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localeprioritylist.h (3612B)

      1 // © 2019 and later: Unicode, Inc. and others.
      2 // License & terms of use: http://www.unicode.org/copyright.html
      3 
      4 // localeprioritylist.h
      5 // created: 2019jul11 Markus W. Scherer
      6 
      7 #ifndef __LOCALEPRIORITYLIST_H__
      8 #define __LOCALEPRIORITYLIST_H__
      9 
     10 #include "unicode/utypes.h"
     11 #include "unicode/locid.h"
     12 #include "unicode/stringpiece.h"
     13 #include "unicode/uobject.h"
     14 
     15 struct UHashtable;
     16 
     17 U_NAMESPACE_BEGIN
     18 
     19 struct LocaleAndWeightArray;
     20 
     21 /**
     22 * Parses a list of locales from an accept-language string.
     23 * We are a bit more lenient than the spec:
     24 * We accept extra whitespace in more places, empty range fields,
     25 * and any number of qvalue fraction digits.
     26 *
     27 * https://tools.ietf.org/html/rfc2616#section-14.4
     28 * 14.4 Accept-Language
     29 *
     30 *        Accept-Language = "Accept-Language" ":"
     31 *                          1#( language-range [ ";" "q" "=" qvalue ] )
     32 *        language-range  = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" )
     33 *
     34 *    Each language-range MAY be given an associated quality value which
     35 *    represents an estimate of the user's preference for the languages
     36 *    specified by that range. The quality value defaults to "q=1". For
     37 *    example,
     38 *
     39 *        Accept-Language: da, en-gb;q=0.8, en;q=0.7
     40 *
     41 * https://tools.ietf.org/html/rfc2616#section-3.9
     42 * 3.9 Quality Values
     43 *
     44 *    HTTP content negotiation (section 12) uses short "floating point"
     45 *    numbers to indicate the relative importance ("weight") of various
     46 *    negotiable parameters.  A weight is normalized to a real number in
     47 *    the range 0 through 1, where 0 is the minimum and 1 the maximum
     48 *    value. If a parameter has a quality value of 0, then content with
     49 *    this parameter is `not acceptable' for the client. HTTP/1.1
     50 *    applications MUST NOT generate more than three digits after the
     51 *    decimal point. User configuration of these values SHOULD also be
     52 *    limited in this fashion.
     53 *
     54 *        qvalue         = ( "0" [ "." 0*3DIGIT ] )
     55 *                       | ( "1" [ "." 0*3("0") ] )
     56 */
     57 class U_COMMON_API LocalePriorityList : public UMemory {
     58 public:
     59    class Iterator : public Locale::Iterator {
     60    public:
     61        UBool hasNext() const override { return count < length; }
     62 
     63        const Locale &next() override {
     64            for(;;) {
     65                const Locale *locale = list.localeAt(index++);
     66                if (locale != nullptr) {
     67                    ++count;
     68                    return *locale;
     69                }
     70            }
     71        }
     72 
     73    private:
     74        friend class LocalePriorityList;
     75 
     76        Iterator(const LocalePriorityList &list) : list(list), length(list.getLength()) {}
     77 
     78        const LocalePriorityList &list;
     79        int32_t index = 0;
     80        int32_t count = 0;
     81        const int32_t length;
     82    };
     83 
     84    LocalePriorityList(StringPiece s, UErrorCode &errorCode);
     85 
     86    ~LocalePriorityList();
     87 
     88    int32_t getLength() const { return listLength - numRemoved; }
     89 
     90    int32_t getLengthIncludingRemoved() const { return listLength; }
     91 
     92    Iterator iterator() const { return Iterator(*this); }
     93 
     94    const Locale *localeAt(int32_t i) const;
     95 
     96    Locale *orphanLocaleAt(int32_t i);
     97 
     98 private:
     99    LocalePriorityList(const LocalePriorityList &) = delete;
    100    LocalePriorityList &operator=(const LocalePriorityList &) = delete;
    101 
    102    bool add(const Locale &locale, int32_t weight, UErrorCode &errorCode);
    103 
    104    void sort(UErrorCode &errorCode);
    105 
    106    LocaleAndWeightArray *list = nullptr;
    107    int32_t listLength = 0;
    108    int32_t numRemoved = 0;
    109    bool hasWeights = false;  // other than 1.0
    110    UHashtable *map = nullptr;
    111 };
    112 
    113 U_NAMESPACE_END
    114 
    115 #endif  // __LOCALEPRIORITYLIST_H__