/// <seealso cref="IScorer.StartFragment"/>
public virtual void StartFragment(TextFragment newFragment)
{
foundTerms = new JCG.HashSet <string>();
totalScore = 0;
}
/// <summary>
/// Improves readability of a score-sorted list of TextFragments by merging any fragments
/// that were contiguous in the original text into one larger fragment with the correct order.
/// This will leave a "null" in the array entry for the lesser scored fragment.
/// </summary>
/// <param name="frag">An array of document fragments in descending score</param>
private void MergeContiguousFragments(TextFragment[] frag)
{
bool mergingStillBeingDone;
if (frag.Length > 1)
{
do
{
mergingStillBeingDone = false; //initialise loop control flag
//for each fragment, scan other frags looking for contiguous blocks
for (int i = 0; i < frag.Length; i++)
{
if (frag[i] == null)
{
continue;
}
//merge any contiguous blocks
for (int x = 0; x < frag.Length; x++)
{
if (frag[x] == null)
{
continue;
}
if (frag[i] == null)
{
break;
}
TextFragment frag1 = null;
TextFragment frag2 = null;
int frag1Num = 0;
int frag2Num = 0;
int bestScoringFragNum;
int worstScoringFragNum;
//if blocks are contiguous....
if (frag[i].Follows(frag[x]))
{
frag1 = frag[x];
frag1Num = x;
frag2 = frag[i];
frag2Num = i;
}
else if (frag[x].Follows(frag[i]))
{
frag1 = frag[i];
frag1Num = i;
frag2 = frag[x];
frag2Num = x;
}
//merging required..
if (frag1 != null)
{
if (frag1.Score > frag2.Score)
{
bestScoringFragNum = frag1Num;
worstScoringFragNum = frag2Num;
}
else
{
bestScoringFragNum = frag2Num;
worstScoringFragNum = frag1Num;
}
frag1.Merge(frag2);
frag[worstScoringFragNum] = null;
mergingStillBeingDone = true;
frag[bestScoringFragNum] = frag1;
}
}
}
} while (mergingStillBeingDone);
}
}
/// <summary>
/// Low level api to get the most relevant (formatted) sections of the document.
/// This method has been made public to allow visibility of score information held in <see cref="TextFragment"/> objects.
/// Thanks to Jason Calabrese for help in redefining the interface.
/// </summary>
/// <exception cref="IOException">If there is a low-level I/O error</exception>
/// <exception cref="InvalidTokenOffsetsException">thrown if any token's EndOffset exceeds the provided text's length</exception>
public TextFragment[] GetBestTextFragments(
TokenStream tokenStream,
string text,
bool mergeContiguousFragments,
int maxNumFragments)
{
var docFrags = new List <TextFragment>();
var newText = new StringBuilder();
var termAtt = tokenStream.AddAttribute <ICharTermAttribute>();
var offsetAtt = tokenStream.AddAttribute <IOffsetAttribute>();
tokenStream.Reset();
var currentFrag = new TextFragment(newText, newText.Length, docFrags.Count);
if (_fragmentScorer is QueryScorer)
{
((QueryScorer)_fragmentScorer).SetMaxDocCharsToAnalyze(_maxDocCharsToAnalyze);
}
var newStream = _fragmentScorer.Init(tokenStream);
if (newStream != null)
{
tokenStream = newStream;
}
_fragmentScorer.StartFragment(currentFrag);
docFrags.Add(currentFrag);
var fragQueue = new FragmentQueue(maxNumFragments);
try
{
string tokenText;
int startOffset;
int endOffset;
int lastEndOffset = 0;
_textFragmenter.Start(text, tokenStream);
var tokenGroup = new TokenGroup(tokenStream);
for (bool next = tokenStream.IncrementToken();
next && (offsetAtt.StartOffset < _maxDocCharsToAnalyze);
next = tokenStream.IncrementToken())
{
if ((offsetAtt.EndOffset > text.Length)
||
(offsetAtt.StartOffset > text.Length)
)
{
throw new InvalidTokenOffsetsException("Token " + termAtt.ToString()
+ " exceeds length of provided text sized " + text.Length);
}
if ((tokenGroup.NumTokens > 0) && (tokenGroup.IsDistinct()))
{
//the current token is distinct from previous tokens -
// markup the cached token group info
startOffset = tokenGroup.MatchStartOffset;
endOffset = tokenGroup.MatchEndOffset;
tokenText = text.Substring(startOffset, endOffset - startOffset);
string markedUpText = _formatter.HighlightTerm(_encoder.EncodeText(tokenText), tokenGroup);
//store any whitespace etc from between this and last group
if (startOffset > lastEndOffset)
{
newText.Append(_encoder.EncodeText(text.Substring(lastEndOffset, startOffset - lastEndOffset)));
}
newText.Append(markedUpText);
lastEndOffset = Math.Max(endOffset, lastEndOffset);
tokenGroup.Clear();
//check if current token marks the start of a new fragment
if (_textFragmenter.IsNewFragment())
{
currentFrag.Score = _fragmentScorer.FragmentScore;
//record stats for a new fragment
currentFrag.TextEndPos = newText.Length;
currentFrag = new TextFragment(newText, newText.Length, docFrags.Count);
_fragmentScorer.StartFragment(currentFrag);
docFrags.Add(currentFrag);
}
}
tokenGroup.AddToken(_fragmentScorer.GetTokenScore());
// if(lastEndOffset>maxDocBytesToAnalyze)
// {
// break;
// }
}
currentFrag.Score = _fragmentScorer.FragmentScore;
if (tokenGroup.NumTokens > 0)
{
//flush the accumulated text (same code as in above loop)
startOffset = tokenGroup.MatchStartOffset;
endOffset = tokenGroup.MatchEndOffset;
tokenText = text.Substring(startOffset, endOffset - startOffset);
var markedUpText = _formatter.HighlightTerm(_encoder.EncodeText(tokenText), tokenGroup);
//store any whitespace etc from between this and last group
if (startOffset > lastEndOffset)
{
newText.Append(_encoder.EncodeText(text.Substring(lastEndOffset, startOffset - lastEndOffset)));
}
newText.Append(markedUpText);
lastEndOffset = Math.Max(lastEndOffset, endOffset);
}
//Test what remains of the original text beyond the point where we stopped analyzing
if (
// if there is text beyond the last token considered..
(lastEndOffset < text.Length)
&&
// and that text is not too large...
(text.Length <= _maxDocCharsToAnalyze)
)
{
//append it to the last fragment
newText.Append(_encoder.EncodeText(text.Substring(lastEndOffset)));
}
currentFrag.TextEndPos = newText.Length;
//sort the most relevant sections of the text
foreach (var f in docFrags)
{
currentFrag = f;
//If you are running with a version of Lucene before 11th Sept 03
// you do not have PriorityQueue.insert() - so uncomment the code below
/*
* if (currentFrag.getScore() >= minScore)
* {
* fragQueue.put(currentFrag);
* if (fragQueue.size() > maxNumFragments)
* { // if hit queue overfull
* fragQueue.pop(); // remove lowest in hit queue
* minScore = ((TextFragment) fragQueue.top()).getScore(); // reset minScore
* }
* }
*/
//The above code caused a problem as a result of Christoph Goller's 11th Sept 03
//fix to PriorityQueue. The correct method to use here is the new "insert" method
// USE ABOVE CODE IF THIS DOES NOT COMPILE!
fragQueue.InsertWithOverflow(currentFrag);
}
//return the most relevant fragments
var frag = new TextFragment[fragQueue.Count];
for (int i = frag.Length - 1; i >= 0; i--)
{
frag[i] = fragQueue.Pop();
}
//merge any contiguous fragments to improve readability
if (mergeContiguousFragments)
{
MergeContiguousFragments(frag);
List <TextFragment> fragTexts = new List <TextFragment>();
for (int i = 0; i < frag.Length; i++)
{
if ((frag[i] != null) && (frag[i].Score > 0))
{
fragTexts.Add(frag[i]);
}
}
frag = new TextFragment[fragTexts.Count];
fragTexts.CopyTo(frag);
}
return(frag);
}
finally
{
if (tokenStream != null)
{
try
{
tokenStream.End();
tokenStream.Dispose();
}
catch (Exception)
{
}
}
}
}
/// <seealso cref="IScorer.StartFragment"/>
public virtual void StartFragment(TextFragment newFragment)
{
foundTerms = Support.Compatibility.SetFactory.CreateHashSet <string>();
totalScore = 0;
}
public virtual void StartFragment(TextFragment newFragment)
{
uniqueTermsInFragment = new JCG.HashSet <string>();
currentTextFragment = newFragment;
totalScore = 0;
}
public virtual void StartFragment(TextFragment newFragment)
{
uniqueTermsInFragment = new JCG.HashSet <string>();
//currentTextFragment = newFragment; // LUCENENET: Not used
totalScore = 0;
}
