src/be/nikiroo/utils/streams/NextableInputStreamStep.java

   1 package be.nikiroo.utils.streams;
   2
   3 import java.io.InputStream;
   4
   5 /**
   6  * Divide an {@link InputStream} into sub-streams.
   7  *
   8  * @author niki
   9  */
  10 public class NextableInputStreamStep {
  11         private int stopAt;
  12         private int resumeLen;
  13         private int last = -1;
  14         private int skip;
  15
  16         /**
  17          * Create a new divider that will separate the sub-streams each time it sees
  18          * this byte.
  19          * <p>
  20          * Note that the byte will be bypassed by the {@link InputStream} as far as
  21          * the consumers will be aware.
  22          *
  23          * @param byt
  24          *            the byte at which to separate two sub-streams
  25          */
  26         public NextableInputStreamStep(int byt) {
  27                 stopAt = byt;
  28         }
  29
  30         /**
  31          * Check if we need to stop the {@link InputStream} reading at some point in
  32          * the current buffer.
  33          * <p>
  34          * If we do, return the index at which to stop; if not, return -1.
  35          * <p>
  36          * This method will <b>not</b> return the same index a second time (unless
  37          * we cleared the buffer).
  38          *
  39          * @param buffer
  40          *            the buffer to check
  41          * @param pos
  42          *            the current position of what was read in the buffer
  43          * @param len
  44          *            the maximum index to use in the buffer (anything above that is
  45          *            not to be used)
  46          *
  47          * @return the index at which to stop, or -1
  48          */
  49         public int stop(byte[] buffer, int pos, int len) {
  50                 for (int i = pos; i < len; i++) {
  51                         if (buffer[i] == stopAt) {
  52                                 if (i > this.last) {
  53                                         // we skip the sep
  54                                         this.skip = 1;
  55
  56                                         this.resumeLen = len;
  57                                         this.last = i;
  58                                         return i;
  59                                 }
  60                         }
  61                 }
  62
  63                 return -1;
  64         }
  65
  66         /**
  67          * Get the maximum index to use in the buffer used in
  68          * {@link NextableInputStreamStep#stop(byte[], int, int)} at resume time.
  69          *
  70          * @return the index
  71          */
  72         public int getResumeLen() {
  73                 return resumeLen;
  74         }
  75
  76         /**
  77          * Get the number of bytes to skip at resume time.
  78          *
  79          * @return the number of bytes to skip
  80          */
  81         public int getResumeSkip() {
  82                 return skip;
  83         }
  84
  85         /**
  86          * Clear the information we may have kept about the current buffer
  87          * <p>
  88          * You should call this method each time you change the content of the
  89          * buffer used in {@link NextableInputStreamStep#stop(byte[], int, int)}.
  90          */
  91         public void clearBuffer() {
  92                 this.last = -1;
  93                 this.skip = 0;
  94                 this.resumeLen = 0;
  95         }
  96 }