Coverage Report - org.apache.commons.io.input.NullReader
 
Classes in this File Line Coverage Branch Coverage Complexity
NullReader
96%
61/63
100%
26/26
2.6
 
 1  
 /*
 2  
  * Licensed to the Apache Software Foundation (ASF) under one or more
 3  
  * contributor license agreements.  See the NOTICE file distributed with
 4  
  * this work for additional information regarding copyright ownership.
 5  
  * The ASF licenses this file to You under the Apache License, Version 2.0
 6  
  * (the "License"); you may not use this file except in compliance with
 7  
  * the License.  You may obtain a copy of the License at
 8  
  * 
 9  
  *      http://www.apache.org/licenses/LICENSE-2.0
 10  
  * 
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 package org.apache.commons.io.input;
 18  
 
 19  
 import static org.apache.commons.io.IOUtils.EOF;
 20  
 
 21  
 import java.io.EOFException;
 22  
 import java.io.IOException;
 23  
 import java.io.Reader;
 24  
 
 25  
 /**
 26  
  * A functional, light weight {@link Reader} that emulates
 27  
  * a reader of a specified size.
 28  
  * <p>
 29  
  * This implementation provides a light weight
 30  
  * object for testing with an {@link Reader}
 31  
  * where the contents don't matter.
 32  
  * <p>
 33  
  * One use case would be for testing the handling of
 34  
  * large {@link Reader} as it can emulate that
 35  
  * scenario without the overhead of actually processing
 36  
  * large numbers of characters - significantly speeding up
 37  
  * test execution times.
 38  
  * <p>
 39  
  * This implementation returns a space from the method that
 40  
  * reads a character and leaves the array unchanged in the read
 41  
  * methods that are passed a character array.
 42  
  * If alternative data is required the <code>processChar()</code> and
 43  
  * <code>processChars()</code> methods can be implemented to generate
 44  
  * data, for example:
 45  
  *
 46  
  * <pre>
 47  
  *  public class TestReader extends NullReader {
 48  
  *      public TestReader(int size) {
 49  
  *          super(size);
 50  
  *      }
 51  
  *      protected char processChar() {
 52  
  *          return ... // return required value here
 53  
  *      }
 54  
  *      protected void processChars(char[] chars, int offset, int length) {
 55  
  *          for (int i = offset; i &lt; length; i++) {
 56  
  *              chars[i] = ... // set array value here
 57  
  *          }
 58  
  *      }
 59  
  *  }
 60  
  * </pre>
 61  
  *
 62  
  * @since 1.3
 63  
  * @version $Id: NullReader.java 1586350 2014-04-10 15:57:20Z ggregory $
 64  
  */
 65  
 public class NullReader extends Reader {
 66  
 
 67  
     private final long size;
 68  
     private long position;
 69  9
     private long mark = -1;
 70  
     private long readlimit;
 71  
     private boolean eof;
 72  
     private final boolean throwEofException;
 73  
     private final boolean markSupported;
 74  
 
 75  
     /**
 76  
      * Create a {@link Reader} that emulates a specified size
 77  
      * which supports marking and does not throw EOFException.
 78  
      *
 79  
      * @param size The size of the reader to emulate.
 80  
      */
 81  
     public NullReader(final long size) {
 82  5
        this(size, true, false);
 83  5
     }
 84  
 
 85  
     /**
 86  
      * Create a {@link Reader} that emulates a specified
 87  
      * size with option settings.
 88  
      *
 89  
      * @param size The size of the reader to emulate.
 90  
      * @param markSupported Whether this instance will support
 91  
      * the <code>mark()</code> functionality.
 92  
      * @param throwEofException Whether this implementation
 93  
      * will throw an {@link EOFException} or return -1 when the
 94  
      * end of file is reached.
 95  
      */
 96  9
     public NullReader(final long size, final boolean markSupported, final boolean throwEofException) {
 97  9
        this.size = size;
 98  9
        this.markSupported = markSupported;
 99  9
        this.throwEofException = throwEofException;
 100  9
     }
 101  
 
 102  
     /**
 103  
      * Return the current position.
 104  
      *
 105  
      * @return the current position.
 106  
      */
 107  
     public long getPosition() {
 108  31
         return position;
 109  
     }
 110  
 
 111  
     /**
 112  
      * Return the size this {@link Reader} emulates.
 113  
      *
 114  
      * @return The size of the reader to emulate.
 115  
      */
 116  
     public long getSize() {
 117  0
         return size;
 118  
     }
 119  
 
 120  
     /**
 121  
      * Close this Reader - resets the internal state to
 122  
      * the initial values.
 123  
      *
 124  
      * @throws IOException If an error occurs.
 125  
      */
 126  
     @Override
 127  
     public void close() throws IOException {
 128  9
         eof = false;
 129  9
         position = 0;
 130  9
         mark = -1;
 131  9
     }
 132  
 
 133  
     /**
 134  
      * Mark the current position.
 135  
      *
 136  
      * @param readlimit The number of characters before this marked position
 137  
      * is invalid.
 138  
      * @throws UnsupportedOperationException if mark is not supported.
 139  
      */
 140  
     @Override
 141  
     public synchronized void mark(final int readlimit) {
 142  2
         if (!markSupported) {
 143  1
             throw new UnsupportedOperationException("Mark not supported");
 144  
         }
 145  1
         mark = position;
 146  1
         this.readlimit = readlimit;
 147  1
     }
 148  
 
 149  
     /**
 150  
      * Indicates whether <i>mark</i> is supported.
 151  
      *
 152  
      * @return Whether <i>mark</i> is supported or not.
 153  
      */
 154  
     @Override
 155  
     public boolean markSupported() {
 156  2
         return markSupported;
 157  
     }
 158  
 
 159  
     /**
 160  
      * Read a character.
 161  
      *
 162  
      * @return Either The character value returned by <code>processChar()</code>
 163  
      * or <code>-1</code> if the end of file has been reached and
 164  
      * <code>throwEofException</code> is set to {@code false}.
 165  
      * @throws EOFException if the end of file is reached and
 166  
      * <code>throwEofException</code> is set to {@code true}.
 167  
      * @throws IOException if trying to read past the end of file.
 168  
      */
 169  
     @Override
 170  
     public int read() throws IOException {
 171  30
         if (eof) {
 172  1
             throw new IOException("Read after end of file");
 173  
         }
 174  29
         if (position == size) {
 175  2
             return doEndOfFile();
 176  
         }
 177  27
         position++;
 178  27
         return processChar();
 179  
     }
 180  
 
 181  
     /**
 182  
      * Read some characters into the specified array.
 183  
      *
 184  
      * @param chars The character array to read into
 185  
      * @return The number of characters read or <code>-1</code>
 186  
      * if the end of file has been reached and
 187  
      * <code>throwEofException</code> is set to {@code false}.
 188  
      * @throws EOFException if the end of file is reached and
 189  
      * <code>throwEofException</code> is set to {@code true}.
 190  
      * @throws IOException if trying to read past the end of file.
 191  
      */
 192  
     @Override
 193  
     public int read(final char[] chars) throws IOException {
 194  1048582
         return read(chars, 0, chars.length);
 195  
     }
 196  
 
 197  
     /**
 198  
      * Read the specified number characters into an array.
 199  
      *
 200  
      * @param chars The character array to read into.
 201  
      * @param offset The offset to start reading characters into.
 202  
      * @param length The number of characters to read.
 203  
      * @return The number of characters read or <code>-1</code>
 204  
      * if the end of file has been reached and
 205  
      * <code>throwEofException</code> is set to {@code false}.
 206  
      * @throws EOFException if the end of file is reached and
 207  
      * <code>throwEofException</code> is set to {@code true}.
 208  
      * @throws IOException if trying to read past the end of file.
 209  
      */
 210  
     @Override
 211  
     public int read(final char[] chars, final int offset, final int length) throws IOException {
 212  1048584
         if (eof) {
 213  1
             throw new IOException("Read after end of file");
 214  
         }
 215  1048583
         if (position == size) {
 216  4
             return doEndOfFile();
 217  
         }
 218  1048579
         position += length;
 219  1048579
         int returnLength = length;
 220  1048579
         if (position > size) {
 221  1
             returnLength = length - (int)(position - size);
 222  1
             position = size;
 223  
         }
 224  1048579
         processChars(chars, offset, returnLength);
 225  1048579
         return returnLength;
 226  
     }
 227  
 
 228  
     /**
 229  
      * Reset the stream to the point when mark was last called.
 230  
      *
 231  
      * @throws UnsupportedOperationException if mark is not supported.
 232  
      * @throws IOException If no position has been marked
 233  
      * or the read limit has been exceed since the last position was
 234  
      * marked.
 235  
      */
 236  
     @Override
 237  
     public synchronized void reset() throws IOException {
 238  4
         if (!markSupported) {
 239  1
             throw new UnsupportedOperationException("Mark not supported");
 240  
         }
 241  3
         if (mark < 0) {
 242  1
             throw new IOException("No position has been marked");
 243  
         }
 244  2
         if (position > mark + readlimit) {
 245  1
             throw new IOException("Marked position [" + mark +
 246  
                     "] is no longer valid - passed the read limit [" +
 247  
                     readlimit + "]");
 248  
         }
 249  1
         position = mark;
 250  1
         eof = false;
 251  1
     }
 252  
 
 253  
     /**
 254  
      * Skip a specified number of characters.
 255  
      *
 256  
      * @param numberOfChars The number of characters to skip.
 257  
      * @return The number of characters skipped or <code>-1</code>
 258  
      * if the end of file has been reached and
 259  
      * <code>throwEofException</code> is set to {@code false}.
 260  
      * @throws EOFException if the end of file is reached and
 261  
      * <code>throwEofException</code> is set to {@code true}.
 262  
      * @throws IOException if trying to read past the end of file.
 263  
      */
 264  
     @Override
 265  
     public long skip(final long numberOfChars) throws IOException {
 266  4
         if (eof) {
 267  1
             throw new IOException("Skip after end of file");
 268  
         }
 269  3
         if (position == size) {
 270  1
             return doEndOfFile();
 271  
         }
 272  2
         position += numberOfChars;
 273  2
         long returnLength = numberOfChars;
 274  2
         if (position > size) {
 275  1
             returnLength = numberOfChars - (position - size);
 276  1
             position = size;
 277  
         }
 278  2
         return returnLength;
 279  
     }
 280  
 
 281  
     /**
 282  
      * Return a character value for the  <code>read()</code> method.
 283  
      * <p>
 284  
      * This implementation returns zero.
 285  
      *
 286  
      * @return This implementation always returns zero.
 287  
      */
 288  
     protected int processChar() {
 289  
         // do nothing - overridable by subclass
 290  0
         return 0;
 291  
     }
 292  
 
 293  
     /**
 294  
      * Process the characters for the <code>read(char[], offset, length)</code>
 295  
      * method.
 296  
      * <p>
 297  
      * This implementation leaves the character array unchanged.
 298  
      *
 299  
      * @param chars The character array
 300  
      * @param offset The offset to start at.
 301  
      * @param length The number of characters.
 302  
      */
 303  
     protected void processChars(final char[] chars, final int offset, final int length) {
 304  
         // do nothing - overridable by subclass
 305  1048576
     }
 306  
 
 307  
     /**
 308  
      * Handle End of File.
 309  
      *
 310  
      * @return <code>-1</code> if <code>throwEofException</code> is
 311  
      * set to {@code false}
 312  
      * @throws EOFException if <code>throwEofException</code> is set
 313  
      * to {@code true}.
 314  
      */
 315  
     private int doEndOfFile() throws EOFException {
 316  7
         eof = true;
 317  7
         if (throwEofException) {
 318  1
             throw new EOFException();
 319  
         }
 320  6
         return EOF;
 321  
     }
 322  
 
 323  
 }