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diff --git a/intl/icu/source/common/unicode/localematcher.h b/intl/icu/source/common/unicode/localematcher.h new file mode 100644 index 0000000000..603daf7231 --- /dev/null +++ b/intl/icu/source/common/unicode/localematcher.h @@ -0,0 +1,708 @@ +// © 2019 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html + +// 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. + */ + +/** + * Builder option for whether the language subtag or the script subtag is most important. + * + * @see LocaleMatcher::Builder#setFavorSubtag(ULocMatchFavorSubtag) + * @stable ICU 65 + */ +enum ULocMatchFavorSubtag { + /** + * Language differences are most important, then script differences, then region differences. + * (This is the default behavior.) + * + * @stable ICU 65 + */ + ULOCMATCH_FAVOR_LANGUAGE, + /** + * Makes script differences matter relatively more than language differences. + * + * @stable 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 LocaleMatcher::Builder#setDemotionPerDesiredLocale(ULocMatchDemotion) + * @stable ICU 65 + */ +enum ULocMatchDemotion { + /** + * All desired locales are treated equally. + * + * @stable 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> + * + * @stable ICU 65 + */ + ULOCMATCH_DEMOTION_REGION +}; +#ifndef U_IN_DOXYGEN +typedef enum ULocMatchDemotion ULocMatchDemotion; +#endif + +/** + * Builder option for whether to include or ignore one-way (fallback) match data. + * The LocaleMatcher uses CLDR languageMatch data which includes fallback (oneway=true) entries. + * Sometimes it is desirable to ignore those. + * + * <p>For example, consider a web application with the UI in a given language, + * with a link to another, related web app. + * The link should include the UI language, and the target server may also use + * the client’s Accept-Language header data. + * The target server has its own list of supported languages. + * One may want to favor UI language consistency, that is, + * if there is a decent match for the original UI language, we want to use it, + * but not if it is merely a fallback. + * + * @see LocaleMatcher::Builder#setDirection(ULocMatchDirection) + * @stable ICU 67 + */ +enum ULocMatchDirection { + /** + * Locale matching includes one-way matches such as Breton→French. (default) + * + * @stable ICU 67 + */ + ULOCMATCH_DIRECTION_WITH_ONE_WAY, + /** + * Locale matching limited to two-way matches including e.g. Danish↔Norwegian + * but ignoring one-way matches. + * + * @stable ICU 67 + */ + ULOCMATCH_DIRECTION_ONLY_TWO_WAY +}; +#ifndef U_IN_DOXYGEN +typedef enum ULocMatchDirection ULocMatchDirection; +#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. + * + * @stable 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. + * + * @stable 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. + * @stable ICU 65 + */ + Result(Result &&src) noexcept; + + /** + * Destructor. + * + * @stable 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. + * @stable ICU 65 + */ + Result &operator=(Result &&src) 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. + * @stable 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 Builder::setNoDefaultLocale() was called, + * or if the list of supported locales is empty and no explicit default locale is set. + * + * @return the best-matching supported locale, or nullptr. + * @stable 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. + * @stable 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. + * @stable 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. + * @stable 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. + * + * @stable 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 + * @stable 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. + * @stable ICU 65 + */ + Builder(Builder &&src) noexcept; + + /** + * Destructor. + * + * @stable 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. + * @stable ICU 65 + */ + Builder &operator=(Builder &&src) 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 + * @stable 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 + * @stable 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 + * @stable 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 + * @stable 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 + * @stable ICU 65 + */ + Builder &addSupportedLocale(const Locale &locale); + + /** + * Sets no default locale. + * There will be no explicit or implicit default locale. + * If there is no good match, then the matcher will return nullptr for the + * best supported locale. + * + * @stable ICU 68 + */ + Builder &setNoDefaultLocale(); + + /** + * Sets the default locale; if nullptr, or if it is not set explicitly, + * then the first supported locale is used as the default locale. + * There is no default locale at all (nullptr will be returned instead) + * if setNoDefaultLocale() is called. + * + * @param defaultLocale the default locale (will be copied) + * @return this Builder object + * @stable 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 + * @stable 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 + * @stable ICU 65 + */ + Builder &setDemotionPerDesiredLocale(ULocMatchDemotion demotion); + + /** + * Option for whether to include or ignore one-way (fallback) match data. + * By default, they are included. + * + * @param matchDirection the match direction to set. + * @return this Builder object + * @stable ICU 67 + */ + Builder &setDirection(ULocMatchDirection matchDirection) { + if (U_SUCCESS(errorCode_)) { + direction_ = matchDirection; + } + return *this; + } + + /** + * Sets the maximum distance for an acceptable match. + * The matcher will return a match for a pair of locales only if + * they match at least as well as the pair given here. + * + * For example, setMaxDistance(en-US, en-GB) limits matches to ones where the + * (desired, support) locales have a distance no greater than a region subtag difference. + * This is much stricter than the CLDR default. + * + * The details of locale matching are subject to changes in + * CLDR data and in the algorithm. + * Specifying a maximum distance in relative terms via a sample pair of locales + * insulates from changes that affect all distance metrics similarly, + * but some changes will necessarily affect relative distances between + * different pairs of locales. + * + * @param desired the desired locale for distance comparison. + * @param supported the supported locale for distance comparison. + * @return this Builder object + * @stable ICU 68 + */ + Builder &setMaxDistance(const Locale &desired, const Locale &supported); + + /** + * 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) + * @stable 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 LocaleMatcher + * @stable 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; + bool withDefault_ = true; + ULocMatchFavorSubtag favor_ = ULOCMATCH_FAVOR_LANGUAGE; + ULocMatchDirection direction_ = ULOCMATCH_DIRECTION_WITH_ONE_WAY; + Locale *maxDistanceDesired_ = nullptr; + Locale *maxDistanceSupported_ = nullptr; + }; + + // 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 + * @stable ICU 65 + */ + LocaleMatcher(LocaleMatcher &&src) noexcept; + + /** + * Destructor. + * @stable 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 + * @stable ICU 65 + */ + LocaleMatcher &operator=(LocaleMatcher &&src) 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. + * @stable 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. + * @stable 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. + * @stable 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. + * @stable 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. + * @stable ICU 65 + */ + Result getBestMatchResult(Locale::Iterator &desiredLocales, UErrorCode &errorCode) const; + + /** + * Returns true if the pair of locales matches acceptably. + * This is influenced by Builder options such as setDirection(), setFavorSubtag(), + * and setMaxDistance(). + * + * @param desired The desired locale. + * @param supported The 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 true if the pair of locales matches acceptably. + * @stable ICU 68 + */ + UBool isMatch(const Locale &desired, const Locale &supported, 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 putIfAbsent(const LSR &lsr, int32_t i, int32_t suppLength, UErrorCode &errorCode); + + int32_t getBestSuppIndex(LSR desiredLSR, LocaleLsrIterator *remainingIter, UErrorCode &errorCode) const; + + const XLikelySubtags &likelySubtags; + const LocaleDistance &localeDistance; + int32_t thresholdDistance; + int32_t demotionPerDesiredLocale; + ULocMatchFavorSubtag favorSubtag; + ULocMatchDirection direction; + + // 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> + // 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; +}; + +U_NAMESPACE_END + +#endif // U_SHOW_CPLUSPLUS_API +#endif // __LOCALEMATCHER_H__ |