public override IEnumerable <ISearchMatch> Search(string toFind, string toSearch)
{
if (toFind.Length > 0 && toSearch.Length > 0)
{
BadMatchTable badMatchTable = new BadMatchTable(toFind);
int currStartIndex = 0;
while (currStartIndex <= toSearch.Length - toFind.Length)
{
int charsLeftToMatch = toFind.Length - 1;
while (charsLeftToMatch >= 0 &&
Compare(toFind[charsLeftToMatch], toSearch[currStartIndex + charsLeftToMatch]) == 0)
{
charsLeftToMatch--;
}
if (charsLeftToMatch < 0)
{
yield return(new SearchMatchStruct(currStartIndex, toFind.Length));
currStartIndex += toFind.Length;
}
else
{
currStartIndex += badMatchTable[toSearch[currStartIndex + toFind.Length - 1]];
}
}
}
}
public static List <int> BoyerMooreSearch(string pattern, string toSearch)
{
if (string.IsNullOrWhiteSpace(pattern) || string.IsNullOrWhiteSpace(toSearch) || pattern.Length > toSearch.Length)
{
return(null);
}
var matchIndexesFound = new List <int>();
var badMatchTbl = new BadMatchTable(pattern);
var currentIdx = 0;
while (currentIdx <= toSearch.Length - pattern.Length)
{
int charsLeftToMatch = pattern.Length - 1;//reset & start from right
while (charsLeftToMatch >= 0 && (pattern[charsLeftToMatch] == toSearch[currentIdx + charsLeftToMatch]))
{
charsLeftToMatch--;
}
if (charsLeftToMatch < 0) //match found
{
matchIndexesFound.Add(currentIdx);
currentIdx += pattern.Length;
}
else
{
currentIdx += badMatchTbl[toSearch[currentIdx + pattern.Length - 1]];
}
}
return(matchIndexesFound);
}
public static int BoyerMooreSearch(string pattern, string toSearch)
{
if (string.IsNullOrWhiteSpace(toSearch))
{
return(-1);
}
var badMatchTbl = new BadMatchTable(pattern);
var currentIdx = 0;
while (currentIdx <= toSearch.Length - pattern.Length)
{
int charsLeftToMatch = pattern.Length - 1;
while (charsLeftToMatch >= 0 && pattern[charsLeftToMatch] == toSearch[currentIdx + charsLeftToMatch])
{
charsLeftToMatch--;
}
if (charsLeftToMatch < 0)
{
return(currentIdx);
}
currentIdx += badMatchTbl[toSearch[currentIdx + pattern.Length - 1]];
}
return(-1);
}
public void TestBadMatchTable()
{
// Arrange
// Act
var badMatchTable = new BadMatchTable("TRUTH");
// Assert
Assert.AreEqual(1, badMatchTable.GetShift('T'));
Assert.AreEqual(3, badMatchTable.GetShift('R'));
Assert.AreEqual(2, badMatchTable.GetShift('U'));
Assert.AreEqual(5, badMatchTable.GetShift('Z'));
}
