1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Copyright 1999-2004 The Apache Software Foundation.
   7  *
   8  * Licensed under the Apache License, Version 2.0 (the "License");
   9  * you may not use this file except in compliance with the License.
  10  * You may obtain a copy of the License at
  11  *
  12  *     http://www.apache.org/licenses/LICENSE-2.0
  13  *
  14  * Unless required by applicable law or agreed to in writing, software
  15  * distributed under the License is distributed on an "AS IS" BASIS,
  16  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  17  * See the License for the specific language governing permissions and
  18  * limitations under the License.
  19  */
  20 
  21 package com.sun.org.apache.regexp.internal;
  22 
  23 import java.io.InputStream;
  24 import java.io.IOException;
  25 
  26 /**
  27  * Encapsulates java.io.InputStream as CharacterIterator.
  28  *
  29  * @author <a href="mailto:ales.novak@netbeans.com">Ales Novak</a>
  30  */
  31 public final class StreamCharacterIterator implements CharacterIterator
  32 {
  33     /** Underlying is */
  34     private final InputStream is;
  35 
  36     /** Buffer of read chars */
  37     private final StringBuffer buff;
  38 
  39     /** read end? */
  40     private boolean closed;
  41 
  42     /** @param is an InputStream, which is parsed */
  43     public StreamCharacterIterator(InputStream is)
  44     {
  45         this.is = is;
  46         this.buff = new StringBuffer(512);
  47         this.closed = false;
  48     }
  49 
  50     /** @return a substring */
  51     public String substring(int beginIndex, int endIndex)
  52     {
  53         try
  54         {
  55             ensure(endIndex);
  56             return buff.toString().substring(beginIndex, endIndex);
  57         }
  58         catch (IOException e)
  59         {
  60             throw new StringIndexOutOfBoundsException(e.getMessage());
  61         }
  62     }
  63 
  64     /** @return a substring */
  65     public String substring(int beginIndex)
  66     {
  67         try
  68         {
  69             readAll();
  70             return buff.toString().substring(beginIndex);
  71         }
  72         catch (IOException e)
  73         {
  74             throw new StringIndexOutOfBoundsException(e.getMessage());
  75         }
  76     }
  77 
  78 
  79     /** @return a character at the specified position. */
  80     public char charAt(int pos)
  81     {
  82         try
  83         {
  84             ensure(pos);
  85             return buff.charAt(pos);
  86         }
  87         catch (IOException e)
  88         {
  89             throw new StringIndexOutOfBoundsException(e.getMessage());
  90         }
  91     }
  92 
  93     /** @return <tt>true</tt> iff if the specified index is after the end of the character stream */
  94     public boolean isEnd(int pos)
  95     {
  96         if (buff.length() > pos)
  97         {
  98             return false;
  99         }
 100         else
 101         {
 102             try
 103             {
 104                 ensure(pos);
 105                 return (buff.length() <= pos);
 106             }
 107             catch (IOException e)
 108             {
 109                 throw new StringIndexOutOfBoundsException(e.getMessage());
 110             }
 111         }
 112     }
 113 
 114     /** Reads n characters from the stream and appends them to the buffer */
 115     private int read(int n) throws IOException
 116     {
 117         if (closed)
 118         {
 119             return 0;
 120         }
 121 
 122         int c;
 123         int i = n;
 124         while (--i >= 0)
 125         {
 126             c = is.read();
 127             if (c < 0) // EOF
 128             {
 129                 closed = true;
 130                 break;
 131             }
 132             buff.append((char) c);
 133         }
 134         return n - i;
 135     }
 136 
 137     /** Reads rest of the stream. */
 138     private void readAll() throws IOException
 139     {
 140         while(! closed)
 141         {
 142             read(1000);
 143         }
 144     }
 145 
 146     /** Reads chars up to the idx */
 147     private void ensure(int idx) throws IOException
 148     {
 149         if (closed)
 150         {
 151             return;
 152         }
 153 
 154         if (idx < buff.length())
 155         {
 156             return;
 157         }
 158 
 159         read(idx + 1 - buff.length());
 160     }
 161 }