ANY FILE_TOOLS FILTER_INPUT_STREAM INPUT_STREAM NONE TEXT_FILE_READ
class interface TEXT_FILE_READ
   --
   -- Basic input facilities to read a named file on the disc.
   --
   -- Note: most features are common with STD_INPUT so you can test your
   --       program on the screen first and then, just changing of
   --       instance (STD_INPUT/TEXT_FILE_READ), doing the same in a file.
   --
   -- Input stream usage is available in tutorial/io and SmartEiffel FAQ.
   --

creation
   make
      -- The new created object is not connected. (See also connect_to.)
      ensure
         not is_connected

   connect_to (new_path: STRING)
      --  Open text file for reading. The stream is positioned at the
      --  beginning of the file.
      require
         not is_connected;
         not new_path.is_empty
      ensure
         is_connected implies not end_of_input;
         is_connected implies path.same_as(new_path)

feature(s) from FILE
   path: STRING
      -- Not Void when connected to the corresponding file on the disk.

   is_connected: BOOLEAN
      -- Is this file connected to some file of the operating system?
      ensure
         definition: Result = (path /= Void)

   connect_to (new_path: STRING)
      --  Open text file for reading. The stream is positioned at the
      --  beginning of the file.
      require
         not is_connected;
         not new_path.is_empty
      ensure
         is_connected implies not end_of_input;
         is_connected implies path.same_as(new_path)

   disconnect
      -- Disconnect from any file.
      require
         is_connected
      require else
         is_connected
      ensure
         filter = Void;
         not is_connected

feature(s) from STREAM
   is_filtered: BOOLEAN

   detach
      ensure
         not is_filtered

feature(s) from STREAM
   set_filter (a_filter: FILTER_INPUT_STREAM)
      require
         a_filter /= Void
      ensure
         filter = a_filter

   filter: FILTER_INPUT_STREAM

feature(s) from INPUT_STREAM
   read_character
      -- If read_character fail, end_of_input is set and thus 
      -- any further read is forbidden. Else, use last_character.
      require
         is_connected;
         not end_of_input;
         not is_filtered and then can_read_character
      ensure
         is_connected

   read_line_in (buffer: STRING)
      -- Same job as read_line but storage is directly done in buffer.
      require
         is_connected;
         not end_of_input;
         not is_filtered and then can_read_line;
         buffer /= Void

   unread_character
      require
         is_connected;
         not is_filtered and then can_unread_character
      ensure
         not end_of_input

   last_character: CHARACTER
      require
         is_connected;
         not end_of_input;
         not is_filtered and then valid_last_character
      ensure
         is_connected;
         not end_of_input

   can_read_character: BOOLEAN

   can_read_line: BOOLEAN

   can_unread_character: BOOLEAN

   valid_last_character: BOOLEAN

   end_of_input: BOOLEAN
      -- end_of_input means the previous attempt in character 
      -- reading failed because the end has been reached. So
      -- last_character is not valid and you are not allowed to do
      -- any read attempt anymore. (NOTE: just after a successful
      -- connect, end_of_input is always false because you never read).
      --
      -- Please refer to SmartEiffel FAQ or tutorial/io examples.

feature(s) from INPUT_STREAM
   filtered_read_character
      require
         is_connected;
         not end_of_input;
         can_read_character

   filtered_unread_character
      require
         is_connected;
         can_unread_character

   filtered_last_character: CHARACTER
      require
         is_connected;
         valid_last_character

   filtered_read_line_in (str: STRING)
      require
         is_connected;
         not end_of_input;
         str /= Void

feature(s) from INPUT_STREAM
   -- Skipping separators:

   skip_separators
      -- Skip all separators (see is_separator of class CHARACTER) and
      -- make the first non-separator available in last_character. This
      -- non-separator character is pushed back into the stream (see
      -- unread_character) to be available one more time (the next
      -- read_character will consider this non-separator). When
      -- end_of_input occurs, this process is automatically stopped.
      require
         is_connected;
         not is_filtered;
         not end_of_input

   skip_separators_using (separators: STRING)
      -- Same job as skip_separators using the separators set.
      require
         is_connected;
         not is_filtered;
         separators /= Void;
         not end_of_input

   skip_remainder_of_line
      -- Skip all the remainder of the line including the end of
      -- line delimiter itself.
      require
         is_connected;
         not is_filtered

feature(s) from INPUT_STREAM
   -- To read one number at a time:

   read_integer
      -- Read an integer according to the Eiffel syntax.
      -- Make result available in last_integer.
      -- Heading separators are automatically skipped using
      -- is_separator of class CHARACTER.
      -- Trailing separators are not skipped.
      require
         is_connected;
         not is_filtered;
         not end_of_input

   last_integer: INTEGER
      -- Last integer read using read_integer.

   read_real
      -- Read a REAL and make the result available in last_real
      -- and in last_double.
      require
         is_connected;
         not is_filtered;
         not end_of_input

   last_real: REAL
      -- Last real read with read_real.

   read_double
      -- Read a DOUBLE and make the result available in last_double.
      require
         is_connected;
         not is_filtered;
         not end_of_input

   last_double: DOUBLE
      -- Last double read with read_double.

feature(s) from INPUT_STREAM
   -- To read one line or one word at a time:

   last_string: STRING
      -- Access to the unique common buffer to get for example the result
      -- computed by read_line, read_word, newline, etc. This is a
      -- once function (the same common buffer is used for all streams).

   read_line
      -- Read a complete line ended by '%N' or end_of_input. Make the
      -- result available in last_string common buffer. The end of line
      -- character (usually '%N') is not added in the last_string buffer.
      require
         is_connected;
         not is_filtered;
         not end_of_input

   read_word
      -- Read a word using is_separator of class CHARACTER. The result is
      -- available in the last_string common buffer. Heading separators are
      -- automatically skipped. Trailing separators are not skipped
      -- (last_character is left on the first one). If end_of_input is
      -- encountered, Result can be the empty string.
      require
         is_connected;
         not is_filtered;
         not end_of_input

   newline
      -- Consume input until newline ('%N') is found. The corresponding
      -- STRING is stored in last_string common buffer.
      require
         is_connected;
         not is_filtered

   reach_and_skip (keyword: STRING)
      -- Try to skip enough characters in order to reach the keyword
      -- which is skipped too. If the keyword is not in the remainder of
      -- this stream, the process is stopped as soon  as end_of_input
      -- occurs. As for skip_separators the following character of the
      -- keyword is available in last_character and not yet read.
      require
         is_connected;
         not is_filtered;
         not keyword.is_empty
      ensure
         not end_of_input implies last_string.is_equal(keyword)

feature(s) from INPUT_STREAM
   -- Other features:

   read_word_using (separators: STRING)
      -- Same job as read_word using separators.
      require
         is_connected;
         not is_filtered;
         not end_of_input;
         separators /= Void

   read_tail_in (str: STRING)
      -- Read all remaining character of the stream in str.
      require
         is_connected;
         not is_filtered;
         str /= Void
      ensure
         end_of_input

feature(s) from INPUT_STREAM
   io_getc (stream_pointer: POINTER): INTEGER

   io_fread (buf: NATIVE_ARRAY[CHARACTER]; size: INTEGER; stream_pointer: POINTER): INTEGER
      -- return size read or 0 if end of input (-1 on error => exception ?)

   eof: INTEGER

feature(s) from TEXT_FILE_READ
   same_as (other: like Current): BOOLEAN
      require
         is_connected;
         other.is_connected
      ensure
         not is_connected;
         not other.is_connected

feature(s) from TEXT_FILE_READ
   input_stream: POINTER

feature(s) from TEXT_FILE_READ
   buffer: NATIVE_ARRAY[CHARACTER]

   end_reached: BOOLEAN

   buffer_position: INTEGER

   buffer_size: INTEGER

   capacity: INTEGER

   fill_buffer

feature(s) from TEXT_FILE_READ
   unread_character_flag: BOOLEAN

   make
      -- The new created object is not connected. (See also connect_to.)
      ensure
         not is_connected

   text_file_read_open (path_pointer: POINTER): POINTER

   io_fclose (stream_pointer: POINTER)



end of TEXT_FILE_READ