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/*******************************************************************************
* Copyright (c) 2009, 2010 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.ql;
import java.util.Iterator;
import org.eclipse.equinox.p2.query.IQueryResult;
/**
* An IQuery 'context query' implementation that is based on the p2 query language.
*/
public class QLContextQuery<T> extends QLQuery<T> {
private final IContextExpression<T> expression;
/**
* Creates a new query instance with indexed parameters.
* @param expression The expression that represents the query.
* @param parameters Parameters to use for the query.
*/
public QLContextQuery(IContextExpression<T> expression, Object... parameters) {
super(expression.getElementClass(), parameters);
this.expression = expression;
}
/**
* Creates a new query instance with keyed parameters.
* @param elementClass The class used for filtering elements in 'everything'
* @param expression The expression that represents the query.
* @param parameters Parameters to use for the query.
*/
public QLContextQuery(Class<T> elementClass, String expression, Object... parameters) {
this(parser.parseQuery(elementClass, expression), parameters);
}
public IQueryResult<T> perform(Iterator<T> iterator) {
return new QueryResult<T>(evaluate(iterator));
}
public Iterator<T> evaluate(Iterator<T> iterator) {
IEvaluationContext ctx;
if (expression.needsTranslations()) {
IQueryContext<T> queryContext = QL.newQueryContext(iterator);
ctx = expression.createContext(iterator, parameters, queryContext.getTranslationSupport(getLocale()));
} else
ctx = expression.createContext(iterator, parameters);
@SuppressWarnings("unchecked")
Iterator<T> result = (Iterator<T>) expression.evaluateAsIterator(ctx);
return result;
}
/**
* Query without using a collector. Instead, return the result of the query directly.
* @param queryContext The context for the query.
* @return The result of the query.
*/
public Object query(IQueryContext<T> queryContext) {
// Check if we need translation support
//
IEvaluationContext ctx;
if (expression.needsTranslations())
ctx = expression.createContext(queryContext.iterator(), parameters, queryContext.getTranslationSupport(getLocale()));
else
ctx = expression.createContext(queryContext.iterator(), parameters);
return expression.evaluate(ctx);
}
}
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