/// <summary>
/// Test the match of this charset with the input text data which is obtained
/// via the CharsetDetector object.
/// </summary>
///
/// <param name="det">The CharsetDetector, which contains the input text to bechecked for being in this charset.</param>
/// <returns>Two values packed into one int (Damn java, anyhow) <br/>
/// bits 0-7: the match confidence, ranging from 0-100 <br/>
/// bits 8-15: The match reason, an enum-like value.</returns>
internal int Match(CharsetDetector det, int[] commonChars)
{
int singleByteCharCount = 0;
int doubleByteCharCount = 0;
int commonCharCount = 0;
int badCharCount = 0;
int totalCharCount = 0;
int confidence = 0;
CharsetRecog_mbcs.iteratedChar iter = new CharsetRecog_mbcs.iteratedChar();
detectBlock : {
{
for (iter.Reset(); NextChar(iter, det);)
{
totalCharCount++;
if (iter.error)
{
badCharCount++;
}
else
{
long cv = iter.charValue & -1;
if (cv <= 0xff)
{
singleByteCharCount++;
}
else
{
doubleByteCharCount++;
if (commonChars != null)
{
// NOTE: This assumes that there are no 4-byte
// common chars.
if (System.Array.BinarySearch(commonChars, (int)cv) >= 0)
{
commonCharCount++;
}
}
}
}
if (badCharCount >= 2 &&
badCharCount * 5 >= doubleByteCharCount)
{
goto gotodetectBlock;
}
}
if (doubleByteCharCount <= 10 && badCharCount == 0)
{
// Not many multi-byte chars.
// ASCII or ISO file? It's probably not our encoding,
// but is not incompatible with our encoding, so don't give it a
// zero.
confidence = 10;
goto gotodetectBlock;
}
//
// No match if there are too many characters that don't fit the
// encoding scheme.
// (should we have zero tolerance for these?)
//
if (doubleByteCharCount < 20 * badCharCount)
{
confidence = 0;
goto gotodetectBlock;
}
if (commonChars == null)
{
// We have no statistics on frequently occuring characters.
// Assess confidence purely on having a reasonable number of
// multi-byte characters (the more the better
confidence = 30 + doubleByteCharCount - 20 * badCharCount;
if (confidence > 100)
{
confidence = 100;
}
}
else
{
//
// Frequency of occurence statistics exist.
//
double maxVal = Math.Log((float)doubleByteCharCount / 4);
double scaleFactor = 90.0d / maxVal;
confidence = (int)(Math.Log(commonCharCount + 1) * scaleFactor + 10);
confidence = Math.Min(confidence, 100);
}
} // end of detectBlock:
}
gotodetectBlock:
;
return(confidence);
}
