/* * HTML Parser * Copyright (C) 1997 David McNicol * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * file COPYING for more details. */package cvu.html;import java.util.Hashtable;import java.util.Vector;import java.util.Enumeration;/** * This class represents the attribute list of an tag. * @see TagToken * @author <a href="http://www.strath.ac.uk/~ras97108/">David McNicol</a> */public class AttributeList {	private Hashtable list;	 // Stores the attributes.	public AttributeList () {		// Create a new hashtable to store the attributes.		list = new Hashtable();	}	/**	 * Returns the number of attributes currently defined.	 */	public int size () {		return list.size();	}	/**	 * Returns the value of the attribute with the specified name.	 * @param the name of the attribute.	 */	public String get (String name) {				// Check the name of the attribute is not null.		if (name == null) return null;		// Check that the attribute list is there.		if (list == null) return null;		// Return the value associated with the attribute name.		return (String) list.get(name.toLowerCase());	}	/**	 * Sets the attribute with the specified name to the specified	 * value. If the attribute already has a value it will be	 * overwritten.	 * @param name the name of the attribute.	 * @param value the new value of the attribute.	 */	public void set (String name, String value) {		// Check that the name is not null.		if (name == null) return;		// Replace a null value with an empty string.		if (value == null) value = "";		// Return if the list of attributes is not defined.		if (list == null) return;		// Otherwise, add the attribute and value to the list.		list.put(name.toLowerCase(), value);	}	/**	 * Returns true if the specified attribute name exists within	 * the list.	 * @param the name of the attribute to check.	 */	public boolean exists (String name) {		// Return false if the name is not null.		if (name == null) return false;		// Return false of the list is not defined.		if (list == null) return false;		// Check the list to see if the attribute exists.		return list.containsKey(name.toLowerCase());	}	/**	 * Removes the specified attribute from the list.	 * @param name the name of the attribue to remove.	 */	public void unset (String name) {		// Return if the attribute name is null.		if (name == null) return;		// Return if the attribute list is not defined.		if (list == null) return;		// Otherwise, remove the attribute from the list.		list.remove(name.toLowerCase());	}	/**	 * Returns an enumeration of defined attributes.	 */	public Enumeration names () {		// Check that the attribute table has been defined.		if (list == null) return null;		// Return an enumeration of all of the defined attributes.		return list.keys();	}	/**	 * Returns an attribute with all double quote characters	 * escaped with a backslash.	 * @param name the name of the attribute.	 */	public String getQuoted (String name) {		String value;	     // Stores the value of the attribute.		char[] array;	     // Character array from 'value'.		StringBuffer quoted; // Stores the quoted version of the value.		int i;		     // Loop variable.		// Check the name of the attribute is not null.		if (name == null) return null;		// Check that the attribute list is there.		if (list == null) return null;		// Get the value of the attribute.		value = (String) list.get(name.toLowerCase());		// Return nothing if there is no such attribute.		if (value == null) return null;		// Return an empty string if that is what is stored.		if (value.length() == 0) return "";		// Convert the value into a character array.		array = value.toCharArray();		// Create a new StringBuffer to store the quoted value.		quoted = new StringBuffer(array.length);		// Loop round the characters in the array.		for (i = 0; i < array.length; i++) {			// Escape any quotation marks.			if (array[i] == '"') {				quoted.append("\\\"");				continue;			}			// Escape any additional backslash characters.			if (array[i] == '\\') {				quoted.append("\\\\");				continue;			}			// Otherwise append the character without an escape.			quoted.append(array[i]);		}		// Return a string version of the buffer.		return quoted.toString();	}	/**	 * Returns a string version of the attribute and its value.	 * @param name the name of the attribute.	 */	public String toString (String name) {		String value; // The value of the attribute.		// Return an empty string if the name is null.		if (name == null) return "";		// Return an empty string if the attribute is not defined.		if (! exists(name)) return "";		// Get a quoted version of the value.		value = getQuoted(name);		// If the value is null return the attribute name by itself.		if (value == null) return name;		// Otherwise return the complete string.		if (value.length() > 0)			return name + "=\"" + value + '"';		else			return name;	}	/**	 * Returns a string version of the attribute list.	 */	public String toString () {		StringBuffer buffer;  // Stores the string version of the list.		Enumeration nameList; // Stores a list of attribute names.		String name;	      // Name of the current attribute.		String attr;	      // String version of a single attribute.		// Create a new StringBuffer.		buffer = new StringBuffer();		// Get a list of all of the attribute names.		nameList = names();		while (nameList.hasMoreElements()) {			// Get the next attribute name from the list.			name = (String) nameList.nextElement();			// Get the string version of the attribute.			attr = toString(name);			// Add it to the buffer.			buffer.append(attr);			// Add whitespace if there are more attributes.			if (nameList.hasMoreElements())				buffer.append(' ');		}		// Return a string version of the buffer.		return buffer.toString();	}}