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

   1 package be.nikiroo.utils.streams;
   2
   3 import java.io.IOException;
   4 import java.io.InputStream;
   5
   6 /**
   7  * This {@link InputStream} will change some of its content by replacing it with
   8  * something else.
   9  *
  10  * @author niki
  11  */
  12 public class ReplaceInputStream extends BufferedInputStream {
  13         private byte[][] froms;
  14         private byte[][] tos;
  15         private int maxToSize;
  16
  17         private byte[] source;
  18         private int spos;
  19         private int slen;
  20
  21         /**
  22          * Create a {@link ReplaceInputStream} that will replace <tt>from</tt> with
  23          * <tt>to</tt>.
  24          *
  25          * @param in
  26          *            the under-laying {@link InputStream}
  27          * @param from
  28          *            the {@link String} to replace
  29          * @param to
  30          *            the {@link String} to replace with
  31          */
  32         public ReplaceInputStream(InputStream in, String from, String to) {
  33                 this(in, StreamUtils.bytes(from), StreamUtils.bytes(to));
  34         }
  35
  36         /**
  37          * Create a {@link ReplaceInputStream} that will replace <tt>from</tt> with
  38          * <tt>to</tt>.
  39          *
  40          * @param in
  41          *            the under-laying {@link InputStream}
  42          * @param from
  43          *            the value to replace
  44          * @param to
  45          *            the value to replace with
  46          */
  47         public ReplaceInputStream(InputStream in, byte[] from, byte[] to) {
  48                 this(in, new byte[][] { from }, new byte[][] { to });
  49         }
  50
  51         /**
  52          * Create a {@link ReplaceInputStream} that will replace all <tt>froms</tt>
  53          * with <tt>tos</tt>.
  54          * <p>
  55          * Note that they will be replaced in order, and that for each <tt>from</tt>
  56          * a <tt>to</tt> must correspond.
  57          *
  58          * @param in
  59          *            the under-laying {@link InputStream}
  60          * @param froms
  61          *            the values to replace
  62          * @param tos
  63          *            the values to replace with
  64          */
  65         public ReplaceInputStream(InputStream in, String[] froms, String[] tos) {
  66                 this(in, StreamUtils.bytes(froms), StreamUtils.bytes(tos));
  67         }
  68
  69         /**
  70          * Create a {@link ReplaceInputStream} that will replace all <tt>froms</tt>
  71          * with <tt>tos</tt>.
  72          * <p>
  73          * Note that they will be replaced in order, and that for each <tt>from</tt>
  74          * a <tt>to</tt> must correspond.
  75          *
  76          * @param in
  77          *            the under-laying {@link InputStream}
  78          * @param froms
  79          *            the values to replace
  80          * @param tos
  81          *            the values to replace with
  82          */
  83         public ReplaceInputStream(InputStream in, byte[][] froms, byte[][] tos) {
  84                 super(in);
  85
  86                 if (froms.length != tos.length) {
  87                         throw new IllegalArgumentException(
  88                                         "For replacing, each FROM must have a corresponding TO");
  89                 }
  90
  91                 this.froms = froms;
  92                 this.tos = tos;
  93
  94                 for (int i = 0; i < tos.length; i++) {
  95                         maxToSize = Math.max(maxToSize, tos[i].length);
  96                 }
  97
  98                 source = new byte[4096];
  99                 spos = 0;
 100                 slen = 0;
 101         }
 102
 103         @Override
 104         protected int read(InputStream in, byte[] buffer) throws IOException {
 105                 if (buffer.length < maxToSize || source.length < maxToSize * 2) {
 106                         throw new IOException(
 107                                         "An underlaying buffer is too small for these replace values");
 108                 }
 109
 110                 if (spos >= slen) {
 111                         spos = 0;
 112                         slen = in.read(source);
 113                 }
 114
 115                 // Note: very simple, not efficient implementation, sorry.
 116                 int count = 0;
 117                 while (spos < slen && count < buffer.length - maxToSize) {
 118                         boolean replaced = false;
 119                         for (int i = 0; i < froms.length; i++) {
 120                                 if (froms[i] != null && froms[i].length > 0
 121                                                 && StreamUtils.startsWith(froms[i], source, spos, slen)) {
 122                                         if (tos[i] != null && tos[i].length > 0) {
 123                                                 System.arraycopy(tos[i], 0, buffer, spos, tos[i].length);
 124                                                 count += tos[i].length;
 125                                         }
 126
 127                                         spos += froms[i].length;
 128                                         replaced = true;
 129                                         break;
 130                                 }
 131                         }
 132
 133                         if (!replaced) {
 134                                 buffer[count++] = source[spos++];
 135                         }
 136                 }
 137
 138                 return count;
 139         }
 140 }