/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.sparql.expr;

import java.util.regex.Matcher ;
import java.util.regex.Pattern ;
import java.util.regex.PatternSyntaxException ;

import org.apache.jena.query.QueryParseException ;

public class RegexJava implements RegexEngine
{
    Pattern regexPattern ;

    public RegexJava(String pattern, String flags)
    {
        regexPattern = makePattern(pattern, flags) ;
    }
    
    @Override
    public boolean match(String s)
    {
        Matcher m = regexPattern.matcher(s) ;
        return m.find() ;
    }
    
    private Pattern makePattern(String patternStr, String flags)
    {
        try { 
            int mask = 0 ;
            if ( flags != null )
                mask = makeMask(flags) ;
            return Pattern.compile(patternStr, mask) ;
        } 
        catch (PatternSyntaxException pEx)
        { throw new ExprException("Regex: Pattern exception: "+pEx) ; }
    }


    public static int makeMask(String modifiers)
    {
        if ( modifiers == null )
            return 0 ;
        
        int newMask = 0 ;
        for ( int i = 0 ; i < modifiers.length() ; i++ )
        {
            switch(modifiers.charAt(i))
            {
                //case 'i' : newMask |= Pattern.CASE_INSENSITIVE;     break ;
                case 'i' : 
                    // Need both (Java 1.4)
                    newMask |= Pattern.UNICODE_CASE ;
                    newMask |= Pattern.CASE_INSENSITIVE;
                    break ;
                case 'm' : newMask |= Pattern.MULTILINE ;           break ;
                case 's' : newMask |= Pattern.DOTALL ;              break ;
                //case 'x' : newMask |= Pattern.;  break ;
                
                default  : 
                    throw new QueryParseException("Illegal flag in regex modifiers: "+modifiers.charAt(i), -1, -1) ;
            }
        }
        return newMask ;
    }

}