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AspectJ tools most notably contains the AspectJ compiler (AJC). AJC applies aspects to Java classes during compilation, fully replacing Javac for plain Java classes and also compiling native AspectJ or annotation-based @AspectJ syntax. Furthermore, AJC can weave aspects into existing class files in a post-compile binary weaving step. This library is a superset of AspectJ weaver and hence also of AspectJ runtime.

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/*******************************************************************************
 * Copyright (c) 2004, 2005 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.core.runtime.content;

import org.eclipse.core.internal.content.IContentConstants;
import org.eclipse.core.runtime.QualifiedName;

/**
 * A content description object contains information about the nature of
 * arbitrary data.
 * 
 * A content description object will always include the content type for the
 * examined contents, and may also include information on:
 * 
 * 
 * charset;
 * byte order mark;
 * other custom properties provided by third-party plug-ins.
 * 
 * 
 * Content describers provided by plug-ins will fill in most of the
 * properties in a content description object, except for the content type,
 * what is done by the platform. After a content
 * description is filled in by a content interpreter, it is marked as immutable
 * by the platform, so calling any of the mutator methods defined in this
 * interface will cause an IllegalStateException to be thrown.
 * 
 * 
 * Default values for properties can be contributed by plug-ins as part of
 * the content type definition markup.
 * 
 * 
 * This interface is not intended to be implemented by clients.
 * 
 *
 * @see IContentDescriber
 * @since 3.0
 */
public interface IContentDescription {
	/**
	 * Key for the "charset" property.
	 */
	QualifiedName CHARSET = new QualifiedName(IContentConstants.RUNTIME_NAME, "charset"); //$NON-NLS-1$
	/**
	 * Key for the "byte order mark" property. This property is only meaningful
	 * when describing byte streams.
	 */
	QualifiedName BYTE_ORDER_MARK = new QualifiedName(IContentConstants.RUNTIME_NAME, "bom"); //$NON-NLS-1$
	/**
	 * Options constant meaning that all properties should be described.
	 */
	QualifiedName[] ALL = null;
	/**
	 * Constant that identifies the Byte-Order-Mark for contents encoded with
	 * the UTF-8 character encoding scheme.
	 */
	byte[] BOM_UTF_8 = {(byte) 0xEF, (byte) 0xBB, (byte) 0xBF};
	/**
	 * Constant that identifies the Byte-Order-Mark for contents encoded with
	 * the UTF-16 Big Endian character encoding scheme.
	 */
	byte[] BOM_UTF_16BE = {(byte) 0xFE, (byte) 0xFF};
	/**
	 * Constant that identifies the Byte-Order-Mark for contents encoded with
	 * the UTF-16 Little Endian character encoding scheme.
	 */
	byte[] BOM_UTF_16LE = {(byte) 0xFF, (byte) 0xFE};

	/**
	 * Returns whether the given property is requested to be described. This
	 * method is intended to allow content describers to determine  which
	 * properties should be described.
	 *
	 * @param key a key for the property to be verified
	 * @return true if the property is to be described,
	 * false otherwise
	 */
	boolean isRequested(QualifiedName key);

	/**
	 * Returns the charset name to be used when reading the contents
	 * described by this object.
	 * 
	 * If a Unicode byte order mark has been found (the
	 * BYTE_ORDER_MARK property has been set),
	 * a corresponding charset name will be returned (e.g. "UTF-8",
	 * "UTF-16"). Otherwise, the value of the CHARSET
	 * property will be returned.
	 * 
	 * @return a charset name, or null
	 */
	String getCharset();

	/**
	 * Returns the content type detected. Returns null if the
	 * content type could not be determined.
	 *
	 * @return the corresponding content type, or null
	 */
	IContentType getContentType();

	/**
	 * Returns the value of custom property set by the content describer,
	 * or the default value for the property, if one has been defined.
	 * 
	 * The qualifier part of the property name must be the unique identifier
	 * of the declaring plug-in (e.g. "com.example.plugin").
	 * 
	 *
	 * @param key the property key
	 * @return the property value, or null, if the property is not
	 * found
	 */
	Object getProperty(QualifiedName key);

	/**
	 * Sets the given property to the given value.
	 * 
	 * The qualifier part of the property name must be the unique identifier
	 * of the declaring plug-in (e.g. "com.example.plugin").
	 * 
	 * 
	 * This method should not be called by clients other than content
	 * describers. An attempt to set a property from other contexts will cause
	 * an IllegalStateException to be thrown.
	 * 
	 *
	 * @param key the qualified name of the property
	 * @param value the property value, or null,
	 * if the property is to be removed
	 * @throws IllegalStateException if called after this description has been
	 * filled in
	 */
	void setProperty(QualifiedName key, Object value);
}