001    /*
002     * Copyright 2005 Stephen J. McConnell.
003     *
004     * Licensed  under the  Apache License,  Version 2.0  (the "License");
005     * you may not use  this file  except in  compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     *   http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed  under the  License is distributed on an "AS IS" BASIS,
012     * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
013     * implied.
014     *
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package net.dpml.lang;
020    
021    import java.io.Writer;
022    import java.io.IOException;
023    
024    /**
025     * Utility class used as a destination during generalized object encoding.
026     *
027     * @author <a href="http://www.dpml.net">Digital Product Management Library</a>
028     * @version 2.1.0
029     */
030    public final class Buffer
031    {
032        private final String m_namespace;
033        private final String m_pad;
034        private final Writer m_writer;
035        
036       /**
037        * Construct a new encoding buffer.
038        *
039        * @param writer the output stream writer
040        * @param namespace the current namespace
041        * @param pad the current offset
042        * @exception NullPointerException of the writer or namespace arguments are null
043        */
044        public Buffer( final Writer writer, final String namespace, final String pad ) throws NullPointerException
045        {
046            if( null == writer )
047            {
048                throw new NullPointerException( "writer" );
049            }
050            if( null == namespace )
051            {
052                throw new NullPointerException( "namespace" );
053            }
054            if( null == pad )
055            {
056                m_pad = "";
057            }
058            else
059            {
060                m_pad = pad;
061            }
062            m_namespace = namespace;
063            m_writer = writer;
064        }
065        
066       /**
067        * Get the current namespace.
068        * @return the namespace
069        */
070        public String getEnclosingNamespace()
071        {
072            return m_namespace;
073        }
074        
075       /**
076        * Get the space indent offset.
077        * @return the offset value
078        */
079        public String getOffset()
080        {
081            return m_pad;
082        }
083        
084       /**
085        * Write a value to the buffer.
086        * @param value the value to write to the buffer
087        * @exception IOException if an IO error occurs
088        */
089        public void write( String value ) throws IOException
090        {
091            m_writer.write( value );
092        }
093        
094       /**
095        * Write an int value to the buffer.
096        * @param n the int value to write to the buffer
097        * @exception IOException if an IO error occurs
098        */
099        public void write( int n ) throws IOException
100        {
101            m_writer.write( n );
102        }
103        
104       /**
105        * Write an character array value to the buffer.
106        * @param array the array value to write to the buffer
107        * @exception IOException if an IO error occurs
108        */
109        public void write( char[] array ) throws IOException
110        {
111            m_writer.write( array );
112        }
113        
114       /**
115        * Write a value to the buffer following a nl character.
116        * @param value the value to write to the buffer
117        * @exception IOException if an IO error occurs
118        */
119        public void nl( String value ) throws IOException
120        {
121            m_writer.write( "\n" + m_pad + value );
122        }
123        
124       /**
125        * Write an int value to the buffer following a nl character.
126        * @param n the int value to write to the buffer
127        * @exception IOException if an IO error occurs
128        */
129        public void nl( int n ) throws IOException
130        {
131            m_writer.write( "\n" + m_pad + n );
132        }
133        
134       /**
135        * Write an character array value to the buffer following a nl character.
136        * @param array the array value to write to the buffer
137        * @exception IOException if an IO error occurs
138        */
139        public void nl( char[] array ) throws IOException
140        {
141            m_writer.write( "\n" + m_pad );
142            m_writer.write( array );
143        }
144        
145       /**
146        * Indent the current offset value by 2 space characters.
147        * @return a buffer
148        */
149        public Buffer indent()
150        {
151            return indent( "  " );
152        }
153        
154       /**
155        * Indent the current offset value by a supplied value.
156        * @param indent the indent value
157        * @return a new buffer
158        */
159        public Buffer indent( String indent )
160        {
161            return new Buffer( m_writer, m_namespace, m_pad + indent );
162        }
163        
164       /**
165        * Test id the supplied namespace is the current namesapce.
166        * @param namespace to namespace to compare with the current namespace
167        * @return true if the namesapce is current
168        */
169        public boolean isNamespace( String namespace )
170        {
171            return m_namespace.equals( namespace );
172        }
173        
174       /**
175        * Creation of a new buffer mapped to the supplied namespace.
176        * @param namespace the namespace
177        * @return a buffer
178        */
179        public Buffer namespace( String namespace )
180        {
181            if( m_namespace.equals( namespace ) )
182            {
183                return this;
184            }
185            else
186            {
187                return new Buffer( m_writer, namespace, m_pad );
188            }
189        }
190    }