initial commit, 4.5 stable

thirdparty/icu4c/common/localeprioritylist.h

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+// © 2019 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+// localeprioritylist.h
+// created: 2019jul11 Markus W. Scherer
+
+#ifndef __LOCALEPRIORITYLIST_H__
+#define __LOCALEPRIORITYLIST_H__
+
+#include "unicode/utypes.h"
+#include "unicode/locid.h"
+#include "unicode/stringpiece.h"
+#include "unicode/uobject.h"
+
+struct UHashtable;
+
+U_NAMESPACE_BEGIN
+
+struct LocaleAndWeightArray;
+
+/**
+ * Parses a list of locales from an accept-language string.
+ * We are a bit more lenient than the spec:
+ * We accept extra whitespace in more places, empty range fields,
+ * and any number of qvalue fraction digits.
+ *
+ * https://tools.ietf.org/html/rfc2616#section-14.4
+ * 14.4 Accept-Language
+ *
+ *        Accept-Language = "Accept-Language" ":"
+ *                          1#( language-range [ ";" "q" "=" qvalue ] )
+ *        language-range  = ( ( 1*8ALPHA *( "-" 1*8ALPHA ) ) | "*" )
+ *
+ *    Each language-range MAY be given an associated quality value which
+ *    represents an estimate of the user's preference for the languages
+ *    specified by that range. The quality value defaults to "q=1". For
+ *    example,
+ *
+ *        Accept-Language: da, en-gb;q=0.8, en;q=0.7
+ *
+ * https://tools.ietf.org/html/rfc2616#section-3.9
+ * 3.9 Quality Values
+ *
+ *    HTTP content negotiation (section 12) uses short "floating point"
+ *    numbers to indicate the relative importance ("weight") of various
+ *    negotiable parameters.  A weight is normalized to a real number in
+ *    the range 0 through 1, where 0 is the minimum and 1 the maximum
+ *    value. If a parameter has a quality value of 0, then content with
+ *    this parameter is `not acceptable' for the client. HTTP/1.1
+ *    applications MUST NOT generate more than three digits after the
+ *    decimal point. User configuration of these values SHOULD also be
+ *    limited in this fashion.
+ *
+ *        qvalue         = ( "0" [ "." 0*3DIGIT ] )
+ *                       | ( "1" [ "." 0*3("0") ] )
+ */
+class U_COMMON_API LocalePriorityList : public UMemory {
+public:
+    class Iterator : public Locale::Iterator {
+    public:
+        UBool hasNext() const override { return count < length; }
+
+        const Locale &next() override {
+            for(;;) {
+                const Locale *locale = list.localeAt(index++);
+                if (locale != nullptr) {
+                    ++count;
+                    return *locale;
+                }
+            }
+        }
+
+    private:
+        friend class LocalePriorityList;
+
+        Iterator(const LocalePriorityList &list) : list(list), length(list.getLength()) {}
+
+        const LocalePriorityList &list;
+        int32_t index = 0;
+        int32_t count = 0;
+        const int32_t length;
+    };
+
+    LocalePriorityList(StringPiece s, UErrorCode &errorCode);
+
+    ~LocalePriorityList();
+
+    int32_t getLength() const { return listLength - numRemoved; }
+
+    int32_t getLengthIncludingRemoved() const { return listLength; }
+
+    Iterator iterator() const { return Iterator(*this); }
+
+    const Locale *localeAt(int32_t i) const;
+
+    Locale *orphanLocaleAt(int32_t i);
+
+private:
+    LocalePriorityList(const LocalePriorityList &) = delete;
+    LocalePriorityList &operator=(const LocalePriorityList &) = delete;
+
+    bool add(const Locale &locale, int32_t weight, UErrorCode &errorCode);
+
+    void sort(UErrorCode &errorCode);
+
+    LocaleAndWeightArray *list = nullptr;
+    int32_t listLength = 0;
+    int32_t numRemoved = 0;
+    bool hasWeights = false;  // other than 1.0
+    UHashtable *map = nullptr;
+};
+
+U_NAMESPACE_END
+
+#endif  // __LOCALEPRIORITYLIST_H__