001/*
002 * Copyright (c) 2016-2021 Chris K Wensel <[email protected]>. All Rights Reserved.
003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
004 *
005 * Project and contact information: http://www.cascading.org/
006 *
007 * This file is part of the Cascading project.
008 *
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 *
013 *     http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 */
021
022package cascading.operation.expression;
023
024import java.beans.ConstructorProperties;
025import java.io.IOException;
026import java.io.StringReader;
027
028import cascading.operation.OperationException;
029import cascading.tuple.Fields;
030import org.codehaus.commons.compiler.CompileException;
031import org.codehaus.janino.ExpressionEvaluator;
032import org.codehaus.janino.Scanner;
033
034import 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 */
040public 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 Evaluator getEvaluator( Class returnType, String[] parameterNames, Class[] parameterTypes )
091    {
092    try
093      {
094      ExpressionEvaluator evaluator = new ExpressionEvaluator();
095      evaluator.setReturnType( returnType );
096      evaluator.setParameters( parameterNames, parameterTypes );
097      evaluator.setExtendedClass( getExtendedClass() );
098      evaluator.cook( block );
099
100      return evaluator::evaluate;
101      }
102    catch( CompileException exception )
103      {
104      throw new OperationException( "could not compile expression: " + block, exception );
105      }
106    }
107  }