Copyright (c) 2004, 2012 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2004, 2012 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.osgi.service.resolver;

A helper class that provides convenience methods for manipulating 
state objects. PlatformAdmin provides an access point
for a state helper.

This interface is not intended to be implemented by clients.

See Also:
PlatformAdmin.getStateHelper
Since:
3.1
@noimplement
This interface is not intended to be implemented by clients./**
 * A helper class that provides convenience methods for manipulating 
 * state objects. <code>PlatformAdmin</code> provides an access point
 * for a state helper.
 * <p>
 * This interface is not intended to be implemented by clients.
 * </p>
 * @since 3.1
 * @see PlatformAdmin#getStateHelper
 * @noimplement This interface is not intended to be implemented by clients.
 */
public interface StateHelper {
	
Indicates that access is encouraged to an ExportPackageDescription.
/**
	 * Indicates that access is encouraged to an <code>ExportPackageDescription</code>.
	 */
	public static int ACCESS_ENCOURAGED = 0x01;
	
Indicates that access is discouraged to an ExportPackageDescription.
/**
	 * Indicates that access is discouraged to an <code>ExportPackageDescription</code>.
	 */
	public static int ACCESS_DISCOURAGED = 0x02;

	
An option to include packages available from the execution environment when 
getting the visible packages of a bundle.  For example, when running on a 
J2SE 1.4 VM the system bundle will export the javax.xml.parsers package as part of the 
execution environment.  When this option is used then any packages from the execution
environment which the bundle is wired to will be included.
See Also:
getVisiblePackages.getVisiblePackages(BundleDescription, int)/**
	 * An option to include packages available from the execution environment when 
	 * getting the visible packages of a bundle.  For example, when running on a 
	 * J2SE 1.4 VM the system bundle will export the javax.xml.parsers package as part of the 
	 * execution environment.  When this option is used then any packages from the execution
	 * environment which the bundle is wired to will be included.
	 * @see StateHelper#getVisiblePackages(BundleDescription, int)
	 */
	public static int VISIBLE_INCLUDE_EE_PACKAGES = 0x01;

	
An option to get all visible packages that a host bundle is currently wired to.  This 
includes packages wired to as a result of a dynamic import and packages wired to as a 
result of additional constraints specified by a fragment bundle.  Using this option 
with a fragment will cause an empty array to be returned.
See Also:
getVisiblePackages.getVisiblePackages(BundleDescription, int)
Since:
3.6/**
	 * An option to get all visible packages that a host bundle is currently wired to.  This 
	 * includes packages wired to as a result of a dynamic import and packages wired to as a 
	 * result of additional constraints specified by a fragment bundle.  Using this option 
	 * with a fragment will cause an empty array to be returned.
	 * @see StateHelper#getVisiblePackages(BundleDescription, int)
	 * @since 3.6
	 */
	public static int VISIBLE_INCLUDE_ALL_HOST_WIRES = 0x02;

	
Returns all bundles in the state depending on the given bundles. The given bundles
appear in the returned array.
Params:
bundles – the initial set of bundles
Returns:
an array containing bundle descriptions for the given roots and all
bundles in the state that depend on them/**
	 * Returns all bundles in the state depending on the given bundles. The given bundles
	 * appear in the returned array.
	 * 
	 * @param bundles the initial set of bundles
	 * @return an array containing bundle descriptions for the given roots and all
	 * bundles in the state that depend on them
	 */
	public BundleDescription[] getDependentBundles(BundleDescription[] bundles);

	
Returns all the prerequisite bundles in the state for the given bundles.  The given
bundles appear in the returned array.
Params:
bundles – the inital set of bundles
Returns:
an array containing bundle descriptions for the given leaves and their
prerequisite bundles in the state.
Since:
3.2/**
	 * Returns all the prerequisite bundles in the state for the given bundles.  The given
	 * bundles appear in the returned array.
	 * @param bundles the inital set of bundles
	 * @return an array containing bundle descriptions for the given leaves and their
	 * prerequisite bundles in the state.
	 * @since 3.2
	 */
	public BundleDescription[] getPrerequisites(BundleDescription[] bundles);

	
Returns all unsatisfied constraints in the given bundle. Returns an 
empty array if no unsatisfied constraints can be found.

Note that a bundle may have no unsatisfied constraints and still not be 
resolved.
  
Params:
bundle – the bundle to examine
Returns:
an array containing all unsatisfied constraints for the given bundle/**
	 * Returns all unsatisfied constraints in the given bundle. Returns an 
	 * empty array if no unsatisfied constraints can be found.
	 * <p>
	 * Note that a bundle may have no unsatisfied constraints and still not be 
	 * resolved.
	 * </p>  
	 * 
	 * @param bundle the bundle to examine
	 * @return an array containing all unsatisfied constraints for the given bundle
	 */
	public VersionConstraint[] getUnsatisfiedConstraints(BundleDescription bundle);

	
Returns all unsatisfied constraints in the given bundles that have no possible supplier. 
Returns an empty array if no unsatisfied leaf constraints can be found.

The returned constraints include only the unsatisfied constraints in the given 
state that have no possible supplier (leaf constraints).  There may 
be additional unsatisfied constraints in the given bundles but these will have at 
least one possible supplier.  In this case the possible supplier of the constraint 
is not resolved for some reason.  For example, a given state only has Bundles X and Y
installed and Bundles X and Y have the following constraints:

Bundle X requires Bundle Y
Bundle Y requires Bundle Z

In this case Bundle Y has an unsatisfied constraint leaf on Bundle Z.  This will 
cause Bundle X's constraint on Bundle Y to be unsatisfied as well because the 
bundles are involved in a dependency chain.  Bundle X's constraint on Bundle Y is 
not considered a leaf because there is a possible supplier Y in the given state.


Note that a bundle may have no unsatisfied constraints and still not be 
resolved.
  
Params:
bundles – the bundles to examine
Returns:
an array containing all unsatisfied leaf constraints for the given bundles
Since:
3.2/**
	 * Returns all unsatisfied constraints in the given bundles that have no possible supplier. 
	 * Returns an empty array if no unsatisfied leaf constraints can be found.
	 * <p>
	 * The returned constraints include only the unsatisfied constraints in the given 
	 * state that have no possible supplier (leaf constraints).  There may 
	 * be additional unsatisfied constraints in the given bundles but these will have at 
	 * least one possible supplier.  In this case the possible supplier of the constraint 
	 * is not resolved for some reason.  For example, a given state only has Bundles X and Y
	 * installed and Bundles X and Y have the following constraints:
	 * </p>
	 * <pre>
	 * Bundle X requires Bundle Y
	 * Bundle Y requires Bundle Z</pre>
	 * <p>
	 * In this case Bundle Y has an unsatisfied constraint leaf on Bundle Z.  This will 
	 * cause Bundle X's constraint on Bundle Y to be unsatisfied as well because the 
	 * bundles are involved in a dependency chain.  Bundle X's constraint on Bundle Y is 
	 * not considered a leaf because there is a possible supplier Y in the given state.
	 * </p>
	 * <p>
	 * Note that a bundle may have no unsatisfied constraints and still not be 
	 * resolved.
	 * </p>  
	 * 
	 * @param bundles the bundles to examine
	 * @return an array containing all unsatisfied leaf constraints for the given bundles
	 * @since 3.2
	 */
	public VersionConstraint[] getUnsatisfiedLeaves(BundleDescription[] bundles);

	
Returns whether the given package specification constraint is resolvable. 
A package specification constraint may be 
resolvable but not resolved, which means that the bundle that provides
it has not been resolved for some other reason (e.g. another constraint 
could not be resolved, another version has been picked, etc).
 
Params:
specification – the package specification constraint to be examined
Returns:
true if the constraint can be resolved, 
false otherwise/**
	 * Returns whether the given package specification constraint is resolvable. 
	 * A package specification constraint may be 
	 * resolvable but not resolved, which means that the bundle that provides
	 * it has not been resolved for some other reason (e.g. another constraint 
	 * could not be resolved, another version has been picked, etc).
	 *  
	 * @param specification the package specification constraint to be examined
	 * @return <code>true</code> if the constraint can be resolved, 
	 * <code>false</code> otherwise
	 */
	public boolean isResolvable(ImportPackageSpecification specification);

	
Returns whether the given bundle specification constraint is resolvable. 
A bundle specification constraint may be 
resolvable but not resolved, which means that the bundle that provides
it has not been resolved for some other reason (e.g. another constraint 
could not be resolved, another version has been picked, etc).
 
Params:
specification – the bundle specification constraint to be examined
Returns:
true if the constraint can be resolved, 
false otherwise/**
	 * Returns whether the given bundle specification constraint is resolvable. 
	 * A bundle specification constraint may be 
	 * resolvable but not resolved, which means that the bundle that provides
	 * it has not been resolved for some other reason (e.g. another constraint 
	 * could not be resolved, another version has been picked, etc).
	 *  
	 * @param specification the bundle specification constraint to be examined
	 * @return <code>true</code> if the constraint can be resolved, 
	 * <code>false</code> otherwise
	 */
	public boolean isResolvable(BundleSpecification specification);

	
Returns whether the given host specification constraint is resolvable. 
A host specification constraint may be 
resolvable but not resolved, which means that the bundle that provides
it has not been resolved for some other reason (e.g. another constraint 
could not be resolved, another version has been picked, etc).
 
Params:
specification – the host specification constraint to be examined
Returns:
true if the constraint can be resolved, 
false otherwise/**
	 * Returns whether the given host specification constraint is resolvable. 
	 * A host specification constraint may be 
	 * resolvable but not resolved, which means that the bundle that provides
	 * it has not been resolved for some other reason (e.g. another constraint 
	 * could not be resolved, another version has been picked, etc).
	 *  
	 * @param specification the host specification constraint to be examined
	 * @return <code>true</code> if the constraint can be resolved, 
	 * <code>false</code> otherwise
	 */
	public boolean isResolvable(HostSpecification specification);

	
Sorts the given array of resolved bundles in pre-requisite order. If A 
requires B, A appears after B. 
Fragments will appear after all of their hosts. Constraints contributed by fragments will 
be treated as if contributed by theirs hosts, affecting their position. This is true even if
the fragment does not appear in the given bundle array.

Unresolved bundles are ignored.

 
Params:
toSort – an array of bundles to be sorted
Returns:
any cycles found/**
	 * Sorts the given array of <strong>resolved</strong> bundles in pre-requisite order. If A 
	 * requires B, A appears after B. 
	 * Fragments will appear after all of their hosts. Constraints contributed by fragments will 
	 * be treated as if contributed by theirs hosts, affecting their position. This is true even if
	 * the fragment does not appear in the given bundle array.
	 * <p>
	 * Unresolved bundles are ignored.
	 * </p>
	 *  
	 * @param toSort an array of bundles to be sorted
	 * @return any cycles found 
	 */
	public Object[][] sortBundles(BundleDescription[] toSort);

	
Returns a list of all packages that the specified bundle has access to which are
exported by other bundles.

Same as calling getVisiblePackages(bundle, 0)

Params:
bundle – a bundle to get the list of packages for.
Returns:
a list of all packages that the specified bundle has access to which are
exported by other bundles./**
	 * Returns a list of all packages that the specified bundle has access to which are
	 * exported by other bundles.
	 * <p>
	 * Same as calling getVisiblePackages(bundle, 0)
	 * </p>
	 * @param bundle a bundle to get the list of packages for.
	 * @return a list of all packages that the specified bundle has access to which are
	 * exported by other bundles.
	 */
	public ExportPackageDescription[] getVisiblePackages(BundleDescription bundle);

	
Returns a list of all packages that the specified bundle has access to which are
exported by other bundles.  This takes into account all constraint specifications
(Import-Package, Require-Bundle etc).  A deep dependency search is done for all 
packages which are available through the required bundles and any bundles which 
are reexported.  This method also takes into account all directives
which may be specified on the constraint specifications (e.g. uses, x-friends etc.)
Params:
bundle – a bundle to get the list of packages for.
options – the options for selecting the visible packages
See Also:
VISIBLE_INCLUDE_EE_PACKAGES
VISIBLE_INCLUDE_ALL_HOST_WIRES
Returns:
a list of all packages that the specified bundle has access to which are
exported by other bundles.
Since:
3.3/**
	 * Returns a list of all packages that the specified bundle has access to which are
	 * exported by other bundles.  This takes into account all constraint specifications
	 * (Import-Package, Require-Bundle etc).  A deep dependency search is done for all 
	 * packages which are available through the required bundles and any bundles which 
	 * are reexported.  This method also takes into account all directives
	 * which may be specified on the constraint specifications (e.g. uses, x-friends etc.)
	 * 
	 * @param bundle a bundle to get the list of packages for.
	 * @param options the options for selecting the visible packages
	 * @return a list of all packages that the specified bundle has access to which are
	 * exported by other bundles.
	 * @see StateHelper#VISIBLE_INCLUDE_EE_PACKAGES
	 * @see StateHelper#VISIBLE_INCLUDE_ALL_HOST_WIRES
	 * @since 3.3
	 */
	public ExportPackageDescription[] getVisiblePackages(BundleDescription bundle, int options);

	
Returns the access code that the specified BundleDescription has to the 
specified ExportPackageDescription.
Params:
bundle – the bundle to find the access code for
export – the export to find the access code for
See Also:
ACCESS_ENCOURAGED
ACCESS_DISCOURAGED
Returns:
the access code to the export./**
	 * Returns the access code that the specified <code>BundleDescription</code> has to the 
	 * specified <code>ExportPackageDescription</code>.
	 * @param bundle the bundle to find the access code for
	 * @param export the export to find the access code for
	 * @return the access code to the export.
	 * @see StateHelper#ACCESS_ENCOURAGED
	 * @see StateHelper#ACCESS_DISCOURAGED
	 */
	public int getAccessCode(BundleDescription bundle, ExportPackageDescription export);
}