michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsISupports.idl"
michael@0: 
michael@0: interface nsIUnicharInputStream;
michael@0: interface nsIInputStream;
michael@0: 
michael@0: %{C++
michael@0: /**
michael@0:  * The signature of the writer function passed to ReadSegments. This
michael@0:  * is the "consumer" of data that gets read from the stream's buffer.
michael@0:  *
michael@0:  * @param aInStream stream being read
michael@0:  * @param aClosure opaque parameter passed to ReadSegments
michael@0:  * @param aFromSegment pointer to memory owned by the input stream
michael@0:  * @param aToOffset amount already read (since ReadSegments was called)
michael@0:  * @param aCount length of fromSegment
michael@0:  * @param aWriteCount number of bytes read
michael@0:  *
michael@0:  * Implementers should return the following:
michael@0:  *
michael@0:  * @throws <any-error> if not interested in consuming any data
michael@0:  *
michael@0:  * Errors are never passed to the caller of ReadSegments.
michael@0:  *
michael@0:  * NOTE: returning NS_OK and (*aWriteCount = 0) has undefined behavior.
michael@0:  */
michael@0: typedef NS_CALLBACK(nsWriteUnicharSegmentFun)(nsIUnicharInputStream *aInStream,
michael@0:                                               void *aClosure,
michael@0:                                               const char16_t *aFromSegment,
michael@0:                                               uint32_t aToOffset,
michael@0:                                               uint32_t aCount,
michael@0:                                               uint32_t *aWriteCount);
michael@0: %}
michael@0: native nsWriteUnicharSegmentFun(nsWriteUnicharSegmentFun);
michael@0: 
michael@0: /**
michael@0:  * Abstract unicode character input stream
michael@0:  * @see nsIInputStream
michael@0:  */
michael@0: [scriptable, uuid(d5e3bd80-6723-4b92-b0c9-22f6162fd94f)]
michael@0: interface nsIUnicharInputStream : nsISupports {
michael@0:   /**
michael@0:    * Reads into a caller-provided character array.
michael@0:    *
michael@0:    * @return The number of characters that were successfully read. May be less
michael@0:    *         than aCount, even if there is more data in the input stream.
michael@0:    *         A return value of 0 means EOF.
michael@0:    *
michael@0:    * @note To read more than 2^32 characters, call this method multiple times.
michael@0:    */
michael@0:   [noscript] unsigned long read([array, size_is(aCount)] in char16_t aBuf,
michael@0:                                 in unsigned long aCount);
michael@0: 
michael@0:   /**
michael@0:    * Low-level read method that has access to the stream's underlying buffer.
michael@0:    * The writer function may be called multiple times for segmented buffers.
michael@0:    * ReadSegments is expected to keep calling the writer until either there is
michael@0:    * nothing left to read or the writer returns an error.  ReadSegments should
michael@0:    * not call the writer with zero characters to consume.
michael@0:    *
michael@0:    * @param aWriter the "consumer" of the data to be read
michael@0:    * @param aClosure opaque parameter passed to writer 
michael@0:    * @param aCount the maximum number of characters to be read
michael@0:    *
michael@0:    * @return number of characters read (may be less than aCount)
michael@0:    * @return 0 if reached end of file (or if aWriter refused to consume data)
michael@0:    *
michael@0:    * @throws NS_BASE_STREAM_WOULD_BLOCK if reading from the input stream would
michael@0:    *   block the calling thread (non-blocking mode only)
michael@0:    * @throws <other-error> on failure
michael@0:    *
michael@0:    * NOTE: this function may be unimplemented if a stream has no underlying
michael@0:    * buffer
michael@0:    */
michael@0:   [noscript] unsigned long readSegments(in nsWriteUnicharSegmentFun aWriter,
michael@0:                                         in voidPtr aClosure,
michael@0:                                         in unsigned long aCount);
michael@0: 
michael@0:   /**
michael@0:    * Read into a string object.
michael@0:    * @param aCount The number of characters that should be read
michael@0:    * @return The number of characters that were read.
michael@0:    */
michael@0:   unsigned long readString(in unsigned long aCount, out AString aString);
michael@0: 
michael@0:  /**
michael@0:   * Close the stream and free associated resources. This also closes the
michael@0:   * underlying stream, if any.
michael@0:   */
michael@0:   void close();
michael@0: };