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package leap.lang.jsoup.parser;


import java.util.ArrayList;
import java.util.List;

import leap.lang.jsoup.helper.DescendableLinkedList;
import leap.lang.jsoup.helper.Validate;
import leap.lang.jsoup.nodes.Document;
import leap.lang.jsoup.nodes.Element;

/**
 * @author Jonathan Hedley
 */
abstract class TreeBuilder {
    CharacterReader reader;
    Tokeniser tokeniser;
    protected Document doc; // current doc we are building into
    protected DescendableLinkedList stack; // the stack of open elements
    protected String baseUri; // current base uri, for creating new elements
    protected Token currentToken; // currentToken is used only for error tracking.
    protected ParseErrorList errors; // null when not tracking errors

    protected void initialiseParse(String input, String baseUri, ParseErrorList errors) {
        Validate.notNull(input, "String input must not be null");
        Validate.notNull(baseUri, "BaseURI must not be null");

        doc = new Document(baseUri);
        reader = new CharacterReader(input);
        this.errors = errors;
        tokeniser = new Tokeniser(reader, errors);
        stack = new DescendableLinkedList();
        this.baseUri = baseUri;
    }

    Document parse(String input, String baseUri) {
        return parse(input, baseUri, ParseErrorList.noTracking());
    }

    Document parse(String input, String baseUri, ParseErrorList errors) {
        initialiseParse(input, baseUri, errors);
        runParser();
        return doc;
    }

    protected void runParser() {
        while (true) {
            Token token = tokeniser.read();
            process(token);

            if (token.type == Token.TokenType.EOF)
                break;
        }
    }

    protected abstract boolean process(Token token);

    protected Element currentElement() {
        return stack.getLast();
    }
    
    //added by evan
    protected Element tryGetCurrentElement() {
    	return stack.isEmpty() ? null : stack.getLast();
    }
}