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| |
| #include "simtexth.h" |
| #include "translator.h" |
| |
| #include <QtCore/QByteArray> |
| #include <QtCore/QString> |
| #include <QtCore/QList> |
| |
| |
| QT_BEGIN_NAMESPACE |
| |
| typedef QList<TranslatorMessage> TML; |
| |
| /* |
| How similar are two texts? The approach used here relies on co-occurrence |
| matrices and is very efficient. |
| |
| Let's see with an example: how similar are "here" and "hither"? The |
| co-occurrence matrix M for "here" is M[h,e] = 1, M[e,r] = 1, M[r,e] = 1, and 0 |
| elsewhere; the matrix N for "hither" is N[h,i] = 1, N[i,t] = 1, ..., |
| N[h,e] = 1, N[e,r] = 1, and 0 elsewhere. The union U of both matrices is the |
| matrix U[i,j] = max { M[i,j], N[i,j] }, and the intersection V is |
| V[i,j] = min { M[i,j], N[i,j] }. The score for a pair of texts is |
| |
| score = (sum of V[i,j] over all i, j) / (sum of U[i,j] over all i, j), |
| |
| a formula suggested by Arnt Gulbrandsen. Here we have |
| |
| score = 2 / 6, |
| |
| or one third. |
| |
| The implementation differs from this in a few details. Most importantly, |
| repetitions are ignored; for input "xxx", M[x,x] equals 1, not 2. |
| */ |
| |
| /* |
| Every character is assigned to one of 20 buckets so that the co-occurrence |
| matrix requires only 20 * 20 = 400 bits, not 256 * 256 = 65536 bits or even |
| more if we want the whole Unicode. Which character falls in which bucket is |
| arbitrary. |
| |
| The second half of the table is a replica of the first half, because of |
| laziness. |
| */ |
| static const int indexOf[256] = { |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| // ! " # $ % & ' ( ) * + , - . / |
| 0, 2, 6, 7, 10, 12, 15, 19, 2, 6, 7, 10, 12, 15, 19, 0, |
| // 0 1 2 3 4 5 6 7 8 9 : ; < = > ? |
| 1, 3, 4, 5, 8, 9, 11, 13, 14, 16, 2, 6, 7, 10, 12, 15, |
| // @ A B C D E F G H I J K L M N O |
| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 6, 10, 11, 12, 13, 14, |
| // P Q R S T U V W X Y Z [ \ ] ^ _ |
| 15, 12, 16, 17, 18, 19, 2, 10, 15, 7, 19, 2, 6, 7, 10, 0, |
| // ` a b c d e f g h i j k l m n o |
| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 6, 10, 11, 12, 13, 14, |
| // p q r s t u v w x y z { | } ~ |
| 15, 12, 16, 17, 18, 19, 2, 10, 15, 7, 19, 2, 6, 7, 10, 0, |
| |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 2, 6, 7, 10, 12, 15, 19, 2, 6, 7, 10, 12, 15, 19, 0, |
| 1, 3, 4, 5, 8, 9, 11, 13, 14, 16, 2, 6, 7, 10, 12, 15, |
| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 6, 10, 11, 12, 13, 14, |
| 15, 12, 16, 17, 18, 19, 2, 10, 15, 7, 19, 2, 6, 7, 10, 0, |
| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 6, 10, 11, 12, 13, 14, |
| 15, 12, 16, 17, 18, 19, 2, 10, 15, 7, 19, 2, 6, 7, 10, 0 |
| }; |
| |
| /* |
| The entry bitCount[i] (for i between 0 and 255) is the number of bits used to |
| represent i in binary. |
| */ |
| static const int bitCount[256] = { |
| 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, |
| 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
| 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
| 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
| 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
| 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
| 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
| 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
| 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, |
| 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
| 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
| 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
| 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, |
| 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
| 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, |
| 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8 |
| }; |
| |
| struct CoMatrix |
| { |
| /* |
| The matrix has 20 * 20 = 400 entries. This requires 50 bytes, or 13 |
| words. Some operations are performed on words for more efficiency. |
| */ |
| union { |
| quint8 b[52]; |
| quint32 w[13]; |
| }; |
| |
| CoMatrix() { memset( b, 0, 52 ); } |
| |
| CoMatrix(const QString &str) |
| { |
| QByteArray ba = str.toUtf8(); |
| const char *text = ba.constData(); |
| char c = '\0', d; |
| memset( b, 0, 52 ); |
| /* |
| The Knuth books are not in the office only for show; they help make |
| loops 30% faster and 20% as readable. |
| */ |
| while ( (d = *text) != '\0' ) { |
| setCoOccurence( c, d ); |
| if ( (c = *++text) != '\0' ) { |
| setCoOccurence( d, c ); |
| text++; |
| } |
| } |
| } |
| |
| void setCoOccurence( char c, char d ) { |
| int k = indexOf[(uchar) c] + 20 * indexOf[(uchar) d]; |
| b[k >> 3] |= (1 << (k & 0x7)); |
| } |
| |
| int worth() const { |
| int w = 0; |
| for ( int i = 0; i < 50; i++ ) |
| w += bitCount[b[i]]; |
| return w; |
| } |
| }; |
| |
| static inline CoMatrix reunion(const CoMatrix &m, const CoMatrix &n) |
| { |
| CoMatrix p; |
| for (int i = 0; i < 13; ++i) |
| p.w[i] = m.w[i] | n.w[i]; |
| return p; |
| } |
| |
| static inline CoMatrix intersection(const CoMatrix &m, const CoMatrix &n) |
| { |
| CoMatrix p; |
| for (int i = 0; i < 13; ++i) |
| p.w[i] = m.w[i] & n.w[i]; |
| return p; |
| } |
| |
| StringSimilarityMatcher::StringSimilarityMatcher(const QString &stringToMatch) |
| { |
| m_cm = new CoMatrix(stringToMatch); |
| m_length = stringToMatch.length(); |
| } |
| |
| int StringSimilarityMatcher::getSimilarityScore(const QString &strCandidate) |
| { |
| CoMatrix cmTarget(strCandidate); |
| int delta = qAbs(m_length - strCandidate.size()); |
| int score = ( (intersection(*m_cm, cmTarget).worth() + 1) << 10 ) / |
| ( reunion(*m_cm, cmTarget).worth() + (delta << 1) + 1 ); |
| return score; |
| } |
| |
| StringSimilarityMatcher::~StringSimilarityMatcher() |
| { |
| delete m_cm; |
| } |
| |
| /** |
| * Checks how similar two strings are. |
| * The return value is the score, and a higher score is more similar |
| * than one with a low score. |
| * Linguist considers a score over 190 to be a good match. |
| * \sa StringSimilarityMatcher |
| */ |
| int getSimilarityScore(const QString &str1, const QString &str2) |
| { |
| CoMatrix cmTarget(str2); |
| CoMatrix cm(str1); |
| int delta = qAbs(str1.size() - str2.size()); |
| |
| int score = ( (intersection(cm, cmTarget).worth() + 1) << 10 ) |
| / ( reunion(cm, cmTarget).worth() + (delta << 1) + 1 ); |
| |
| return score; |
| } |
| |
| CandidateList similarTextHeuristicCandidates(const Translator *tor, |
| const QString &text, int maxCandidates) |
| { |
| QList<int> scores; |
| CandidateList candidates; |
| |
| TML all = tor->translatedMessages(); |
| |
| foreach (const TranslatorMessage &mtm, all) { |
| if (mtm.type() == TranslatorMessage::Unfinished |
| || mtm.translation().isEmpty()) |
| continue; |
| |
| QString s = mtm.sourceText(); |
| int score = getSimilarityScore(s, text); |
| |
| if (candidates.size() == maxCandidates && score > scores[maxCandidates - 1] ) |
| candidates.removeLast(); |
| |
| if (candidates.size() < maxCandidates && score >= textSimilarityThreshold) { |
| Candidate cand( s, mtm.translation() ); |
| |
| int i; |
| for (i = 0; i < candidates.size(); i++) { |
| if (score >= scores.at(i)) { |
| if (score == scores.at(i)) { |
| if (candidates.at(i) == cand) |
| goto continue_outer_loop; |
| } else { |
| break; |
| } |
| } |
| } |
| scores.insert(i, score); |
| candidates.insert(i, cand); |
| } |
| continue_outer_loop: |
| ; |
| } |
| return candidates; |
| } |
| |
| QT_END_NAMESPACE |