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Diffstat (limited to 'libjava/classpath/javax/swing/text/html/parser/ContentModel.java')
| -rw-r--r-- | libjava/classpath/javax/swing/text/html/parser/ContentModel.java | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/libjava/classpath/javax/swing/text/html/parser/ContentModel.java b/libjava/classpath/javax/swing/text/html/parser/ContentModel.java new file mode 100644 index 000000000..d5c4418de --- /dev/null +++ b/libjava/classpath/javax/swing/text/html/parser/ContentModel.java @@ -0,0 +1,223 @@ +/* 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(); + } +} |