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localematcher.h
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// © 2019 and later: Unicode, Inc. and others. // License & terms of use: http://www.unicode.org/copyright.html#License // localematcher.h // created: 2019may08 Markus W. Scherer #ifndef __LOCALEMATCHER_H__ #define __LOCALEMATCHER_H__ #include "unicode/utypes.h" #if U_SHOW_CPLUSPLUS_API #include "unicode/locid.h" #include "unicode/stringpiece.h" #include "unicode/uobject.h" /** * \file * \brief C++ API: Locale matcher: User's desired locales vs. application's supported locales. */ #ifndef U_HIDE_DRAFT_API /** * Builder option for whether the language subtag or the script subtag is most important. * * @see Builder#setFavorSubtag(FavorSubtag) * @draft ICU 65 */ enum ULocMatchFavorSubtag { /** * Language differences are most important, then script differences, then region differences. * (This is the default behavior.) * * @draft ICU 65 */ ULOCMATCH_FAVOR_LANGUAGE, /** * Makes script differences matter relatively more than language differences. * * @draft ICU 65 */ ULOCMATCH_FAVOR_SCRIPT }; #ifndef U_IN_DOXYGEN typedef enum ULocMatchFavorSubtag ULocMatchFavorSubtag; #endif /** * Builder option for whether all desired locales are treated equally or * earlier ones are preferred. * * @see Builder#setDemotionPerDesiredLocale(Demotion) * @draft ICU 65 */ enum ULocMatchDemotion { /** * All desired locales are treated equally. * * @draft ICU 65 */ ULOCMATCH_DEMOTION_NONE, /** * Earlier desired locales are preferred. * * <p>From each desired locale to the next, * the distance to any supported locale is increased by an additional amount * which is at least as large as most region mismatches. * A later desired locale has to have a better match with some supported locale * due to more than merely having the same region subtag. * * <p>For example: <code>Supported={en, sv} desired=[en-GB, sv]</code> * yields <code>Result(en-GB, en)</code> because * with the demotion of sv its perfect match is no better than * the region distance between the earlier desired locale en-GB and en=en-US. * * <p>Notes: * <ul> * <li>In some cases, language and/or script differences can be as small as * the typical region difference. (Example: sr-Latn vs. sr-Cyrl) * <li>It is possible for certain region differences to be larger than usual, * and larger than the demotion. * (As of CLDR 35 there is no such case, but * this is possible in future versions of the data.) * </ul> * * @draft ICU 65 */ ULOCMATCH_DEMOTION_REGION }; #ifndef U_IN_DOXYGEN typedef enum ULocMatchDemotion ULocMatchDemotion; #endif struct UHashtable; U_NAMESPACE_BEGIN struct LSR; class LocaleDistance; class LocaleLsrIterator; class UVector; class XLikelySubtags; /** * Immutable class that picks the best match between a user's desired locales and * an application's supported locales. * Movable but not copyable. * * <p>Example: * <pre> * UErrorCode errorCode = U_ZERO_ERROR; * LocaleMatcher matcher = LocaleMatcher::Builder().setSupportedLocales("fr, en-GB, en").build(errorCode); * Locale *bestSupported = matcher.getBestLocale(Locale.US, errorCode); // "en" * </pre> * * <p>A matcher takes into account when languages are close to one another, * such as Danish and Norwegian, * and when regional variants are close, like en-GB and en-AU as opposed to en-US. * * <p>If there are multiple supported locales with the same (language, script, region) * likely subtags, then the current implementation returns the first of those locales. * It ignores variant subtags (except for pseudolocale variants) and extensions. * This may change in future versions. * * <p>For example, the current implementation does not distinguish between * de, de-DE, de-Latn, de-1901, de-u-co-phonebk. * * <p>If you prefer one equivalent locale over another, then provide only the preferred one, * or place it earlier in the list of supported locales. * * <p>Otherwise, the order of supported locales may have no effect on the best-match results. * The current implementation compares each desired locale with supported locales * in the following order: * 1. Default locale, if supported; * 2. CLDR "paradigm locales" like en-GB and es-419; * 3. other supported locales. * This may change in future versions. * * <p>Often a product will just need one matcher instance, built with the languages * that it supports. However, it may want multiple instances with different * default languages based on additional information, such as the domain. * * <p>This class is not intended for public subclassing. * * @draft ICU 65 */ class U_COMMON_API LocaleMatcher : public UMemory { public: /** * Data for the best-matching pair of a desired and a supported locale. * Movable but not copyable. * * @draft ICU 65 */ class U_COMMON_API Result : public UMemory { public: /** * Move constructor; might modify the source. * This object will have the same contents that the source object had. * * @param src Result to move contents from. * @draft ICU 65 */ Result(Result &&src) U_NOEXCEPT; /** * Destructor. * * @draft ICU 65 */ ~Result(); /** * Move assignment; might modify the source. * This object will have the same contents that the source object had. * * @param src Result to move contents from. * @draft ICU 65 */ Result &operator=(Result &&src) U_NOEXCEPT; /** * Returns the best-matching desired locale. * nullptr if the list of desired locales is empty or if none matched well enough. * * @return the best-matching desired locale, or nullptr. * @draft ICU 65 */ inline const Locale *getDesiredLocale() const { return desiredLocale; } /** * Returns the best-matching supported locale. * If none matched well enough, this is the default locale. * The default locale is nullptr if the list of supported locales is empty and * no explicit default locale is set. * * @return the best-matching supported locale, or nullptr. * @draft ICU 65 */ inline const Locale *getSupportedLocale() const { return supportedLocale; } /** * Returns the index of the best-matching desired locale in the input Iterable order. * -1 if the list of desired locales is empty or if none matched well enough. * * @return the index of the best-matching desired locale, or -1. * @draft ICU 65 */ inline int32_t getDesiredIndex() const { return desiredIndex; } /** * Returns the index of the best-matching supported locale in the * constructor’s or builder’s input order (“set” Collection plus “added” locales). * If the matcher was built from a locale list string, then the iteration order is that * of a LocalePriorityList built from the same string. * -1 if the list of supported locales is empty or if none matched well enough. * * @return the index of the best-matching supported locale, or -1. * @draft ICU 65 */ inline int32_t getSupportedIndex() const { return supportedIndex; } /** * Takes the best-matching supported locale and adds relevant fields of the * best-matching desired locale, such as the -t- and -u- extensions. * May replace some fields of the supported locale. * The result is the locale that should be used for date and number formatting, collation, etc. * Returns the root locale if getSupportedLocale() returns nullptr. * * <p>Example: desired=ar-SA-u-nu-latn, supported=ar-EG, resolved locale=ar-SA-u-nu-latn * * @return a locale combining the best-matching desired and supported locales. * @draft ICU 65 */ Locale makeResolvedLocale(UErrorCode &errorCode) const; private: Result(const Locale *desired, const Locale *supported, int32_t desIndex, int32_t suppIndex, UBool owned) : desiredLocale(desired), supportedLocale(supported), desiredIndex(desIndex), supportedIndex(suppIndex), desiredIsOwned(owned) {} Result(const Result &other) = delete; Result &operator=(const Result &other) = delete; const Locale *desiredLocale; const Locale *supportedLocale; int32_t desiredIndex; int32_t supportedIndex; UBool desiredIsOwned; friend class LocaleMatcher; }; /** * LocaleMatcher builder. * Movable but not copyable. * * @see LocaleMatcher#builder() * @draft ICU 65 */ class U_COMMON_API Builder : public UMemory { public: /** * Constructs a builder used in chaining parameters for building a LocaleMatcher. * * @return a new Builder object * @draft ICU 65 */ Builder() {} /** * Move constructor; might modify the source. * This builder will have the same contents that the source builder had. * * @param src Builder to move contents from. * @draft ICU 65 */ Builder(Builder &&src) U_NOEXCEPT; /** * Destructor. * * @draft ICU 65 */ ~Builder(); /** * Move assignment; might modify the source. * This builder will have the same contents that the source builder had. * * @param src Builder to move contents from. * @draft ICU 65 */ Builder &operator=(Builder &&src) U_NOEXCEPT; /** * Parses an Accept-Language string * (<a href="https://tools.ietf.org/html/rfc2616#section-14.4">RFC 2616 Section 14.4</a>), * such as "af, en, fr;q=0.9", and sets the supported locales accordingly. * Allows whitespace in more places but does not allow "*". * Clears any previously set/added supported locales first. * * @param locales the Accept-Language string of locales to set * @return this Builder object * @draft ICU 65 */ Builder &setSupportedLocalesFromListString(StringPiece locales); /** * Copies the supported locales, preserving iteration order. * Clears any previously set/added supported locales first. * Duplicates are allowed, and are not removed. * * @param locales the list of locale * @return this Builder object * @draft ICU 65 */ Builder &setSupportedLocales(Locale::Iterator &locales); /** * Copies the supported locales from the begin/end range, preserving iteration order. * Clears any previously set/added supported locales first. * Duplicates are allowed, and are not removed. * * Each of the iterator parameter values must be an * input iterator whose value is convertible to const Locale &. * * @param begin Start of range. * @param end Exclusive end of range. * @return this Builder object * @draft ICU 65 */ template<typename Iter> Builder &setSupportedLocales(Iter begin, Iter end) { if (U_FAILURE(errorCode_)) { return *this; } clearSupportedLocales(); while (begin != end) { addSupportedLocale(*begin++); } return *this; } /** * Copies the supported locales from the begin/end range, preserving iteration order. * Calls the converter to convert each *begin to a Locale or const Locale &. * Clears any previously set/added supported locales first. * Duplicates are allowed, and are not removed. * * Each of the iterator parameter values must be an * input iterator whose value is convertible to const Locale &. * * @param begin Start of range. * @param end Exclusive end of range. * @param converter Converter from *begin to const Locale & or compatible. * @return this Builder object * @draft ICU 65 */ template<typename Iter, typename Conv> Builder &setSupportedLocalesViaConverter(Iter begin, Iter end, Conv converter) { if (U_FAILURE(errorCode_)) { return *this; } clearSupportedLocales(); while (begin != end) { addSupportedLocale(converter(*begin++)); } return *this; } /** * Adds another supported locale. * Duplicates are allowed, and are not removed. * * @param locale another locale * @return this Builder object * @draft ICU 65 */ Builder &addSupportedLocale(const Locale &locale); /** * Sets the default locale; if nullptr, or if it is not set explicitly, * then the first supported locale is used as the default locale. * * @param defaultLocale the default locale (will be copied) * @return this Builder object * @draft ICU 65 */ Builder &setDefaultLocale(const Locale *defaultLocale); /** * If ULOCMATCH_FAVOR_SCRIPT, then the language differences are smaller than script * differences. * This is used in situations (such as maps) where * it is better to fall back to the same script than a similar language. * * @param subtag the subtag to favor * @return this Builder object * @draft ICU 65 */ Builder &setFavorSubtag(ULocMatchFavorSubtag subtag); /** * Option for whether all desired locales are treated equally or * earlier ones are preferred (this is the default). * * @param demotion the demotion per desired locale to set. * @return this Builder object * @draft ICU 65 */ Builder &setDemotionPerDesiredLocale(ULocMatchDemotion demotion); /** * Sets the UErrorCode if an error occurred while setting parameters. * Preserves older error codes in the outErrorCode. * * @param outErrorCode Set to an error code if it does not contain one already * and an error occurred while setting parameters. * Otherwise unchanged. * @return TRUE if U_FAILURE(outErrorCode) * @draft ICU 65 */ UBool copyErrorTo(UErrorCode &outErrorCode) const; /** * Builds and returns a new locale matcher. * This builder can continue to be used. * * @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test, * or else the function returns immediately. Check for U_FAILURE() * on output or use with function chaining. (See User Guide for details.) * @return new LocaleMatcher. * @draft ICU 65 */ LocaleMatcher build(UErrorCode &errorCode) const; private: friend class LocaleMatcher; Builder(const Builder &other) = delete; Builder &operator=(const Builder &other) = delete; void clearSupportedLocales(); bool ensureSupportedLocaleVector(); UErrorCode errorCode_ = U_ZERO_ERROR; UVector *supportedLocales_ = nullptr; int32_t thresholdDistance_ = -1; ULocMatchDemotion demotion_ = ULOCMATCH_DEMOTION_REGION; Locale *defaultLocale_ = nullptr; ULocMatchFavorSubtag favor_ = ULOCMATCH_FAVOR_LANGUAGE; }; // FYI No public LocaleMatcher constructors in C++; use the Builder. /** * Move copy constructor; might modify the source. * This matcher will have the same settings that the source matcher had. * @param src source matcher * @draft ICU 65 */ LocaleMatcher(LocaleMatcher &&src) U_NOEXCEPT; /** * Destructor. * @draft ICU 65 */ ~LocaleMatcher(); /** * Move assignment operator; might modify the source. * This matcher will have the same settings that the source matcher had. * The behavior is undefined if *this and src are the same object. * @param src source matcher * @return *this * @draft ICU 65 */ LocaleMatcher &operator=(LocaleMatcher &&src) U_NOEXCEPT; /** * Returns the supported locale which best matches the desired locale. * * @param desiredLocale Typically a user's language. * @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test, * or else the function returns immediately. Check for U_FAILURE() * on output or use with function chaining. (See User Guide for details.) * @return the best-matching supported locale. * @draft ICU 65 */ const Locale *getBestMatch(const Locale &desiredLocale, UErrorCode &errorCode) const; /** * Returns the supported locale which best matches one of the desired locales. * * @param desiredLocales Typically a user's languages, in order of preference (descending). * @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test, * or else the function returns immediately. Check for U_FAILURE() * on output or use with function chaining. (See User Guide for details.) * @return the best-matching supported locale. * @draft ICU 65 */ const Locale *getBestMatch(Locale::Iterator &desiredLocales, UErrorCode &errorCode) const; /** * Parses an Accept-Language string * (<a href="https://tools.ietf.org/html/rfc2616#section-14.4">RFC 2616 Section 14.4</a>), * such as "af, en, fr;q=0.9", * and returns the supported locale which best matches one of the desired locales. * Allows whitespace in more places but does not allow "*". * * @param desiredLocaleList Typically a user's languages, as an Accept-Language string. * @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test, * or else the function returns immediately. Check for U_FAILURE() * on output or use with function chaining. (See User Guide for details.) * @return the best-matching supported locale. * @draft ICU 65 */ const Locale *getBestMatchForListString(StringPiece desiredLocaleList, UErrorCode &errorCode) const; /** * Returns the best match between the desired locale and the supported locales. * If the result's desired locale is not nullptr, then it is the address of the input locale. * It has not been cloned. * * @param desiredLocale Typically a user's language. * @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test, * or else the function returns immediately. Check for U_FAILURE() * on output or use with function chaining. (See User Guide for details.) * @return the best-matching pair of the desired and a supported locale. * @draft ICU 65 */ Result getBestMatchResult(const Locale &desiredLocale, UErrorCode &errorCode) const; /** * Returns the best match between the desired and supported locales. * If the result's desired locale is not nullptr, then it is a clone of * the best-matching desired locale. The Result object owns the clone. * * @param desiredLocales Typically a user's languages, in order of preference (descending). * @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test, * or else the function returns immediately. Check for U_FAILURE() * on output or use with function chaining. (See User Guide for details.) * @return the best-matching pair of a desired and a supported locale. * @draft ICU 65 */ Result getBestMatchResult(Locale::Iterator &desiredLocales, UErrorCode &errorCode) const; #ifndef U_HIDE_INTERNAL_API /** * Returns a fraction between 0 and 1, where 1 means that the languages are a * perfect match, and 0 means that they are completely different. * * <p>This is mostly an implementation detail, and the precise values may change over time. * The implementation may use either the maximized forms or the others ones, or both. * The implementation may or may not rely on the forms to be consistent with each other. * * <p>Callers should construct and use a matcher rather than match pairs of locales directly. * * @param desired Desired locale. * @param supported Supported locale. * @param errorCode ICU error code. Its input value must pass the U_SUCCESS() test, * or else the function returns immediately. Check for U_FAILURE() * on output or use with function chaining. (See User Guide for details.) * @return value between 0 and 1, inclusive. * @internal (has a known user) */ double internalMatch(const Locale &desired, const Locale &supported, UErrorCode &errorCode) const; #endif // U_HIDE_INTERNAL_API private: LocaleMatcher(const Builder &builder, UErrorCode &errorCode); LocaleMatcher(const LocaleMatcher &other) = delete; LocaleMatcher &operator=(const LocaleMatcher &other) = delete; int32_t getBestSuppIndex(LSR desiredLSR, LocaleLsrIterator *remainingIter, UErrorCode &errorCode) const; const XLikelySubtags &likelySubtags; const LocaleDistance &localeDistance; int32_t thresholdDistance; int32_t demotionPerDesiredLocale; ULocMatchFavorSubtag favorSubtag; // These are in input order. const Locale ** supportedLocales; LSR *lsrs; int32_t supportedLocalesLength; // These are in preference order: 1. Default locale 2. paradigm locales 3. others. UHashtable *supportedLsrToIndex; // Map<LSR, Integer> stores index+1 because 0 is "not found" // Array versions of the supportedLsrToIndex keys and values. // The distance lookup loops over the supportedLSRs and returns the index of the best match. const LSR **supportedLSRs; int32_t *supportedIndexes; int32_t supportedLSRsLength; Locale *ownedDefaultLocale; const Locale *defaultLocale; int32_t defaultLocaleIndex; }; U_NAMESPACE_END #endif // U_HIDE_DRAFT_API #endif // U_SHOW_CPLUSPLUS_API #endif // __LOCALEMATCHER_H__