intl/uconv/nsIUnicodeDecoder.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef nsIUnicodeDecoder_h___
   7 #define nsIUnicodeDecoder_h___
   8
   9 #include "nscore.h"
  10 #include "nsISupports.h"
  11
  12 // Interface ID for our Unicode Decoder interface
  13 // {25359602-FC70-4d13-A9AB-8086D3827C0D}
  14 //NS_DECLARE_ID(kIUnicodeDecoderIID,
  15 //  0x25359602, 0xfc70, 0x4d13, 0xa9, 0xab, 0x80, 0x86, 0xd3, 0x82, 0x7c, 0xd);
  16
  17 #define NS_IUNICODEDECODER_IID  \
  18         { 0x25359602, 0xfc70, 0x4d13,   \
  19                 { 0xa9, 0xab, 0x80, 0x86, 0xd3, 0x82, 0x7c, 0xd }}
  20
  21
  22 #define NS_UNICODEDECODER_CONTRACTID_BASE "@mozilla.org/intl/unicode/decoder;1?charset="
  23
  24 /**
  25  * Interface for a Converter from a Charset into Unicode.
  26  *
  27  * @created         23/Nov/1998
  28  * @author  Catalin Rotaru [CATA]
  29  */
  30 class nsIUnicodeDecoder : public nsISupports
  31 {
  32 public:
  33   NS_DECLARE_STATIC_IID_ACCESSOR(NS_IUNICODEDECODER_IID)
  34
  35   enum {
  36     kOnError_Recover,       // on an error, recover and continue
  37     kOnError_Signal         // on an error, stop and signal
  38   };
  39
  40   /**
  41    * Converts the data from one Charset to Unicode.
  42    *
  43    * About the byte ordering:
  44    * - For input, if the converter cares (that depends of the charset, for
  45    * example a singlebyte will ignore the byte ordering) it should assume
  46    * network order. If necessary and requested, we can add a method
  47    * SetInputByteOrder() so that the reverse order can be used, too. That
  48    * method would have as default the assumed network order.
  49    * - The output stream is Unicode, having the byte order which is internal
  50    * for the machine on which the converter is running on.
  51    *
  52    * Unless there is not enough output space, this method must consume all the
  53    * available input data! The eventual incomplete final character data will be
  54    * stored internally in the converter and used when the method is called
  55    * again for continuing the conversion. This way, the caller will not have to
  56    * worry about managing incomplete input data by mergeing it with the next
  57    * buffer.
  58    *
  59    * Error conditions:
  60    * If the read value does not belong to this character set, one should
  61    * replace it with the Unicode special 0xFFFD. When an actual input error is
  62    * encountered, like a format error, the converter stop and return error.
  63    * However, we should keep in mind that we need to be lax in decoding. When
  64    * a decoding error is returned to the caller, it is the caller's
  65    * responsibility to advance over the bad byte (unless aSrcLength is -1 in
  66    * which case the caller should call the decoder with 0 offset again) and
  67    * reset the decoder before trying to call the decoder again.
  68    *
  69    * Converter required behavior:
  70    * In this order: when output space is full - return right away. When input
  71    * data is wrong, return input pointer right after the wrong byte. When
  72    * partial input, it will be consumed and cached. All the time input pointer
  73    * will show how much was actually consumed and how much was actually
  74    * written.
  75    *
  76    * @param aSrc        [IN] the source data buffer
  77    * @param aSrcLength  [IN/OUT] the length of source data buffer; after
  78    *                    conversion will contain the number of bytes read or
  79    *                    -1 on error to indicate that the caller should re-push
  80    *                    the same buffer after resetting the decoder
  81    * @param aDest       [OUT] the destination data buffer
  82    * @param aDestLength [IN/OUT] the length of the destination data buffer;
  83    *                    after conversion will contain the number of Unicode
  84    *                    characters written
  85    * @return            NS_PARTIAL_MORE_INPUT if only a partial conversion was
  86    *                    done; more input is needed to continue
  87    *                    NS_PARTIAL_MORE_OUTPUT if only  a partial conversion
  88    *                    was done; more output space is needed to continue
  89    *                    NS_ERROR_ILLEGAL_INPUT if an illegal input sequence
  90    *                    was encountered and the behavior was set to "signal";
  91    *                    the caller must skip over one byte, reset the decoder
  92    *                    and retry.
  93    */
  94   NS_IMETHOD Convert(const char * aSrc, int32_t * aSrcLength,
  95       char16_t * aDest, int32_t * aDestLength) = 0;
  96
  97   /**
  98    * Returns a quick estimation of the size of the buffer needed to hold the
  99    * converted data. Remember: this estimation is >= with the actual size of
 100    * the buffer needed. It will be computed for the "worst case"
 101    *
 102    * @param aSrc        [IN] the source data buffer
 103    * @param aSrcLength  [IN] the length of source data buffer
 104    * @param aDestLength [OUT] the needed size of the destination buffer
 105    * @return            NS_EXACT_LENGTH if an exact length was computed
 106    *                    NS_OK is all we have is an approximation
 107    */
 108   NS_IMETHOD GetMaxLength(const char * aSrc, int32_t aSrcLength,
 109       int32_t * aDestLength) = 0;
 110
 111   /**
 112    * Resets the charset converter so it may be recycled for a completely
 113    * different and urelated buffer of data.
 114    */
 115   NS_IMETHOD Reset() = 0;
 116
 117   /**
 118    * Specify what to do when a character cannot be mapped into unicode
 119    *
 120    * @param aBehavior [IN] the desired behavior
 121    * @see kOnError_Recover
 122    * @see kOnError_Signal
 123    */
 124   virtual void SetInputErrorBehavior(int32_t aBehavior) = 0;
 125
 126   /**
 127    * return the UNICODE character for unmapped character
 128    */
 129   virtual char16_t GetCharacterForUnMapped() = 0;
 130 };
 131
 132 NS_DEFINE_STATIC_IID_ACCESSOR(nsIUnicodeDecoder, NS_IUNICODEDECODER_IID)
 133
 134 #endif /* nsIUnicodeDecoder_h___ */