Add Provides tag to languages

This allows to specify macros that are provided by specific (Babel)
languages (such as \textgreek)

lib/languages

@@ -26,6 +26,7 @@
 #	  <extra latex code inserted after babel>
 #	EndPostBabelPreamble
 #	Requires           <requirement>
+#	Provides           <feature>
 # End
 #
 #
@@ -167,6 +168,7 @@ Language ancientgreek
 	InternalEncoding  true
 	FontEncoding      LGR
 	LangCode          grc_GR
+	Provides          textgreek
 End
 
 # FIXME: dummy babel language for arabic_arabtex to be able
@@ -618,6 +620,7 @@ Language greek
 	InternalEncoding  true
 	FontEncoding      LGR
 	LangCode          el_GR
+	Provides          textgreek
 End
 
 Language polutonikogreek
@@ -630,6 +633,7 @@ Language polutonikogreek
 	InternalEncoding  true
 	FontEncoding      LGR
 	LangCode          el_GR
+	Provides          textgreek
 End
 
 Language hebrew

src/LaTeXFeatures.cpp

@@ -544,6 +544,12 @@ void LaTeXFeatures::require(set<string> const & names)
 }
 
 
+void LaTeXFeatures::provide(string const & name)
+{
+	provides_.insert(name);
+}
+
+
 void LaTeXFeatures::useLayout(docstring const & layoutname)
 {
 	useLayout(layoutname, 0);
@@ -609,19 +615,11 @@ bool LaTeXFeatures::isRequired(string const & name) const
 
 bool LaTeXFeatures::isProvided(string const & name) const
 {
-	// \textgreek is provided by babel globally if a Greek language/variety
-	// is used in the document
-	if (useBabel() && name == "textgreek"
-	    && params_.main_font_encoding() != "default") {
-		// get main font encodings
-		vector<string> fontencs = params_.font_encodings();
-		// get font encodings of secondary languages
-		getFontEncodings(fontencs, true);
-		for (auto & fe : fontencs) {
-			if (!Encodings::needsScriptWrapper(name, fe))
-				return true;
-		}
-	}
+	// \textgreek is provided by babel globally if a Greek
+	// language/variety is used in the document
+	if (provides_.find(name) != provides_.end())
+		return true;
+
 	// FIXME: Analoguously, babel provides a command \textcyrillic, but
 	//        for some reason, we roll our own \textcyr definition
 	//        We should use \textcyrillic instead and only define it
@@ -756,6 +754,9 @@ void LaTeXFeatures::useLanguage(Language const * lang)
 		UsedLanguages_.insert(lang);
 	if (!lang->requires().empty())
 		require(lang->requires());
+	// currently only supported for Babel
+	if (!lang->provides().empty() && useBabel())
+		provide(lang->provides());
 	// CJK languages do not have a babel name.
 	// They use the CJK package
 	if (lang->encoding()->package() == Encoding::CJK)

src/LaTeXFeatures.h

@@ -103,6 +103,8 @@ public:
 	void require(std::string const & name);
 	/// Add a set of feature names requirements
 	void require(std::set<std::string> const & names);
+	/// Add a feature name provision
+	void provide(std::string const & name);
 	/// Is the (required) package available?
 	static bool isAvailable(std::string const & name);
 	/// Has the package been required?
@@ -186,10 +188,12 @@ private:
 	std::list<docstring> usedLayouts_;
 	///
 	std::list<docstring> usedInsetLayouts_;
-	/// The features that are needed by the document
-	typedef std::set<std::string> Features;
 	///
+	typedef std::set<std::string> Features;
+	/// The features that are needed by the document
 	Features features_;
+	/// Features that are provided
+	Features provides_;
 	/// Static preamble bits, from external templates, or anywhere else
 	typedef std::list<TexString> SnippetList;
 	///

src/Language.cpp

@@ -87,9 +87,10 @@ bool Language::readLanguage(Lexer & lex)
 		LA_POLYGLOSSIANAME,
 		LA_POLYGLOSSIAOPTS,
 		LA_POSTBABELPREAMBLE,
-		LA_QUOTESTYLE,
 		LA_PREBABELPREAMBLE,
+		LA_PROVIDES,
 		LA_REQUIRES,
+		LA_QUOTESTYLE,
 		LA_RTL
 	};
 
@@ -109,6 +110,7 @@ bool Language::readLanguage(Lexer & lex)
 		{ "polyglossiaopts",      LA_POLYGLOSSIAOPTS },
 		{ "postbabelpreamble",    LA_POSTBABELPREAMBLE },
 		{ "prebabelpreamble",     LA_PREBABELPREAMBLE },
+		{ "provides",             LA_PROVIDES },
 		{ "quotestyle",           LA_QUOTESTYLE },
 		{ "requires",             LA_REQUIRES },
 		{ "rtl",                  LA_RTL }
@@ -184,6 +186,9 @@ bool Language::readLanguage(Lexer & lex)
 		case LA_REQUIRES:
 			lex >> requires_;
 			break;
+		case LA_PROVIDES:
+			lex >> provides_;
+			break;
 		case LA_RTL:
 			lex >> rightToLeft_;
 			break;

src/Language.h

@@ -50,6 +50,8 @@ public:
 	std::string const quoteStyle() const { return quote_style_; }
 	/// requirement (package, function)
 	std::string const requires() const { return requires_; }
+	/// provides feature
+	std::string const provides() const { return provides_; }
 	/// translatable GUI name
 	std::string const display() const { return display_; }
 	/// is this a RTL language?
@@ -109,6 +111,8 @@ private:
 	///
 	trivstring requires_;
 	///
+	trivstring provides_;
+	///
 	trivstring display_;
 	///
 	bool rightToLeft_;