001    // Copyright Aug 6, 2006 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    package org.apache.tapestry.form;
015    
016    import org.apache.tapestry.IMarkupWriter;
017    import org.apache.tapestry.IRequestCycle;
018    import org.apache.tapestry.form.validator.Validator;
019    
020    
021    /**
022     * Marker interface for components that would like to override the default
023     * logic used to render validation contributions made for client side form
024     * validation.
025     * 
026     * @author jkuhnert
027     */
028    public interface ValidatableFieldExtension extends ValidatableField
029    {
030    
031        /**Called during render of the specified component. Renders any contributions from validators.
032         * Check to see if this field would like to override the default
033         * contributions made by the specified {@link Validator} with it's own
034         * contributions.
035         * 
036         * @param validator The validator to check if component wants to override. 
037         * @param cycle The current request cycle.
038         * 
039         * @return True if this field wants to override default, false otherwise.
040         */
041        boolean overrideValidator(Validator validator, IRequestCycle cycle);
042        
043        /**
044         * Very similar to the method signature used by {@link ValidatableFieldSupport#renderContributions(ValidatableField, IMarkupWriter, IRequestCycle)}, 
045         * with the additional parameter being the {@link Validator} that this component has chosen to override.
046         * 
047         * <p>
048         * This method will only be called if {@link #overrideValidator(Validator, IRequestCycle)} returns true
049         * for the specified {@link Validator}.
050         * </p>
051         * 
052         * @param validator The original {@link Validator} that component opted to override.
053         * @param context The context object used by validation contributors.
054         * @param writer The markup writer to send content to. (if any is needed)
055         * @param cycle The current request cycle.
056         */
057        void overrideContributions(Validator validator, FormComponentContributorContext context, 
058                IMarkupWriter writer, IRequestCycle cycle);
059    }