IBinding.java

/*******************************************************************************
 * Copyright (c) 2000, 2010 IBM Corporation 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 Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jdt.core.dom;

import org.eclipse.jdt.core.IAnnotation;
import org.eclipse.jdt.core.IJavaElement;

/**
 * A binding represents a named entity in the Java language. The world of bindings provides an
 * integrated picture of the structure of the program as seen from the compiler's point of view.
 * This interface declare protocol common to the various different kinds of named entities in the
 * Java language: packages, types, fields, methods, constructors, and local variables.
 * 
 * @see IPackageBinding
 * @see ITypeBinding
 * @see IVariableBinding
 * @see IMethodBinding
 * @see IAnnotationBinding
 * @see IMemberValuePairBinding
 * @since 2.0
 * @noimplement This interface is not intended to be implemented by clients.
 */
public interface IBinding {

	/**
	 * Kind constant (value 1) indicating a package binding. Bindings of this kind can be safely
	 * cast to <code>IPackageBinding</code>.
	 * 
	 * @see #getKind()
	 * @see IPackageBinding
	 */
	public static final int PACKAGE= 1;

	/**
	 * Kind constant (value 2) indicating a type binding. Bindings of this kind can be safely cast
	 * to <code>ITypeBinding</code>.
	 * 
	 * @see #getKind()
	 * @see ITypeBinding
	 */
	public static final int TYPE= 2;

	/**
	 * Kind constant (value 3) indicating a field or local variable binding. Bindings of this kind
	 * can be safely cast to <code>IVariableBinding</code>.
	 * 
	 * @see #getKind()
	 * @see IVariableBinding
	 */
	public static final int VARIABLE= 3;

	/**
	 * Kind constant (value 4) indicating a method or constructor binding. Bindings of this kind can
	 * be safely cast to <code>IMethodBinding</code>.
	 * 
	 * @see #getKind()
	 * @see IMethodBinding
	 */
	public static final int METHOD= 4;

	/**
	 * Kind constant (value 5) indicating an annotation binding. Bindings of this kind can be safely
	 * cast to <code>IAnnotationBinding</code>.
	 * 
	 * @see #getKind()
	 * @see IAnnotationBinding
	 * @since 3.2
	 */
	public static final int ANNOTATION= 5;

	/**
	 * Kind constant (value 6) indicating a member value pair binding. Bindings of this kind can be
	 * safely cast to <code>IMemberValuePairBinding</code>.
	 * 
	 * @see #getKind()
	 * @see IMemberValuePairBinding
	 * @since 3.2
	 */
	public static final int MEMBER_VALUE_PAIR= 6;

	/**
	 * Return the resolved annotations associated with this binding.
	 * <ul>
	 * <li>Package bindings - these are annotations on a package declaration.</li>
	 * <li>Type bindings - these are annotations on a class, interface, enum, or annotation type
	 * declaration. The result is the same regardless of whether the type is parameterized.</li>
	 * <li>Method bindings - these are annotations on a method or constructor declaration. The
	 * result is the same regardless of whether the method is parameterized.</li>
	 * <li>Variable bindings - these are annotations on a field, enum constant, or formal parameter
	 * declaration.</li>
	 * <li>Annotation bindings - an empty array is always returned</li>
	 * <li>Member value pair bindings - an empty array is always returned</li>
	 * </ul>
	 * 
	 * @return the list of resolved annotations, or the empty list if there are no annotations
	 *         associated with the object
	 * @since 3.2
	 */
	public IAnnotationBinding[] getAnnotations();

	/**
	 * Returns the kind of bindings this is. That is one of the kind constants: <code>PACKAGE</code>
	 * , <code>TYPE</code>, <code>VARIABLE</code>, <code>METHOD</code>, <code>ANNOTATION</code>, or
	 * <code>MEMBER_VALUE_PAIR</code>.
	 * <p>
	 * Note that additional kinds might be added in the future, so clients should not assume this
	 * list is exhaustive and should program defensively, e.g. by having a reasonable default in a
	 * switch statement.
	 * </p>
	 * 
	 * @return one of the kind constants
	 */
	public int getKind();

	/**
	 * Returns the name of this binding. Details of the name are specified with each specific kind
	 * of binding.
	 * 
	 * @return the name of this binding
	 */
	public String getName();

	/**
	 * Returns the modifiers for this binding.
	 * <p>
	 * Note that deprecated is not included among the modifiers. Use <code>isDeprecated</code> to
	 * find out whether a binding is deprecated.
	 * </p>
	 * 
	 * @return the bit-wise or of <code>Modifier</code> constants
	 * @see Modifier
	 */
	public int getModifiers();

	/**
	 * Return whether this binding is for something that is deprecated. A deprecated class,
	 * interface, field, method, or constructor is one that is marked with the 'deprecated' tag in
	 * its Javadoc comment.
	 * 
	 * @return <code>true</code> if this binding is deprecated, and <code>false</code> otherwise
	 */
	public boolean isDeprecated();

	/**
	 * Return whether this binding is created because the bindings recovery is enabled. This binding
	 * is considered to be incomplete. Its internal state might be incomplete.
	 * 
	 * @return <code>true</code> if this binding is a recovered binding, and <code>false</code>
	 *         otherwise
	 * @since 3.3
	 */
	public boolean isRecovered();

	/**
	 * Returns whether this binding is synthetic. A synthetic binding is one that was made up by the
	 * compiler, rather than something declared in the source code. Note that default constructors
	 * (the 0-argument constructor that the compiler generates for class declarations with no
	 * explicit constructors declarations) are not generally considered synthetic (although they may
	 * be if the class itself is synthetic). But see {@link IMethodBinding#isDefaultConstructor()
	 * IMethodBinding.isDefaultConstructor} for cases where the compiled-generated default
	 * constructor can be recognized instead.
	 * 
	 * @return <code>true</code> if this binding is synthetic, and <code>false</code> otherwise
	 * @see IMethodBinding#isDefaultConstructor()
	 */
	public boolean isSynthetic();

	/**
	 * Returns the Java element that corresponds to this binding. Returns <code>null</code> if this
	 * binding has no corresponding Java element.
	 * <p>
	 * For array types, this method returns the Java element that corresponds to the array's element
	 * type. For raw and parameterized types, this method returns the Java element of the erasure.
	 * For annotations, this method returns the Java element of the annotation (i.e. an
	 * {@link IAnnotation}).
	 * </p>
	 * <p>
	 * Here are the cases where a <code>null</code> should be expected:
	 * <ul>
	 * <li>primitive types, including void</li>
	 * <li>null type</li>
	 * <li>wildcard types</li>
	 * <li>capture types</li>
	 * <li>array types of any of the above</li>
	 * <li>the "length" field of an array type</li>
	 * <li>the default constructor of a source class</li>
	 * <li>the constructor of an anonymous class</li>
	 * <li>member value pairs</li>
	 * </ul>
	 * For all other kind of type, method, variable, annotation and package bindings, this method
	 * returns non-<code>null</code>.
	 * </p>
	 * 
	 * @return the Java element that corresponds to this binding, or <code>null</code> if none
	 * @since 3.1
	 */
	public IJavaElement getJavaElement();

	/**
	 * Returns the key for this binding.
	 * <p>
	 * Within a connected cluster of bindings (for example, all bindings reachable from a given
	 * AST), each binding will have a distinct keys. The keys are generated in a manner that is
	 * predictable and as stable as possible. This last property makes these keys useful for
	 * comparing bindings between disconnected clusters of bindings (for example, the bindings
	 * between the "before" and "after" ASTs of the same compilation unit).
	 * </p>
	 * <p>
	 * The exact details of how the keys are generated is unspecified. However, it is a function of
	 * the following information:
	 * <ul>
	 * <li>packages - the name of the package (for an unnamed package, some internal id)</li>
	 * <li>classes or interfaces - the VM name of the type and the key of its package</li>
	 * <li>array types - the key of the component type and number of dimensions</li>
	 * <li>primitive types - the name of the primitive type</li>
	 * <li>fields - the name of the field and the key of its declaring type</li>
	 * <li>methods - the name of the method, the key of its declaring type, and the keys of the
	 * parameter types</li>
	 * <li>constructors - the key of its declaring class, and the keys of the parameter types</li>
	 * <li>local variables - the name of the local variable, the index of the declaring block
	 * relative to its parent, the key of its method</li>
	 * <li>local types - the name of the type, the index of the declaring block relative to its
	 * parent, the key of its method</li>
	 * <li>anonymous types - the occurence count of the anonymous type relative to its declaring
	 * type, the key of its declaring type</li>
	 * <li>enum types - treated like classes</li>
	 * <li>annotation types - treated like interfaces</li>
	 * <li>type variables - the name of the type variable and the key of the generic type or generic
	 * method that declares that type variable</li>
	 * <li>wildcard types - the key of the optional wildcard type bound</li>
	 * <li>capture type bindings - the key of the wildcard captured</li>
	 * <li>generic type instances - the key of the generic type and the keys of the type arguments
	 * used to instantiate it, and whether the instance is explicit (a parameterized type reference)
	 * or implicit (a raw type reference)</li>
	 * <li>generic method instances - the key of the generic method and the keys of the type
	 * arguments used to instantiate it, and whether the instance is explicit (a parameterized
	 * method reference) or implicit (a raw method reference)</li>
	 * <li>members of generic type instances - the key of the generic type instance and the key of
	 * the corresponding member in the generic type</li>
	 * <li>annotations - the key of the annotated element and the key of the annotation type</li>
	 * </ul>
	 * </p>
	 * <p>
	 * Note that the key for member value pair bindings is not yet implemented. This returns
	 * <code>null</code> for this kind of bindings.<br>
	 * Recovered bindings have a unique key.
	 * </p>
	 * 
	 * @return the key for this binding
	 */
	public String getKey();

	/**
	 * There is no special definition of equality for bindings; equality is simply object identity.
	 * Within the context of a single cluster of bindings, each binding is represented by a distinct
	 * object. However, between different clusters of bindings, the binding objects may or may not
	 * be different; in these cases, the client should compare bindings using
	 * {@link #isEqualTo(IBinding)}, which checks their keys.
	 * 
	 * @param obj {@inheritDoc}
	 * @return {@inheritDoc}
	 */
	public boolean equals(Object obj);

	/**
	 * Returns whether this binding has the same key as that of the given binding. Within the
	 * context of a single cluster of bindings, each binding is represented by a distinct object.
	 * However, between different clusters of bindings, the binding objects may or may not be
	 * different objects; in these cases, the binding keys are used where available.
	 * 
	 * @param binding the other binding, or <code>null</code>
	 * @return <code>true</code> if the given binding is the identical object as this binding, or if
	 *         the keys of both bindings are the same string; <code>false</code> if the given
	 *         binding is <code>null</code>, or if the bindings do not have the same key, or if one
	 *         or both of the bindings have no key
	 * @see #getKey()
	 * @since 3.1
	 */
	public boolean isEqualTo(IBinding binding);

	/**
	 * Returns a string representation of this binding suitable for debugging purposes only.
	 * 
	 * @return a debug string
	 */
	public String toString();
}