IAccessRule.java

/*******************************************************************************
 * Copyright (c) 2000, 2008 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;

import org.eclipse.core.runtime.IPath;

/**
 * Describes an access rule to source and class files on a classpath entry. An access rule is
 * composed of a file pattern and a kind (accessible, non accessible, or discouraged).
 * <p>
 * On a given classpath entry, the access rules are considered in the order given when the entry was
 * created. When a source or class file matches an access rule's pattern, the access rule's kind
 * define whether the file is considered accessible, non accessible, or its access is discouraged.
 * If the source or class file doesn't match any accessible rule, it is considered accessible. A
 * source or class file that is not accessible or discouraged can still be refered to but it is
 * tagged as being not accessible - the Java builder will create a problem marker for example. The
 * severity of the marker created from a non accessible rule is controled through the
 * {@link JavaCore#COMPILER_PB_FORBIDDEN_REFERENCE} compiler option. The severity of the marker
 * created from a discouraged rule is controled through the
 * {@link JavaCore#COMPILER_PB_DISCOURAGED_REFERENCE} compiler option. Note this is different from
 * inclusion and exclusion patterns on source classpath entries, where a source file that is
 * excluded is not even compiled. Files patterns look like relative file paths with wildcards and
 * are interpreted relative to each entry's path. File patterns are case-sensitive and they can
 * contain '**', '*' or '?' wildcards (see {@link IClasspathEntry#getExclusionPatterns()} for the
 * full description of their syntax and semantics). Note that file patterns must not include the
 * file extension. <code>com/xyz/tests/MyClass</code> is a valid file pattern, whereas
 * <code>com/xyz/tests/MyClass.class</code> is not valid.
 * </p>
 * <p>
 * For example, if one of the entry path is <code>/Project/someLib.jar</code>, there are no
 * accessible rules, and there is one non accessible rule whith pattern
 * <code>com/xyz/tests/**</code>, then class files like
 * <code>/Project/someLib.jar/com/xyz/Foo.class</code> and
 * <code>/Project/someLib.jar/com/xyz/utils/Bar.class</code> would be accessible, whereas
 * <code>/Project/someLib.jar/com/xyz/tests/T1.class</code> and
 * <code>/Project/someLib.jar/com/xyz/tests/quick/T2.class</code> would not be accessible.
 * </p>
 * <p>
 * This interface is not intended to be implemented by clients.
 * </p>
 * 
 * @since 3.1
 */
public interface IAccessRule {

	/**
	 * Constant indicating that files matching the rule's pattern are accessible.
	 */
	int K_ACCESSIBLE= 0;

	/**
	 * Constant indicating that files matching the rule's pattern are non accessible.
	 */
	int K_NON_ACCESSIBLE= 1;

	/**
	 * Constant indicating that access to the files matching the rule's pattern is discouraged.
	 */
	int K_DISCOURAGED= 2;

	/**
	 * <p>
	 * Flag indicating that whether a type matching this rule should be ignored iff a type with the
	 * same qualified name can be found on a later classpath entry with a better accessibility.
	 * </p>
	 * <p>
	 * E.g. if a type p.X matches a rule K_NON_ACCESSIBLE | IGNORE_IF_BETTER on a library entry
	 * 'lib1' and another type p.X also matches a rule K_DISCOURAGED on library entry 'lib2' ('lib2'
	 * being after 'lib1' on the classpath), then p.X from 'lib2' will be used and reported as
	 * discouraged.
	 * </p>
	 * 
	 * @since 3.2
	 */
	int IGNORE_IF_BETTER= 0x100;

	/**
	 * Returns the file pattern for this access rule.
	 * 
	 * @return the file pattern for this access rule
	 */
	IPath getPattern();

	/**
	 * Returns the kind of this access rule (one of {@link #K_ACCESSIBLE}, {@link #K_NON_ACCESSIBLE}
	 * or {@link #K_DISCOURAGED}).
	 * 
	 * @return the kind of this access rule
	 */
	int getKind();

	/**
	 * <p>
	 * Returns whether a type matching this rule should be ignored iff a type with the same
	 * qualified name can be found on a later classpath entry with a better accessibility.
	 * </p>
	 * <p>
	 * E.g. if a type p.X matches a rule K_NON_ACCESSIBLE | IGNORE_IF_BETTER on a library entry
	 * 'lib1' and another type p.X also matches a rule K_DISCOURAGED on library entry 'lib2' ('lib2'
	 * being after 'lib1' on the classpath), then p.X from 'lib2' will be used and reported as
	 * discouraged.
	 * </p>
	 * 
	 * @return whether a type matching this rule should be ignored iff a type with the same
	 *         qualified name can be found on a later classpath entry with a better accessibility
	 * @since 3.2
	 */
	boolean ignoreIfBetter();

}