Use a separate class for sky translation

src/core/StelLocaleMgr.cpp

@@ -114,7 +114,7 @@ void StelLocaleMgr::loadSkyTranslator()
 	// Update the translator with new locale name
 	const auto cultureId = StelApp::getInstance().getSkyCultureMgr().getCurrentSkyCultureID();
 	delete skyTranslator;
-	skyTranslator = new StelTranslator("stellarium-skycultures-"+cultureId, planetaryFeaturesTranslator->getTrueLocaleName());
+	skyTranslator = new StelSkyTranslator(cultureId, planetaryFeaturesTranslator->getTrueLocaleName());
 	qDebug().noquote() << "Sky language:" << skyTranslator->getTrueLocaleName();
 }
 

src/core/StelTranslator.cpp

@@ -41,17 +41,7 @@ StelTranslator::StelTranslator(const QString& adomain, const QString& alangName)
 	  langName(alangName)
 {
 	translator = new QTranslator();
-	const char skyCulturePrefix[] = "stellarium-skycultures-";
-	QString path;
-	if (adomain.startsWith(skyCulturePrefix))
-	{
-		const auto culture = adomain.mid(sizeof skyCulturePrefix - 1);
-		path = StelFileMgr::getInstallationDir() + "/skycultures/" + culture + "/translations/" + getTrueLocaleName()+".qm";
-	}
-	else
-	{
-		path = StelFileMgr::getLocaleDir()+"/"+adomain+"/"+getTrueLocaleName()+".qm";
-	}
+	const auto path = StelFileMgr::getLocaleDir()+"/"+adomain+"/"+getTrueLocaleName()+".qm";
 	const bool res = translator->load(path);
 	if (!res)
 		qWarning() << "Couldn't load translations for language " << getTrueLocaleName() << "in section" << adomain;
@@ -65,6 +55,11 @@ StelTranslator::~StelTranslator()
 	translator = Q_NULLPTR;
 }
 
+bool StelTranslator::isEmpty() const
+{
+	return translator->isEmpty();
+}
+
 QString StelTranslator::qtranslate(const QString& s, const QString& c) const
 {
 	if (s.isEmpty())
@@ -211,3 +206,33 @@ void StelTranslator::initIso639_1LanguageCodes(const QString& fileName)
 		iso639codes.insert(fields.at(0), fields.at(2));
 	}
 }
+
+static constexpr char skyCulturePrefix[] = "stellarium-skycultures-";
+StelSkyTranslator::StelSkyTranslator(const QString& skyCultureId, const QString& langName)
+	: commonSkyTranslator("stellarium-skycultures", langName)
+{
+	domain = skyCulturePrefix + skyCultureId;
+	this->langName = langName;
+	translator = new QTranslator();
+
+	const auto path = StelFileMgr::getInstallationDir() + "/skycultures/" + skyCultureId + "/translations/" + getTrueLocaleName()+".qm";
+	const bool res = translator->load(path);
+	if (!res)
+		qWarning() << "Couldn't load sky translations for language" << getTrueLocaleName() << "in sky culture" << skyCultureId;
+	if (translator->isEmpty())
+		qWarning() << "Empty translation file for language " << getTrueLocaleName() << "in sky culture" << skyCultureId;
+	if (commonSkyTranslator.isEmpty())
+		qWarning() << "Empty skyculture-independent translation file for language " << getTrueLocaleName() << "in sky culture" << skyCultureId;
+}
+
+QString StelSkyTranslator::tryQtranslate(const QString& s, const QString& c) const
+{
+	const auto res = StelTranslator::tryQtranslate(s, c);
+	if (!res.isEmpty()) return res;
+	return commonSkyTranslator.tryQtranslate(s, c);
+}
+
+bool StelSkyTranslator::isEmpty() const
+{
+	return StelTranslator::isEmpty() && commonSkyTranslator.isEmpty();
+}

src/core/StelTranslator.hpp

@@ -64,6 +64,9 @@ class StelTranslator
 	StelTranslator(const QString& adomain, const QString& alangName);
 
 	~StelTranslator();
+
+	//! Checks whether any translations have been loaded
+	virtual bool isEmpty() const;
 
 	//! Translate input message and return it as a QString.
 	//! If the string is not translated in the current locale, the input string is returned unchanged.
@@ -77,7 +80,7 @@ class StelTranslator
 	//! @param s input string in english.
 	//! @param c disambiguation string (gettext "context" string).
 	//! @return The translated QString
-	QString tryQtranslate(const QString& s, const QString& c = QString()) const;
+	virtual QString tryQtranslate(const QString& s, const QString& c = QString()) const;
 
 	//! Get true translator locale name. Actual locale, never "system".
 	//! @return Locale name e.g "fr_FR"
@@ -106,6 +109,18 @@ class StelTranslator
 	//! @param fileName file containing the list of language codes
 	static void init(const QString& fileName);
 
+protected:
+	StelTranslator() = default;
+
+	//! The domain name
+	QString domain;
+
+	//! The two letter string defining the current language name
+	QString langName;
+
+	//! QTranslator instance
+	class QTranslator* translator = nullptr;
+
 private:
 	StelTranslator(const StelTranslator& );
 	const StelTranslator& operator=(const StelTranslator&);
@@ -117,15 +132,6 @@ class StelTranslator
 	//! Get available language codes from passed locales directory
 	static QStringList getAvailableIso639_1Codes(const QString& localeDir="");
 
-	//! The domain name
-	QString domain;
-
-	//! The two letter string defining the current language name
-	QString langName;
-
-	//! QTranslator instance
-	class QTranslator* translator;
-
 	//! Try to determine system language from system configuration
 	static void initSystemLanguage(void);
 
@@ -136,5 +142,16 @@ class StelTranslator
 	static QMap<QString, QString> iso639codes;
 };
 
+class StelSkyTranslator : public StelTranslator
+{
+public:
+	StelSkyTranslator(const QString& skyCultureId, const QString& langName);
+	QString tryQtranslate(const QString& s, const QString& c = QString()) const override;
+	bool isEmpty() const override;
+private:
+	//! Used as a skyculture-independent fallback when current sky culture doesn't have a translation
+	StelTranslator commonSkyTranslator;
+};
+
 #endif // STELTRANSLATOR_HPP