retroforth/interfaces/rre.forth

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# RRE Listener and Extensions
In this file I am implementing the interactive listener that
RRE will run when started with `-i` or `-c`.
## Console Input
The RRE interface provides a keyboard device. This exposes it
via `c:get`.
~~~
{{
'io:Keyboard var
:identify
@io:Keyboard n:zero? [
#1 io:scan-for dup n:negative?
[ drop 'IO_DEVICE_TYPE_0001_NOT_FOUND s:put nl ]
[ !io:Keyboard ] choose ] if ;
---reveal---
:c:get (-c) identify @io:Keyboard 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.
~~~
{{
:gather (c-)
dup [ #8 eq? ] [ #127 eq? ] bi or [ drop ] [ buffer:add ] choose ;
:cycle (q-qc) 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 ;
~~~
## Scripting: Command Line Arguments
RRE also provides access to the command line arguments passed
to a script. The next few words map the scripting device to
words we can use.
~~~
{{
'io:Scripting var
:identify
@io:Scripting n:zero? [
#9 io:scan-for dup n:negative?
[ drop 'IO_DEVICE_TYPE_0009_NOT_FOUND s:put nl ]
[ !io:Scripting ] choose ] if ;
---reveal---
:sys:argc (-n) identify #0 @io:Scripting io:invoke ;
:sys:argv (n-s) s:empty swap identify #1 @io:Scripting io:invoke ;
:include (s-) identify #2 @io:Scripting io:invoke ;
}}
~~~
## 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.
~~~
'NoEcho var
{{
:version (-) @Version #100 /mod n:put $. c:put n:put ;
:eol? (c-f) [ ASCII:CR eq? ] [ ASCII:LF eq? ] [ ASCII:SPACE eq? ] tri or or ;
:valid? (s-sf) dup s:length n:-zero? ;
:ok (-) @NoEcho not 0; drop compiling? [ nl 'Ok_ s:put ] -if ;
:check-eof (c-c) dup [ #-1 eq? ] [ #4 eq? ] bi or [ 'bye d:lookup d:xt fetch call ] if ;
:check-bs (c-c) dup [ #8 eq? ] [ #127 eq? ] bi or [ buffer:get buffer:get drop-pair ] if ;
:s:get (-s) [ #1025 buffer:set
[ c:get dup buffer:add check-eof check-bs eol? ] until
buffer:start s:chop ] buffer:preserve ;
---reveal---
:banner (-) @NoEcho not 0; drop
'RETRO_12_(rx- s:put version $) c:put nl
EOM n:put '_MAX,_TIB_@_1025,_Heap_@_ s:put here n:put nl ;
:bye (-) #0 unix:exit ;
:listen (-)
ok repeat s:get valid? [ interpret ok ] [ drop ] choose again ;
}}
&listen #1 store
~~~