TagHandler.java

// Copyright 2000, CERN, Geneva, Switzerland and University of Santa Cruz, California, U.S.A.
package org.freehep.graphics2d;

/**
 * 
 * @author Mark Donszelmann
 * @version $Id: TagHandler.java,v 1.6 2009-08-17 21:44:44 murkle Exp $
 */
public class TagHandler {

	public TagHandler() {
	}

	/**
	 * parses string and calls methods for every tag and every not recognized
	 * entity The characters < and > have to be written as < and > while
	 * the & is written as &
	 * 
	 * The following three methods are called: defaultEntity(entity) for &
	 * < > " ' entity(entity) for all other entities
	 * openTag(tag) for all <tags> endTag(tag) for all </tags> text(text) for
	 * all text
	 * 
	 * The startTag, endTag and text methods returns a string which is added to
	 * the fully parsed string.
	 * 
	 * Strings returned from the entity methods will show up in the text methods
	 * parameter.
	 * 
	 * It returns the fully parsed string, including any additions made by the
	 * three methods above.
	 */
	public String parse(TagString string) {
		String src = string.toString();
		StringBuffer parsedString = new StringBuffer();
		StringBuffer textString = new StringBuffer();
		int i = 0;
		int p = 0;
		try {
			while (i < src.length()) {
				switch (src.charAt(i)) {
				case '&':
					// handle entities
					// look for closing ';'
					i++;
					p = i;
					while (src.charAt(i) != ';') {
						i++;
					}
					String ent = src.substring(p, i);
					if (ent.equals("amp") || ent.equals("gt")
							|| ent.equals("lt") || ent.equals("quot")
							|| ent.equals("apos")) {
						textString.append(defaultEntity(ent));
					} else {
						textString.append(entity(ent));
					}
					break;

				case '<':
					// handle tags

					// handle any outstanding text
					if (textString.length() > 0) {
						parsedString.append(text(textString.toString()));
						textString = new StringBuffer();
					}

					// look for closing '>'
					i++;
					p = i;
					while (src.charAt(i) != '>') {
						i++;
					}

					if (src.charAt(p) == '/') {
						parsedString.append(closeTag(src.substring(p + 1, i)));
					} else {
						parsedString.append(openTag(src.substring(p, i)));
					}
					break;
				default:
					// just move the pointer
					textString.append(src.charAt(i));
					break;
				} // switch
				i++;
			} // while

		} catch (ArrayIndexOutOfBoundsException aoobe) {
			// just abort, but give most of the string
			parsedString.append("!PARSEERROR!");
		}

		// final part
		if (textString.length() > 0) {
			parsedString.append(text(textString.toString()));
		}
		return parsedString.toString();
	}

	protected String defaultEntity(String entity) {
		StringBuffer dst = new StringBuffer();
		if (entity.equals("amp")) {
			dst.append('&');
		} else if (entity.equals("gt")) {
			dst.append('>');
		} else if (entity.equals("lt")) {
			dst.append('<');
		} else if (entity.equals("quot")) {
			dst.append('"');
		} else if (entity.equals("apos")) {
			dst.append('\'');
		}
		return dst.toString();
	}

	protected String entity(String entity) {
		StringBuffer dst = new StringBuffer();
		dst.append('&');
		dst.append(entity);
		dst.append(';');
		return dst.toString();
	}

	protected String openTag(String tag) {
		StringBuffer dst = new StringBuffer();
		dst.append('<');
		dst.append(tag);
		dst.append('>');
		return dst.toString();
	}

	protected String closeTag(String tag) {
		StringBuffer dst = new StringBuffer();
		dst.append("</");
		dst.append(tag);
		dst.append('>');
		return dst.toString();
	}

	protected String text(String text) {
		return text;
	}

	// public static void main(String[] args) {
	// String text = "<Vector<sup><b>Graphics</b></sup> &
	// Card<i><sub>Adapter</sub></i>>";
	//
	// TagString s = new TagString(text);
	// TagHandler handler = new TagHandler();
	// // System.out.println("\"" + s + "\"");
	// // System.out.println(handler.parse(s));
	// }
}