swiinputstream.hpp

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 /****************License************************************************
  *
  * Copyright 2000-2003.  ScanSoft, Inc.    
  *
  * Use of this software is subject to notices and obligations set forth 
  * in the SpeechWorks Public License - Software Version 1.2 which is 
  * included with this software. 
  *
  * ScanSoft is a registered trademark of ScanSoft, Inc., and OpenSpeech, 
  * SpeechWorks and the SpeechWorks logo are registered trademarks or 
  * trademarks of SpeechWorks International, Inc. in the United States 
  * and other countries.
  *
  ***********************************************************************/
 

 #ifndef SWIinputStream_HPP
 #define SWIinputStream_HPP
 
 #include <SWIstream.hpp>
 
 class SWIoutputStream;
 
 /**
  * Abstract input stream class.  The basic method that sub-classes need to
  * re-implement is the <code>read</code> method.
  *
  *
  * @doc <p>
  * Copyright 1998, 1999, 2000, 2001 SpeechWorks International, Inc.
  *  All Rights Reserved.
  **/
 class SWIUTIL_API_CLASS SWIinputStream: public SWIstream
 {
   // ................. CONSTRUCTORS, DESTRUCTOR  ............
   //
   // ------------------------------------------------------------
   /// default constructor
  public:
   SWIinputStream()
   {}
 
 
   // ------------------------------------------------------------
   /// destructor
  public:
   virtual ~SWIinputStream()
   {}
 
   //
   // ......... DATA MEMBERS, GETTERS, SETTERS  .......
   //
 
   //
   // ......... METHODS ..........
   //
   /**
    * Reads some number of bytes from the input stream and stores them into the
    * buffer array <code>data</code>.  @doc The number of bytes actually read
    * is returned as an integer.  In blocking mode, this method blocks until
    * data is available, end of file is detected, or an error is detected.
    * Otherwise it returns immediately after having read available bytes.
    *
    * <p> If <code>data</code> is <code>null</code>, a
    * <code>SWI_STREAM_INVALID_ARGUMENT</code> is returned.  If
    * <code>dataSize</code> of is zero, then no bytes are read and
    * <code>0</code> is returned; otherwise, there is an attempt to read at
    * least one byte. If no byte is available because the stream is at end of
    * file, the value <code>SWI_STREAM_EOF</code> is returned. If the stream
    * is not opened, <code>SWI_STREAM_ILLEGAL_STATE</code> is returned.
    *
    * @param data [out] the buffer into which the data is read.
    * @param dataSize [in] the number of bytes to be read.
    * @return the total number of bytes read into the buffer, or a negative
    * number indicating there is no more data because the end of the stream has
    * been reached, or to indicate an error.
    **/
  public:
   virtual int readBytes(void* data, int dataSize) = 0;
 
   /**
    * Reads one character from the stream.
 
    * Returns either a non-negative number that can be cast to a char or a negative
    * number representing an error.  See SWIstream.hpp for error codes.
    * Default implementation calls readBytes with dataSize of 1 and returns the character read.
    * Subclass can re-implement this for better efficiency.
    **/
  public:
   virtual int read();
 
   /**
    * Skips over and discards <code>n</code> bytes of data from this input
    * stream.  @doc The <code>skip</code> method may end up skipping over some
    * smaller number of bytes, possibly <code>0</code>.  This may result from
    * reaching end of file before <code>n</code> bytes have been skipped.  The
    * actual number of bytes skipped is returned.  If <code>n</code> is
    * negative, no bytes are skipped.  The default implementation just attemps
    * to read up to <code>n</code> bytes into a buffer and discards the buffer.
    * Subclasses can re-implement this method for better efficiency.
    *
    * @param n [in] the number of bytes to be skipped.
    * @return the actual number of bytes skipped, or a negative number
    * indicating an error.
    **/
  public:
   virtual int skip(int n);
 
   /**
    * Reads a line of text.  A line is considered to be terminated by any one
    * of a line feed ('\n'), a carriage return ('\r'), or a carriage return
    * followed immediately by a linefeed.  The carriage return and line feed
    * are extracted from the stream but not stored.
    *
    * returns the number of characters in the string, or a negative number
    * representing the cause of the error. See SWIstream.hpp for error codes.
    * In any case the string is 0-terminated.  In particular, if we exceed the
    * buffer capacity before reaching the end of line, the BUFFER_OVERFLOW
    * value is returned.
    *
    * If the stream does not support lookAhead, then a NOT_SUPPORTED error is
    * returned.
    *
    **/
  public:
   virtual int readLine(char *buffer, int bufSize);
 
   /**
    * Reads a line of text and store the result into an OutputStream.
    *
    * Returns the number of characters that have been successfully put into the
    * stream.
    * If the stream does not support lookAhead, then a NOT_SUPPORTED error is
    * returned.
    **/
  public:
   virtual int readLine(SWIoutputStream& out);
 
   /**
    * Looks at the stream for look-ahead character.
    *
    * @param offset The offset compared to the current read position in the
    * stream.  An offset of 0 means the character that would be returned by the
    * next read().
    *
    * @return Returns either a positive number that can be cast to a char or a
    * negative number representing an error.  If offset is negative or not
    * smaller than the value returned by getLookAhead(), then INVALID_ARGUMENT
    * is returned.
 
    * Default implementation returns NOT_SUPPORTED.  See SWIstream.hpp for
    * error codes.
    **/
  public:
   virtual int peek(int offset = 0) const;
 
   /**
    * Returns the maximum look ahead allowed by the stream.  The default
    * implementation returns 0, this method should be re-implemented subclasses
    * that allow look ahead.
    **/
  public:
   virtual int getLookAhead() const;
 
   /**
    * Returns true if this InputStream is an instance of SWIbufferedStream and
    * can be safely cast to a SWIbufferedStream.  This implementation returns
    * false.
    **/
  public:
   virtual bool isBuffered() const;
 
   /**
    * Waits until some bytes are available for reading or the specified timeout
    * expires.
    *
    * @param timeoutMs timeout, if less than 0, no timeout, a value of 0 means
    * polling, verify the state of the stream and return immediately.
    *
    * Returns SUCCESS if the stream is ready, TIMED_OUT if the delay has
    * expired or any other Stream::Result value to indicate a failure.
    *
    * Default implementation returns SWIstream::SUCCESS.
    **/
  public:
   virtual Result waitReady(long delayMs = -1);
 
   /**
    * Closes this input stream and releases any system resources associated
    * with the stream.
    *
    **/
  public:
   virtual Result close() = 0;
 };
 
 #endif