added LanguageTag::equals(), fdo#62278 related

Change-Id: I6471f8eaa46d9203c75569436b233a09fe337910

i18npool/inc/i18npool/languagetag.hxx

@@ -236,10 +236,30 @@ public:
      */
     ::std::vector< OUString >       getFallbackStrings() const;
 
-    /* Test equality of two LangageTag. */
+    /** Test equality of two LanguageTag, possibly resolving system locale.
+
+        @param bResolveSystem
+               If TRUE, resolve empty language tags denoting the system
+               locale to the real locale used before comparing.
+               If FALSE, the behavior is identical to operator==(), system
+               locales are not resolved first.
+      */
+    bool                            equals( const LanguageTag & rLanguageTag, bool bResolveSystem = false ) const;
+
+    /** Test equality of two LanguageTag.
+
+        Does NOT resolve system, i.e. if the system locale is en-US
+        LanguageTag("")==LanguageTag("en-US") returns false! Use
+        equals(...,true) instead if system locales shall be resolved.
+     */
     bool    operator==( const LanguageTag & rLanguageTag ) const;
 
-    /* Test inequality of two LangageTag. */
+    /** Test inequality of two LanguageTag.
+
+        Does NOT resolve system, i.e. if the system locale is en-US
+        LanguageTag("")!=LanguageTag("en-US") returns true! Use
+        !equals(,...true) instead if system locales shall be resolved.
+     */
     bool    operator!=( const LanguageTag & rLanguageTag ) const;
 
 private:

i18npool/source/languagetag/languagetag.cxx

@@ -1094,6 +1094,13 @@ LanguageTag & LanguageTag::makeFallback()
 }
 
 
+bool LanguageTag::equals( const LanguageTag & rLanguageTag, bool bResolveSystem ) const
+{
+    // Compare full language tag strings.
+    return getBcp47( bResolveSystem) == rLanguageTag.getBcp47( bResolveSystem);
+}
+
+
 bool LanguageTag::operator==( const LanguageTag & rLanguageTag ) const
 {
     // Compare full language tag strings but SYSTEM unresolved.