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