Correctly track opened polyglossia languages

A language switch may also occur outside of output_latex.cpp, apparently.

src/Font.cpp

@@ -287,6 +287,7 @@ int Font::latexWriteStartChanges(odocstream & os, BufferParams const & bparams,
 			tmp += "{";
 			os << from_ascii(tmp);
 			count += tmp.length();
+			runparams.pushPolyglossiaLang(language()->polyglossia());
 		} else if (language()->encoding()->package() != Encoding::CJK) {
 			os << '{';
 			count += 1;
@@ -545,6 +546,8 @@ int Font::latexWriteEndChanges(otexstream & os, BufferParams const & bparams,
 	    && language()->encoding()->package() != Encoding::CJK) {
 		os << '}';
 		++count;
+		if (runparams.use_polyglossia)
+			runparams.popPolyglossiaLang();
 	}
 
 	return count;

src/OutputParams.cpp

@@ -21,7 +21,8 @@ namespace lyx {
 OutputParams::OutputParams(Encoding const * enc)
 	: flavor(LATEX), math_flavor(NotApplicable), nice(false), is_child(false),
 	  moving_arg(false), intitle(false), inulemcmd(0), local_font(0), master_language(0),
-	  encoding(enc), free_spacing(false), use_babel(false), use_polyglossia(false),
+	  encoding(enc), pushPolyglossiaLang(0), popPolyglossiaLang(0),
+	  free_spacing(false), use_babel(false), use_polyglossia(false),
 	  use_indices(false), use_japanese(false), linelen(0), depth(0),
 	  exportdata(new ExportData),
 	  inComment(false), inTableCell(NO), inFloat(NONFLOAT),

src/OutputParams.h

@@ -141,6 +141,16 @@ public:
 	 */
 	mutable Encoding const * encoding;
 
+	/** Pointer to a function for registering a language switch
+	    when using polyglossia.
+	*/
+	mutable void (* pushPolyglossiaLang)(std::string const & lang_name);
+
+	/** Pointer to a function for unregistering  the last language
+	    switch when using polyglossia.
+	*/
+	mutable void (* popPolyglossiaLang)();
+
 	/** free_spacing == true means that the inset is in a free-spacing
 	    paragraph.
 	*/

src/Paragraph.cpp

@@ -2441,6 +2441,8 @@ void Paragraph::latex(BufferParams const & bparams,
 							running_lang);
 				os << from_ascii(end_tag);
 				column += end_tag.length();
+				if (runparams.use_polyglossia)
+					runparams.popPolyglossiaLang();
 		}
 
 		// Switch file encoding if necessary (and allowed)

src/output_latex.cpp

@@ -478,6 +478,24 @@ void getArgInsets(otexstream & os, OutputParams const & runparams, Layout::LaTeX
 } // namespace anon
 
 
+void pushPolyglossiaLang(string const & lang_name)
+{
+	OutputState * state = getOutputState();
+
+	state->lang_switch_depth_.push(state->nest_level_);
+	state->open_polyglossia_lang_.push(lang_name);
+}
+
+
+void popPolyglossiaLang()
+{
+	OutputState * state = getOutputState();
+
+	state->lang_switch_depth_.pop();
+	state->open_polyglossia_lang_.pop();
+}
+
+
 void latexArgInsets(Paragraph const & par, otexstream & os,
 	OutputParams const & runparams, Layout::LaTeXArgMap const & latexargs, string const & prefix)
 {
@@ -1265,8 +1283,15 @@ void latexParagraphs(Buffer const & buf,
 			  : subst(lang_begin_command, "$$lang", mainlang);
 		os << bc;
 		os << '\n';
+		if (runparams.use_polyglossia) {
+			state->lang_switch_depth_.push(state->nest_level_);
+			state->open_polyglossia_lang_.push(mainlang);
+		}
 	}
 
+	runparams.pushPolyglossiaLang = pushPolyglossiaLang;
+	runparams.popPolyglossiaLang = popPolyglossiaLang;
+
 	ParagraphList const & paragraphs = text.paragraphs();
 
 	if (runparams.par_begin == runparams.par_end) {

src/output_latex.h

@@ -29,6 +29,14 @@ class Paragraph;
 class OutputParams;
 class Text;
 
+/** Register a language switch when using polyglossia.
+ */
+void pushPolyglossiaLang(std::string const & lang);
+
+/** Unregister the last language switch when using polyglossia.
+ */
+void popPolyglossiaLang();
+
 /** Export optional and required arguments of the paragraph \p par.
     Non-existing required arguments are output empty: {}.
  */