This page (revision-5) was last changed on 03-Feb-2023 15:21 by Carsten Strotmann 

This page was created on 08-Aug-2010 08:30 by Carsten Strotmann

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Version Date Modified Size Author Changes ... Change note
5 03-Feb-2023 15:21 9 KB Carsten Strotmann to previous
4 08-Aug-2010 09:02 6 KB Carsten Strotmann to previous | to last
3 08-Aug-2010 08:46 5 KB Carsten Strotmann to previous | to last
2 08-Aug-2010 08:34 2 KB Carsten Strotmann to previous | to last
1 08-Aug-2010 08:30 2 KB Carsten Strotmann to last

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Ultimate CASE Statement
Ultimate CASE Statement

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At line 68 changed one line
Figure 2a would look as shown in Figure 3. Let's add two more spoons of syntactic sugar, as in Figure 4. As has been noted elsewhere, too much syntactic sugar causes semantic diabetes. Our __case__ is sweet enough. Figure Five is an example to show some of the possibilities.
Figure 2b
{{{
craps(n)
int n;
{ switch(n) {
case 7, 11: printf("You win"); break;
case 2..3, 12: printf("You lose"); break;
default: printf("%d is you point",n);
}
}
}}}
At line 80 added 38 lines
Figure 3
{{{
: CASE DUP ;
: CRAPS ( n -- )
CASE 7 = IF DROP ." You win" EXIT THEN
CASE 11 = IF DROP ." You win" EXIT THEN
CASE 2 = IF DROP ." You lose" EXIT THEN
CASE 3 = IF DROP ." You lose" EXIT THEN
CASE 12 = IF DROP ." You lose" EXIT THEN
. . is your point" ;
}}}
Figure 2a would look as shown in Figure 3. Let's add two more spoons of syntactic sugar, as in Figure 4. As has been noted elsewhere, too much syntactic sugar causes semantic diabetes. Our __case__ is sweet enough. Figure 5 is an example to show some of the possibilities.
Figure 3
{{{
: OF ( n flag -- ) [COMPILE] IF COMPILE DROP ; IMMEDIATE
: =OR ( n flag n -- n flag ) 2 PICK = DROP ;
: CRAPS ( n -- )
CASE 7 = 11 =OR OF ." You win" EXIT THEN
CASE 2 3 BETWEEN 12 =OR OF ." You lose" EXIT THEN
. ." is your point" ;
}}}
Figure 4
{{{
: WHATEVER ( n -- )
CASE 0= OF ." zero" EXIT THEN
CASE 0< OF ." Negative" EXIT THEN
CASE DUP 1- AND 0= OF ." Power of 2" EXIT THEN
CASE ASCII 0 ASCII 9 BETWEEN OF ." Digit" EXIT THEN
CASE ASCII , ASCII / BETWEEN
ASCII : =OR OF ." Punctuation ,-./: " EXIT THEN
DROP ." Whatever" ;
}}}
At line 120 added 59 lines
Figure 6
{{{
: ?OUT ( c -- ) 127 AND
CASE 0= 13 ( return ) 0O
OF ?NEW-LINE EXIT THEN
CASE 10 ( linefeed ) = 12 ( formfeed ) = OR
OF #BLANK-LINES @ 0=
IF ?NEW-LINE THEN
EXIT THEN
0 #BLANK-LINES !
CASE 32 < OF ( do nothing ) EXIT THEN
EXIT ;
}}}
Figure 7
{{{
( #YEAR is a variable holding the year )
:LEAPYEAR? ( -- tf : true if the year is a leap year )
#YEAR @
CASE 400 MOD 0= OF TRUE EXIT THEN
CASE 100 MOD 0= OF FALSE EXIT THEN
CASE 4 MOD 0= OF TRUE EXIT THEN
DROP FALSE ;
: DAYS ( month# -- days-in-month )
CASE 9 = 4 =OR 6 =OR 1 =OR OF 30 EXIT THEN
CASE 2 = NOT OF 31 EXIT THEN
DROP LEAPYEAR? IF 29 ELSE 28 THEN ;
}}}
Figure 8
{{{
: CBASE! ( a c -- a' )
CASE ASCII $ = OF HEX 1+ EXIT THEN
CASE ASCII @ = OF OCTAL 1+ EXIT THEN
CASE ASCII % = OF BINARY 1+ EXIT THEN
CASE ASCII & = OF DECIMAL 1+ EXIT THEN
DROP ;
: BASE-NUMBER ( a -- d )
BASE @ >R DUP 1+ C@ CBASE!
NUMBER? R> BASE ! 0= ABORT" ?" ;
}}}
Figure 9
{{{
HEX
: CLASSIFY ( n -- )
CASE 20 < 7F =OR OF ." Control character" EXIT THEN
CASE 20 2f BETWEEN
OVER 3A 40 BETWEEN OR
OVER 5B 60 BETWEEN OR
OVER 7B 7E BETWEEN OR OF ." Punctuation" EXIT THEN
CASE 30 39 BETWEEN OF ." Digit" EXIT THEN
CASE 41 5A BETWEEN OF ." Upper case letter" EXIT THEN
CASE 61 7A BETWEEN OF ." Lower case letter" EXIT THEN
DROP ." Not a character" ;
}}}
At line 181 added 15 lines
Figure 10a
{{{
CREATE CASE ' DUP ( CFA ) @ ' CASE (CFA ) !
}}}
Figure 10b
{{{
: =OR ( n tf n -- n tf ) 3 PICK = OR ;
}}}
Figure 10c
{{{
: =OR ( n tf n -- n tf ) >R OVER R> = OR ;
}}}
At line 205 added 23 lines
Figure 11a
{{{
: WITHIN ( n n1 n2 -- tf : true when n1 <= n & n < n2 )
over - >R - R> U< ;
:BETWEEN ( n n1 n2 -- tf : true when n1 <= n & n <= n2 )
WITHIN 1+ ;
: ASCII ( ^ c -- c : integer value for character c )
BL WORD COUNT 1- ABORT" ?" C@ STATE @
IF [COMPILE] LITERAL THEN ; IMMEDIATE
}}}
Figure 11b
{{{
: HEX ( -- ) 16 BASE ! ;
: OCTAL ( -- ) 8 BASE ! ;
: BINARY ( -- ) 2 BASE ! ;
: DECIMAL ( -- ) 10 BASE ! ;
: NUMBER? ( addr -- dn tf ) 0 0 ROT CONVERT C@ BL = ;
}}}
This page (revision-5) was last changed on 03-Feb-2023 15:21 by Carsten Strotmann  Top