fixed empty attribute reading bug

src/xml.cxx

@@ -552,7 +552,7 @@ namespace xml {
         if (nameRead) { // read attribute
           std::string attrname(1, c), attrvalue;
           while (is && is.get(c) && c!='=' && c!='>' && !ws(c)) attrname+=c;
-          while (c!='=' && is && is.get(c) && ws(c)); // skip ws, search '='
+          while (ws(c) && is && is.get(c)); // skip ws, search '='
           if (c=='=') { // get the value
             while (is && is.get(c) && ws(c)); // skip ws
             if (c!='"')
@@ -560,7 +560,9 @@ namespace xml {
             while (is && is.get(c) && c!='"') attrvalue+=c;
             if (c!='"')
               throw attribute_value_not_quoted(position, is, tag, c, attrname);
-          } else is.unget(); // read too far
+          } else {
+            is.unget();
+          }// read too far
           if (tag.attributes.find(attrname)!=tag.attributes.end())
             throw duplicate_attribute(position, is, tag, attrname);
           tag.attributes[attrname] = attrvalue;