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package javax.lang.model.element;

import java.util.List;
import javax.lang.model.type.TypeMirror;

Represents a module program element.  Provides access to
information about the module, its directives, and its members.
See Also:
getModuleOf.getModuleOf
Since:
9
@jls
7.7 Module Declarations
@spec
JPMS/**
 * Represents a module program element.  Provides access to
 * information about the module, its directives, and its members.
 *
 * @see javax.lang.model.util.Elements#getModuleOf
 * @since 9
 * @jls 7.7 Module Declarations
 * @spec JPMS
 */
public interface ModuleElement extends Element, QualifiedNameable {
    
Returns a pseudo-type for this module. 
See Also:
NoType
TypeKind.MODULE
Returns:
a pseudo-type for this module/**
     * Returns a {@linkplain javax.lang.model.type.NoType pseudo-type}
     * for this module.
     * @return a pseudo-type for this module
     *
     * @see javax.lang.model.type.NoType
     * @see javax.lang.model.type.TypeKind#MODULE
     */
    @Override
    TypeMirror asType();

    
Returns the fully qualified name of this module. For an unnamed module, an empty name is returned. 
API Note:
If the module name consists of one identifier, then
this method returns that identifier, which is deemed to be
module's fully qualified name despite not being in qualified
form.  If the module name consists of more than one identifier,
then this method returns the entire name.
Returns:
the fully qualified name of this module, or an
empty name if this is an unnamed module
@jls
6.2 Names and Identifiers/**
     * Returns the fully qualified name of this module.  For an
     * {@linkplain #isUnnamed() unnamed module}, an empty name is returned.
     *
     * @apiNote If the module name consists of one identifier, then
     * this method returns that identifier, which is deemed to be
     * module's fully qualified name despite not being in qualified
     * form.  If the module name consists of more than one identifier,
     * then this method returns the entire name.
     *
     * @return the fully qualified name of this module, or an
     * empty name if this is an unnamed module
     *
     * @jls 6.2 Names and Identifiers
     */
    @Override
    Name getQualifiedName();

    
Returns the simple name of this module. For an unnamed module, an empty name is returned. 
API Note:
If the module name consists of one identifier, then
this method returns that identifier.  If the module name
consists of more than one identifier, then this method returns
the rightmost such identifier, which is deemed to be the
module's simple name.
Returns:
the simple name of this module or an empty name if
this is an unnamed module
@jls
6.2 Names and Identifiers/**
     * Returns the simple name of this module.  For an {@linkplain
     * #isUnnamed() unnamed module}, an empty name is returned.
     *
     * @apiNote If the module name consists of one identifier, then
     * this method returns that identifier.  If the module name
     * consists of more than one identifier, then this method returns
     * the rightmost such identifier, which is deemed to be the
     * module's simple name.
     *
     * @return the simple name of this module or an empty name if
     * this is an unnamed module
     *
     * @jls 6.2 Names and Identifiers
     */
    @Override
    Name getSimpleName();

    
Returns the packages within this module.
Returns:
the packages within this module/**
     * Returns the packages within this module.
     * @return the packages within this module
     */
    @Override
    List<? extends Element> getEnclosedElements();

    
Returns true if this is an open module and 
false otherwise. 
Returns:
true if this is an open module and 
false otherwise/**
     * Returns {@code true} if this is an open module and {@code
     * false} otherwise.
     *
     * @return {@code true} if this is an open module and {@code
     * false} otherwise
     */
    boolean isOpen();

    
Returns true if this is an unnamed module and 
false otherwise. 
Returns:
true if this is an unnamed module and 
false otherwise
@jls
7.7.5 Unnamed Modules/**
     * Returns {@code true} if this is an unnamed module and {@code
     * false} otherwise.
     *
     * @return {@code true} if this is an unnamed module and {@code
     * false} otherwise
     *
     * @jls 7.7.5 Unnamed Modules
     */
    boolean isUnnamed();

    
Returns null since a module is not enclosed by another element. 
Returns:
null/**
     * Returns {@code null} since a module is not enclosed by another
     * element.
     *
     * @return {@code null}
     */
    @Override
    Element getEnclosingElement();

    
Returns the directives contained in the declaration of this module.
Returns:
 the directives in the declaration of this module/**
     * Returns the directives contained in the declaration of this module.
     * @return  the directives in the declaration of this module
     */
    List<? extends Directive> getDirectives();

    
The kind of a directive. 
Note that it is possible additional directive kinds will be added
to accommodate new, currently unknown, language structures added to
future versions of the Java programming language.
Since:
9
@spec
JPMS/**
     * The {@code kind} of a directive.
     *
     * <p>Note that it is possible additional directive kinds will be added
     * to accommodate new, currently unknown, language structures added to
     * future versions of the Java programming language.
     *
     * @since 9
     * @spec JPMS
     */
    enum DirectiveKind {
        
A "requires (static|transitive)* module-name" directive. /** A "requires (static|transitive)* module-name" directive. */
        REQUIRES,
        
An "exports package-name [to module-name-list]" directive. /** An "exports package-name [to module-name-list]" directive. */
        EXPORTS,
        
An "opens package-name [to module-name-list]" directive. /** An "opens package-name [to module-name-list]" directive. */
        OPENS,
        
A "uses service-name" directive. /** A "uses service-name" directive. */
        USES,
        
A "provides service-name with implementation-name" directive. /** A "provides service-name with implementation-name" directive. */
        PROVIDES
    };

    
Represents a directive within the declaration of this
module. The directives of a module declaration configure the
module in the Java Platform Module System.
Since:
9
@spec
JPMS/**
     * Represents a directive within the declaration of this
     * module. The directives of a module declaration configure the
     * module in the Java Platform Module System.
     *
     * @since 9
     * @spec JPMS
     */
    interface Directive {
        
Returns the kind of this directive. 

 The kind of a requires
directive is REQUIRES. 
 The kind of an exports
directive is EXPORTS. 
 The kind of an opens
directive is OPENS. 
 The kind of a uses
directive is USES. 
 The kind of a provides
directive is PROVIDES. 
Returns:
the kind of this directive/**
         * Returns the {@code kind} of this directive.
         * <ul>
         *
         * <li> The kind of a {@linkplain RequiresDirective requires
         * directive} is {@link DirectiveKind#REQUIRES REQUIRES}.
         *
         * <li> The kind of an {@linkplain ExportsDirective exports
         * directive} is {@link DirectiveKind#EXPORTS EXPORTS}.
         *
         * <li> The kind of an {@linkplain OpensDirective opens
         * directive} is {@link DirectiveKind#OPENS OPENS}.
         *
         * <li> The kind of a {@linkplain UsesDirective uses
         * directive} is {@link DirectiveKind#USES USES}.
         *
         * <li> The kind of a {@linkplain ProvidesDirective provides
         * directive} is {@link DirectiveKind#PROVIDES PROVIDES}.
         *
         * </ul>
         *
         * @return the kind of this directive
         */
        DirectiveKind getKind();

        
Applies a visitor to this directive.
Params:
v –   the visitor operating on this directive
p –   additional parameter to the visitor
Type parameters:
<R> – the return type of the visitor's methods
<P> – the type of the additional parameter to the visitor's methods
Returns:
a visitor-specified result/**
         * Applies a visitor to this directive.
         *
         * @param <R> the return type of the visitor's methods
         * @param <P> the type of the additional parameter to the visitor's methods
         * @param v   the visitor operating on this directive
         * @param p   additional parameter to the visitor
         * @return a visitor-specified result
         */
        <R, P> R accept(DirectiveVisitor<R, P> v, P p);
    }

    
A visitor of module directives, in the style of the visitor design pattern. Classes implementing this interface are used to operate on a directive when the kind of directive is unknown at compile time. When a visitor is passed to a directive's 
accept method, the visitXyz method applicable
to that directive is invoked.
 Classes implementing this interface may or may not throw a NullPointerException if the additional parameter p is null; see documentation of the implementing class for details. 
 WARNING: It is possible that methods will be added to
this interface to accommodate new, currently unknown, language
structures added to future versions of the Java programming
language. Methods to accommodate new language constructs will
be added in a source compatible way using
default methods.
Type parameters:
<R> – the return type of this visitor's methods. Use Void for visitors that do not need to return results.
<P> – the type of the additional parameter to this visitor's methods. Use Void for visitors that do not need an additional parameter.
Since:
9
@spec
JPMS/**
     * A visitor of module directives, in the style of the visitor design
     * pattern.  Classes implementing this interface are used to operate
     * on a directive when the kind of directive is unknown at compile time.
     * When a visitor is passed to a directive's {@link Directive#accept
     * accept} method, the <code>visit<i>Xyz</i></code> method applicable
     * to that directive is invoked.
     *
     * <p> Classes implementing this interface may or may not throw a
     * {@code NullPointerException} if the additional parameter {@code p}
     * is {@code null}; see documentation of the implementing class for
     * details.
     *
     * <p> <b>WARNING:</b> It is possible that methods will be added to
     * this interface to accommodate new, currently unknown, language
     * structures added to future versions of the Java programming
     * language. Methods to accommodate new language constructs will
     * be added in a source <em>compatible</em> way using
     * <em>default methods</em>.
     *
     * @param <R> the return type of this visitor's methods.  Use {@link
     *            Void} for visitors that do not need to return results.
     * @param <P> the type of the additional parameter to this visitor's
     *            methods.  Use {@code Void} for visitors that do not need an
     *            additional parameter.
     *
     * @since 9
     * @spec JPMS
     */
    interface DirectiveVisitor<R, P> {
        
Visits any directive as if by passing itself to that directive's accept method and passing null for the additional parameter. 
Params:
d –  the directive to visit
Returns:
a visitor-specified result
Implementation Requirements:
The default implementation is d.accept(v, null)./**
         * Visits any directive as if by passing itself to that
         * directive's {@link Directive#accept accept} method and passing
         * {@code null} for the additional parameter.
         *
         * @param d  the directive to visit
         * @return a visitor-specified result
         * @implSpec The default implementation is {@code d.accept(v, null)}.
         */
        default R visit(Directive d) {
            return d.accept(this, null);
        }

        
Visits any directive as if by passing itself to that directive's accept method. 
Params:
d –  the directive to visit
p –  a visitor-specified parameter
Returns:
a visitor-specified result
Implementation Requirements:
The default implementation is d.accept(v, p)./**
         * Visits any directive as if by passing itself to that
         * directive's {@link Directive#accept accept} method.
         *
         * @param d  the directive to visit
         * @param p  a visitor-specified parameter
         * @return a visitor-specified result
         * @implSpec The default implementation is {@code d.accept(v, p)}.
         */
        default R visit(Directive d, P p) {
            return d.accept(this, p);
        }

        
Visits a requires directive. 
Params:
d –  the directive to visit
p –  a visitor-specified parameter
Returns:
a visitor-specified result/**
         * Visits a {@code requires} directive.
         * @param d  the directive to visit
         * @param p  a visitor-specified parameter
         * @return a visitor-specified result
         */
        R visitRequires(RequiresDirective d, P p);

        
Visits an exports directive. 
Params:
d –  the directive to visit
p –  a visitor-specified parameter
Returns:
a visitor-specified result/**
         * Visits an {@code exports} directive.
         * @param d  the directive to visit
         * @param p  a visitor-specified parameter
         * @return a visitor-specified result
         */
        R visitExports(ExportsDirective d, P p);

        
Visits an opens directive. 
Params:
d –  the directive to visit
p –  a visitor-specified parameter
Returns:
a visitor-specified result/**
         * Visits an {@code opens} directive.
         * @param d  the directive to visit
         * @param p  a visitor-specified parameter
         * @return a visitor-specified result
         */
        R visitOpens(OpensDirective d, P p);

        
Visits a uses directive. 
Params:
d –  the directive to visit
p –  a visitor-specified parameter
Returns:
a visitor-specified result/**
         * Visits a {@code uses} directive.
         * @param d  the directive to visit
         * @param p  a visitor-specified parameter
         * @return a visitor-specified result
         */
        R visitUses(UsesDirective d, P p);

        
Visits a provides directive. 
Params:
d –  the directive to visit
p –  a visitor-specified parameter
Returns:
a visitor-specified result/**
         * Visits a {@code provides} directive.
         * @param d  the directive to visit
         * @param p  a visitor-specified parameter
         * @return a visitor-specified result
         */
        R visitProvides(ProvidesDirective d, P p);

        
Visits an unknown directive.
This can occur if the language evolves and new kinds of directive are added.
Params:
d –  the directive to visit
p –  a visitor-specified parameter
Throws:
UnknownDirectiveException – a visitor implementation may optionally throw this exception
Returns:
a visitor-specified result
Implementation Requirements:
The default implementation throws new UnknownDirectiveException(d, p)./**
         * Visits an unknown directive.
         * This can occur if the language evolves and new kinds of directive are added.
         * @param d  the directive to visit
         * @param p  a visitor-specified parameter
         * @return a visitor-specified result
         * @throws UnknownDirectiveException a visitor implementation may optionally throw this exception
         * @implSpec The default implementation throws {@code new UnknownDirectiveException(d, p)}.
         */
        default R visitUnknown(Directive d, P p) {
            throw new UnknownDirectiveException(d, p);
        }
    }

    
A dependency of a module.
Since:
9
@spec
JPMS/**
     * A dependency of a module.
     * @since 9
     * @spec JPMS
     */
    interface RequiresDirective extends Directive {
        
Returns whether or not this is a static dependency.
Returns:
whether or not this is a static dependency/**
         * Returns whether or not this is a static dependency.
         * @return whether or not this is a static dependency
         */
        boolean isStatic();

        
Returns whether or not this is a transitive dependency.
Returns:
whether or not this is a transitive dependency/**
         * Returns whether or not this is a transitive dependency.
         * @return whether or not this is a transitive dependency
         */
        boolean isTransitive();

        
Returns the module that is required
Returns:
the module that is required/**
         * Returns the module that is required
         * @return the module that is required
         */
        ModuleElement getDependency();
    }

    
An exported package of a module.
Since:
9
@spec
JPMS/**
     * An exported package of a module.
     * @since 9
     * @spec JPMS
     */
    interface ExportsDirective extends Directive {

        
Returns the package being exported.
Returns:
the package being exported/**
         * Returns the package being exported.
         * @return the package being exported
         */
        PackageElement getPackage();

        
Returns the specific modules to which the package is being exported, or null, if the package is exported to all modules which have readability to this module. 
Returns:
the specific modules to which the package is being exported/**
         * Returns the specific modules to which the package is being exported,
         * or {@code null}, if the package is exported to all modules which
         * have readability to this module.
         * @return the specific modules to which the package is being exported
         */
        List<? extends ModuleElement> getTargetModules();
    }

    
An opened package of a module.
Since:
9
@spec
JPMS/**
     * An opened package of a module.
     * @since 9
     * @spec JPMS
     */
    interface OpensDirective extends Directive {

        
Returns the package being opened.
Returns:
the package being opened/**
         * Returns the package being opened.
         * @return the package being opened
         */
        PackageElement getPackage();

        
Returns the specific modules to which the package is being open or null, if the package is open all modules which have readability to this module. 
Returns:
the specific modules to which the package is being opened/**
         * Returns the specific modules to which the package is being open
         * or {@code null}, if the package is open all modules which
         * have readability to this module.
         * @return the specific modules to which the package is being opened
         */
        List<? extends ModuleElement> getTargetModules();
    }

    
An implementation of a service provided by a module.
Since:
9
@spec
JPMS/**
     * An implementation of a service provided by a module.
     * @since 9
     * @spec JPMS
     */
    interface ProvidesDirective extends Directive {
        
Returns the service being provided.
Returns:
the service being provided/**
         * Returns the service being provided.
         * @return the service being provided
         */
        TypeElement getService();

        
Returns the implementations of the service being provided.
Returns:
the implementations of the service being provided/**
         * Returns the implementations of the service being provided.
         * @return the implementations of the service being provided
         */
        List<? extends TypeElement> getImplementations();
    }

    
A reference to a service used by a module.
Since:
9
@spec
JPMS/**
     * A reference to a service used by a module.
     * @since 9
     * @spec JPMS
     */
    interface UsesDirective extends Directive {
        
Returns the service that is used.
Returns:
the service that is used/**
         * Returns the service that is used.
         * @return the service that is used
         */
        TypeElement getService();
    }
}