Re: Reverse SCAN SPLIT

In article <5c65a8f1fdfc3e9937a825842fe23dc2758f48ef@i2pn2.org>,
dxf  <dxforth@gmail.com> wrote:

Earlier I mentioned scanning in reverse.  Here's an implementation.
>
[undefined] dxforth [if]
: \CHAR ( a u -- a2 u2 c )  1- 2dup + c@ ;
[then]
>
\ As for SCAN but scan from end
: SCAN< ( a u c -- a2 u2 | a 0 )
 >r over swap begin dup while \char r@ = until 1+ then
 rot drop rdrop ;

Compare that with the meticulously designed, exhaustedly specified
and eminently useful -- $/ -- .
After 40 years it has not taken over the world ...

NAME: $/

STACKEFFECT: sc c --- sc1 sc2

DESCRIPTION: []

Find the first c in the string constant sc and split it at that
address. Return the strings after and before c into sc1 and sc2
respectively. If the character is not present sc1 is a null string
(its address is zero) and sc2 is the original string. Both sc1 and sc2
may be empty strings (i.e. their count is zero), if c is the last or
first character in sc .
(sc is c-addr len )


The subtle difference between an empty string (a-add 0 ) and
a null-string ( 0 0 ) allows you to handle empty lines in a file
gracefully.

>
\ As for SPLIT but scan from end. Latter string is topmost.
: SPLIT< ( a u c -- a2 u2 a3 u3 )
 >r 2dup r> scan< 2swap 2 pick /string ;

If you go for SPLIT< from end define SCAN< .
I have named it $\

Get the name of an executable from the source file:
"aap.frt" &. $\ 2DROP TYPE
aap OK

These words are elementary and should be defined in the core
in assembler, possibly (Intel) taking advantage of the string
words.

SSLAS0:
        POP     AX      _C{ char}
        POP     CX      _C{ count}
        MOV     BX,CX
        POP     DI      _C{ addr}
        OR      DI,DI   _C{Clear zero flag.}
        MOV     DX,DI   _C{ Copy}
        CLD             _C{ INC DIRECTION}
        REPNZ     SCASB   _C{ Compare BYTE}    <<<<<<<<<<<
        JZ      SSLAS1
<loads of stuff to handle the corner cases)

>

<SNIP>

Groetjes Albert
--
Temu exploits Christians: (Disclaimer, only 10 apostles)
Last Supper Acrylic Suncatcher - 15Cm Round Stained Glass- Style Wall
Art For Home, Office And Garden Decor - Perfect For Windows, Bars,
And Gifts For Friends Family And Colleagues.