Wow. That’s impressive
On Thu, 1 Mar 2018 at 09:49, Chris Locke <sql...@chrisjlocke.co.uk> wrote:
> "Thats the beauty of it. It doesn't *do* anything." ;)
>
>
>
> On Thu, Mar 1, 2018 at 6:55 AM, Gary Briggs <chu...@icculus.org> wrote:
>
> > Thanks to the help the other day with the strange concatentation result.
> >
> > I was referring to a BF interpreter I was working on, in pure SQLite SQL.
> > Well, here it is, working.
> >
> > Hopefully no-one finds this useful,
> > Gary
> >
> > WITH RECURSIVE
> > program AS
> > (SELECT '++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+
> > ++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.' AS p,
> > '' AS input, 3 AS width
> > ),
> > jumpdepth AS
> > (SELECT 0 AS idx, 0 AS jumpdepth, '' AS jumplist, NULL as jumpback,
> > NULL AS direction, p || '0' AS p, width FROM program
> > UNION ALL
> > SELECT idx+1, CASE SUBSTR(p, idx+1, 1)
> > WHEN '[' THEN jumpdepth+1
> > WHEN ']' THEN jumpdepth-1
> > ELSE jumpdepth END,
> > CASE SUBSTR(p, idx+1, 1)
> > WHEN '[' THEN SUBSTR('0000000' || (idx+1), -width) ||
> > jumplist
> > WHEN ']' THEN SUBSTR(jumplist,width+1)
> > ELSE jumplist END,
> > CASE SUBSTR(p, idx+1, 1)
> > WHEN ']' THEN CAST(SUBSTR(jumplist,1,width) AS INTEGER)
> > ELSE NULL END,
> > CASE SUBSTR(p, idx+1, 1)
> > WHEN '[' THEN 'L'
> > WHEN ']' THEN 'R'
> > ELSE NULL END,
> > p, width
> > FROM jumpdepth
> > WHERE LENGTH(p)>=idx),
> > jumptable(a,b,dir) AS
> > (SELECT idx,jumpback,'L' FROM jumpdepth WHERE jumpback IS NOT NULL
> > UNION ALL
> > SELECT jumpback,idx+1,'R' FROM jumpdepth WHERE jumpback IS NOT
> > NULL),
> > bf(ep, p, width, defaulttapeentry, ip, dp, instruction, output, input,
> > tape) AS
> > (SELECT 0, p, width, SUBSTR('0000000', -width), 1, 1, '', '',
> > input, SUBSTR('000000', -width)
> > FROM program
> > UNION ALL
> > SELECT ep+1, p, width, defaulttapeentry, CASE WHEN jumptable.b IS
> > NOT NULL AND
> > ((dir='R' AND CAST(SUBSTR(tape, width*(dp-1)+1, width) AS
> > INTEGER)=0)
> > OR
> > (dir='L' AND CAST(SUBSTR(tape, width*(dp-1)+1, width) AS
> > INTEGER)!=0)) THEN jumptable.b
> > ELSE ip+1 END,
> > CASE SUBSTR(p, ip, 1)
> > WHEN '>' THEN dp+1
> > WHEN '<' THEN MAX(dp-1,1)
> > ELSE dp END,
> > SUBSTR(p, ip, 1),
> > CASE WHEN SUBSTR(p, ip, 1)='.' THEN (output || CHAR(SUBSTR(tape,
> > (dp-1)*width+1, width))) ELSE output END,
> > CASE WHEN SUBSTR(p, ip, 1)=',' THEN SUBSTR(input, 2) ELSE input
> > END,
> > CASE SUBSTR(p, ip, 1)
> > WHEN '<' THEN CASE WHEN dp=1 THEN defaulttapeentry ||
> tape
> > ELSE tape END
> > WHEN '>' THEN CASE WHEN dp*width=LENGTH(tape) THEN tape
> ||
> > defaulttapeentry ELSE tape END
> > WHEN '+' THEN SUBSTR(tape,1,width*(dp-1)) ||
> > SUBSTR('0000000' || (CAST(SUBSTR(tape,width*(dp-1)+1,width) AS
> > INTEGER)+1), -width) || SUBSTR(tape,width*dp+1)
> > WHEN '-' THEN SUBSTR(tape,1,width*(dp-1)) ||
> > SUBSTR('0000000' || (CAST(SUBSTR(tape,width*(dp-1)+1,width) AS
> > INTEGER)-1), -width) || SUBSTR(tape,width*dp+1)
> > WHEN ',' THEN SUBSTR(tape,1,width*(dp-1)) ||
> > SUBSTR('0000000' || (UNICODE(SUBSTR(input,1,1))), -width) ||
> > SUBSTR(tape,width*(dp+1))
> > ELSE tape END
> > FROM bf LEFT JOIN jumptable ON jumptable.a=ip WHERE LENGTH(p) >= ip)
> > SELECT output FROM bf ORDER BY ep DESC LIMIT 1;
> >
> > _______________________________________________
> > sqlite-users mailing list
> > sqlite-users@mailinglists.sqlite.org
> > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
> >
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