001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.wml;
016    
017    import org.apache.hivemind.ApplicationRuntimeException;
018    import org.apache.hivemind.HiveMind;
019    import org.apache.tapestry.AbstractComponent;
020    import org.apache.tapestry.IMarkupWriter;
021    import org.apache.tapestry.IRequestCycle;
022    import org.apache.tapestry.Tapestry;
023    
024    /**
025     * The Select element lets users pick from a list of options. Each option is specified by an Option
026     * element. Each Option element may have one line of formatted text (which may be wrapped or
027     * truncated by the user agent if too long). Unless multiple selections are required it is generally
028     * easier to use the {@link PropertySelection}component.
029     * 
030     * @author David Solis
031     * @since 3.0
032     */
033    public abstract class Select extends AbstractComponent
034    {
035        /**
036         * Used by the <code>Select</code> to record itself as a {@link IRequestCycle}attribute, so
037         * that the {@link Option}components it wraps can have access to it.
038         */
039    
040        private static final String ATTRIBUTE_NAME = "org.apache.tapestry.active.Select";
041    
042        /**
043         * @see org.apache.tapestry.AbstractComponent#renderComponent(IMarkupWriter, IRequestCycle)
044         */
045    
046        protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
047        {
048            if (cycle.getAttribute(ATTRIBUTE_NAME) != null)
049                throw new ApplicationRuntimeException(Tapestry.getMessage("Select.may-not-nest"), this,
050                        null, null);
051    
052            cycle.setAttribute(ATTRIBUTE_NAME, this);
053    
054            boolean render = !cycle.isRewinding();
055    
056            if (render)
057            {
058                writer.begin("select");
059    
060                writer.attribute("name", getName());
061    
062                String value = getValue();
063                if (HiveMind.isNonBlank(value))
064                    writer.attribute("value", value);
065    
066                String title = getTitle();
067                if (HiveMind.isNonBlank(title))
068                    writer.attribute("title", title);
069    
070                boolean multiple = isMultiple();
071                if (multiple)
072                    writer.attribute("multiple", multiple);
073    
074                renderInformalParameters(writer, cycle);
075            }
076    
077            renderBody(writer, cycle);
078    
079            if (render)
080            {
081                writer.end();
082            }
083    
084            cycle.removeAttribute(ATTRIBUTE_NAME);
085        }
086    
087        public abstract boolean isMultiple();
088    
089        public abstract String getName();
090    
091        public abstract String getValue();
092    
093        public abstract String getTitle();
094    }