001    /*
002     * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved.
003     *
004     * Project and contact information: http://www.cascading.org/
005     *
006     * This file is part of the Cascading project.
007     *
008     * Licensed under the Apache License, Version 2.0 (the "License");
009     * you may not use this file except in compliance with the License.
010     * You may obtain a copy of the License at
011     *
012     *     http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing, software
015     * distributed under the License is distributed on an "AS IS" BASIS,
016     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017     * See the License for the specific language governing permissions and
018     * limitations under the License.
019     */
020    
021    package cascading.operation.expression;
022    
023    import java.beans.ConstructorProperties;
024    import java.io.IOException;
025    import java.io.StringReader;
026    
027    import cascading.operation.OperationException;
028    import cascading.tuple.Fields;
029    import org.codehaus.commons.compiler.CompileException;
030    import org.codehaus.janino.ExpressionEvaluator;
031    import org.codehaus.janino.Scanner;
032    import org.codehaus.janino.ScriptEvaluator;
033    
034    import static cascading.tuple.coerce.Coercions.asClass;
035    
036    /**
037     * Class ExpressionOperation is the base class for {@link ExpressionFunction}, {@link ExpressionFilter},
038     * {@link cascading.operation.assertion.AssertExpression}.
039     */
040    public class ExpressionOperation extends ScriptOperation
041      {
042      @ConstructorProperties( {"expression"} )
043      protected ExpressionOperation( String expression )
044        {
045        super( ANY, expression, Boolean.class );
046        }
047    
048      @ConstructorProperties({"fieldDeclaration", "expression"})
049      protected ExpressionOperation( Fields fieldDeclaration, String expression )
050        {
051        super( ANY, fieldDeclaration, expression, asClass( fieldDeclaration.getType( 0 ) ) );
052        }
053    
054      @ConstructorProperties({"fieldDeclaration", "expression", "parameterType"})
055      protected ExpressionOperation( Fields fieldDeclaration, String expression, Class parameterType )
056        {
057        super( 1, fieldDeclaration, expression, asClass( fieldDeclaration.getType( 0 ) ), null,
058          new Class[]{parameterType} );
059        }
060    
061      @ConstructorProperties({"fieldDeclaration", "expression", "parameterNames", "parameterTypes"})
062      protected ExpressionOperation( Fields fieldDeclaration, String expression, String[] parameterNames, Class[] parameterTypes )
063        {
064        super( parameterTypes.length, fieldDeclaration, expression, asClass( fieldDeclaration.getType( 0 ) ), parameterNames, parameterTypes );
065        }
066    
067      @ConstructorProperties({"expression", "parameterType"})
068      protected ExpressionOperation( String expression, Class parameterType )
069        {
070        super( 1, expression, Object.class, null, new Class[]{parameterType} );
071        }
072    
073      @ConstructorProperties({"expression", "parameterNames", "parameterTypes"})
074      protected ExpressionOperation( String expression, String[] parameterNames, Class[] parameterTypes )
075        {
076        super( parameterTypes.length, expression, Object.class, parameterNames, parameterTypes );
077        }
078    
079      public String getExpression()
080        {
081        return getBlock();
082        }
083    
084      protected String[] guessParameterNames() throws CompileException, IOException
085        {
086        return ExpressionEvaluator.guessParameterNames( new Scanner( "expressionEval", new StringReader( block ) ) );
087        }
088    
089      @Override
090      protected ScriptEvaluator getEvaluator( Class returnType, String[] parameterNames, Class[] parameterTypes )
091        {
092        try
093          {
094          return new ExpressionEvaluator( block, getReturnType(), parameterNames, parameterTypes );
095          }
096        catch( CompileException exception )
097          {
098          throw new OperationException( "could not compile expression: " + block, exception );
099          }
100        }
101      }