AbstractReader.java

/*
 * This software is Copyright 2005,2006,2007,2008 Langdale Consultants.
 * Langdale Consultants can be contacted at: http://www.langdale.com.au
 */
package au.com.langdale.sax;

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Enumeration;

import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.stream.StreamResult;

import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;
import org.xml.sax.helpers.NamespaceSupport;

public abstract class AbstractReader extends XMLReaderBase {

	/** Optimisation provides a single copy of the empty atts */
	private final Attributes empty = new AttributesImpl();

	/** The top of the current element stack */
	private Element top = null;
	
	protected Element getTop() {
	  return top;
	}

	/** The current namespace bindings */
	NamespaceSupport spaces = new NamespaceSupport();

	/**
	 * Convenience class to generate an element from a given word or the current
	 * token.
	 */
	protected class Element {
		private Element parent;
		private String type;
		private boolean committed = false;
		private AttributesImpl atts = null;
		private int depth = 0;
		private boolean printing = false;
		private String[] parts = new String[3];
		private String[] attr_parts;

		public Element(String type, String namespace) throws SAXException {
			this(type);
			spaces.declarePrefix("", namespace);
			output.startPrefixMapping("", namespace);
		}

		public Element(String type) throws SAXException {
			parent = top;
			top = this;
			this.type = type;
			spaces.pushContext();
			if (parent != null) {
				parent.commit();
				depth = parent.depth + 1;
			}
		}

		public void commit() throws SAXException {
			if (!committed) {
				print("+" + type);
				Attributes passed = atts != null ? atts : empty;
				if (spaces.processName(type, parts, false) == null)
					throw new SAXException("undeclared namespace prefix: "
							+ type);
				output.startElement(parts[0], parts[1], parts[2], passed);
				committed = true;
			}
		}

		public void close() throws SAXException {
			commit();
			output.endElement(parts[0], parts[1], parts[2]);
			Enumeration ix = spaces.getDeclaredPrefixes();
			while (ix.hasMoreElements()) {
				String prefix = (String) ix.nextElement();
				output.endPrefixMapping(prefix);
			}
			print("-" + type);
			if (top != this) {
				throw new SAXException("internal error: elements out of order");
			}
			if (depth == 0) {
				print("the end");
			}
			top = parent;
			spaces.popContext();
		}

		private void declare(String name, String value) throws SAXException {
			int colon = name.indexOf(':');
			if (colon == -1) {
				spaces.declarePrefix("", value);
				output.startPrefixMapping("", value);
			} else {
				String prefix = name.substring(colon + 1);
				spaces.declarePrefix(prefix, value);
				output.startPrefixMapping(prefix, value);
			}
		}

		public void set(String name, String value) throws SAXException {
			if (committed)
				throw new SAXException("attribute out of order");

			if (name.startsWith("xmlns")) {
				declare(name, value);
				return;
			}

			if (atts == null) {
				atts = new AttributesImpl();
				attr_parts = new String[3];
			}

			if (spaces.processName(name, attr_parts, true) == null)
				throw new SAXException("undeclared namespace prefix in: "
						+ name);

			atts.addAttribute(attr_parts[0], attr_parts[1], attr_parts[2],
					"CDATA", value);
		}

		public void set(String name, StringBuffer value) throws SAXException {
			set(name, value.toString());
		}

		public void append(String text) throws SAXException {
			commit();
			char[] ch = new char[text.length()];
			text.getChars(0, text.length(), ch, 0);
			output.characters(ch, 0, text.length());
		}

		public void append(StringBuffer text) throws SAXException {
			commit();
			char[] ch = new char[text.length()];
			text.getChars(0, text.length(), ch, 0);
			output.characters(ch, 0, text.length());
		}

		public void print(String message) {
			if (printing) {
				for (int i = 0; i < depth; i++)
					System.out.print("  ");
				System.out.println(message);
			}
		}
	}

	public void write(OutputStream ostream) throws TransformerException {
		Result result = new StreamResult(ostream);
		Source source = new SAXSource(this, new InputSource());
		TransformerFactory.newInstance().newTransformer().transform(source,
				result);
	}

	public void write(String filename) throws TransformerException, IOException {
		BufferedOutputStream ostream = new BufferedOutputStream( new FileOutputStream(filename));
		write(ostream);
		ostream.close();
	}
	

        @Override
	protected void parse() throws SAXException, IOException {
	    output.startDocument();
	    emit();
	    output.endDocument();
	}
        
        protected abstract void emit() throws SAXException;
}