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/*******************************************************************************
* Copyright (c) 2010-2016, Gabor Bergmann, IncQueryLabs Ltd.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-v20.html.
*
* SPDX-License-Identifier: EPL-2.0
*******************************************************************************/
package tools.refinery.viatra.runtime.matchers.backend;
import java.util.Map;
import java.util.Objects;
/**
* Each instance of this class corresponds to a given hint option.
*
* It is recommended to expose options to clients (and query backends) as public static fields.
*
* @author Gabor Bergmann
* @since 1.5
*/
public class QueryHintOption<HintValue> {
private String optionQualifiedName;
private HintValue defaultValue;
/**
* Instantiates an option object with the given name and default value.
*/
public QueryHintOption(String optionQualifiedName, HintValue defaultValue) {
this.optionQualifiedName = optionQualifiedName;
this.defaultValue = defaultValue;
}
/**
* This is the recommended constructor for hint options defined as static fields within an enclosing class.
* Combines the qualified name of the hint from the (qualified) name of the enclosing class and a local name (unique within that class).
*/
public <T extends HintValue> QueryHintOption(Class<?> optionNamespace, String optionLocalName, T defaultValue) {
this(String.format("%s@%s", optionLocalName, optionNamespace.getName()), defaultValue);
}
/**
* Returns the qualified name, a unique string identifier of the option.
*/
public String getQualifiedName() {
return optionQualifiedName;
}
/**
* Returns the default value of this hint option, which is to be used by query backends in the case no overriding value is assigned.
*/
public HintValue getDefaultValue() {
return defaultValue;
}
/**
* Returns the value of this hint option from the given hint collection, or the default value if not defined.
* Intended to be called by backends to find out the definitive value that should be considered.
*/
@SuppressWarnings("unchecked")
public HintValue getValueOrDefault(QueryEvaluationHint hints) {
Object value = hints.getValueOrNull(this);
if (value == null)
return getDefaultValue();
else {
return (HintValue) value;
}
}
/**
* Returns the value of this hint option from the given hint collection, or null if not defined.
*/
public HintValue getValueOrNull(QueryEvaluationHint hints) {
return hints.getValueOrNull(this);
}
/**
* Returns whether this hint option is defined in the given hint collection.
*/
public boolean isOverriddenIn(QueryEvaluationHint hints) {
return hints.isOptionOverridden(this);
}
/**
* Puts a value of this hint option into an option-to-value map.
*
* <p> This method is offered in lieu of a builder API.
* Use this method on any number of hint options in order to populate an option-value map.
* Then instantiate the immutable {@link QueryEvaluationHint} using the map.
*
* @see #insertValueIfNondefault(Map, Object)
* @return the hint value that was previously present in the map under this hint option, carrying over the semantics of {@link Map#put(Object, Object)}.
*/
@SuppressWarnings("unchecked")
public HintValue insertOverridingValue(Map<QueryHintOption<?>, Object> hints, HintValue overridingValue) {
return (HintValue) hints.put(this, overridingValue);
}
/**
* Puts a value of this hint option into an option-to-value map, if the given value differs from the default value of the option.
* If the default value is provided instead, then the map is not updated.
*
* <p> This method is offered in lieu of a builder API.
* Use this method on any number of hint options in order to populate an option-value map.
* Then instantiate the immutable {@link QueryEvaluationHint} using the map.
*
* @see #insertOverridingValue(Map, Object)
* @since 2.0
*/
public void insertValueIfNondefault(Map<QueryHintOption<?>, Object> hints, HintValue overridingValue) {
if (!Objects.equals(defaultValue, overridingValue))
hints.put(this, overridingValue);
}
@Override
public String toString() {
return optionQualifiedName;
}
}
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