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"

#ifndef U_HIDE_DRAFT_API

enum ULocMatchFavorSubtag {
    ULOCMATCH_FAVOR_LANGUAGE,
    ULOCMATCH_FAVOR_SCRIPT
};
#ifndef U_IN_DOXYGEN
typedef enum ULocMatchFavorSubtag ULocMatchFavorSubtag;
#endif

enum ULocMatchDemotion {
    ULOCMATCH_DEMOTION_NONE,
    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;

class U_COMMON_API LocaleMatcher : public UMemory {
public:
    class U_COMMON_API Result : public UMemory {
    public:
        Result(Result &&src) U_NOEXCEPT;

        ~Result();

        Result &operator=(Result &&src) U_NOEXCEPT;

        inline const Locale *getDesiredLocale() const { return desiredLocale; }

        inline const Locale *getSupportedLocale() const { return supportedLocale; }

        inline int32_t getDesiredIndex() const { return desiredIndex; }

        inline int32_t getSupportedIndex() const { return supportedIndex; }

        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;
    };

    class U_COMMON_API Builder : public UMemory {
    public:
        Builder() {}

        Builder(Builder &&src) U_NOEXCEPT;

        ~Builder();

        Builder &operator=(Builder &&src) U_NOEXCEPT;

        Builder &setSupportedLocalesFromListString(StringPiece locales);

        Builder &setSupportedLocales(Locale::Iterator &locales);

        template<typename Iter>
        Builder &setSupportedLocales(Iter begin, Iter end) {
            if (U_FAILURE(errorCode_)) { return *this; }
            clearSupportedLocales();
            while (begin != end) {
                addSupportedLocale(*begin++);
            }
            return *this;
        }

        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;
        }

        Builder &addSupportedLocale(const Locale &locale);

        Builder &setDefaultLocale(const Locale *defaultLocale);

        Builder &setFavorSubtag(ULocMatchFavorSubtag subtag);

        Builder &setDemotionPerDesiredLocale(ULocMatchDemotion demotion);

        UBool copyErrorTo(UErrorCode &outErrorCode) const;

        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.

    LocaleMatcher(LocaleMatcher &&src) U_NOEXCEPT;

    ~LocaleMatcher();

    LocaleMatcher &operator=(LocaleMatcher &&src) U_NOEXCEPT;

    const Locale *getBestMatch(const Locale &desiredLocale, UErrorCode &errorCode) const;

    const Locale *getBestMatch(Locale::Iterator &desiredLocales, UErrorCode &errorCode) const;

    const Locale *getBestMatchForListString(StringPiece desiredLocaleList, UErrorCode &errorCode) const;

    Result getBestMatchResult(const Locale &desiredLocale, UErrorCode &errorCode) const;

    Result getBestMatchResult(Locale::Iterator &desiredLocales, UErrorCode &errorCode) const;

#ifndef U_HIDE_INTERNAL_API

    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__