XML Validation

Question

Since there is no XML validation currently in the Flex/Flash framework, I've decided to start a class that parses a string in an effort to validate the markup, returning whether the XML is valid. I have a need for it in my non-server based application, and have read in numerous places where there is desire for it as well. I have built the class far enough to get the ball rollin', but figure it should be :
A) available to the community
B) able to be improved upon by the community
If you improve upon the code, please post your work here so everyone can benefit.
Here is the source code :
XML Validator : v0.2 - last edit by Justin Myers | J2 CREATIVE MEDIA DESIGN
NOTES:
Parser is a bit weak and needs work.
Still need to :
- Make sure tags are ended properly
- Make sure there is space between tag name and attribute
Parser currently handles :
- Making sure there is no space between tags (with exception to white space)
- Making sure that attributes open and close properly
- Making sure there is proper space after an attribute or that it is immediately followed with the tag closing
package community.classes.parsers
       public class XMLValidator
              public function XMLValidator()
              public static function validate(str:String , ignoreWhiteSpace:Boolean = true):Boolean
                      // validation defaults to true (innocent til proven guilty)
                      var valid:Boolean = true;
                      // minimum char length to be valid XML
                      if (str.length < 4)
                             valid = false;
                      var withinTag:Boolean;
                      var withinAttribute:Boolean;
                      var tags:Array = [];
                      var tag:String;
                      for (var i:uint = 0 ; i < str.length ; i++)
                             var char:String = str.charAt(i);
                             // if we are closing a tag
                             if (char == ">")
                                    // invalid if we never opened a tag, or if we never closed the last attribute
                                    if (!withinTag || withinAttribute)
                                           valid = false;
                                           break;
                                    else
                                           withinTag = false;
                                           tags.push(tag);
                             // invalid if last character is not a closing tag
                             else if (i == str.length - 1)
                                    valid = false;
                                    break;
                                    // if we are entering a tag
                             else if (char == "<")
                                    // invalid if we haven't closed the last tag
                                    if (withinTag)
                                           valid = false;
                                           break;
                                    else
                                           withinTag = true;
                                           tag = "";
                                    // all other characters
                             else
                                    if ((char != " " || char != "\n") || ((char == " " || char == "\n") && !ignoreWhiteSpace) )
                                           // invalid if there are any characters between tags
                                           if (!withinTag)
                                                  valid = false;
                                                  break;
                                           else
                                                  if (char == "\"")
                                                          // entering attribute
                                                          if (!withinAttribute)
                                                                 // invalid if = does not preclude ", or there is space before =
                                                                 if (str.charAt(i-1) != "=" || str.charAt(i-2) == " ")
                                                                        valid = false;
                                                                        break;
                                                                 else
                                                                        withinAttribute = true;
                                                                 // exiting attribute
                                                  

Answer 1

961190 wrote:
so whats the best way to store Rules?
How to get the data validated with those rules given the source data is in a xml file
The "integrity rules"?
Since they have to be ececutable code I'd suggest Java classes...
How to get the data validated with those rules given the source data is in a xml file
as @hsc71 wrote, that each XML element select the rules this particular element should pass and run each rule with the current element as parameter.
This meight be easiser in the Rules have a common interface like
interface Rule{
  public boolean isPassedBy(XmlElement theCurrentElement, XmlElement theRootElement);
You could use the ServiceRegistry class from the JVM to fetch the known rules, so that you can add new ones with minimum effort.
bye
TPD