Add some inline methods to make code more readable

Give QLocaleId matchesAny() and isValid() checks and some acceptance
tests for their use as filters. Give QLocaleData a QLocaleId id().
A few messy pieces of code get easier to read.

In the process, greatly simplify a do-while loop (sacrificing some
pretest-before-loop optimizations - benchmarking shows they made
negligible difference) and change a while loop to match its form,
since it was doing essentially the same iteration and (thus) its
condition was guaranteed true on the first iteration.

Change-Id: I36b1a6ca8a3cf350b3f3abbe75b177e5a7637cd8
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

src/corelib/text/qlocale.cpp

@@ -331,8 +331,7 @@ QByteArray QLocalePrivate::bcp47Name(char separator) const
     if (m_data->m_language_id == QLocale::C)
         return QByteArrayLiteral("en");
 
-    QLocaleId localeId { m_data->m_language_id, m_data->m_script_id, m_data->m_country_id };
+    return m_data->id().withLikelySubtagsRemoved().name(separator);
-    return localeId.withLikelySubtagsRemoved().name(separator);
 }
 
 /*!
@@ -360,40 +359,13 @@ static const QLocaleData *findLocaleDataById(const QLocaleId &localeId)
         return locale_data;
 
     const QLocaleData *data = locale_data + idx;
-    Q_ASSERT(localeId.language_id
+    Q_ASSERT(localeId.acceptLanguage(data->m_language_id));
-             ? data->m_language_id == localeId.language_id
-             : data->m_language_id);
 
-    if (localeId.script_id == QLocale::AnyScript && localeId.country_id == QLocale::AnyCountry)
+    do {
-        return data;
+        if (localeId.acceptScriptCountry(data->id()))
-
+            return data;
-    if (localeId.script_id == QLocale::AnyScript) {
+        ++data;
-        do {
+    } while (localeId.acceptLanguage(data->m_language_id));
-            if (data->m_country_id == localeId.country_id)
-                return data;
-            ++data;
-        } while (localeId.language_id
-                 ? data->m_language_id == localeId.language_id
-                 : data->m_language_id);
-    } else if (localeId.country_id == QLocale::AnyCountry) {
-        do {
-            if (data->m_script_id == localeId.script_id)
-                return data;
-            ++data;
-        } while (localeId.language_id
-                 ? data->m_language_id == localeId.language_id
-                 : data->m_language_id);
-    } else {
-        do {
-            if (data->m_script_id == localeId.script_id
-                && data->m_country_id == localeId.country_id) {
-                return data;
-            }
-            ++data;
-        } while (localeId.language_id
-                 ? data->m_language_id == localeId.language_id
-                 : data->m_language_id);
-    }
 
     return nullptr;
 }
@@ -2516,28 +2488,28 @@ QList<QLocale> QLocale::matchingLocales(QLocale::Language language,
                                         QLocale::Script script,
                                         QLocale::Country country)
 {
-    if (uint(language) > QLocale::LastLanguage || uint(script) > QLocale::LastScript ||
+    const QLocaleId filter { language, script, country };
-            uint(country) > QLocale::LastCountry)
+    if (!filter.isValid())
         return QList<QLocale>();
 
     if (language == QLocale::C)
         return QList<QLocale>() << QLocale(QLocale::C);
 
     QList<QLocale> result;
-    if (language == QLocale::AnyLanguage && script == QLocale::AnyScript
+    if (filter.matchesAll())
-        && country == QLocale::AnyCountry) {
         result.reserve(locale_data_size);
-    }
+
     const QLocaleData *data = locale_data + locale_index[language];
-    while ( (data != locale_data + locale_data_size)
+    Q_ASSERT(filter.acceptLanguage(data->m_language_id));
-            && (language == QLocale::AnyLanguage || data->m_language_id == uint(language))) {
+    do {
-        if ((script == QLocale::AnyScript || data->m_script_id == uint(script))
+        const QLocaleId id = data->id();
-            && (country == QLocale::AnyCountry || data->m_country_id == uint(country))) {
+        if (filter.acceptScriptCountry(id)) {
-            result.append(QLocale(*(data->m_language_id == C ? c_private()
+            result.append(QLocale(*(id.language_id == C ? c_private()
                                     : QLocalePrivate::create(data))));
         }
         ++data;
-    }
+        // Only the terminating entry in locale_data has 0 as language_id:
+    } while (filter.acceptLanguage(data->m_language_id));
     return result;
 }
 
@@ -4204,7 +4176,7 @@ QStringList QLocale::uiLanguages() const
         }
         const auto data = locale.d->m_data;
 
-        QLocaleId id { data->m_language_id, data->m_script_id, data->m_country_id };
+        QLocaleId id = data->id();
         const QLocaleId max = id.withLikelySubtagsAdded();
         const QLocaleId min = max.withLikelySubtagsRemoved();
         id.script_id = 0; // For re-use as script-less variant.

src/corelib/text/qlocale_p.h

@@ -152,6 +152,27 @@ struct QLocaleId
     { return language_id == other.language_id && script_id == other.script_id && country_id == other.country_id; }
     inline bool operator!=(QLocaleId other) const
     { return !operator==(other); }
+    inline bool isValid() const
+    {
+        return language_id <= QLocale::LastLanguage && script_id <= QLocale::LastScript
+                && country_id <= QLocale::LastCountry;
+    }
+    inline bool matchesAll() const
+    {
+        return !language_id && !script_id && !country_id;
+    }
+    // Use as: filter.accept...(candidate)
+    inline bool acceptLanguage(quint16 lang) const
+    {
+        // Always reject AnyLanguage (only used for last entry in locale_data array).
+        // So, when searching for AnyLanguage, accept everything *but* AnyLanguage.
+        return language_id ? lang == language_id : lang;
+    }
+    inline bool acceptScriptCountry(QLocaleId other) const
+    {
+        return (!country_id || other.country_id == country_id)
+                && (!script_id || other.script_id == script_id);
+    }
 
     QLocaleId withLikelySubtagsAdded() const;
     QLocaleId withLikelySubtagsRemoved() const;
@@ -270,6 +291,9 @@ public:
     Q_CORE_EXPORT bool validateChars(QStringView str, NumberMode numMode, QByteArray *buff, int decDigits = -1,
             QLocale::NumberOptions number_options = QLocale::DefaultNumberOptions) const;
 
+    // Access to assorted data members:
+    QLocaleId id() const { return QLocaleId { m_language_id, m_script_id, m_country_id }; }
+
     QString decimalPoint() const;
     QString groupSeparator() const;
     QString listSeparator() const;