001    // Copyright 2007 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.tapestry5.internal.beaneditor;
016    
017    import org.apache.tapestry5.beaneditor.Validate;
018    import org.apache.tapestry5.ioc.AnnotationProvider;
019    import org.apache.tapestry5.services.ValidationConstraintGenerator;
020    
021    import java.util.Arrays;
022    import java.util.List;
023    import java.util.regex.Pattern;
024    
025    /**
026     * Checks for the {@link Validate} annotation, and extracts its value to form the result.
027     */
028    public class ValidateAnnotationConstraintGenerator implements ValidationConstraintGenerator
029    {
030    
031        static final String VALIDATOR_PATTERN="(?<!\\\\)\\s*,\\s*(?!([0-9]*\\}))";
032    
033        private final Pattern validatorPattern;
034    
035        public ValidateAnnotationConstraintGenerator()
036        {
037            validatorPattern = Pattern.compile(VALIDATOR_PATTERN);
038        }
039    
040        public List<String> buildConstraints(Class propertyType, AnnotationProvider annotationProvider)
041        {
042            Validate annotation = annotationProvider.getAnnotation(Validate.class);
043    
044            if (annotation == null)
045                return null;
046    
047            //TAP5-520: Commas within regular expressions like {n,m} or {n,} or a\,b .
048            //We use Negative Lookahead to avoid matching the case a\,b .
049            //We use Positive Lookahead to avoid matching cases {n,m} and {n,}.
050            //http://www.regular-expressions.info/lookaround.html
051            return Arrays.asList(validatorPattern.split(annotation.value()));
052        }
053    
054    }