| /******************************************************************************* |
| * Copyright (c) 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.metadata.index; |
| |
| import java.util.Iterator; |
| import org.eclipse.equinox.p2.metadata.expression.IEvaluationContext; |
| import org.eclipse.equinox.p2.metadata.expression.IExpression; |
| |
| /** |
| * Indexed access to the elements provided by an IQueryable |
| * @since 2.0 |
| */ |
| public interface IIndex<T> { |
| /** |
| * Obtains the elements that are candidates for the given <code>booleanExpr</code> when applied |
| * using the given <code>variable</code> as <code>this</code>. |
| * The returned set of elements are the elements that must be present in order for the expression |
| * to evaluate to <code>true</code>. The set may contain false positives. |
| * |
| * TODO: Write more about how the valid set of elements is determined. |
| * |
| * @param ctx The evaluation context used when examining the <code>booleanExpr</code>. |
| * @param variable The variable used as <code>this</code>. |
| * @param booleanExpr The boolean expression. |
| * @return The candidate elements or <code>null</code> if this index cannot be used. |
| */ |
| Iterator<T> getCandidates(IEvaluationContext ctx, IExpression variable, IExpression booleanExpr); |
| } |