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     */
020    package org.apache.directory.shared.asn1.ber.grammar;
021    
022    
023    import org.apache.directory.shared.asn1.ber.IAsn1Container;
024    import org.apache.directory.shared.asn1.codec.DecoderException;
025    import org.apache.directory.shared.asn1.util.Asn1StringUtils;
026    import org.apache.directory.shared.i18n.I18n;
027    
028    import org.slf4j.Logger;
029    import org.slf4j.LoggerFactory;
030    
031    
032    /**
033     * The abstract IGrammar which is the Mother of all the grammars. It contains
034     * the transitions table.
035     * 
036     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
037     * @version $Rev: 912399 $, $Date: 2010-02-21 21:52:31 +0100 (Sun, 21 Feb 2010) $
038     */
039    public abstract class AbstractGrammar implements IGrammar
040    {
041        // ~ Static fields/initializers
042        // -----------------------------------------------------------------
043    
044        /** The logger */
045        private static final Logger log = LoggerFactory.getLogger( AbstractGrammar.class );
046    
047        /** Speedup for logs */
048        private static final boolean IS_DEBUG = log.isDebugEnabled();
049    
050        // ~ Instance fields
051        // ----------------------------------------------------------------------------
052    
053        /**
054         * Table of transitions. It's a two dimension array, the first dimension
055         * indice the states, the second dimension indices the Tag value, so it is
056         * 256 wide.
057         */
058        protected GrammarTransition[][] transitions;
059    
060        /** The grammar name */
061        protected String name;
062    
063        /** The grammar's states */
064        protected IStates statesEnum;
065    
066        /** Default constructor */
067        public AbstractGrammar()
068        {
069        }
070    
071    
072        // ~ Methods
073        // ------------------------------------------------------------------------------------
074    
075        /**
076         * Return the grammar's name
077         * 
078         * @return The grammar name
079         */
080        public String getName()
081        {
082            return name;
083        }
084    
085    
086        /**
087         * Set the grammar's name
088         * 
089         * @param name The new grammar name
090         */
091        public void setName( String name )
092        {
093            this.name = name;
094        }
095    
096        /**
097         * Get the transition associated with the state and tag
098         * 
099         * @param state The current state
100         * @param tag The current tag
101         * @return A valid transition if any, or null.
102         */
103        public GrammarTransition getTransition( int state, int tag )
104        {
105            return transitions[state][tag & 0x00FF];
106        }
107    
108    
109        /**
110         * The main function. This is where an action is executed. If the action is
111         * null, nothing is done.
112         * 
113         * @param container The Asn1Container
114         * @throws DecoderException Thrown if anything went wrong
115         */
116        public void executeAction( IAsn1Container container ) throws DecoderException
117        {
118    
119            int currentState = container.getTransition();
120            IGrammar currentGrammar = container.getGrammar();
121    
122            // We have to deal with the special case of a GRAMMAR_END state
123            if ( currentState == IStates.END_STATE )
124            {
125                return;
126            }
127    
128            byte tagByte = container.getCurrentTLV().getTag();
129    
130            // We will loop until no more actions are to be executed
131            GrammarTransition transition = ( ( AbstractGrammar ) container.getGrammar() ).getTransition( currentState, tagByte );
132    
133            if ( transition == null )
134            {
135    
136                String errorMessage = I18n.err( I18n.ERR_00001, currentGrammar.getStatesEnum().getState( currentState ), 
137                            Asn1StringUtils.dumpByte( tagByte ) );
138    
139                log.error( errorMessage );
140    
141                // If we have no more grammar on the stack, then this is an
142                // error
143                throw new DecoderException( I18n.err( I18n.ERR_00002 ) );
144            }
145    
146            if ( IS_DEBUG )
147            {
148                log.debug( transition.toString( currentGrammar.getStatesEnum() ) );
149            }
150    
151            if ( transition.hasAction() )
152            {
153                transition.getAction().action( container );
154            }
155    
156            container.setTransition( transition.getCurrentState() );
157        }
158    
159    
160        /**
161         * Get the states of the current grammar
162         * 
163         * @return Returns the statesEnum.
164         */
165        public IStates getStatesEnum()
166        {
167            return statesEnum;
168        }
169    
170    
171        /**
172         * Set the states for this grammar
173         * 
174         * @param statesEnum The statesEnum to set.
175         */
176        public void setStatesEnum( IStates statesEnum )
177        {
178            this.statesEnum = statesEnum;
179        }
180    }