/**
* Parse an HTML file.
*
* @param buffer - buffer containing HTML file text
* @return true if file is valid HTML, false otherwise
*/
public boolean validate(StringBuffer buffer) {
ITag root = new RootTag();
try {
ParseHtml(buffer, root);
} catch (HtmlParseException e) {
/*
* Debugging output off. System.out.println(e.getMessage());
* e.printStackTrace();
*/
return false;
}
ValidationVisitor visitor = new ValidationVisitor();
root.Accept(visitor);
System.out.println("Validation result: " + visitor.IsValid());
return visitor.IsValid();
}
/**
* Add a text object to the tree (leaf). May either be pure whitespace or may contain characters.
*/
private void AddTextElement(String str, ITag tag) {
try {
if (!str.isEmpty()) {
tag.Add(textFactory.Create(str));
}
} catch (NotImplementedException e) {
e.printStackTrace();
}
}
/**
* Build the HTML composite tree.
*
* @param buffer - File text from which to build the tree.
* @param root - Root node of the tree.
* @throws HtmlParseException
*/
private void ParseHtml(StringBuffer buffer, ITag root) throws HtmlParseException {
int startIndex = 0;
// Iterate as long as there are children
while (true) {
int startTagStartIndex = 0;
int startTagEndIndex = 0;
int endTagStartIndex = 0;
int endTagEndIndex = 0;
// Find the beginning of the next start tag ------------------------
startTagStartIndex = buffer.indexOf(START_TAG_START, startIndex);
// This is the base case.
if (startTagStartIndex < 0) {
AddTextElement(buffer.substring(startIndex), root);
return;
}
// Find the end of the next start tag ------------------------------
startTagEndIndex = buffer.indexOf(TAG_END, startTagStartIndex);
if (startTagEndIndex < 0) {
throw new HtmlParseException("No '>' found for opening tag.");
}
String startTag = buffer.substring(startTagStartIndex + 1, startTagEndIndex);
String tagname = startTag.replaceAll("\\s+$", "");
// Find the beginning of the corresponding end tag -----------------
endTagStartIndex = buffer.indexOf(END_TAG_START + startTag.trim(), startTagEndIndex);
if (endTagStartIndex < 0) {
throw new HtmlParseException("No '</' found for closing tag.");
}
// Find the corresponding end tag ----------------------------------
endTagEndIndex = buffer.indexOf(TAG_END, endTagStartIndex);
if (endTagEndIndex < 0) {
throw new HtmlParseException("No '>' found for closing tag.");
}
String endTag = buffer.substring(endTagStartIndex + 1, endTagEndIndex);
// See if there is a string before this tag.
if (startIndex != startTagStartIndex) {
String str = buffer.substring(startIndex, startTagStartIndex);
AddTextElement(str, root);
}
// Create the tag
ITag tag = (ITag) factory.Create(startTag, endTag);
if (tag == null) {
throw new HtmlParseException("Invalid HTML tag: '" + tagname + "'");
}
try {
root.Add(tag);
} catch (NotImplementedException e) {
e.printStackTrace();
}
// Make the recursive parsing call to parse below the tag
String tagstring = buffer.substring(startTagEndIndex + 1, endTagStartIndex);
StringBuffer subbuffer = new StringBuffer(tagstring);
ParseHtml(subbuffer, tag);
// Set up the starting index for the iteration
startIndex = endTagEndIndex + 1;
}
}
