retroforth/nga-c/listen.retro
crc 85502aed7a nga-c: fix hang when building
FossilOrigin-Name: acd940e821a3eedd45688297c308ae584352bbff327802dc9ee0b5f31cb26d0c
2021-04-14 11:55:46 +00:00

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# RETRO on Unix - Listener and Extensions
In this file I am implementing the interactive listener that
RETRO will run when started with `-i`, `-i,c`, or `-i,fs`.
The basic image has a space allocated for input at the end of
the kernel. This is at address 1024 (the kernel space is fixed
at addresses 0 to 1023).
~~~
#1024 'TIB const
~~~
## Console Input
The RRE interface provides a keyboard device. This exposes it
via `c:get`.
~~~
:c:get (-c) #1 io:scan-for io:invoke ;
~~~
Now that I can read characters, it's time to support reading
strings. I do this via two words. The first is `parse-until`.
This will setup a temporary string as an input buffer, then
read input, passing each character ot a provided quote. When
the quote returns `TRUE`, it ends and returns the string. When
not `TRUE` it will add the character to the buffer.
~~~
{{
(c-cf) :edit? dup [ ASCII:BS eq? ] [ ASCII:DEL eq? ] bi or ;
(c-) :gather edit? &drop &buffer:add choose ;
(q-qc) :cycle repeat c:get dup-pair swap call not 0; drop gather again ;
---reveal---
:parse-until (q-s)
[ s:empty buffer:set cycle drop-pair buffer:start ] buffer:preserve ;
}}
~~~
Using this, a simple `s:get` can be implemented very easily as
a quote which looks for an end of line character.
~~~
:s:get (-s) [ [ ASCII:LF eq? ] [ ASCII:CR eq? ] bi or ] parse-until ;
:s:get-word (-s) &c:whitespace? parse-until ;
~~~
~~~
:clear '\^[2J\^[0;0H s:format s:put ;
~~~
Hide the support words.
# Standard Interactive Listener
The main part of this file is the *listener*, an interactive
read-eval-print loop.
RRE's C part will access a couple parts of this, based on the
startup flags passed.
~~~
:bye #0 unix:exit ;
{{
'EOT var
FALSE 'Ignoring var-n
(-f) :ignoring? @Ignoring ;
(-nn) :version @Version #100 /mod ;
(c-f) :done? dup !EOT
[ ASCII:CR eq? ]
[ ASCII:LF eq? ]
[ ASCII:SPACE eq? ] tri or or ;
(c-f) :eol? @EOT [ ASCII:CR eq? ] [ ASCII:LF eq? ] bi or ;
(s-sf) :valid? dup s:length n:strictly-positive? ;
(c-c) :check-eof dup [ #-1 eq? ] [ ASCII:EOT eq? ] bi or &bye if ;
:bs buffer:get buffer:get drop-pair ;
(c-c) :check-bs dup [ ASCII:BS eq? ] [ ASCII:DEL eq? ] bi or &bs if ;
(c-c) :check check-eof check-bs ;
(-c) :character c:get dup buffer:add ;
(q-) :buffer [ TIB buffer:set call buffer:start ] buffer:preserve ;
(-s) :read-token [ [ character check done? ] until ] buffer s:chop ;
(-sf) :input read-token valid? ;
(sf-) :process ignoring? [ drop-pair eol? [ &Ignoring v:off ] if ] if;
&interpret &drop choose ;
---reveal---
:// script:ignore-to-eol &Ignoring v:on ; immediate
:listen repeat input process again ;
}}
&listen #1 store
~~~