/*
* Copyright 2006 JBoss Inc
*
* Licensed 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.drools.rule.builder.dialect.mvel;
import java.io.Serializable;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.drools.base.mvel.DroolsMVELFactory;
import org.drools.base.mvel.MVELEvalExpression;
import org.drools.compiler.Dialect;
import org.drools.compiler.RuleError;
import org.drools.lang.descr.BaseDescr;
import org.drools.lang.descr.EvalDescr;
import org.drools.rule.Declaration;
import org.drools.rule.EvalCondition;
import org.drools.rule.Pattern;
import org.drools.rule.RuleConditionElement;
import org.drools.rule.builder.RuleBuildContext;
import org.drools.rule.builder.RuleConditionBuilder;
import org.drools.spi.DeclarationScopeResolver;
import org.mvel.ExpressionCompiler;
import org.mvel.MVEL;
import org.mvel.ParserContext;
import org.mvel.util.ParseTools;
/**
* @author etirelli
*
*/
public class MVELEvalBuilder
implements
RuleConditionBuilder {
public RuleConditionElement build(final RuleBuildContext context,
final BaseDescr descr) {
return build( context,
descr,
null );
}
/**
* Builds and returns an Eval Conditional Element
*
* @param context The current build context
* @param utils The current build utils instance
* @param patternBuilder not used by EvalBuilder
* @param descr The Eval Descriptor to build the eval conditional element from
*
* @return the Eval Conditional Element
*/
public RuleConditionElement build(final RuleBuildContext context,
final BaseDescr descr,
final Pattern prefixPattern) {
// it must be an EvalDescr
final EvalDescr evalDescr = (EvalDescr) descr;
try {
final DroolsMVELFactory factory = new DroolsMVELFactory( context.getDeclarationResolver().getDeclarations(),
null,
context.getPkg().getGlobals() );
Dialect.AnalysisResult analysis = context.getDialect().analyzeExpression( context,
evalDescr,
evalDescr.getContent() );
final List[] usedIdentifiers = analysis.getBoundIdentifiers();
final Declaration[] declarations = new Declaration[usedIdentifiers[0].size()];
for ( int i = 0, size = usedIdentifiers[0].size(); i < size; i++ ) {
declarations[i] = context.getDeclarationResolver().getDeclaration( (String) usedIdentifiers[0].get( i ) );
}
final EvalCondition eval = new EvalCondition( declarations );
Serializable expr = ((MVELDialect) context.getDialect()).compile( (String) evalDescr.getContent(),
analysis,
null,
null,
null,
context );
eval.setEvalExpression( new MVELEvalExpression( expr,
factory ) );
return eval;
} catch ( final Exception e ) {
context.getErrors().add( new RuleError( context.getRule(),
evalDescr,
e,
"Unable to build expression for 'eval' node '" + evalDescr.getContent() + "'" ) );
return null;
}
}
}