|
case ASCII:
|
|
case Error:
|
|
// when the file seems to be ASCII or non-UTF8,
|
|
// we read it using the user-specified encoding so it is saved again
|
|
// using that encoding.
|
|
if (IsUnicode(defaultEncoding)) {
|
|
// the file is not Unicode, so don't read it using Unicode even if the
|
|
// user has choosen Unicode as the default encoding.
|
|
|
|
// If we don't do this, SD will end up always adding a Byte Order Mark
|
|
// to ASCII files.
|
|
defaultEncoding = Encoding.Default; // use system encoding instead
|
|
}
|
|
return new StreamReader(fs, defaultEncoding);
|
|
default:
|
|
return new StreamReader(fs);
|
|
}
|
|
}
|
|
}
|
|
}
|