private static TermFinderResult FindTermsWordBased(Core.Segment searchSegment,
Core.Segment textSegment, bool expectContinuousMatch)
{
// compute the maximum overlap scores for each token in the source and each token in the text,
// using LCS or ED
const bool useLcsScoreAdjustment = true;
int[,] overlaps = ComputeTokenAssociationScores(searchSegment, textSegment);
int[] maxScores = new int[searchSegment.Tokens.Count];
TermFinderResult result = new TermFinderResult();
result.MatchingRanges = new List <Sdl.LanguagePlatform.Core.SegmentRange>();
System.Collections.BitArray coveredTargetTokens
= new System.Collections.BitArray(textSegment.Tokens.Count);
IList <string> srcConcatenatedTokens = new List <string>();
IList <string> trgConcatenatedTokens = new List <string>();
int nonwhiteSearchTokens = 0;
for (int s = 0; s < searchSegment.Tokens.Count; ++s)
{
if (!searchSegment.Tokens[s].IsWhitespace)
{
++nonwhiteSearchTokens;
if (useLcsScoreAdjustment)
{
srcConcatenatedTokens.Add(searchSegment.Tokens[s].Text.ToLowerInvariant());
}
}
for (int t = 0; t < textSegment.Tokens.Count; ++t)
{
if (overlaps[s, t] > 0)
{
if (!coveredTargetTokens[t])
{
result.MatchingRanges.Add(textSegment.Tokens[t].Span);
coveredTargetTokens[t] = true;
}
if (overlaps[s, t] > maxScores[s])
{
System.Diagnostics.Debug.Assert(overlaps[s, t] >= 0 && overlaps[s, t] <= 100);
maxScores[s] = overlaps[s, t];
}
}
}
}
if (nonwhiteSearchTokens == 0)
{
return(null);
}
int tokenOverlapScore = (int)((float)maxScores.Sum() / (float)nonwhiteSearchTokens);
if (useLcsScoreAdjustment)
{
int relevantTextTokens = 0;
// TODO this won't work really well if the same search token appears
// multiple times int the match - the concatenation will include all
// occurrences (which will reduce the LCS score) and also increase the
// text token count (further reducing the LCS score)
for (int tokenIndex = 0; tokenIndex < textSegment.Tokens.Count; ++tokenIndex)
{
if (coveredTargetTokens[tokenIndex])
{
if (trgConcatenatedTokens.Count > 0)
{
int previousWordTokenIndex = GetPreviousWordTokenIndex(textSegment.Tokens, tokenIndex);
if ((previousWordTokenIndex > -1) && (!coveredTargetTokens[previousWordTokenIndex]))
{
const string UnmatchedToken = "#";
trgConcatenatedTokens.Add(UnmatchedToken);
}
}
++relevantTextTokens;
trgConcatenatedTokens.Add(textSegment.Tokens[tokenIndex].Text.ToLowerInvariant());
}
}
string srcConcat = string.Join("~", srcConcatenatedTokens.ToArray());
string trgConcat = string.Join("~", trgConcatenatedTokens.ToArray());
int lcsOverlapScore = 0;
if ((expectContinuousMatch || tokenOverlapScore < 100) &&
srcConcat.Length > 0 && trgConcat.Length > 0)
{
List <AlignedSubstring> lcs = SequenceAlignmentComputer <char> .ComputeLongestCommonSubsequence(srcConcat.ToCharArray(),
trgConcat.ToCharArray(), 1,
new SimpleCharLSAScoreProvider(), null);
int lcsOverlap = lcs.Sum(x => x.Length);
// dice again, this time on the concatenated strings of the tokens, with a
// penalty if the number of tokens differs [0..1]
float tokenCountDeltaPenalty = 2.0f * (float)Math.Min(nonwhiteSearchTokens, relevantTextTokens)
/ (float)(nonwhiteSearchTokens + relevantTextTokens);
// another dice
// 2009-08-10, OC: reduce token count delta penalty
lcsOverlapScore = (int)(((75.0f + 25.0f * tokenCountDeltaPenalty)
* 2.0f * (float)lcsOverlap) / (float)(srcConcat.Length + trgConcat.Length));
if (lcsOverlapScore < 0)
{
lcsOverlapScore = 0;
}
if (lcsOverlapScore > 100)
{
lcsOverlapScore = 100;
}
System.Diagnostics.Debug.Assert(lcsOverlapScore >= 0 && lcsOverlapScore <= 100);
}
if (tokenOverlapScore == 100 && lcsOverlapScore > 0)
{
// discontinuous/swapped match - not sure how to penalize
// TODO work out exact scoring
result.Score = (200 + lcsOverlapScore) / 3;
}
else
{
result.Score = Math.Max(tokenOverlapScore, lcsOverlapScore);
}
}
else
{
result.Score = tokenOverlapScore;
}
return(result);
}
private static TermFinderResult FindTermsCharBased(Core.Segment searchSegment,
Core.Segment textSegment, bool expectContinuousMatch)
{
// This should only be used for far-east languages
// these ranges capture the mapping from a character position in the plain text arrays
// to a segment position (run/position pairs)
List <Core.SegmentPosition> searchSegmentPositions;
List <Core.SegmentPosition> textSegmentPositions;
string searchPlain = searchSegment.ToPlain(true, true, out searchSegmentPositions);
string textPlain = textSegment.ToPlain(true, true, out textSegmentPositions);
if (searchPlain.Length == 0)
{
// TODO may need to look into what may cause such an issue:
System.Diagnostics.Debug.Assert(false, "Let Oli know and provide test data");
return(null);
}
char[] searchPlainArray = searchPlain.ToCharArray();
char[] textPlainArray = textPlain.ToCharArray();
int searchPlainLength = searchPlain.Length;
int textPlainLength = textPlain.Length;
System.Diagnostics.Debug.Assert(searchPlainLength == searchPlainArray.Length);
System.Diagnostics.Debug.Assert(textPlainLength == textPlainArray.Length);
List <AlignedSubstring> lcs = null;
SubstringAlignmentDisambiguator picker
= new SubstringAlignmentDisambiguator();
lcs = SequenceAlignmentComputer <char> .ComputeCoverage(searchPlainArray,
textPlainArray, new CharSubstringScoreProvider(), picker);
if (lcs == null || lcs.Count == 0)
{
return(null);
}
TermFinderResult result = new TermFinderResult();
result.MatchingRanges = new List <Sdl.LanguagePlatform.Core.SegmentRange>();
List <Core.SegmentPosition> textPositions = new List <Core.SegmentPosition>();
for (int subIdx = 0; subIdx < lcs.Count; ++subIdx)
{
AlignedSubstring sub = lcs[subIdx];
if (sub.Source.Length != sub.Target.Length)
{
// NOTE LCSubseq instead of Substring? Check scorer if this fires
System.Diagnostics.Debug.Assert(false, "Not supported - let Oli know and provide test data");
return(null);
}
for (int p = 0; p < sub.Source.Length; ++p)
{
textPositions.Add(textSegmentPositions[sub.Target.Start + p]);
}
}
if (textPositions.Count == 0)
{
return(null);
}
// covered ranges in the text segment:
result.MatchingRanges = SortAndMelt(textPositions);
// TODO this does not capture adjacency
float baseScore = (float)textPositions.Count / (float)searchPlainLength;
#if DEBUG
bool ok = VerifyRanges(result.MatchingRanges,
textSegment);
if (!ok)
{
System.Diagnostics.Debug.Assert(false, "Range verification failed");
}
#endif
result.Score = (int)(100.0f * baseScore);
if (result.Score < 0)
{
result.Score = 0;
}
else if (result.Score > 100)
{
result.Score = 100;
}
return(result);
}
