xpcom/io/nsIUnicharInputStream.idl

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  37
  38 #include "nsISupports.idl"
  39
  40 interface nsIUnicharInputStream;
  41 interface nsIInputStream;
  42
  43 %{C++
  44 /**
  45  * The signature of the writer function passed to ReadSegments. This
  46  * is the "consumer" of data that gets read from the stream's buffer.
  47  *
  48  * @param aInStream stream being read
  49  * @param aClosure opaque parameter passed to ReadSegments
  50  * @param aFromSegment pointer to memory owned by the input stream
  51  * @param aToOffset amount already read (since ReadSegments was called)
  52  * @param aCount length of fromSegment
  53  * @param aWriteCount number of bytes read
  54  *
  55  * Implementers should return the following:
  56  *
  57  * @return NS_OK and (*aWriteCount > 0) if consumed some data
  58  * @return <any-error> if not interested in consuming any data
  59  *
  60  * Errors are never passed to the caller of ReadSegments.
  61  *
  62  * NOTE: returning NS_OK and (*aWriteCount = 0) has undefined behavior.
  63  */
  64 typedef NS_CALLBACK(nsWriteUnicharSegmentFun)(nsIUnicharInputStream *aInStream,
  65                                               void *aClosure,
  66                                               const PRUnichar *aFromSegment,
  67                                               PRUint32 aToOffset,
  68                                               PRUint32 aCount,
  69                                               PRUint32 *aWriteCount);
  70 %}
  71 native nsWriteUnicharSegmentFun(nsWriteUnicharSegmentFun);
  72
  73 /**
  74  * Abstract unicode character input stream
  75  * @see nsIInputStream
  76  */
  77 [scriptable, uuid(d5e3bd80-6723-4b92-b0c9-22f6162fd94f)]
  78 interface nsIUnicharInputStream : nsISupports {
  79   /**
  80    * Reads into a caller-provided character array.
  81    *
  82    * @return The number of characters that were successfully read. May be less
  83    *         than aCount, even if there is more data in the input stream.
  84    *         A return value of 0 means EOF.
  85    *
  86    * @note To read more than 2^32 characters, call this method multiple times.
  87    */
  88   [noscript] unsigned long read([array, size_is(aCount)] in PRUnichar aBuf,
  89                                 in unsigned long aCount);
  90
  91   /**
  92    * Low-level read method that has access to the stream's underlying buffer.
  93    * The writer function may be called multiple times for segmented buffers.
  94    * ReadSegments is expected to keep calling the writer until either there is
  95    * nothing left to read or the writer returns an error.  ReadSegments should
  96    * not call the writer with zero characters to consume.
  97    *
  98    * @param aWriter the "consumer" of the data to be read
  99    * @param aClosure opaque parameter passed to writer
 100    * @param aCount the maximum number of characters to be read
 101    *
 102    * @return number of characters read (may be less than aCount)
 103    * @return 0 if reached end of file (or if aWriter refused to consume data)
 104    *
 105    * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
 106    *   block the calling thread (non-blocking mode only)
 107    * @throws <other-error> on failure
 108    *
 109    * NOTE: this function may be unimplemented if a stream has no underlying
 110    * buffer
 111    */
 112   [noscript] unsigned long readSegments(in nsWriteUnicharSegmentFun aWriter,
 113                                         in voidPtr aClosure,
 114                                         in unsigned long aCount);
 115
 116   /**
 117    * Read into a string object.
 118    * @param aCount The number of characters that should be read
 119    * @return The number of characters that were read.
 120    */
 121   unsigned long readString(in unsigned long aCount, out AString aString);
 122
 123  /**
 124   * Close the stream and free associated resources. This also closes the
 125   * underlying stream, if any.
 126   */
 127   void close();
 128 };