/**
* Copyright 2010 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.base.evaluators;
import java.io.Externalizable;
import org.drools.base.ValueType;
import org.drools.spi.Evaluator;
/**
* An evaluator definition interface that allows for pluggable
* evaluator implementation.
*
* This interface is the register entry point for all available
* evaluators and describes all evaluator capabilities
*
* @author etirelli
*/
public interface EvaluatorDefinition extends Externalizable, org.drools.runtime.rule.EvaluatorDefinition {
/**
* Returns the list of identifies this
* evaluator implementation supports
*
* @return
*/
public String[] getEvaluatorIds();
/**
* My apologies to English speakers if the word "negatable" does not
* exist. :)
*
* This method returns true if this evaluator supports negation. Example:
*
* the "matches" operator supports "not matches" and so is "negatable" (!?)
*
* @return
*/
public boolean isNegatable();
/**
* Returns the evaluator instance for the given type and the
* defined parameterText
*
* @param type the type of the attributes this evaluator will
* operate on. This is important because the evaluator
* may do optimisations and type coercion based on the
* types it is evaluating. It is also possible that
* this evaluator does not support a given type.
*
* @param operatorId the string identifier of the evaluator
*
* @param isNegated true if the evaluator instance to be returned is
* the negated version of the evaluator.
*
* @param parameterText some evaluators support parameters and these
* parameters are defined as a String that is
* parsed by the evaluator itself.
*
* @param leftTarget the target of the evaluator on the Left side,
* i.e., on Rete terms, the previous binding or
* the actual value on the right side of the operator.
*
* @param rightTarget the target of the evaluator on the Right side,
* i.e., on Rete terms, the current pattern field.
*
* @return an Evaluator instance capable of evaluating expressions
* between values of the given type, or null in case the type
* is not supported.
*/
public Evaluator getEvaluator(final ValueType type,
final String operatorId,
final boolean isNegated,
final String parameterText,
final Target leftTarget,
final Target rightTarget );
/**
* Returns the evaluator instance for the given type and the
* defined parameterText
*
* @param type the type of the attributes this evaluator will
* operate on. This is important because the evaluator
* may do optimisations and type coercion based on the
* types it is evaluating. It is also possible that
* this evaluator does not support a given type.
*
* @param operatorId the string identifier of the evaluator
*
* @param isNegated true if the evaluator instance to be returned is
* the negated version of the evaluator.
*
* @param parameterText some evaluators support parameters and these
* parameters are defined as a String that is
* parsed by the evaluator itself.
*
* @return an Evaluator instance capable of evaluating expressions
* between values of the given type, or null in case the type
* is not supported.
*/
public Evaluator getEvaluator(final ValueType type,
final String operatorId,
final boolean isNegated,
final String parameterText );
/**
* Returns the evaluator instance for the given type and the
* defined parameterText
*
* @param type the type of the attributes this evaluator will
* operate on. This is important because the evaluator
* may do optimisations and type coercion based on the
* types it is evaluating. It is also possible that
* this evaluator does not support a given type.
*
* @param operator the operator implemented by the evaluator
*
* @param parameterText some evaluators support parameters and these
* parameters are defined as a String that is
* parsed by the evaluator itself.
*
* @return an Evaluator instance capable of evaluating expressions
* between values of the given type, or null in case the type
* is not supported.
*/
public Evaluator getEvaluator(ValueType type,
Operator operator,
String parameterText);
/**
* Returns the evaluator instance for the given type and the
* defined parameterText
*
* @param type the type of the attributes this evaluator will
* operate on. This is important because the evaluator
* may do optimisations and type coercion based on the
* types it is evaluating. It is also possible that
* this evaluator does not support a given type.
*
* @param operator the operator implemented by the evaluator
*
* @return an Evaluator instance capable of evaluating expressions
* between values of the given type, or null in case the type
* is not supported.
*/
public Evaluator getEvaluator(ValueType type,
Operator operator);
/**
* Returns true in case this evaluator supports operations over values
* of that specific type.
*
* @param type
* @return
*/
public boolean supportsType(ValueType type);
/**
* There are evaluators that operate on *fact* attributes,
* evaluators that operate on *fact handle* attributes, and
* evaluators that operate on both. This method returns
* the target of the current evaluator.
*
* @return true if this evaluator operates on fact handle attributes
* and false if it operates on fact attributes
*/
public Target getTarget();
/**
* An enum for the target of the evaluator
*/
public static enum Target {
FACT, HANDLE, BOTH;
}
}