InternalEncoderBestFitFallbackBuffer
using System.Threading;
namespace System.Text
{
internal sealed class InternalEncoderBestFitFallbackBuffer : EncoderFallbackBuffer
{
private char _cBestFit;
private readonly InternalEncoderBestFitFallback _oFallback;
private int _iCount = -1;
private int _iSize;
private static object s_InternalSyncObject;
private static object InternalSyncObject {
get {
if (s_InternalSyncObject == null) {
object value = new object();
Interlocked.CompareExchange<object>(ref s_InternalSyncObject, value, (object)null);
}
return s_InternalSyncObject;
}
}
public override int Remaining {
get {
if (_iCount <= 0)
return 0;
return _iCount;
}
}
public InternalEncoderBestFitFallbackBuffer(InternalEncoderBestFitFallback fallback)
{
_oFallback = fallback;
if (_oFallback.arrayBestFit == null) {
lock (InternalSyncObject) {
InternalEncoderBestFitFallback oFallback = _oFallback;
if (oFallback.arrayBestFit == null)
oFallback.arrayBestFit = fallback.encoding.GetBestFitUnicodeToBytesData();
}
}
}
public override bool Fallback(char charUnknown, int index)
{
_iCount = (_iSize = 1);
_cBestFit = TryBestFit(charUnknown);
if (_cBestFit == ' ')
_cBestFit = '?';
return true;
}
public override bool Fallback(char charUnknownHigh, char charUnknownLow, int index)
{
if (!char.IsHighSurrogate(charUnknownHigh))
throw new ArgumentOutOfRangeException("charUnknownHigh", System.SR.Format(System.SR.ArgumentOutOfRange_Range, 55296, 56319));
if (!char.IsLowSurrogate(charUnknownLow))
throw new ArgumentOutOfRangeException("charUnknownLow", System.SR.Format(System.SR.ArgumentOutOfRange_Range, 56320, 57343));
_cBestFit = '?';
_iCount = (_iSize = 2);
return true;
}
public override char GetNextChar()
{
_iCount--;
if (_iCount < 0)
return ' ';
if (_iCount == 2147483647) {
_iCount = -1;
return ' ';
}
return _cBestFit;
}
public override bool MovePrevious()
{
if (_iCount >= 0)
_iCount++;
if (_iCount >= 0)
return _iCount <= _iSize;
return false;
}
public override void Reset()
{
_iCount = -1;
}
private char TryBestFit(char cUnknown)
{
int num = 0;
int num2 = _oFallback.arrayBestFit.Length;
int num3;
while ((num3 = num2 - num) > 6) {
int num4 = (num3 / 2 + num) & 65534;
char c = _oFallback.arrayBestFit[num4];
if (c == cUnknown)
return _oFallback.arrayBestFit[num4 + 1];
if (c < cUnknown)
num = num4;
else
num2 = num4;
}
for (int num4 = num; num4 < num2; num4 += 2) {
if (_oFallback.arrayBestFit[num4] == cUnknown)
return _oFallback.arrayBestFit[num4 + 1];
}
return ' ';
}
}
}