public SuffixArrayRange(PrecomputedSearchResult precomputedResult, IBigArray <ulong> suffixArray,
FourBitDigitBigArray digits)
{
//If there are no results
if (precomputedResult.MinSuffixArrayIdx == precomputedResult.MaxSuffixArrayIdx)
{
HasResults = false;
}
else //Otherwise there are search results
{
HasResults = true;
Min = precomputedResult.MinSuffixArrayIdx;
//Note that the precomputed results are stored with the max value exclusive so that it can also encode HasResults
// whereas this class uses inclusive, so correct for that by taking 1
Max = precomputedResult.MaxSuffixArrayIdx - 1;
SuffixArray = suffixArray;
Digits = digits;
}
}
public static SuffixArrayRange Search(IBigArray <ulong> suffixArray, FourBitDigitBigArray digitArray, byte[] lookFor,
IBigArray <PrecomputedSearchResult>[] precomputedResults = null)
{
//Validation
if (lookFor.Length == 0)
{
throw new ArgumentException("lookFor must contain at least 1 digit");
}
if (digitArray.Length == 0)
{
return(new SuffixArrayRange(false));
}
if (suffixArray.Length != digitArray.Length)
{
throw new ArgumentException(
"Suffix Array must be the same length as the Digit Array. This is not the correct suffix array for this digit array");
}
//If we've been passed null for the precomputedResults, make an empty array for them
if (precomputedResults == null)
{
precomputedResults = new IBigArray <PrecomputedSearchResult> [0];
}
//If we have been given the precomputed results for strings of the length we're looking for
if (precomputedResults.Length >= lookFor.Length)
{
IBigArray <PrecomputedSearchResult> precomputedResultsOfRequiredLength =
precomputedResults[lookFor.Length - 1];
//Convert the string of bytes we're looking for to a long to use as the array index
long precomputedResultIdx = ByteArrToLong(lookFor);
PrecomputedSearchResult precomputedResult = precomputedResultsOfRequiredLength[precomputedResultIdx];
//Convert this precomputed result into a SuffixArrayRange before returning it
SuffixArrayRange suffixArrayRange = new SuffixArrayRange(precomputedResult, suffixArray, digitArray);
return(suffixArrayRange);
}
else //Otherwise we don't have the precomputed results for this search, run the suffix array search
{
long matchingPosition = binarySearchForPrefix(suffixArray, digitArray, lookFor, 0,
suffixArray.Length - 1);
//If there were no matches
if (matchingPosition == -1)
{
return(new SuffixArrayRange(false));
}
else //Otherwise match found, look for more
{
long min = matchingPosition;
long max = matchingPosition;
while (min > 0 && doesStartWithSuffix(digitArray, lookFor, (long)suffixArray[min - 1]) == 0)
{
min--;
}
while (max < digitArray.Length - 1 &&
doesStartWithSuffix(digitArray, lookFor, (long)suffixArray[max + 1]) == 0)
{
max++;
}
SuffixArrayRange suffixArrayRange = new SuffixArrayRange(min, max, suffixArray, digitArray);
return(suffixArrayRange);
}
}
}