| /* Assembly.java -- |
| Copyright (C) 2003, 2006 Free Software Foundation, Inc. |
| |
| This file is a part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or (at |
| your option) any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; if not, write to the Free Software |
| Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 |
| USA |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.javax.crypto.assembly; |
| |
| import java.util.Map; |
| |
| /** |
| * An <code>Assembly</code> is a construction consisting of a chain of |
| * {@link Transformer} elements; each wired in pre- or post- transformation |
| * mode. This chain is terminated by one <code>LoopbackTransformer</code> |
| * element. |
| * <p> |
| * Once constructed, and correctly initialised, the bulk of the methods |
| * available on the <code>Assembly</code> are delegated to the <i>head</i> of |
| * the {@link Transformer} chain of the <code>Assembly</code>. |
| * |
| * @see Transformer |
| */ |
| public class Assembly |
| { |
| public static final String DIRECTION = "gnu.crypto.assembly.assembly.direction"; |
| |
| /** Flag that tells if the instance is initialised or not; and if yes how. */ |
| private Direction wired; |
| |
| /** The first Transformer in the chain. */ |
| private Transformer head; |
| |
| /** |
| * Trivial constructor that sets the <i>chain</i> to a |
| * <code>LoopbackTransformer</code>. |
| */ |
| public Assembly() |
| { |
| super(); |
| |
| wired = null; |
| head = new LoopbackTransformer(); |
| } |
| |
| /** |
| * Adds the designated {@link Transformer} and signals that it should operate |
| * in pre-processing mode; i.e. it should apply its internal transformation |
| * algorithm on the input data stream, <b>before</b> it passes that stream to |
| * the next element in the <i>chain</i>. |
| * |
| * @param t the {@link Transformer} to add at the head of the current chain. |
| * @throws IllegalArgumentException if the designated {@link Transformer} has |
| * a non-null tail; i.e. it is already an element of a chain. |
| */ |
| public void addPreTransformer(Transformer t) |
| { |
| wireTransformer(t, Operation.PRE_PROCESSING); |
| } |
| |
| /** |
| * Adds the designated {@link Transformer} and signals that it should operate |
| * in post-processing mode; i.e. it should apply its internal transformation |
| * algorithm on the input data stream, <b>after</b> it passes that stream to |
| * the next element in the <i>chain</i>. |
| * |
| * @param t the {@link Transformer} to add at the head of the current chain. |
| * @throws IllegalArgumentException if the designated {@link Transformer} has |
| * a non-null tail; i.e. it is already an element of a chain. |
| */ |
| public void addPostTransformer(Transformer t) |
| { |
| wireTransformer(t, Operation.POST_PROCESSING); |
| } |
| |
| /** |
| * Initialises the <code>Assembly</code> for operation with specific |
| * characteristics. |
| * |
| * @param attributes a set of name-value pairs that describes the desired |
| * future behaviour of this instance. |
| * @throws IllegalStateException if the instance is already initialised. |
| */ |
| public void init(Map attributes) throws TransformerException |
| { |
| if (wired != null) |
| throw new IllegalStateException(); |
| Direction flow = (Direction) attributes.get(DIRECTION); |
| if (flow == null) |
| flow = Direction.FORWARD; |
| attributes.put(Transformer.DIRECTION, flow); |
| head.init(attributes); |
| wired = flow; |
| } |
| |
| /** |
| * Resets the <code>Assembly</code> for re-initialisation and use with other |
| * characteristics. This method always succeeds. |
| */ |
| public void reset() |
| { |
| head.reset(); |
| wired = null; |
| } |
| |
| /** |
| * Convenience method that calls the method with same name and three |
| * arguments, using a byte array of length <code>1</code> whose contents are |
| * the designated byte. |
| * |
| * @param b the byte to process. |
| * @return the result of transformation. |
| * @throws IllegalStateException if the instance is not initialised. |
| * @throws TransformerException if a transformation-related exception occurs |
| * during the operation. |
| * @see #update(byte[], int, int) |
| */ |
| public byte[] update(byte b) throws TransformerException |
| { |
| return update(new byte[] { b }, 0, 1); |
| } |
| |
| /** |
| * Convenience method that calls the method with same name and three |
| * arguments. All bytes in <code>in</code>, starting from index position |
| * <code>0</code> are considered. |
| * |
| * @param in the input data bytes. |
| * @return the result of transformation. |
| * @throws IllegalStateException if the instance is not initialised. |
| * @throws TransformerException if a transformation-related exception occurs |
| * during the operation. |
| * @see #update(byte[], int, int) |
| */ |
| public byte[] update(byte[] in) throws TransformerException |
| { |
| return update(in, 0, in.length); |
| } |
| |
| /** |
| * Processes a designated number of bytes from a given byte array. |
| * |
| * @param in the input data bytes. |
| * @param offset index of <code>in</code> from which to start considering |
| * data. |
| * @param length the count of bytes to process. |
| * @return the result of transformation. |
| * @throws IllegalStateException if the instance is not initialised. |
| * @throws TransformerException if a transformation-related exception occurs |
| * during the operation. |
| */ |
| public byte[] update(byte[] in, int offset, int length) |
| throws TransformerException |
| { |
| if (wired == null) |
| throw new IllegalStateException(); |
| return head.update(in, offset, length); |
| } |
| |
| /** |
| * Convenience method that calls the method with same name and three arguments |
| * using a 0-long byte array. |
| * |
| * @return the result of transformation. |
| * @throws IllegalStateException if the instance is not initialised. |
| * @throws TransformerException if a transformation-related exception occurs |
| * during the operation. |
| * @see #lastUpdate(byte[], int, int) |
| */ |
| public byte[] lastUpdate() throws TransformerException |
| { |
| return lastUpdate(new byte[0], 0, 0); |
| } |
| |
| /** |
| * Convenience method that calls the method with same name and three |
| * arguments, using a byte array of length <code>1</code> whose contents are |
| * the designated byte. |
| * |
| * @param b the byte to process. |
| * @return the result of transformation. |
| * @throws IllegalStateException if the instance is not initialised. |
| * @throws TransformerException if a transformation-related exception occurs |
| * during the operation. |
| * @see #lastUpdate(byte[], int, int) |
| */ |
| public byte[] lastUpdate(byte b) throws TransformerException |
| { |
| return lastUpdate(new byte[] { b }, 0, 1); |
| } |
| |
| /** |
| * Convenience method that calls the method with same name and three |
| * arguments. All bytes in <code>in</code>, starting from index position |
| * <code>0</code> are considered. |
| * |
| * @param in the input data bytes. |
| * @return the result of transformation. |
| * @throws IllegalStateException if the instance is not initialised. |
| * @throws TransformerException if a transformation-related exception occurs |
| * during the operation. |
| * @see #lastUpdate(byte[], int, int) |
| */ |
| public byte[] lastUpdate(byte[] in) throws TransformerException |
| { |
| return lastUpdate(in, 0, in.length); |
| } |
| |
| /** |
| * Processes a designated number of bytes from a given byte array and signals, |
| * at the same time, that this is the last <i>push</i> operation for this |
| * <code>Assembly</code>. |
| * |
| * @param in the input data bytes. |
| * @param offset index of <code>in</code> from which to start considering |
| * data. |
| * @param length the count of bytes to process. |
| * @return the result of transformation. |
| * @throws IllegalStateException if the instance is not initialised. |
| * @throws TransformerException if a transformation-related exception occurs |
| * during the operation. |
| */ |
| public byte[] lastUpdate(byte[] in, int offset, int length) |
| throws TransformerException |
| { |
| if (wired == null) |
| throw new IllegalStateException(); |
| byte[] result = head.lastUpdate(in, offset, length); |
| reset(); |
| return result; |
| } |
| |
| private void wireTransformer(Transformer t, Operation mode) |
| { |
| if (t.tail != null) |
| throw new IllegalArgumentException(); |
| t.setMode(mode); |
| t.tail = head; |
| head = t; |
| } |
| } |