| 1 | /* This file is part of the KDE libraries |
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| 2 | SPDX-FileCopyrightText: 2006 Jacob R Rideout <kde@jacobrideout.net> |
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| 3 | |
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| 4 | SPDX-License-Identifier: LGPL-2.0-or-later |
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| 5 | */ |
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| 6 | |
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| 7 | #ifndef GUESSLANGUAGE_H |
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| 8 | #define GUESSLANGUAGE_H |
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| 9 | |
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| 10 | #include <QString> |
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| 11 | #include <QStringList> |
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| 12 | |
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| 13 | #include "sonnetcore_export.h" |
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| 14 | |
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| 15 | #include <memory> |
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| 16 | |
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| 17 | namespace Sonnet |
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| 18 | { |
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| 19 | // Amount of trigrams in each file |
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| 20 | static const int MAXGRAMS = 300; |
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| 21 | |
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| 22 | class GuessLanguagePrivate; |
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| 23 | |
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| 24 | /*! |
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| 25 | * \class Sonnet::GuessLanguage |
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| 26 | * \inheaderfile Sonnet/GuessLanguage |
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| 27 | * \inmodule SonnetCore |
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| 28 | * |
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| 29 | * \brief GuessLanguage determines the language of a given text. |
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| 30 | * |
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| 31 | * GuessLanguage can determine the difference between ~75 languages for a given string. It is |
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| 32 | * based off a Perl script originally written by Maciej Ceglowski |
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| 33 | * called Languid. His script used a 2 part heuristic to determine language. First the text |
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| 34 | * is checked for the scripts it contains, then for each set of languages using those |
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| 35 | * scripts a n-gram frequency model of a given language is compared to a model of the text. |
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| 36 | * The most similar language model is assumed to be the language. If no language is found |
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| 37 | * an empty string is returned. |
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| 38 | * |
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| 39 | * \since 4.3 |
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| 40 | */ |
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| 41 | class SONNETCORE_EXPORT GuessLanguage |
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| 42 | { |
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| 43 | public: |
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| 44 | /*! |
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| 45 | * Constructor |
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| 46 | * |
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| 47 | * Creates a new GuessLanguage instance. |
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| 48 | */ |
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| 49 | GuessLanguage(); |
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| 50 | |
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| 51 | ~GuessLanguage(); |
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| 52 | |
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| 53 | GuessLanguage(const GuessLanguage &) = delete; |
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| 54 | GuessLanguage &operator=(const GuessLanguage &) = delete; |
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| 55 | |
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| 56 | /*! |
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| 57 | * Sets limits to number of languages returned by identify(). The confidence for each language is computed |
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| 58 | * as difference between this and next language on the list normalized to 0-1 range. Reasonable value to get |
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| 59 | * fairly sure result is 0.1 . Default is returning best guess without caring about confidence - exactly |
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| 60 | * as after call to setLimits(1,0). |
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| 61 | * |
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| 62 | * \a maxItems The list returned by identify() will never have more than maxItems item |
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| 63 | * |
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| 64 | * \a minConfidence The list will have only enough items for their summary confidence equal |
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| 65 | * or exceed minConfidence. |
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| 66 | */ |
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| 67 | void setLimits(int maxItems, double minConfidence); |
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| 68 | |
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| 69 | /*! |
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| 70 | * Returns the 2 digit ISO 639-1 code for the language of the currently |
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| 71 | * set text and. |
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| 72 | * |
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| 73 | * Three digits are returned only in the case where a 2 digit |
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| 74 | * code does not exist. If \a text isn't empty, set the text to checked. |
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| 75 | * \a text to be identified |
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| 76 | * |
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| 77 | * Returns list of the presumed languages of the text, sorted by decreasing confidence. Empty list means |
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| 78 | * it is impossible to determine language with confidence required by setLimits |
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| 79 | */ |
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| 80 | QString identify(const QString &text, const QStringList &suggestions = QStringList()) const; |
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| 81 | |
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| 82 | private: |
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| 83 | std::unique_ptr<GuessLanguagePrivate> const d; |
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| 84 | }; |
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| 85 | } |
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| 86 | |
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| 87 | #endif |
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| 88 | |
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