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/*******************************************************************************
* Copyright (c) 2009, 2012 IBM 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:
* IBM - initial API and implementation
******************************************************************************/
package org.eclipse.equinox.p2.metadata;
import org.eclipse.equinox.p2.metadata.expression.IMatchExpression;
/**
* A requirement represents some external constraint on an {@link IInstallableUnit}.
* Each requirement represents something an {@link IInstallableUnit} needs that
* it expects to be provided by another {@link IInstallableUnit}. Requirements are
* entirely generic, and are intended to be capable of representing anything that
* an {@link IInstallableUnit} may need either at install time, or at runtime.
* <p>
* Instances of this class are handle objects and do not necessarily
* reflect entities that exist in any particular profile or repository. These handle
* objects can be created using {@link MetadataFactory}.
* </p>
*
* @noimplement This interface is not intended to be implemented by clients.
* @noextend This interface is not intended to be extended by clients.
* @since 2.0
* @see IProvidedCapability
* @see MetadataFactory#createRequirement(String, String, VersionRange, String, boolean, boolean, boolean)
*/
public interface IRequirement {
/**
* Returns the minimum cardinality of the requirement. That is, the minimum
* number of capabilities that must be provided that match this requirement before
* this requirement is considered fully satisfied. A minimum cardinality of 0 indicates
* that the requirement is optional.
*
* @return the minimum cardinality of this requirement
*/
int getMin();
/**
* Returns the maximum cardinality of the requirement. That is, the maximum
* number of capabilities that are permitted to be present that satisfy this requirement.
* A maximum cardinality of 0 indicates that there must <em>not</em> be
* any installable unit in the system that satisfies this requirement.
*
* @return the maximum cardinality of this requirement
*/
int getMax();
/**
* @noreference This method is not intended to be referenced by clients.
*/
IMatchExpression<IInstallableUnit> getFilter();
/**
* Returns a boolean match expression that will return true for any
* {@link IInstallableUnit} that matches the requirement.
* @return A boolean match expression for installable unit matching.
*/
IMatchExpression<IInstallableUnit> getMatches();
/**
* Returns whether the provided capabilities of the given installable unit satisfy
* this requirement.
*
* @param iu the installable unit to check for matching capabilities
* @return <code>true</code> if the given installable unit satisfies this
* requirement, and <code>false</code> otherwise.
*/
boolean isMatch(IInstallableUnit iu);
/**
* Returns whether this requirement should cause extra installable units
* to be installed in order to satisfy it.
* @return <code>true</code> if additional installable units should be installed
* to satisfy this requirement, and <code>false</code> otherwise
*/
boolean isGreedy();
/**
* Returns a textual description of this requirement.
*
* @return a textual description of this requirement
*/
String getDescription();
}
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