Artifact 28c43d4a5319c2414e45f79b3a4b6a237108fea7b02ab548d96775b0bb333d38:

• File psl-1983/nmode/terminal-input.sl — part of check-in [eb17ceb7f6] at 2020-04-21 19:40:01 on branch master — Add Reduce 3.0 to the historical section of the archive, and some more
  files relating to version sof PSL from the early 1980s. Thanks are due to
  Paul McJones and Nelson Beebe for these, as well as to all the original
  authors.

  git-svn-id: https://svn.code.sf.net/p/reduce-algebra/code/historical@5328 2bfe0521-f11c-4a00-b80e-6202646ff360 (user: arthurcnorman@users.sourceforge.net, size: 10210) [annotate] [blame] [check-ins using] [more...]

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Terminal-Input.SL - NMODE Terminal Input Routines
% 
% Author:      Alan Snyder
%              Hewlett-Packard/CRC
% Date:        27 August 1982
% Revised:     16 February 1983
%
% 16-Feb-83 Alan Snyder
%   Declare -> Declare-Flavor.
% 26-Jan-83 Alan Snyder
%   Add ability to read from string.
% 21-Dec-82 Alan Snyder
%   Efficiency improvement: Added declarations for text buffers.
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

(CompileTime (load objects fast-int fast-strings))
(load wait)

% External variables used:

(fluid '(nmode-terminal
	 nmode-allow-refresh-breakout
	 ))

% Internal static variables (don't use elsewhere!):

(fluid
 '(nmode-prompt-string			% current prompt for character input
   nmode-prompt-immediately		% true => show prompt immediately
   nmode-terminal-script-buffer		% if non-NIL, is a buffer to script to
   nmode-terminal-input-buffer		% if non-NIL, is a buffer to read from
   nmode-terminal-input-string		% if non-NIL, is a string to read from
   nmode-terminal-input-string-pos	% index of next character in string
   ))

(setf nmode-prompt-string "")
(setf nmode-prompt-immediately NIL)
(setf nmode-terminal-script-buffer NIL)
(setf nmode-terminal-input-buffer NIL)
(setf nmode-terminal-input-string NIL)

(declare-flavor text-buffer
		nmode-terminal-input-buffer
		nmode-terminal-script-buffer)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Functions:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% A primary goal of this module is to support delayed prompting.  Prompting can
% mean both echoing (some kind of confirmation) of the previous input and
% information relating to expected input.  The basic idea behind delayed
% prompting is that as long as the user is rapidly typing input characters,
% there is no need for the system to display any prompts, since the user
% probably knows what he is doing.  However, should the user ever pause for a
% "sufficiently long" time, then the current prompt should be displayed to
% inform the user of the current state.

% An important notion is that some command interactions form a logical sequence.
% In the case of a logical sequence of prompted inputs, each additional prompt
% string should be appended to the existing prompt string, without first erasing
% the prompt line.  Furthermore, once the prompt line for this sequence is
% displayed, any further prompts within the same sequence should be output
% immediately.  A command sequence is started using the function
% NMODE-SET-DELAYED-PROMPT.  Additional prompting within the same sequence is
% specified using either NMODE-APPEND-DELAYED-PROMPT or
% NMODE-APPEND-SEPARATED-PROMPT.

(de nmode-set-immediate-prompt (prompt-string)

  % This function is used to specify the beginning of a command sequence.  It
  % causes the existing prompt string to be discarded and replaced by the
  % specified string.  The specified string may be empty to indicate that the
  % new command sequence has no initial prompt.  The prompt string will be
  % output immediately upon the next request for terminal input.

  (setf nmode-prompt-string prompt-string)
  (setf nmode-prompt-immediately T)
  )

(de nmode-set-delayed-prompt (prompt-string)

  % This function is used to specify the beginning of a command sequence.  It
  % causes the existing prompt string to be discarded and replaced by the
  % specified string.  The specified string may be empty to indicate that the
  % new command sequence has no initial prompt.  The prompt string will be
  % output when terminal input is next requested, provided that the user has
  % paused.

  (setf nmode-prompt-string prompt-string)
  (setf nmode-prompt-immediately NIL)
  )

(de nmode-append-delayed-prompt (prompt-string)

  % This function is used to specify an additional prompt for the current
  % command sequence.  The prompt string will be appended to the existing prompt
  % string.  The prompt string will be output when terminal input is next
  % requested, provided that the user has paused within the current command
  % sequence.  If the prompt string is currently empty, then the user must pause
  % at some future input request to cause the prompt to be displayed.

  (setf nmode-prompt-string (string-concat nmode-prompt-string prompt-string))
  )

(de nmode-append-separated-prompt (prompt-string)

  % This function is the same as NMODE-APPEND-DELAYED-PROMPT, except that if the
  % existing prompt string is non-null, an extra space is appended before the
  % new prompt-string is appended.

  (nmode-append-delayed-prompt
   (if (not (string-empty? nmode-prompt-string))
     (string-concat " " prompt-string)
     prompt-string
     )))

(de nmode-complete-prompt (prompt-string)

  % This function is used to specify an additional prompt for the current
  % command sequence.  The prompt string will be appended to the existing prompt
  % string.  The prompt string will be output immediately, if the current prompt
  % has already been output.  This function is to be used for "completion" or
  % "echoing" of previously read input.

  (setf nmode-prompt-string (string-concat nmode-prompt-string prompt-string))
  (if nmode-prompt-immediately (write-prompt nmode-prompt-string))
  )

(de input-available? ()

  % Return Non-NIL if and only if new terminal input is available.  Note: this
  % function might be somewhat expensive.

  (or (and nmode-terminal-input-buffer
	   (not (=> nmode-terminal-input-buffer at-buffer-end?)))
      nmode-terminal-input-string
      (~= (CharsInInputBuffer) 0)))

(de input-direct-terminal-character ()

  % Prompt for (but do not echo) a single character from the terminal.  The
  % above functions are used to specify the prompt string.  Avoid displaying the
  % prompt string if the user has already typed a character or types a character
  % right away.  Within a sequence of related prompts, once a non-empty prompt
  % is output, further prompting is done immediately.

  (cond
   (nmode-terminal-input-buffer (&input-character-from-buffer))
   (nmode-terminal-input-string (&input-character-from-string))
   (t (&input-character-from-terminal))
   ))

(de &input-character-from-buffer ()

  % Internal function for reading from a buffer.

  (cond ((=> nmode-terminal-input-buffer at-buffer-end?)
	 (setf nmode-terminal-input-buffer NIL)
	 (setf nmode-allow-refresh-breakout T)
	 (input-direct-terminal-character)
	 )
	((=> nmode-terminal-input-buffer at-line-end?)
	 (=> nmode-terminal-input-buffer move-to-next-line)
	 (input-direct-terminal-character)
	 )
	(t
	 (prog1
	  (=> nmode-terminal-input-buffer next-character)
	  (=> nmode-terminal-input-buffer move-forward)
	  ))
	))

(de &input-character-from-string ()

  % Internal function for reading from a string.

  (let ((upper-bound (string-upper-bound nmode-terminal-input-string))
	(pos nmode-terminal-input-string-pos)
	)
    (cond ((= pos upper-bound)
	   (let ((ch (string-fetch nmode-terminal-input-string pos)))
	     (setf nmode-terminal-input-string NIL)
	     (setf nmode-allow-refresh-breakout T)
	     ch
	     ))
	 (t
	   (let ((ch (string-fetch nmode-terminal-input-string pos)))
	     (setf nmode-terminal-input-string-pos (+ pos 1))
	     ch
	     ))
	 )))

(de &input-character-from-terminal ()

  % Internal function for reading from the terminal.

  (let ((prompt-is-empty (string-empty? nmode-prompt-string)))
    (if (not nmode-prompt-immediately)
      (sleep-until-timeout-or-input
       (if prompt-is-empty 120 30) % don't rush to erase the prompt line
       ))
    (if (or nmode-prompt-immediately (not (input-available?)))
      (progn
       (write-prompt nmode-prompt-string)
       (setf nmode-prompt-immediately (not prompt-is-empty))
       ))
    (let ((ch (=> nmode-terminal get-character)))
      (if nmode-terminal-script-buffer (nmode-script-character ch))
      ch
      )))

(de pause-until-terminal-input ()

  % Return when the user has typed a character.  The character is eaten.
  % No refresh is performed.

  (=> nmode-terminal get-character)
  )

(de sleep-until-timeout-or-input (n-60ths)
  (wait-timeout 'input-available? n-60ths)
  )

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

(de nmode-script-terminal-input (b)

  % Make a script of all terminal (command) input by appending characters to the
  % specified buffer.  Supercedes any previous such request.  If B is NIL, then
  % no scripting is performed.  Note: to keep the lines of reasonable length,
  % free Newlines will be inserted from time to time.  Because of this, and
  % because many file systems cannot represent stray Newlines, the Newline
  % character is itself scripted as a CR followed by a TAB, since this is its
  % normal definition.  Someday, perhaps, this hack will be replaced by a better
  % one.

  (setf nmode-terminal-script-buffer b)
  )

(de nmode-execute-buffer (b)

  % Take input from the specified buffer.  Supercedes any previous such request.
  % If B is NIL, then input is taken from the terminal.  Newline characters are
  % ignored when reading from a buffer!

  (setf nmode-terminal-input-buffer b)
  (if b (=> b move-to-buffer-start))
  )

(de nmode-execute-string (s)

  % Take input from the specified string.  Supercedes any previous such request.
  % If S is NIL or empty, then input is taken from the terminal.

  (if (string-empty? s) (setf s NIL))
  (setf nmode-terminal-input-string s)
  (setf nmode-terminal-input-string-pos 0)
  )

(de nmode-script-character (ch)
  % Write CH to the script buffer.
  (let* ((b nmode-terminal-script-buffer)
	 (old-pos (=> b position))
	 )
    (=> b move-to-buffer-end)
    (cond ((= ch #\LF)
	   (=> b insert-character #\CR)
	   (=> b insert-character #\TAB)
	   )
	  (t (=> b insert-character ch))
	  )
    (if (>= (=> b current-line-length) 60)
      (=> b insert-eol)
      )
    (=> b set-position old-pos)
    ))

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

(undeclare-flavor nmode-terminal-input-buffer nmode-terminal-script-buffer)