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HTML elements that do not have an empty content model must never use a self-closing tag

    1: # The LearningOnline Network
    2: # convert_file takes a well-formed XML file content and converts it to LON-CAPA syntax.
    3: #
    4: # $Id: xml_to_loncapa.pm,v 1.4 2016/01/05 18:51:08 damieng Exp $
    5: #
    6: # Copyright Michigan State University Board of Trustees
    7: #
    8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
    9: #
   10: # LON-CAPA is free software; you can redistribute it and/or modify
   11: # it under the terms of the GNU General Public License as published by
   12: # the Free Software Foundation; either version 2 of the License, or
   13: # (at your option) any later version.
   14: #
   15: # LON-CAPA is distributed in the hope that it will be useful,
   16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
   17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   18: # GNU General Public License for more details.
   19: #
   20: # You should have received a copy of the GNU General Public License
   21: # along with LON-CAPA; if not, write to the Free Software
   22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   23: #
   24: # /home/httpd/html/adm/gpl.txt
   25: #
   26: # http://www.lon-capa.org/
   27: #
   28: ###
   29: 
   30: #!/usr/bin/perl
   31: 
   32: package Apache::xml_to_loncapa;
   33: 
   34: use strict;
   35: use utf8;
   36: use warnings;
   37: 
   38: use XML::LibXML;
   39: 
   40: 
   41: my @loncapa_block = ('parameter','location','answer','foil','image','polygon','rectangle','text','conceptgroup','itemgroup','item','label','data','function','array','unit','answergroup','functionplotresponse','functionplotruleset','functionplotelements','functionplotcustomrule','essayresponse','hintpart','formulahint','numericalhint','reactionhint','organichint','optionhint','radiobuttonhint','stringhint','customhint','mathhint','formulahintcondition','numericalhintcondition','reactionhintcondition','organichintcondition','optionhintcondition','radiobuttonhintcondition','stringhintcondition','customhintcondition','mathhintcondition','imageresponse','foilgroup','datasubmission','textfield','hiddensubmission','radiobuttonresponse','rankresponse','matchresponse','import','style','script','window','block','library','notsolved','part','postanswerdate','preduedate','problem','problemtype','randomlabel','bgimg','labelgroup','randomlist','solved','while','tex','print','web','gnuplot','curve','Task','IntroParagraph','ClosingParagraph','Question','QuestionText','Setup','Instance','InstanceText','Criteria','CriteriaText','GraderNote','languageblock','translated','lang','instructorcomment','dataresponse','togglebox','standalone','comment','drawimage','allow','displayduedate','displaytitle','responseparam','organicstructure','scriptlib','parserlib','drawoptionlist','spline','backgroundplot','plotobject','plotvector','drawvectorsum','functionplotrule','functionplotvectorrule','functionplotvectorsumrule','axis','key','xtics','ytics','title','xlabel','ylabel','hiddenline','dtm','stringresponse','optionresponse','numericalresponse','formularesponse','mathresponse','organicresponse','reactionresponse','customresponse','externalresponse', 'hint', 'hintgroup');
   42: 
   43: my @loncapa_inline = ('display','m','lm','chem','num','parse','algebra','displayweight','displaystudentphoto'); # not textline
   44: 
   45: # HTML elements that trigger the addition of startouttext/endouttext
   46: my @html_trigger = ('header','footer','aside','h1','h2','h3','h4','h5','h6','li','dd','dt','tbody','tr','caption','thead','tfoot','td','th','span','a','em','strong','b','i','sup','sub','pre','code','kbd','samp','cite','q','tt','ins','del','var','small','big','br','hr','address','blockquote','img','figure','figcaption','object','param','embed','applet','video','source','audio','map','area','canvas','form','input','select','optgroup','option','textarea','fieldset','legend','button','iframe','section','div','p','ul','ol','dl','table');
   47: 
   48: my @simple_data = ('polygon', 'rectangle', 'vector', 'value', 'answer', 'title', 'data', 'function', 'xlabel', 'ylabel', 'tic', 'parserlib', 'scriptlib', 'import', 'tex', 'text', 'image', 'display', 'm', 'lm', 'num', 'algebra', 'chem', 'parse', 'title', 'style', 'script', 'ins', 'del', 'label', 'option', 'textarea', 'legend' );
   49: 
   50: my @inline_responses = ('stringresponse','optionresponse','numericalresponse','formularesponse','mathresponse','organicresponse','reactionresponse','customresponse','externalresponse');
   51: 
   52: # see http://www.w3.org/TR/html-polyglot/#empty-elements
   53: # and http://tiffanybbrown.com/2011/03/23/html5-does-not-allow-self-closing-tags/
   54: # HTML elements that do not have an empty content, and must never use a self-closing tag:
   55: my @non_empty_html = ('title','style','script','noscript','body','section','header','footer','article','aside','nav','h1','h2','h3','h4','h5','h6','div','p','li','dt','dd','caption','td','th','span','a','em','strong','b','i','sup','sub','pre','code','kbd','samp','cite','q','tt','ins','del','var','small','big','address','blockquote','bdo','ruby','rb','rp','rt','rtc','figure','figcaption','object','applet','video','audio','canvas','label','option','textarea','fieldset','legend','button','iframe');
   56: 
   57: 
   58: # Converts a file and return the modified contents
   59: sub convert_file {
   60:   my ($contents) = @_;
   61: 
   62:   my $dom_doc = XML::LibXML->load_xml(string => $contents);
   63:   add_outtext($dom_doc);
   64:   return node_to_string($dom_doc);
   65: }
   66: 
   67: 
   68: sub node_to_string {
   69:   my ($node) = @_;
   70:   
   71:   if ($node->nodeType == XML_DOCUMENT_NODE) {
   72:     my $root = $node->documentElement();
   73:     return node_to_string($root);
   74:   } elsif ($node->nodeType == XML_TEXT_NODE || $node->nodeType == XML_CDATA_SECTION_NODE) {
   75:     my $parent = $node->parentNode;
   76:     my $parent_name = $parent->nodeName;
   77:     my $grandparent_name;
   78:     if (defined $parent->parentNode) {
   79:       $grandparent_name = $parent->parentNode->nodeName;
   80:     }
   81:     my @no_escape = ('m', 'script', 'display', 'parse', 'answer');
   82:     if (string_in_array(\@no_escape, $parent_name) &&
   83:         ($parent_name ne 'answer' ||
   84:         (defined $grandparent_name &&
   85:         $grandparent_name ne 'numericalresponse' &&
   86:         $grandparent_name ne 'formularesponse'))) {
   87:       return $node->nodeValue;
   88:     } else {
   89:       return $node->toString();
   90:     }
   91:   } elsif ($node->nodeType == XML_ELEMENT_NODE) {
   92:     my $s = '';
   93:     my $tag = $node->nodeName;
   94:     $s .= "<$tag";
   95:     my @attributes = $node->attributes();
   96:     foreach my $attribute (@attributes) {
   97:       $s .= ' ';
   98:       $s .= $attribute->nodeName;
   99:       $s .= '="';
  100:       $s .= escape_attribute($attribute->nodeValue);
  101:       $s .= '"';
  102:     }
  103:     if ($node->hasChildNodes() || string_in_array(\@non_empty_html, $tag)) {
  104:       $s .= '>';
  105:       foreach my $child ($node->childNodes) {
  106:         $s .= node_to_string($child);
  107:       }
  108:       $s .= "</$tag>";
  109:     } else {
  110:       $s .= '/>';
  111:     }
  112:     return $s;
  113:   } else {
  114:     return $node->toString();
  115:   }
  116: }
  117: 
  118: # Escapes an attribute value
  119: sub escape_attribute {
  120:   my ($s) = @_;
  121:   # normal XML escapes do not work with LON-CAPA, for instance with reactionresponse
  122:   #$s =~ s/&/&amp;/sg;
  123:   #$s =~ s/</&lt;/sg;
  124:   #$s =~ s/>/&gt;/sg;
  125:   $s =~ s/"/&quot;/sg;
  126:   return $s;
  127: }
  128: 
  129: # Adds startouttext and endouttext where useful for the colorful editor
  130: sub add_outtext {
  131:   my ($node) = @_;
  132:   
  133:   if ($node->nodeType == XML_DOCUMENT_NODE) {
  134:     my $root = $node->documentElement();
  135:     add_outtext($root);
  136:     return;
  137:   }
  138:   if ($node->nodeType != XML_ELEMENT_NODE) {
  139:     return;
  140:   }
  141:   if (string_in_array(\@simple_data, $node->nodeName)) {
  142:     return;
  143:   }
  144:   convert_paragraphs($node);
  145:   my $next;
  146:   my $in_outtext = 0;
  147:   for (my $child=$node->firstChild; defined $child; $child=$next) {
  148:     $next = $child->nextSibling;
  149:     if (!$in_outtext && inside_outtext($child)) {
  150:       add_startouttext($node, $child);
  151:       $in_outtext = 1;
  152:     } elsif ($in_outtext && !continue_outtext($child)) {
  153:       add_endouttext($node, $child);
  154:       $in_outtext = 0;
  155:     }
  156:     if (!$in_outtext) {
  157:       add_outtext($child);
  158:     }
  159:   }
  160:   if ($in_outtext) {
  161:     add_endouttext($node);
  162:   }
  163: }
  164: 
  165: # Returns 1 if this node should trigger the addition of startouttext before it
  166: sub inside_outtext {
  167:   my ($node) = @_;
  168:   if ($node->nodeType == XML_TEXT_NODE && $node->nodeValue !~ /^\s*$/) {
  169:     return 1;
  170:   }
  171:   if ($node->nodeType == XML_ELEMENT_NODE && string_in_array(\@html_trigger, $node->nodeName)) {
  172:     if (contains_loncapa_block($node)) {
  173:       return 0;
  174:     } else {
  175:       return 1;
  176:     }
  177:   }
  178:   if ($node->nodeType == XML_ELEMENT_NODE && string_in_array(\@loncapa_inline, $node->nodeName)) {
  179:     return 1;
  180:   }
  181:   return 0;
  182: }
  183: 
  184: # Returns 1 if the outtext environment can continue with this node
  185: sub continue_outtext {
  186:   my ($node) = @_;
  187:   if (inside_outtext($node)) {
  188:     return 1;
  189:   }
  190:   if ($node->nodeType == XML_TEXT_NODE) {
  191:     return 1; # continue even if this is just spaces
  192:   }
  193:   return 0;
  194: }
  195: 
  196: # Returns 1 if the node contains a LON-CAPA block in a descendant.
  197: sub contains_loncapa_block {
  198:   my ($node) = @_;
  199:   foreach my $child ($node->childNodes) {
  200:     if ($child->nodeType == XML_ELEMENT_NODE) {
  201:       if (string_in_array(\@loncapa_block, $child->nodeName)) {
  202:         return 1;
  203:       }
  204:       if (contains_loncapa_block($child)) {
  205:         return 1;
  206:       }
  207:     }
  208:   }
  209:   return 0;
  210: }
  211: 
  212: sub add_startouttext {
  213:   my ($parent, $before_node) = @_;
  214:   my $doc = $parent->ownerDocument;
  215:   if ($before_node->nodeType == XML_TEXT_NODE) {
  216:     # split space at the beginning of the node
  217:     if ($before_node->nodeValue =~ /^(\s+)(.*?)$/s) {
  218:       my $space_node = $doc->createTextNode($1);
  219:       $before_node->setData($2);
  220:       $parent->insertBefore($space_node, $before_node);
  221:     }
  222:   }
  223:   my $startouttext = $doc->createElement('startouttext');
  224:   $parent->insertBefore($startouttext, $before_node);
  225: }
  226: 
  227: sub add_endouttext {
  228:   my ($parent, $before_node) = @_;
  229:   my $doc = $parent->ownerDocument;
  230:   my $endouttext = $doc->createElement('endouttext');
  231:   my $before_before;
  232:   if (defined $before_node) {
  233:     $before_before = $before_node->previousSibling;
  234:   } else {
  235:     $before_before = $parent->lastChild;
  236:   }
  237:   if (defined $before_before && $before_before->nodeType == XML_TEXT_NODE) {
  238:     # split space at the end of the node
  239:     if ($before_before->nodeValue =~ /^(.*?)(\s+)$/s) {
  240:       $before_before->setData($1);
  241:       my $space_node = $doc->createTextNode($2);
  242:       if (defined $before_node) {
  243:         $parent->insertBefore($space_node, $before_node);
  244:       } else {
  245:         $parent->appendChild($space_node);
  246:       }
  247:       $before_node = $space_node;
  248:     }
  249:   }
  250:   if (defined $before_node) {
  251:     $parent->insertBefore($endouttext, $before_node);
  252:   } else {
  253:     $parent->appendChild($endouttext);
  254:   }
  255: }
  256: 
  257: # Convert paragraph children when one contains an inline response into content + <br>
  258: # (the colorful editor does not support paragraphs containing inline responses)
  259: sub convert_paragraphs {
  260:   my ($parent) = @_;
  261:   my $p_child_with_inline_response = 0;
  262:   foreach my $child ($parent->childNodes) {
  263:     if ($child->nodeType == XML_ELEMENT_NODE && $child->nodeName eq 'p') {
  264:       foreach my $child2 ($child->childNodes) {
  265:         if ($child2->nodeType == XML_ELEMENT_NODE) {
  266:           if (string_in_array(\@inline_responses, $child2->nodeName)) {
  267:             $p_child_with_inline_response = 1;
  268:             last;
  269:           }
  270:         }
  271:       }
  272:     }
  273:     if ($p_child_with_inline_response) {
  274:       last;
  275:     }
  276:   }
  277:   if ($p_child_with_inline_response) {
  278:     my $doc = $parent->ownerDocument;
  279:     my $next;
  280:     for (my $child=$parent->firstChild; defined $child; $child=$next) {
  281:       $next = $child->nextSibling;
  282:       if ($child->nodeType == XML_ELEMENT_NODE && $child->nodeName eq 'p') {
  283:         replace_by_children($child);
  284:         if (defined $next && (defined $next->nextSibling || $next->nodeType != XML_TEXT_NODE ||
  285:             $next->nodeValue !~ /^\s*$/)) {
  286:           # we only add a br if there is something after
  287:           my $br = $doc->createElement('br');
  288:           $parent->insertBefore($br, $next);
  289:         }
  290:       }
  291:     }
  292:   }
  293: }
  294: 
  295: ##
  296: # Tests if a string is in an array (using eq) (to avoid Smartmatch warnings with $value ~~ @array)
  297: # @param {Array<string>} array - reference to the array of strings
  298: # @param {string} value - the string to look for
  299: # @returns 1 if found, 0 otherwise
  300: ##
  301: sub string_in_array {
  302:   my ($array, $value) = @_;
  303:   foreach my $v (@{$array}) {
  304:     if ($v eq $value) {
  305:       return 1;
  306:     }
  307:   }
  308:   return 0;
  309: }
  310: 
  311: ##
  312: # replaces a node by its children
  313: # @param {Node} node - the DOM node
  314: ##
  315: sub replace_by_children {
  316:   my ($node) = @_;
  317:   my $parent = $node->parentNode;
  318:   my $next;
  319:   my $previous;
  320:   for (my $child=$node->firstChild; defined $child; $child=$next) {
  321:     $next = $child->nextSibling;
  322:     if ((!defined $previous || !defined $next) &&
  323:         $child->nodeType == XML_TEXT_NODE && $child->nodeValue =~ /^\s*$/) {
  324:       next; # do not keep first and last whitespace nodes
  325:     } else {
  326:       if (!defined $previous && $child->nodeType == XML_TEXT_NODE) {
  327:         # remove whitespace at the beginning
  328:         my $value = $child->nodeValue;
  329:         $value =~ s/^\s+//;
  330:         $child->setData($value);
  331:       }
  332:       if (!defined $next && $child->nodeType == XML_TEXT_NODE) {
  333:         # and at the end
  334:         my $value = $child->nodeValue;
  335:         $value =~ s/\s+$//;
  336:         $child->setData($value);
  337:       }
  338:     }
  339:     $node->removeChild($child);
  340:     $parent->insertBefore($child, $node);
  341:     $previous = $child;
  342:   }
  343:   $parent->removeChild($node);
  344: }
  345: 
  346: 1;
  347: __END__