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lightning-sunbird  0.9+nobinonly
Public Types | Public Member Functions | Protected Member Functions | Protected Attributes
nsUTF32BEToUnicode Class Reference

A character set converter from UTF32BE to Unicode. More...

#include <nsUTF32ToUnicode.h>

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List of all members.

Public Types

enum  { kOnError_Recover, kOnError_Signal }

Public Member Functions

NS_IMETHOD Convert (const char *aSrc, PRInt32 *aSrcLength, PRUnichar *aDest, PRInt32 *aDestLength)
 Converts the data from one Charset to Unicode.

Protected Member Functions

NS_IMETHOD GetMaxLength (const char *aSrc, PRInt32 aSrcLength, PRInt32 *aDestLength)
 Returns a quick estimation of the size of the buffer needed to hold the converted data.
NS_IMETHOD Reset ()
 Resets the charset converter so it may be recycled for a completely different and urelated buffer of data.

Protected Attributes

PRUint16 mState
PRUint8 mBufferInc [4]

Detailed Description

A character set converter from UTF32BE to Unicode.

A subclass of UTF32ToUnicode. 08/Dec/2002

Author:
Jungshik Shin

Definition at line 91 of file nsUTF32ToUnicode.h.


Member Enumeration Documentation

anonymous enum [inherited]
Enumerator:
kOnError_Recover 
kOnError_Signal 

Definition at line 98 of file nsIUnicodeDecoder.h.

       {
    kOnError_Recover,       // on an error, recover and continue
    kOnError_Signal         // on an error, stop and signal
  };

Member Function Documentation

NS_IMETHODIMP nsUTF32BEToUnicode::Convert ( const char *  aSrc,
PRInt32 aSrcLength,
PRUnichar aDest,
PRInt32 aDestLength 
) [virtual]

Converts the data from one Charset to Unicode.

About the byte ordering:

  • For input, if the converter cares (that depends of the charset, for example a singlebyte will ignore the byte ordering) it should assume network order. If necessary and requested, we can add a method SetInputByteOrder() so that the reverse order can be used, too. That method would have as default the assumed network order.
  • The output stream is Unicode, having the byte order which is internal for the machine on which the converter is running on.

Unless there is not enough output space, this method must consume all the available input data! The eventual incomplete final character data will be stored internally in the converter and used when the method is called again for continuing the conversion. This way, the caller will not have to worry about managing incomplete input data by mergeing it with the next buffer.

Error conditions: If the read value does not belong to this character set, one should replace it with the Unicode special 0xFFFD. When an actual input error is encountered, like a format error, the converter stop and return error. Hoever, we should keep in mind that we need to be lax in decoding.

Converter required behavior: In this order: when output space is full - return right away. When input data is wrong, return input pointer right after the wrong byte. When partial input, it will be consumed and cached. All the time input pointer will show how much was actually consumed and how much was actually written.

Parameters:
aSrc[IN] the source data buffer
aSrcLength[IN/OUT] the length of source data buffer; after conversion will contain the number of bytes read
aDest[OUT] the destination data buffer
aDestLength[IN/OUT] the length of the destination data buffer; after conversion will contain the number of Unicode characters written
Returns:
NS_PARTIAL_MORE_INPUT if only a partial conversion was done; more input is needed to continue NS_PARTIAL_MORE_OUTPUT if only a partial conversion was done; more output space is needed to continue NS_ERROR_ILLEGAL_INPUT if an illegal input sequence was encountered and the behavior was set to "signal"

Implements nsIUnicodeDecoder.

Definition at line 212 of file nsUTF32ToUnicode.cpp.

{
  return ConvertCommon(aSrc, aSrcLength, aDest, aDestLength, &mState, 
                       mBufferInc, PR_FALSE);
}

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NS_IMETHODIMP nsUTF32ToUnicode::GetMaxLength ( const char *  aSrc,
PRInt32  aSrcLength,
PRInt32 aDestLength 
) [protected, virtual, inherited]

Returns a quick estimation of the size of the buffer needed to hold the converted data.

Remember: this estimation is >= with the actual size of the buffer needed. It will be computed for the "worst case"

Parameters:
aSrc[IN] the source data buffer
aSrcLength[IN] the length of source data buffer
aDestLength[OUT] the needed size of the destination buffer
Returns:
NS_EXACT_LENGTH if an exact length was computed NS_OK is all we have is an approximation

Implements nsIUnicodeDecoder.

Definition at line 182 of file nsUTF32ToUnicode.cpp.

{
  // Non-BMP characters take two PRUnichars(a pair of surrogate codepoints)
  // so that we have to divide by 2 instead of 4 for the worst case.
  *aDestLength = aSrcLength / 2;
  return NS_OK;
}
NS_IMETHODIMP nsUTF32ToUnicode::Reset ( ) [protected, virtual, inherited]

Resets the charset converter so it may be recycled for a completely different and urelated buffer of data.

Implements nsIUnicodeDecoder.

Definition at line 196 of file nsUTF32ToUnicode.cpp.

{
  // the number of additional bytes to read to complete UTF-32 4byte seq.
  mState = 0;  
  memset(mBufferInc, 0, 4);
  return NS_OK;

}

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Member Data Documentation

PRUint8 nsUTF32ToUnicode::mBufferInc[4] [protected, inherited]

Definition at line 69 of file nsUTF32ToUnicode.h.

PRUint16 nsUTF32ToUnicode::mState [protected, inherited]

Definition at line 67 of file nsUTF32ToUnicode.h.


The documentation for this class was generated from the following files: