--- loncom/homework/structuretags.pm	2011/12/12 12:07:45	1.497.2.3
+++ loncom/homework/structuretags.pm	2011/12/26 13:45:10	1.497.2.5
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # definition of tags that give a structure to a document
 #
-# $Id: structuretags.pm,v 1.497.2.3 2011/12/12 12:07:45 foxr Exp $
+# $Id: structuretags.pm,v 1.497.2.5 2011/12/26 13:45:10 foxr Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -69,6 +69,83 @@ BEGIN {
     &Apache::lonxml::register('Apache::structuretags',('block','languageblock','translated','instructorcomment','while','randomlist','problem','library','web','tex','part','preduedate','postanswerdate','solved','notsolved','problemtype','startpartmarker','startouttext','endpartmarker','endouttext','simpleeditbutton','definetag'));
 }
 
+
+#---------------------------------------------------------------------------------
+# 
+#  This section of code deals with hyphenation management.
+#  We must do three things:
+#  - keep track fo the desired languages to alter the header.
+#  - provide hyphenation selection as needed by each language that appears in the
+#    text.
+#  - Provide the header text needed to make available the desired hyphenations.
+#
+#
+
+# Hash whose keys are the languages encountered in the document/resource.
+#
+
+my %languages_required;
+##
+#   Given a language selection as input returns a chunk of LaTeX that
+#   selects the required hyphenator.
+#
+#  @param language - the language being selected.
+#  @return string
+#  @retval The LaTeX needed to select the hyphenation appropriate to the language. 
+#   
+sub select_hyphenation {
+    my $language  = shift;
+
+    $language = &Apache::loncommon::latexlanguage($language); # Translate -> latex language.
+
+    # If there is no latex language there's not much we can do:
+
+    if ($language) {
+	&require_language($language);
+	my $babel_hyphenation = "\\selectlanguage{$language}";
+	
+	return $babel_hyphenation;
+    } else {
+	return '';
+    }
+}
+##
+#  Clears the set of languages required by the document being rendered.
+#
+sub clear_required_languages {
+    %languages_required = ();
+}
+##
+# Allows an external client of this module to register a need for a language:
+#
+# @param LaTeX language required:
+#
+sub require_language {
+    my $language = shift;
+    $languages_required{$language} = 1;
+}
+
+##
+# Provides the header for babel that indicates the languages
+# the document requires.
+# @return string
+# @retval \usepackage[lang1,lang2...]{babel}
+# @retval ''   if there are no languages_required.
+sub languages_header {
+    my $header    ='';
+    my @languages = (keys(%languages_required));
+
+    # Only generate the header if there are languages:
+
+    if (scalar @languages) {
+	my $language_list = join(',', (@languages));
+	$header  = '\usepackage['.$language_list."]{babel}\n";
+    }
+    return $header;
+}
+
+#----------------------------------------------------------------------------------
+
 sub start_web {
     my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
     if ($target ne 'edit' && $target ne 'modified') {
@@ -1265,6 +1342,7 @@ sub end_problem {
 	}
 	my $name_of_resourse= &Apache::lonxml::latex_special_symbols(&get_resource_name($parstack,$safeeval),'header');
 	my $begin_doc=' \typeout{STAMPOFPASSEDRESOURCESTART Resource <h2>"'.$name_of_resourse.'"</h2> located in <br /><small><b>'.$env{'request.uri'}.'</b></small><br /> STAMPOFPASSEDRESOURCEEND} \noindent ';
+	&clear_required_languages();
 	my $toc_line='\vskip 1 mm\noindent '.$startminipage.
 	    '\addcontentsline{toc}{subsection}{'.$name_of_resourse.'}';
 	
@@ -1581,14 +1659,15 @@ sub start_languageblock {
 
         # Now loop over all languages in order of preference
 
+	my $render;
         foreach my $preferred_language (@preferred_languages) {
 
 	    # If neither include/nor exlude is present the block is going
 	    # to get rendered.
 
-           my $render=1;
            my $found=0;
-           
+           $render=1;
+
 	   #  If include is specified,  don't render the block
 	   #  unless the preferred language is included in the set.
 
@@ -1716,7 +1795,10 @@ sub end_languageblock {
 	    my @possibilities = keys(%available_texts);
 	    my $which = 
 		&Apache::loncommon::languages(\@possibilities) || 'default';
-	    $result = $available_texts{$which};
+	    if ($target eq 'tex') {
+		$result = &select_hyphenation($which);
+	    }
+	    $result .= $available_texts{$which};
 	}
 	undef(%available_texts);
 	&Apache::lonxml::deregister('Apache::structuretags',('lang'));