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 java.io.EOFException;
 20  
 import java.io.IOException;
 21  
 import java.io.Reader;
 22  
 
 23  
 /**
 24  
  * A functional, light weight {@link Reader} that emulates
 25  
  * a reader of a specified size.
 26  
  * <p>
 27  
  * This implementation provides a light weight
 28  
  * object for testing with an {@link Reader}
 29  
  * where the contents don't matter.
 30  
  * <p>
 31  
  * One use case would be for testing the handling of
 32  
  * large {@link Reader} as it can emulate that
 33  
  * scenario without the overhead of actually processing
 34  
  * large numbers of characters - significantly speeding up
 35  
  * test execution times.
 36  
  * <p>
 37  
  * This implementation returns a space from the method that
 38  
  * reads a character and leaves the array unchanged in the read
 39  
  * methods that are passed a character array.
 40  
  * If alternative data is required the <code>processChar()</code> and
 41  
  * <code>processChars()</code> methods can be implemented to generate
 42  
  * data, for example:
 43  
  *
 44  
  * <pre>
 45  
  *  public class TestReader extends NullReader {
 46  
  *      public TestReader(int size) {
 47  
  *          super(size);
 48  
  *      }
 49  
  *      protected char processChar() {
 50  
  *          return ... // return required value here
 51  
  *      }
 52  
  *      protected void processChars(char[] chars, int offset, int length) {
 53  
  *          for (int i = offset; i &lt; length; i++) {
 54  
  *              chars[i] = ... // set array value here
 55  
  *          }
 56  
  *      }
 57  
  *  }
 58  
  * </pre>
 59  
  *
 60  
  * @since 1.3
 61  
  * @version $Id: NullReader.java 1563227 2014-01-31 19:45:30Z ggregory $
 62  
  */
 63  
 public class NullReader extends Reader {
 64  
 
 65  
     private final long size;
 66  
     private long position;
 67  18
     private long mark = -1;
 68  
     private long readlimit;
 69  
     private boolean eof;
 70  
     private final boolean throwEofException;
 71  
     private final boolean markSupported;
 72  
 
 73  
     /**
 74  
      * Create a {@link Reader} that emulates a specified size
 75  
      * which supports marking and does not throw EOFException.
 76  
      *
 77  
      * @param size The size of the reader to emulate.
 78  
      */
 79  
     public NullReader(final long size) {
 80  10
        this(size, true, false);
 81  10
     }
 82  
 
 83  
     /**
 84  
      * Create a {@link Reader} that emulates a specified
 85  
      * size with option settings.
 86  
      *
 87  
      * @param size The size of the reader to emulate.
 88  
      * @param markSupported Whether this instance will support
 89  
      * the <code>mark()</code> functionality.
 90  
      * @param throwEofException Whether this implementation
 91  
      * will throw an {@link EOFException} or return -1 when the
 92  
      * end of file is reached.
 93  
      */
 94  18
     public NullReader(final long size, final boolean markSupported, final boolean throwEofException) {
 95  18
        this.size = size;
 96  18
        this.markSupported = markSupported;
 97  18
        this.throwEofException = throwEofException;
 98  18
     }
 99  
 
 100  
     /**
 101  
      * Return the current position.
 102  
      *
 103  
      * @return the current position.
 104  
      */
 105  
     public long getPosition() {
 106  62
         return position;
 107  
     }
 108  
 
 109  
     /**
 110  
      * Return the size this {@link Reader} emulates.
 111  
      *
 112  
      * @return The size of the reader to emulate.
 113  
      */
 114  
     public long getSize() {
 115  0
         return size;
 116  
     }
 117  
 
 118  
     /**
 119  
      * Close this Reader - resets the internal state to
 120  
      * the initial values.
 121  
      *
 122  
      * @throws IOException If an error occurs.
 123  
      */
 124  
     @Override
 125  
     public void close() throws IOException {
 126  18
         eof = false;
 127  18
         position = 0;
 128  18
         mark = -1;
 129  18
     }
 130  
 
 131  
     /**
 132  
      * Mark the current position.
 133  
      *
 134  
      * @param readlimit The number of characters before this marked position
 135  
      * is invalid.
 136  
      * @throws UnsupportedOperationException if mark is not supported.
 137  
      */
 138  
     @Override
 139  
     public synchronized void mark(final int readlimit) {
 140  4
         if (!markSupported) {
 141  2
             throw new UnsupportedOperationException("Mark not supported");
 142  
         }
 143  2
         mark = position;
 144  2
         this.readlimit = readlimit;
 145  2
     }
 146  
 
 147  
     /**
 148  
      * Indicates whether <i>mark</i> is supported.
 149  
      *
 150  
      * @return Whether <i>mark</i> is supported or not.
 151  
      */
 152  
     @Override
 153  
     public boolean markSupported() {
 154  4
         return markSupported;
 155  
     }
 156  
 
 157  
     /**
 158  
      * Read a character.
 159  
      *
 160  
      * @return Either The character value returned by <code>processChar()</code>
 161  
      * or <code>-1</code> if the end of file has been reached and
 162  
      * <code>throwEofException</code> is set to {@code false}.
 163  
      * @throws EOFException if the end of file is reached and
 164  
      * <code>throwEofException</code> is set to {@code true}.
 165  
      * @throws IOException if trying to read past the end of file.
 166  
      */
 167  
     @Override
 168  
     public int read() throws IOException {
 169  60
         if (eof) {
 170  2
             throw new IOException("Read after end of file");
 171  
         }
 172  58
         if (position == size) {
 173  4
             return doEndOfFile();
 174  
         }
 175  54
         position++;
 176  54
         return processChar();
 177  
     }
 178  
 
 179  
     /**
 180  
      * Read some characters into the specified array.
 181  
      *
 182  
      * @param chars The character array to read into
 183  
      * @return The number of characters read or <code>-1</code>
 184  
      * if the end of file has been reached and
 185  
      * <code>throwEofException</code> is set to {@code false}.
 186  
      * @throws EOFException if the end of file is reached and
 187  
      * <code>throwEofException</code> is set to {@code true}.
 188  
      * @throws IOException if trying to read past the end of file.
 189  
      */
 190  
     @Override
 191  
     public int read(final char[] chars) throws IOException {
 192  2097164
         return read(chars, 0, chars.length);
 193  
     }
 194  
 
 195  
     /**
 196  
      * Read the specified number characters into an array.
 197  
      *
 198  
      * @param chars The character array to read into.
 199  
      * @param offset The offset to start reading characters into.
 200  
      * @param length The number of characters to read.
 201  
      * @return The number of characters read or <code>-1</code>
 202  
      * if the end of file has been reached and
 203  
      * <code>throwEofException</code> is set to {@code false}.
 204  
      * @throws EOFException if the end of file is reached and
 205  
      * <code>throwEofException</code> is set to {@code true}.
 206  
      * @throws IOException if trying to read past the end of file.
 207  
      */
 208  
     @Override
 209  
     public int read(final char[] chars, final int offset, final int length) throws IOException {
 210  2097168
         if (eof) {
 211  2
             throw new IOException("Read after end of file");
 212  
         }
 213  2097166
         if (position == size) {
 214  8
             return doEndOfFile();
 215  
         }
 216  2097158
         position += length;
 217  2097158
         int returnLength = length;
 218  2097158
         if (position > size) {
 219  2
             returnLength = length - (int)(position - size);
 220  2
             position = size;
 221  
         }
 222  2097158
         processChars(chars, offset, returnLength);
 223  2097158
         return returnLength;
 224  
     }
 225  
 
 226  
     /**
 227  
      * Reset the stream to the point when mark was last called.
 228  
      *
 229  
      * @throws UnsupportedOperationException if mark is not supported.
 230  
      * @throws IOException If no position has been marked
 231  
      * or the read limit has been exceed since the last position was
 232  
      * marked.
 233  
      */
 234  
     @Override
 235  
     public synchronized void reset() throws IOException {
 236  8
         if (!markSupported) {
 237  2
             throw new UnsupportedOperationException("Mark not supported");
 238  
         }
 239  6
         if (mark < 0) {
 240  2
             throw new IOException("No position has been marked");
 241  
         }
 242  4
         if (position > mark + readlimit) {
 243  2
             throw new IOException("Marked position [" + mark +
 244  
                     "] is no longer valid - passed the read limit [" +
 245  
                     readlimit + "]");
 246  
         }
 247  2
         position = mark;
 248  2
         eof = false;
 249  2
     }
 250  
 
 251  
     /**
 252  
      * Skip a specified number of characters.
 253  
      *
 254  
      * @param numberOfChars The number of characters to skip.
 255  
      * @return The number of characters skipped or <code>-1</code>
 256  
      * if the end of file has been reached and
 257  
      * <code>throwEofException</code> is set to {@code false}.
 258  
      * @throws EOFException if the end of file is reached and
 259  
      * <code>throwEofException</code> is set to {@code true}.
 260  
      * @throws IOException if trying to read past the end of file.
 261  
      */
 262  
     @Override
 263  
     public long skip(final long numberOfChars) throws IOException {
 264  8
         if (eof) {
 265  2
             throw new IOException("Skip after end of file");
 266  
         }
 267  6
         if (position == size) {
 268  2
             return doEndOfFile();
 269  
         }
 270  4
         position += numberOfChars;
 271  4
         long returnLength = numberOfChars;
 272  4
         if (position > size) {
 273  2
             returnLength = numberOfChars - (position - size);
 274  2
             position = size;
 275  
         }
 276  4
         return returnLength;
 277  
     }
 278  
 
 279  
     /**
 280  
      * Return a character value for the  <code>read()</code> method.
 281  
      * <p>
 282  
      * This implementation returns zero.
 283  
      *
 284  
      * @return This implementation always returns zero.
 285  
      */
 286  
     protected int processChar() {
 287  
         // do nothing - overridable by subclass
 288  0
         return 0;
 289  
     }
 290  
 
 291  
     /**
 292  
      * Process the characters for the <code>read(char[], offset, length)</code>
 293  
      * method.
 294  
      * <p>
 295  
      * This implementation leaves the character array unchanged.
 296  
      *
 297  
      * @param chars The character array
 298  
      * @param offset The offset to start at.
 299  
      * @param length The number of characters.
 300  
      */
 301  
     protected void processChars(final char[] chars, final int offset, final int length) {
 302  
         // do nothing - overridable by subclass
 303  2097152
     }
 304  
 
 305  
     /**
 306  
      * Handle End of File.
 307  
      *
 308  
      * @return <code>-1</code> if <code>throwEofException</code> is
 309  
      * set to {@code false}
 310  
      * @throws EOFException if <code>throwEofException</code> is set
 311  
      * to {@code true}.
 312  
      */
 313  
     private int doEndOfFile() throws EOFException {
 314  14
         eof = true;
 315  14
         if (throwEofException) {
 316  2
             throw new EOFException();
 317  
         }
 318  12
         return -1;
 319  
     }
 320  
 
 321  
 }