001    /*
002     * Copyright (c) 2007-2014 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.assertion;
022    
023    import java.beans.ConstructorProperties;
024    
025    import cascading.flow.FlowProcess;
026    import cascading.operation.AssertionLevel;
027    import cascading.operation.PlannerLevel;
028    import cascading.operation.ValueAssertion;
029    import cascading.operation.ValueAssertionCall;
030    import cascading.operation.expression.ExpressionOperation;
031    import cascading.tuple.Fields;
032    import cascading.tuple.TupleEntry;
033    
034    /**
035     * Class AssertExpression dynamically resolves a given expression using argument {@link cascading.tuple.Tuple} values. Any Tuple that
036     * returns true for the given expression pass the assertion. This {@link cascading.operation.Assertion}
037     * is based on the <a href="http://www.janino.net/">Janino</a> compiler.
038     * <p/>
039     * Specifically this filter uses the {@link org.codehaus.janino.ExpressionEvaluator}, thus the syntax from that class is inherited here.
040     * <p/>
041     * An expression may use field names directly as parameters in the expression, or field positions with the syntax
042     * "$n", where n is an integer.
043     * <p/>
044     * Given an argument tuple with the fields "a" and "b", the following expression returns true: <br/>
045     * <code>a + b == $0 + $1</code><br/>
046     * <p/>
047     * Further, the types of the tuple elements will be coerced into the given parameterTypes. Regardless of the actual
048     * tuple element values, they will be converted to the types expected by the expression.
049     */
050    public class AssertExpression extends ExpressionOperation implements ValueAssertion<ExpressionOperation.Context>
051      {
052      /**
053       * Constructor ExpressionFilter creates a new ExpressionFilter instance.
054       *
055       * @param expression    of type String
056       * @param parameterType of type Class
057       */
058      @ConstructorProperties({"expression", "parameterType"})
059      public AssertExpression( String expression, Class parameterType )
060        {
061        super( Fields.ALL, expression, parameterType );
062        }
063    
064      /**
065       * Constructor AssertExpression creates a new AssertExpression instance.
066       *
067       * @param fieldDeclaration of type Fields
068       * @param expression       of type String
069       * @param parameterNames   of type String[]
070       * @param parameterTypes   of type Class[]
071       */
072      @ConstructorProperties({"fieldDeclaration", "expression", "parameterNames", "parameterTypes"})
073      public AssertExpression( Fields fieldDeclaration, String expression, String[] parameterNames, Class[] parameterTypes )
074        {
075        super( fieldDeclaration, expression, parameterNames, parameterTypes );
076        }
077    
078      @Override
079      public boolean supportsPlannerLevel( PlannerLevel plannerLevel )
080        {
081        return plannerLevel instanceof AssertionLevel;
082        }
083    
084      @Override
085      public void doAssert( FlowProcess flowProcess, ValueAssertionCall<Context> assertionCall )
086        {
087        TupleEntry input = assertionCall.getArguments();
088    
089        if( !(Boolean) evaluate( assertionCall.getContext(), input ) )
090          BaseAssertion.throwFail( "argument tuple: %s did not evaluate to true with expression: %s", input.getTuple().print(), block );
091        }
092      }