mnj/lua/BaseLibReader.java

   1 /*  $Header: //info.ravenbrook.com/project/jili/version/1.1/code/mnj/lua/BaseLibReader.java#1 $
   2  * Copyright (c) 2006 Nokia Corporation and/or its subsidiary(-ies).
   3  * All rights reserved.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining
   6  * a copy of this software and associated documentation files (the
   7  * "Software"), to deal in the Software without restriction, including
   8  * without limitation the rights to use, copy, modify, merge, publish,
   9  * distribute, sublicense, and/or sell copies of the Software, and to
  10  * permit persons to whom the Software is furnished to do so, subject
  11  * to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be
  14  * included in all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  17  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  18  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  19  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
  20  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
  21  * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  22  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23  */
  24
  25 package mnj.lua;
  26
  27 import java.io.IOException;
  28
  29 /**
  30  * Extends {@link java.io.Reader} to create a Reader from a Lua
  31  * function.  So that the <code>load</code> function from Lua's base
  32  * library can be implemented.
  33  */
  34 final class BaseLibReader extends java.io.Reader
  35 {
  36   private String s = "";
  37   private int i;        // = 0;
  38   private int mark = -1;
  39   private Lua L;
  40   private Object f;
  41
  42   BaseLibReader(Lua L, Object f)
  43   {
  44     this.L = L;
  45     this.f = f;
  46   }
  47
  48   public void close()
  49   {
  50     f = null;
  51   }
  52
  53   public void mark(int l) throws IOException
  54   {
  55     if (l > 1)
  56     {
  57       throw new IOException("Readahead must be <= 1");
  58     }
  59     mark = i;
  60   }
  61
  62   public boolean markSupported()
  63   {
  64     return true;
  65   }
  66
  67   public int read()
  68   {
  69     if (i >= s.length())
  70     {
  71       L.push(f);
  72       L.call(0, 1);
  73       if (Lua.isNil(L.value(-1)))
  74       {
  75         return -1;
  76       }
  77       else if(Lua.isString(L.value(-1)))
  78       {
  79         s = L.toString(L.value(-1));
  80         if (s.length() == 0)
  81         {
  82           return -1;
  83         }
  84         if (mark == i)
  85         {
  86           mark = 0;
  87         }
  88         else
  89         {
  90           mark = -1;
  91         }
  92         i = 0;
  93       }
  94       else
  95       {
  96         L.error("reader function must return a string");
  97       }
  98     }
  99     return s.charAt(i++);
 100   }
 101
 102   public int read(char[] cbuf, int off, int len)
 103   {
 104     int j = 0;  // loop index required after loop
 105     for (j=0; j<len; ++j)
 106     {
 107       int c = read();
 108       if (c == -1)
 109       {
 110         if (j == 0)
 111         {
 112           return -1;
 113         }
 114         else
 115         {
 116           return j;
 117         }
 118       }
 119       cbuf[off+j] = (char)c;
 120     }
 121     return j;
 122   }
 123
 124   public void reset() throws IOException
 125   {
 126     if (mark < 0)
 127     {
 128       throw new IOException("reset() not supported now");
 129     }
 130     i = mark;
 131   }
 132 }