| /* ContentModel.java -- |
| Copyright (C) 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath 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, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package javax.swing.text.html.parser; |
| |
| import gnu.javax.swing.text.html.parser.models.transformer; |
| |
| import java.io.Serializable; |
| |
| import java.util.Vector; |
| |
| /** |
| * A representation of the element content. The instances of this class |
| * can be arranged into the linked list, representing a BNF expression. |
| * The content model is constructed as a branched tree structure in the |
| * following way: |
| * <pre> |
| * a = new ContentModel('+', A, null); // a reprensents A+ |
| * b = new ContentModel('&', B, a); // b represents B & A+ |
| * c = new ContentModel('*', b, null); // c represents ( B & A+) * |
| * d = new ContentModel('|', new ContentModel('*', A, null), |
| * new ContentModel('?', B, null)); // d represents ( A* | B? ) |
| * </pre> |
| * where the valid operations are: |
| * <ul> |
| * <li><code>E* </code> E occurs zero or more times</li> |
| * <li><code>E+ </code> E occurs one or more times</li> |
| * <li><code>E? </code> E occurs once or not atl all</li> |
| * <li><code>A,B</code> A occurs before B</li> |
| * <li><code>A|B</code> both A and B are permitted in any order. |
| * The '|' alone does not permit the repetetive occurence of A or B |
| * (use <code>(A|B)*</code>.</li> |
| * <li><code>A&B</code> both A and B must occur once (in any order)</li> |
| * </ul> |
| * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org) |
| */ |
| public final class ContentModel |
| implements Serializable |
| { |
| /** Use serialVersionUID for interoperability. */ |
| private static final long serialVersionUID = -1130825523866321257L; |
| |
| /** |
| * The next content model model ( = pointer to the next element of |
| * the linked list) for the binary expression (',','&' or '|'). Null |
| * for the last element in the list. |
| */ |
| public ContentModel next; |
| |
| /** |
| * The document content, containing either Element or the enclosed |
| * content model (that would be in the parentheses in BNF expression). |
| */ |
| public Object content; |
| |
| /** |
| * Specifies the BNF operation between this node and the node, |
| * stored in the field <code>next</code> (or for this node, if it is |
| * an unary operation. |
| */ |
| public int type; |
| |
| /** |
| * Create a content model initializing all fields to default values. |
| */ |
| public ContentModel() |
| { |
| // Nothing to do here. |
| } |
| |
| /** |
| * Create a content model, consisting of the single element. |
| * Examples: |
| *<code> |
| * a = new ContentModel('+', A, null); // a reprensents A+ |
| * b = new ContentModel('&', B, a); // b represents B & A+ |
| * c = new ContentModel('*', b, null); // c represents ( B & A+) * |
| * d = new ContentModel('|', A, |
| * new ContentModel('?',b, null); |
| * // d represents |
| * </code> |
| */ |
| public ContentModel(Element a_content) |
| { |
| content = a_content; |
| } |
| |
| /** |
| * Create a content model, involving expression of the given type. |
| * @param a_type The expression operation type ('*','?' or '+' |
| * @param a_content The content for that the expression is applied. |
| */ |
| public ContentModel(int a_type, ContentModel a_content) |
| { |
| content = a_content; |
| type = a_type; |
| } |
| |
| /** |
| * Create a content model, involving binary expression of the given type. |
| * @param a_type The expression operation type ( ',', '|' or '&'). |
| * @param a_content The content of the left part of the expression. |
| * @param a_next The content model, representing the right part of the |
| * expression. |
| */ |
| public ContentModel(int a_type, Object a_content, ContentModel a_next) |
| { |
| content = a_content; |
| type = a_type; |
| next = a_next; |
| } |
| |
| /** |
| * Adds all list elements to the given vector, ignoring the |
| * operations between the elements. The old vector values are not |
| * discarded. |
| * @param elements - a vector to add the values to. |
| */ |
| public void getElements(Vector<Element> elements) |
| { |
| ContentModel c = this; |
| |
| while (c != null) |
| { |
| // FIXME: correct? |
| if (c.content instanceof Element) |
| elements.add((Element) c.content); |
| c = c.next; |
| } |
| } |
| |
| /** |
| * Checks if the content model matches an empty input stream. |
| * The empty content is created using SGML DTD keyword EMPTY. |
| * The empty model is a model with the content field equal to null. |
| * |
| * @return true if the content field is equal to null. |
| */ |
| public boolean empty() |
| { |
| return content == null; |
| } |
| |
| /** |
| * Get the element, stored in the <code>next.content</code>. |
| * The method is programmed as the part of the standard API, but not |
| * used in this implementation. |
| * @return the value of the field <code>next</code>. |
| */ |
| public Element first() |
| { |
| return (Element) next.content; |
| } |
| |
| /** |
| * Checks if this object can potentially be the first token in the |
| * ContenModel list. The method is programmed as the part of the |
| * standard API, but not used in this implementation. |
| */ |
| public boolean first(Object token) |
| { |
| ContentModel c = this; |
| while (c.next != null) |
| { |
| if (c.content != null && c.content.toString().equals(token.toString()) && |
| c.type != ',' |
| ) |
| |
| // Agree if the operation with the preceeding element |
| // is not the comma operation. |
| return true; |
| c = c.next; |
| } |
| return false; |
| } |
| |
| /** |
| * Returns a string representation (an expression) of this content model. |
| * The expression has BNF-like syntax, except the absence of the |
| * unary operator is additionally indicated by " ' ". It is |
| * advisable to check the created models for correctness using this |
| * method. |
| */ |
| public String toString() |
| { |
| return transformer.transform(this).toString(); |
| } |
| } |