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
015package org.apache.tapestry5.internal.beaneditor;
016
017import org.apache.tapestry5.beaneditor.Validate;
018import org.apache.tapestry5.commons.AnnotationProvider;
019import org.apache.tapestry5.services.ValidationConstraintGenerator;
020
021import java.util.Arrays;
022import java.util.List;
023import java.util.regex.Pattern;
024
025/**
026 * Checks for the {@link Validate} annotation, and extracts its value to form the result.
027 */
028public 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}