public CIBMSearcher(string Pattern, bool CaseSensitive)
: base(Pattern)
{
if (!CaseSensitive)
{
BMHashTable TmpHT = new BMHashTable();
foreach (char key in PatternCharShifts.Keys)
{
TmpHT.Add(key, PatternCharShifts.Get(key));
char ch;
if (char.IsLower(key))
{
ch = char.ToUpper(key);
}
else
{
ch = char.ToLower(key);
}
TmpHT.Add(ch, PatternCharShifts.Get(key));
}
PatternCharShifts = TmpHT;
}
}
private int PatternLength; // Length of the search pattern
/// <summary>
/// Class constructor. Pattern is a string to search for.
/// </summary>
public BMSearcher(string Pattern)
{
PatternCharShifts = new BMHashTable();
// Building shift table
PatternLength = Pattern.Length;
int MaxShift = PatternLength;
// Constructing the table where number of columns is equal to PatternLength
// and number of rows is equal to the number of distinct chars in the pattern
for (int i = 0; i < PatternLength; i++)
{
PatternCharShifts.Add(Pattern[i], new int[PatternLength]);
}
OtherCharShifts = new int[PatternLength];
// Filling the last column of the table with maximum shifts (pattern length)
foreach (char key in PatternCharShifts.Keys)
{
PatternCharShifts.Get(key)[PatternLength - 1] = MaxShift;
}
OtherCharShifts[PatternLength - 1] = MaxShift;
// Calculating other shifts (filling each column from PatternLength - 2 to 0 (from right to left)
for (int i = PatternLength - 1; i >= 0; i--)
{
// Suffix string contains the characters right to the character being processsed
string Suffix = new String(Pattern.ToCharArray(), i + 1, PatternLength - i - 1);
// if Pattern begins with Suffix the maximum shift is equal to i + 1
if (Pattern.StartsWith(Suffix))
{
MaxShift = i + 1;
}
// Store shift for characters not present in the pattern
OtherCharShifts[i] = MaxShift;
// We shorten patter by one char in NewPattern.
string NewPattern = new string(Pattern.ToCharArray(), 0, Pattern.Length - 1);
if ((NewPattern.LastIndexOf(Suffix) > 0) || (Suffix.Length == 0))
{
foreach (char key in PatternCharShifts.Keys)
{
string NewSuffix = key + Suffix;
// Calculate shifts:
//Check if there are other occurences of the new suffix in the pattern
// If several occurences exist, we need the rightmost one
int NewSuffixPos = NewPattern.LastIndexOf(NewSuffix);
if (NewSuffixPos >= 0)
{
PatternCharShifts.Get(key)[i] = i - NewSuffixPos;
}
else
{
PatternCharShifts.Get(key)[i] = MaxShift;
}
// Storing 0 if characters in a row and a columnt are the same
if (key == Pattern[i])
{
PatternCharShifts.Get(key)[i] = 0;
}
}
}
else
{
foreach (char key in PatternCharShifts.Keys)
{
// if Suffix doesn't occure in NewPattern we simply use previous shift value
PatternCharShifts.Get(key)[i] = MaxShift;
if (key == Pattern[i])
{
PatternCharShifts.Get(key)[i] = 0;
}
}
}
}
}
