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/*******************************************************************************
* Copyright (c) 2009, 2017 Cloudsmith Inc. and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Cloudsmith Inc. - initial API and implementation
*******************************************************************************/
package org.eclipse.equinox.internal.p2.metadata.expression;
import java.util.Iterator;
import org.eclipse.equinox.p2.metadata.expression.*;
import org.eclipse.equinox.p2.metadata.index.IIndexProvider;
/**
* The context expression is the top expression in context queries. It introduces the
* variable 'everything' and initialized it with the iterator that represents all
* available items.
*/
public class ContextExpression<T> extends Unary implements IContextExpression<T> {
private static final Object[] noParams = new Object[0];
protected final Object[] parameters;
public ContextExpression(Expression expression, Object[] parameters) {
super(expression);
this.parameters = parameters == null ? noParams : parameters;
}
@Override
public boolean accept(IExpressionVisitor visitor) {
return super.accept(visitor) && operand.accept(visitor);
}
@Override
public void toString(StringBuffer bld, Variable rootVariable) {
operand.toString(bld, rootVariable);
}
@Override
public IEvaluationContext createContext(Class<? extends T> elementClass, IIndexProvider<T> indexProvider) {
Variable everything = ExpressionFactory.EVERYTHING;
IEvaluationContext context = EvaluationContext.create(parameters, everything);
context.setValue(everything, new Everything<>(elementClass, indexProvider));
context.setIndexProvider(indexProvider);
return context;
}
@Override
public IEvaluationContext createContext(Class<? extends T> elementClass, Iterator<T> iterator) {
Variable everything = ExpressionFactory.EVERYTHING;
IEvaluationContext context = EvaluationContext.create(parameters, everything);
context.setValue(everything, new Everything<>(elementClass, iterator, operand));
return context;
}
@Override
public Object evaluate(IEvaluationContext context) {
return operand.evaluate(parameters.length == 0 ? context : EvaluationContext.create(context, parameters));
}
@Override
public int getExpressionType() {
return 0;
}
@Override
public String getOperator() {
throw new UnsupportedOperationException();
}
@Override
public int getPriority() {
return operand.getPriority();
}
@Override
public Object[] getParameters() {
return parameters;
}
@Override
public int hashCode() {
return operand.hashCode();
}
@Override
@SuppressWarnings("unchecked")
public Iterator<T> iterator(IEvaluationContext context) {
return (Iterator<T>) operand.evaluateAsIterator(context);
}
@Override
public void toString(StringBuffer bld) {
toString(bld, ExpressionFactory.EVERYTHING);
}
}
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