PropertyBasedElement: extend HTML5 (Canvas) data props interface

Allow check if property exists and removing properties.

simgear/props/PropertyBasedElement.cxx

@@ -17,6 +17,7 @@
 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
 
 #include "PropertyBasedElement.hxx"
+#include <boost/algorithm/string/predicate.hpp>
 
 namespace simgear
 {
@@ -65,4 +66,86 @@ namespace simgear
     return _node;
   }
 
+  //----------------------------------------------------------------------------
+  bool PropertyBasedElement::hasDataProp(const std::string& name) const
+  {
+    return getDataProp<SGPropertyNode*>(name) != NULL;
+  }
+
+  //----------------------------------------------------------------------------
+  void PropertyBasedElement::removeDataProp(const std::string& name)
+  {
+    SGPropertyNode* node = getDataProp<SGPropertyNode*>(name);
+    if( node )
+      _node->removeChild(node);
+  }
+
+  //----------------------------------------------------------------------------
+  static const std::string DATA_PREFIX("data-");
+
+  //----------------------------------------------------------------------------
+  std::string PropertyBasedElement::dataPropToAttrName(const std::string& name)
+  {
+    // http://www.w3.org/TR/html5/dom.html#attr-data-*
+    //
+    // 3. Insert the string data- at the front of name.
+
+    std::string attr_name;
+    for( std::string::const_iterator cur = name.begin();
+                                     cur != name.end();
+                                   ++cur )
+    {
+      // If name contains a "-" (U+002D) character followed by a lowercase ASCII
+      // letter, throw a SyntaxError exception and abort these steps.
+      if( *cur == '-' )
+      {
+        std::string::const_iterator next = cur + 1;
+        if( next != name.end() && islower(*next) )
+          return std::string();
+      }
+
+      // For each uppercase ASCII letter in name, insert a "-" (U+002D)
+      // character before the character and replace the character with the same
+      // character converted to ASCII lowercase.
+      if( isupper(*cur) )
+      {
+        attr_name.push_back('-');
+        attr_name.push_back( tolower(*cur) );
+      }
+      else
+        attr_name.push_back( *cur );
+    }
+    return DATA_PREFIX + attr_name;
+  }
+
+  //----------------------------------------------------------------------------
+  std::string PropertyBasedElement::attrToDataPropName(const std::string& name)
+  {
+    // http://www.w3.org/TR/html5/dom.html#attr-data-*
+    //
+    // For each "-" (U+002D) character in the name that is followed by a
+    // lowercase ASCII letter, remove the "-" (U+002D) character and replace the
+    // character that followed it by the same character converted to ASCII
+    // uppercase.
+
+    if( !boost::starts_with(name, DATA_PREFIX) )
+      return std::string();
+
+    std::string data_name;
+    for( std::string::const_iterator cur = name.begin() + DATA_PREFIX.length();
+                                     cur != name.end();
+                                   ++cur )
+    {
+      std::string::const_iterator next = cur + 1;
+      if( *cur == '-' && next != name.end() && islower(*next) )
+      {
+        data_name.push_back( toupper(*next) );
+        cur = next;
+      }
+      else
+        data_name.push_back(*cur);
+    }
+    return data_name;
+  }
+
 } // namespace simgear