icuSources/common/localeprioritylist.h

   1 // © 2019 and later: Unicode, Inc. and others.
   2 // License & terms of use: http://www.unicode.org/copyright.html#License
   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__