Aminet 30/Aminet 30 (1999)(Schatztruhe)[!][Apr 1999].iso/Aminet/dev/lang/SmallEiffel.lha/SmallEiffel/lib_std/input_stream.e

Text File | 1998-12-22 | 10KB | 425 lines

-- This file is  free  software, which  comes  along  with  SmallEiffel. This
-- software  is  distributed  in the hope that it will be useful, but WITHOUT
-- ANY  WARRANTY;  without  even  the  implied warranty of MERCHANTABILITY or
-- FITNESS  FOR A PARTICULAR PURPOSE. You can modify it as you want, provided
-- this header is kept unaltered, and a notification of the changes is added.
-- You  are  allowed  to  redistribute  it and sell it, alone or as a part of
-- another product.
--          Copyright (C) 1994-98 LORIA - UHP - CRIN - INRIA - FRANCE
--            Dominique COLNET and Suzanne COLLIN - [e-mail]
--                       http://www.loria.fr/SmallEiffel
--
deferred class INPUT_STREAM
   --
   -- This abstract class is the superclass of all classes
   -- representing an input stream of bytes.
   --

feature -- State of the stream :

   is_connected: BOOLEAN is
     -- True when the corresponding stream is connected
     -- to some physical input device.
      deferred
      end;

   end_of_input: BOOLEAN is
     -- Has end-of-input been reached ?
     -- True when the last character has been read.
      require
     is_connected
      deferred
      end;

feature -- To read one character at a time :

   read_character is
     -- Read a character and assign it to `last_character'.
      require
     not end_of_input
      deferred
      ensure
     not push_back_flag
      end;

   last_character: CHARACTER is
     -- Last character read with `read_character'.
      require
     is_connected
      deferred
      end;

   push_back_flag: BOOLEAN;
     -- True in one char is already pushed back.

   unread_character is
     -- Un-read the last character read.
     --
      require
     not push_back_flag
      deferred
      ensure
     push_back_flag
      end;

feature -- Skipping separators :

   skip_separators is
     -- Stop doing `read_character' as soon as `end_of_file' is reached
     -- or as soon as `last_character' is not `is_separator'.
     -- When first character is already not `is_separator' nothing
     -- is done.
      do
     from
     until
        end_of_input or else
        not last_character.is_separator
     loop
        read_character;
     end;
      end;

   skip_separators_using(separators:STRING) is
     -- Same job as `skip_separators' using `separators'.
      require
     separators /= void
      do
     -- Implemented by : Lars Brueckner
     -- ([e-mail])
     from
     until
        end_of_input or else
        not separators.has(last_character)
     loop
        read_character;
     end;
      end;

feature -- To read one number at a time :

   read_integer is
     -- 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
     not end_of_input
      local
     state: INTEGER;
     sign: BOOLEAN;
     -- state = 0 : waiting sign or first digit.
     -- state = 1 : sign read, waiting first digit.
     -- state = 2 : in the number.
     -- state = 3 : end state.
     -- state = 4 : error state.
      do
     from
     until
        state > 2
     loop
        read_character;
        inspect
           state
        when 0 then
           if last_character.is_separator then
           elseif last_character.is_digit then
          last_integer := last_character.value;
          state := 2;
           elseif last_character = '-' then
          sign := true;
          state := 1;
           elseif last_character = '+' then
          state := 1;
           else
          state := 4;
           end;
        when 1 then
           if last_character.is_separator then
           elseif last_character.is_digit then
          last_integer := last_character.value;
          state := 2;
           else
          state := 4;
           end;
        else -- 2
           if last_character.is_digit then
          last_integer := (last_integer * 10) + last_character.value;
           else
          state := 3;
           end;
        end;
        if end_of_input then
           inspect
          state
           when 0 .. 1 then
          state := 4;
           when 2 .. 3 then
          state := 3;
           else -- 4
           end;
        end;
     end;
         if not end_of_input then
            unread_character;
         end;
     debug
        if state = 4 then
           std_error.put_string("Error in INPUT_STREAM.read_integer.%N");
           crash;
        end;
     end;
     if sign then
        last_integer := - last_integer;
     end;
      end;

   last_integer: INTEGER;
     -- Last integer read using `read_integer'.

   read_real is
     -- Read a REAL and make the result available in `last_real'
     -- and in `last_double'.
     -- The integral part is available in `last_integer'.
      require
     not end_of_input
      do
     read_double;
     last_real := last_double.to_real;
      end;

   last_real: REAL;
     -- Last real read with `read_real'.

   read_double is
     -- Read a DOUBLE and make the result available in
     -- `last_double'.
      require
     not end_of_input
      local
     state: INTEGER;
     sign: BOOLEAN;
     ip, i: INTEGER;
     -- state = 0 : waiting sign or first digit.
     -- state = 1 : sign read, waiting first digit.
     -- state = 2 : in the integral part.
         -- state = 3 : in the fractional part.
     -- state = 4 : end state.
     -- state = 5 : error state.
      do
     from
        tmp_read_double.clear;
     until
        state >= 4
     loop
        read_character;
        inspect
           state
        when 0 then
           if last_character.is_separator then
           elseif last_character.is_digit then
          ip := last_character.value;
          state := 2;
           elseif last_character = '-' then
          sign := true;
          state := 1;
           elseif last_character = '+' then
          state := 1;
           elseif last_character = '.' then
          state := 3;
           else
          state := 5;
           end;
        when 1 then
           if last_character.is_separator then
           elseif last_character.is_digit then
          ip := last_character.value;
          state := 2;
           else
          state := 5;
           end;
        when 2 then
           if last_character.is_digit then
          ip := (ip * 10) + last_character.value;
           elseif last_character = '.' then
          state := 3;
           else
          state := 4;
           end;
        else -- 3
           if last_character.is_digit then
          tmp_read_double.extend(last_character);
           else
          state := 4;
           end;
        end;
        if end_of_input then
           inspect
          state
           when 2 .. 4 then
          state := 4;
           else
          state := 5;
           end;
        end;
     end;
         if not end_of_input then
            unread_character;
         end;
     debug
        if state = 5 then
           std_error.put_string("Error in STD_FILE.read_double.%N");
           crash;
        end;
     end;
     from
        last_double := 0;
        i := tmp_read_double.count;
     until
        i = 0
     loop
        last_double := (last_double + tmp_read_double.item(i).value) / 10;
        i := i - 1;
     end;
     last_double := last_double + ip;
     if sign then
        last_double := - last_double;
     end;
      end;

   last_double: DOUBLE;
     -- Last double read with `read_double'.

feature -- To read one line or one word at a time :

   last_string: STRING is
     -- Access to a unique STRING to get the result computed
     -- with `read_line', `read_word' or `newline'.
     -- No new STRING is allocated.
      once
     !!Result.make(256);
      end;

   read_line is
     -- Read a complete line ended by '%N' or `end_of_input'.
     -- Make the result available in `last_string'.
     -- Character '%N' is not added in `last_string'.
     --
     -- NOTE: the result is available in `last_string' without any
     --       memory allocation.
      require
     not end_of_input
      do
     last_string.clear;
     read_line_in(last_string);
      end;

   read_word is
     -- Read a word using `is_separator' of class CHARACTER.
     -- Result is available in `last_string' (no allocation
     -- of memory).
     -- 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
     not end_of_input
      do
     skip_separators;
     from
        last_string.clear;
     until
        end_of_input or else
        last_character.is_separator
     loop
        last_string.extend(last_character);
        read_character;
     end;
      end;

   newline is
     -- Consume input until newline ('%N') is found.
     -- Corresponding STRING is stored in `last_string'.
      local
     stop: BOOLEAN;
      do
     from
        last_string.clear;
        stop := end_of_input;
     until
        stop
     loop
        read_character;
        if end_of_input or else last_character = '%N' then
           stop := true;
        else
           last_string.extend(last_character);
        end;
     end;
      end;

feature -- Other features :

   read_line_in(str: STRING) is
     -- Same jobs as `read_line' but storage is directly done in `str'.
     --
      require
     not end_of_input
      deferred
      end;

   read_word_using(separators: STRING) is
     -- Same jobs as `read_word' using `separators'.
      require
     not end_of_input;
     separators /= void
      do
     -- Implemented by : Lars Brueckner
     -- ([e-mail])
     skip_separators_using(separators);
     from
        last_string.clear;
     until
        end_of_input or else
        separators.has(last_character)
     loop
        last_string.extend(last_character);
        read_character;
     end;
      end;

   read_tail_in(str: STRING) is
     -- Read all remaining character of the file in `str'.
      do
     from
     until
        end_of_input
     loop
        read_character;
        if not end_of_input then
           str.extend(last_character);
        end;
     end;
      ensure
     end_of_input
      end;

feature {NONE}

   eof_code: INTEGER is
      external "SmallEiffel"
      end;

   read_byte(stream_pointer : POINTER): INTEGER is
      external "SmallEiffel"
      end;

   tmp_read_double: STRING is
      once
     !!Result.make(12);
      end;

end -- INPUT_STREAM