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/*******************************************************************************
* Copyright (c) 2009, 2018 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.p2.query;
import java.util.Iterator;
import org.eclipse.equinox.internal.p2.metadata.expression.ContextExpression;
import org.eclipse.equinox.internal.p2.metadata.expression.ExpressionFactory;
import org.eclipse.equinox.internal.p2.metadata.expression.MatchExpression;
import org.eclipse.equinox.internal.p2.metadata.expression.QueryResult;
import org.eclipse.equinox.p2.metadata.expression.ExpressionUtil;
import org.eclipse.equinox.p2.metadata.expression.IContextExpression;
import org.eclipse.equinox.p2.metadata.expression.IExpression;
import org.eclipse.equinox.p2.metadata.expression.IExpressionFactory;
import org.eclipse.equinox.p2.metadata.index.IIndexProvider;
import org.eclipse.equinox.p2.metadata.index.IQueryWithIndex;
/**
* A query that evaluates using an iterator as input and produces a new iterator.
* @since 2.0
*/
public class ExpressionQuery<T> implements IQueryWithIndex<T> {
private final IContextExpression<T> expression;
private final Class<? extends T> elementClass;
public ExpressionQuery(Class<? extends T> elementClass, IExpression expression, Object... parameters) {
this.elementClass = elementClass;
this.expression = ExpressionUtil.getFactory().contextExpression(expression, parameters);
}
public ExpressionQuery(Class<? extends T> matchingClass, String expression, Object... parameters) {
this(matchingClass, ExpressionUtil.parseQuery(expression), parameters);
}
public Class<? extends T> getElementClass() {
return elementClass;
}
@Override
public IQueryResult<T> perform(IIndexProvider<T> indexProvider) {
return new QueryResult<>(expression.iterator(expression.createContext(elementClass, indexProvider)));
}
@Override
public IQueryResult<T> perform(Iterator<T> iterator) {
return new QueryResult<>(expression.iterator(expression.createContext(elementClass, iterator)));
}
@Override
public IContextExpression<T> getExpression() {
return expression;
}
public static <T> Class<? extends T> getElementClass(IQuery<T> query) {
@SuppressWarnings("unchecked")
Class<? extends T> elementClass = (Class<T>) Object.class;
if (query instanceof ExpressionMatchQuery<?>)
elementClass = ((ExpressionMatchQuery<T>) query).getMatchingClass();
else if (query instanceof ExpressionQuery<?>)
elementClass = ((ExpressionQuery<T>) query).getElementClass();
return elementClass;
}
public static <T> IContextExpression<T> createExpression(IQuery<T> query) {
IExpressionFactory factory = ExpressionUtil.getFactory();
IExpression expr = query.getExpression();
Object[] parameters;
if (expr == null) {
expr = factory.toExpression(query);
if (query instanceof IMatchQuery<?>)
expr = factory.select(ExpressionFactory.EVERYTHING, factory.lambda(ExpressionFactory.THIS, expr));
parameters = new Object[0];
} else {
if (expr instanceof MatchExpression<?>) {
MatchExpression<?> matchExpr = (MatchExpression<?>) expr;
parameters = matchExpr.getParameters();
expr = factory.select(ExpressionFactory.EVERYTHING, factory.lambda(ExpressionFactory.THIS, matchExpr.operand));
} else if (expr instanceof ContextExpression<?>) {
ContextExpression<?> contextExpr = (ContextExpression<?>) expr;
parameters = contextExpr.getParameters();
expr = contextExpr.operand;
} else
parameters = new Object[0];
}
return factory.contextExpression(expr, parameters);
}
}
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