001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.directory.api.asn1.ber.grammar;
021
022
023import org.apache.directory.api.asn1.DecoderException;
024import org.apache.directory.api.asn1.ber.Asn1Container;
025import org.apache.directory.api.asn1.util.Asn1StringUtils;
026import org.apache.directory.api.i18n.I18n;
027import org.slf4j.Logger;
028import org.slf4j.LoggerFactory;
029
030
031/**
032 * The abstract Grammar which is the Mother of all the grammars. It contains
033 * the transitions table.
034 *
035 * @param <C> The container type
036 * 
037 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
038 */
039public abstract class AbstractGrammar<C extends Asn1Container> implements Grammar<C>
040{
041    /** The logger */
042    private static final Logger LOG = LoggerFactory.getLogger( AbstractGrammar.class );
043
044    /**
045     * Table of transitions. It's a two dimension array, the first dimension
046     * indices the states, the second dimension indices the Tag value, so it is
047     * 256 wide.
048     */
049    protected GrammarTransition<C>[][] transitions;
050
051    /** The grammar name */
052    private String name;
053
054
055    /** Default constructor */
056    public AbstractGrammar()
057    {
058    }
059
060
061    /**
062     * {@inheritDoc}
063     */
064    @Override
065    public String getName()
066    {
067        return name;
068    }
069
070
071    /**
072     * {@inheritDoc}
073     */
074    @Override
075    public void setName( String name )
076    {
077        this.name = name;
078    }
079
080
081    /**
082     * Get the transition associated with the state and tag
083     *
084     * @param state The current state
085     * @param tag The current tag
086     * @return A valid transition if any, or null.
087     */
088    public GrammarTransition<C> getTransition( Enum<?> state, int tag )
089    {
090        return transitions[state.ordinal()][tag & 0x00FF];
091    }
092
093
094    /**
095     * {@inheritDoc}
096     */
097    @Override
098    public void executeAction( C container ) throws DecoderException
099    {
100
101        Enum<?> currentState = container.getTransition();
102        // We have to deal with the special case of a GRAMMAR_END state
103        if ( ( ( States ) currentState ).isEndState() )
104        {
105            return;
106        }
107
108        byte tagByte = container.getCurrentTLV().getTag();
109
110        // We will loop until no more actions are to be executed
111        @SuppressWarnings("unchecked")
112        GrammarTransition<C> transition = ( ( AbstractGrammar<C> ) container.getGrammar() ).getTransition(
113            currentState,
114            tagByte );
115
116        if ( transition == null )
117        {
118            String errorMessage = I18n.err( I18n.ERR_01200_BAD_TRANSITION_FROM_STATE, currentState,
119                Asn1StringUtils.dumpByte( tagByte ) );
120
121            LOG.error( errorMessage );
122
123            // If we have no more grammar on the stack, then this is an
124            // error
125            throw new DecoderException( errorMessage );
126        }
127
128        if ( LOG.isDebugEnabled() )
129        {
130            LOG.debug( transition.toString() );
131        }
132
133        if ( transition.hasAction() )
134        {
135            Action<C> action = transition.getAction();
136            action.action( container );
137        }
138
139        container.setTransition( transition.getCurrentState() );
140    }
141}