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00001 /*******************************************************************************
00002 
00003         @file TextReader.d
00004         
00005         Copyright (c) 2004 Kris Bell
00006         
00007         This software is provided 'as-is', without any express or implied
00008         warranty. In no event will the authors be held liable for damages
00009         of any kind arising from the use of this software.
00010         
00011         Permission is hereby granted to anyone to use this software for any 
00012         purpose, including commercial applications, and to alter it and/or 
00013         redistribute it freely, subject to the following restrictions:
00014         
00015         1. The origin of this software must not be misrepresented; you must 
00016            not claim that you wrote the original software. If you use this 
00017            software in a product, an acknowledgment within documentation of 
00018            said product would be appreciated but is not required.
00019 
00020         2. Altered source versions must be plainly marked as such, and must 
00021            not be misrepresented as being the original software.
00022 
00023         3. This notice may not be removed or altered from any distribution
00024            of the source.
00025 
00026         4. Derivative works are permitted, but they must carry this notice
00027            in full and credit the original source.
00028 
00029 
00030                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
00031 
00032 
00033         @version        Initial version, March 2004      
00034         @author         Kris
00035 
00036 
00037 *******************************************************************************/
00038 
00039 module mango.io.TextReader;
00040 
00041 private import  mango.convert.Type;
00042 
00043 private import  mango.io.Token,
00044                 mango.io.Reader,
00045                 mango.io.Tokenizer,
00046                 mango.io.Exception;
00047 
00048 /*******************************************************************************
00049 
00050         Grok readable input from a stream. All input is tokenized from the
00051         associated buffer, and converted as necessary into the destination 
00052         location. A SpaceTokenizer is used by default, but you can choose
00053         an alternative (such as a comma-delimiting tokenizer).
00054 
00055 *******************************************************************************/
00056 
00057 class TextReader : Reader
00058 {
00059         alias Reader.get get;
00060 
00061         // an individual token
00062         private Token token;
00063 
00064         // internal tokenizer instance
00065         private ITokenizer tokenizer;
00066 
00067         private final static char[] EOI = "unexpected end of input";
00068 
00069         /***********************************************************************
00070         
00071                 Construct a TextReader on the provided buffer, using the
00072                 specified Tokenizer instead of the default one.
00073 
00074         ***********************************************************************/
00075 
00076         this (IBuffer buffer, ITokenizer tokenizer = Tokenizers.line)
00077         {
00078                 super (buffer);
00079                 this.token = new Token;
00080                 this.tokenizer = tokenizer;
00081         }
00082         
00083         /***********************************************************************
00084                 
00085                 Construct a TextReader upon the buffer associated with the
00086                 given conduit.
00087 
00088         ***********************************************************************/
00089 
00090         this (IConduit conduit, ITokenizer tokenizer = Tokenizers.line)
00091         {
00092                 this (new Buffer(conduit), tokenizer);
00093         }
00094 
00095         /***********************************************************************
00096         
00097         ***********************************************************************/
00098 
00099         override uint read (void* src, uint bytes, uint type)
00100         {
00101                 int length = bytes;
00102 
00103                 // get width of elements (note: does not work for bit[])
00104                 int width = Type.widths[type];
00105 
00106                 // for all bytes in source ...
00107                 while (bytes)
00108                       {
00109                       switch (type)
00110                              {
00111                              case Type.Bool:
00112                                   *cast(bool*) src = cast(bool) (next.toString() == "true");
00113                                   break;
00114 
00115                              case Type.Byte:
00116                              case Type.UByte:
00117                                   *cast(ubyte*) src = cast(ubyte) next.toInt();
00118                                   break;
00119 
00120                              case Type.Short:
00121                              case Type.UShort:
00122                                   *cast(ushort*) src = cast(ushort) next.toInt();
00123                                   break;
00124 
00125                              case Type.Int:
00126                              case Type.UInt:
00127                                   *cast(uint*) src = next.toInt();
00128                                   break;
00129 
00130                              case Type.Long:
00131                              case Type.ULong:
00132                                   *cast(long*) src = next.toLong();
00133                                   break;
00134 
00135                              case Type.Float:
00136                                   *cast(float*) src = next.toReal();
00137                                   break;
00138 
00139                              case Type.Double:
00140                                   *cast(double*) src = next.toReal();
00141                                   break;
00142 
00143                              case Type.Real:
00144                                   *cast(real*) src = next.toReal();
00145                                   break;
00146 
00147                              default:
00148                                   error ("unknown type handed to TextReader.read()");
00149                              }
00150 
00151                       // bump counters and loop around for next instance
00152                       bytes -= width;
00153                       src += width;
00154                       }
00155 
00156                 return length;
00157         }
00158 
00159         /***********************************************************************
00160         
00161         ***********************************************************************/
00162 
00163         override IReader get (inout char[] x, uint elements = uint.max) 
00164         { 
00165                 // dup the input string, to avoid surprises
00166                 x = nextToken.toString (false);
00167                 return this;
00168         }
00169 
00170         /***********************************************************************
00171         
00172                 @todo - Tokenizer needs to handle wchar[] before this will
00173                         operate correctly
00174 
00175         ***********************************************************************/
00176 
00177         override IReader get (inout wchar[] x, uint elements = uint.max) 
00178         { 
00179                 assert (0);
00180         }
00181 
00182         /***********************************************************************
00183         
00184                 @todo - Tokenizer needs to handle dchar[] before this will
00185                         operate correctly
00186 
00187         ***********************************************************************/
00188 
00189         override IReader get (inout dchar[] x, uint elements = uint.max) 
00190         { 
00191                 assert (0);
00192         }
00193 
00194         /***********************************************************************
00195         
00196                 Throw an exception if the input requested is not available.
00197                 Reader instances expect the input to be available, so you 
00198                 might think of them as being applied to a fixed-format 
00199                 file. Tokenizers, on the other hand, are more flexible in
00200                 that they return true until no more tokens are available.
00201                       
00202                 Readers take care of assignment to user-space variables, 
00203                 whereas Tokenizers just make the raw content available.
00204                 
00205         ***********************************************************************/
00206 
00207         private static final void error (char[] msg = EOI)
00208         {
00209                 throw new TokenException (msg);
00210         }
00211 
00212         /***********************************************************************
00213         
00214                 Internal method to capture the next token.
00215 
00216         ***********************************************************************/
00217 
00218         private final Token nextToken ()
00219         {
00220                 if (! tokenizer.next (buffer, token))
00221                       error (); 
00222                 return token;
00223         }
00224 
00225         /***********************************************************************
00226         
00227                 Internal method to isolate the next token, and check its
00228                 length. This is used when converting to non-char types, 
00229                 such as integers ~ an empty token is illegal, since we
00230                 don't support default values.
00231 
00232                 @todo: should the empty-token rule be relaxed?
00233 
00234         ***********************************************************************/
00235 
00236         private final Token next ()
00237         {
00238                 nextToken();
00239                 if (token.getLength == 0)
00240                     error ();
00241                 return token;    
00242         }
00243         
00244         /***********************************************************************
00245         
00246                 Is this Reader text oriented?
00247 
00248         ***********************************************************************/
00249 
00250         bool isTextBased()
00251         {
00252                 return true;
00253         }
00254 }

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