- /*
- * The Apache Software License, Version 1.1
- *
- * Copyright (c) 1999 The Apache Software Foundation. All rights
- * reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. The end-user documentation included with the redistribution, if
- * any, must include the following acknowlegement:
- * "This product includes software developed by the
- * Apache Software Foundation (http://www.apache.org/)."
- * Alternately, this acknowlegement may appear in the software itself,
- * if and wherever such third-party acknowlegements normally appear.
- *
- * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
- * Foundation" must not be used to endorse or promote products derived
- * from this software without prior written permission. For written
- * permission, please contact apache@apache.org.
- *
- * 5. Products derived from this software may not be called "Apache"
- * nor may "Apache" appear in their names without prior written
- * permission of the Apache Group.
- *
- * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- * ====================================================================
- *
- * This software consists of voluntary contributions made by many
- * individuals on behalf of the Apache Software Foundation. For more
- * information on the Apache Software Foundation, please see
- * <http://www.apache.org/>.
- *
- */
- package javax.servlet.jsp.tagext;
-
- import javax.servlet.jsp.*;
- import javax.servlet.jsp.tagext.*;
-
- import javax.servlet.*;
-
- import java.io.Writer;
- import java.io.Serializable;
-
- import java.util.Hashtable;
- import java.util.Enumeration;
-
- /**
- * A base class for defining new tag handlers implementing Tag.
- *
- * <p> The TagSupport class is a utility class intended to be used as
- * the base class for new tag handlers. The TagSupport class
- * implements the Tag and IterationTag interfaces and adds additional
- * convenience methods including getter methods for the properties in
- * Tag. TagSupport has one static method that is included to
- * facilitate coordination among cooperating tags.
- *
- * <p> Many tag handlers will extend TagSupport and only redefine a
- * few methods.
- */
-
- public class TagSupport implements IterationTag, Serializable {
-
- /**
- * Find the instance of a given class type that is closest to a given
- * instance.
- * This method uses the getParent method from the Tag
- * interface.
- * This method is used for coordination among cooperating tags.
- *
- * <p>
- * The current version of the specification only provides one formal
- * way of indicating the observable type of a tag handler: its
- * tag handler implementation class, described in the tag-class
- * subelement of the tag element. This is extended in an
- * informal manner by allowing the tag library author to
- * indicate in the description subelement an observable type.
- * The type should be a subtype of the tag handler implementation
- * class or void.
- * This addititional constraint can be exploited by a
- * specialized container that knows about that specific tag library,
- * as in the case of the JSP standard tag library.
- *
- * <p>
- * When a tag library author provides information on the
- * observable type of a tag handler, client programmatic code
- * should adhere to that constraint. Specifically, the Class
- * passed to findAncestorWithClass should be a subtype of the
- * observable type.
- *
- *
- * @param from The instance from where to start looking.
- * @param klass The subclass of Tag or interface to be matched
- * @returns the nearest ancestor that implements the interface
- * or is an instance of the class specified
- */
-
- public static final Tag findAncestorWithClass(Tag from, Class klass) {
- boolean isInterface = false;
-
- if (from == null ||
- klass == null ||
- (!Tag.class.isAssignableFrom(klass) &&
- !(isInterface = klass.isInterface()))) {
- return null;
- }
-
- for (;;) {
- Tag tag = from.getParent();
-
- if (tag == null) {
- return null;
- }
-
- if ((isInterface && klass.isInstance(tag)) ||
- klass.isAssignableFrom(tag.getClass()))
- return tag;
- else
- from = tag;
- }
- }
-
- /**
- * Default constructor, all subclasses are required to define only
- * a public constructor with the same signature, and to call the
- * superclass constructor.
- *
- * This constructor is called by the code generated by the JSP
- * translator.
- */
-
- public TagSupport() { }
-
- /**
- * Default processing of the start tag, returning SKIP_BODY.
- *
- * @returns SKIP_BODY
- *
- * @see Tag#doStartTag()
- */
-
- public int doStartTag() throws JspException {
- return SKIP_BODY;
- }
-
- /**
- * Default processing of the end tag returning EVAL_PAGE.
- *
- * @returns EVAL_PAGE
- *
- * @see Tag#doEndTag()
- */
-
- public int doEndTag() throws JspException {
- return EVAL_PAGE;
- }
-
-
- /**
- * Default processing for a body
- *
- * @return SKIP_BODY
- *
- * @see IterationTag#doAfterBody()
- */
-
- public int doAfterBody() throws JspException {
- return SKIP_BODY;
- }
-
- // Actions related to body evaluation
-
-
- /**
- * Release state.
- *
- * @see Tag#release()
- */
-
- public void release() {
- parent = null;
- }
-
- /**
- * Set the nesting tag of this tag.
- *
- * @param t The parent Tag.
- * @see Tag#setParent(Tag)
- */
-
- public void setParent(Tag t) {
- parent = t;
- }
-
- /**
- * The Tag instance most closely enclosing this tag instance.
- * @see Tag#getParent()
- *
- * @returns the parent tag instance or null
- */
-
- public Tag getParent() {
- return parent;
- }
-
- /**
- * Set the id attribute for this tag.
- *
- * @param id The String for the id.
- */
-
- public void setId(String id) {
- this.id = id;
- }
-
- /**
- * The value of the id attribute of this tag; or null.
- *
- * @returns the value of the id attribute, or null
- */
-
- public String getId() {
- return id;
- }
-
- /**
- * Set the page context.
- *
- * @param pageContenxt The PageContext.
- * @see Tag#setPageContext
- */
-
- public void setPageContext(PageContext pageContext) {
- this.pageContext = pageContext;
- }
-
- /**
- * Associate a value with a String key.
- *
- * @param k The key String.
- * @param o The value to associate.
- */
-
- public void setValue(String k, Object o) {
- if (values == null) {
- values = new Hashtable();
- }
- values.put(k, o);
- }
-
- /**
- * Get a the value associated with a key.
- *
- * @param k The string key.
- * @returns The value associated with the key, or null.
- */
-
- public Object getValue(String k) {
- if (values == null) {
- return null;
- } else {
- return values.get(k);
- }
- }
-
- /**
- * Remove a value associated with a key.
- *
- * @param k The string key.
- */
-
- public void removeValue(String k) {
- if (values != null) {
- values.remove(k);
- }
- }
-
- /**
- * Enumerate the values kept by this tag handler.
- *
- * @returns An enumeration of all the values set.
- */
-
- public Enumeration getValues() {
- if (values == null) {
- return null;
- }
- return values.keys();
- }
-
- // private fields
-
- private Tag parent;
- private Hashtable values;
- protected String id;
-
- // protected fields
-
- protected PageContext pageContext;
- }
-