ce1zzes@prism.gatech.EDU (Eric Sheppard) (04/14/90)
I wish to perform functions according to commands parsed into a string array.
The CASE operator only works for simple variable types. Is there an elegant way
to perform the CASE for complex (string) variables? Desired sample construct:
case Command of
'1STCOM' : FirstCommand;
'2NDCOM' : SecondCommand;
.
.
end;
Eric, tinkerer-at-large
--
Eric Sheppard Georgia Tech | "Of course the US Constitution isn't
Atlanta, GA | perfect; but it's a lot better than what
ARPA: ce1zzes@prism.gatech.edu | we have now."
uucp: ...!{allegra,amd,hplabs,seismo,ut-ngp}!gatech!prism!ce1zzesmlw@pyr.gatech.EDU (Michael Williams) (04/14/90)
In article <8001@hydra.gatech.EDU> ce1zzes@prism.gatech.EDU (Eric Sheppard) writes: >I wish to perform functions according to commands parsed into a string array. >The CASE operator only works for simple variable types. Is there an elegant way >to perform the CASE for complex (string) variables? Desired sample construct: > >case Command of > '1STCOM' : FirstCommand; > '2NDCOM' : SecondCommand; > . > . >end; The closest constuct I know of is : valid := '1STCOM 2NDCOM 3RDCOM 4THCOM 5THCOM'; case pos(command,valid) of 1 : FirstCommand; 8 : SecondCommand; 15 : ThirdCommand; 22 : FourthCommand; 29 : FifthCommand; else write('Invalid command!'); end; This sounds like a scanner for a compiler, where you are checking for keywords. In this case, a 'perfect' hashing function would be preferable. Hope this helps ... -- Michael Williams Georgia Institute of Technology, Atlanta Georgia, 30332 uucp: ...!{akgua,allegra,amd,hplabs,ihnp4,seismo,ut-ngp}!gatech!gitpyr!mlw ARPA: mlw@pyr.gatech.edu
ce1zzes@prism.gatech.EDU (Eric Sheppard) (04/14/90)
In article <10010@pyr.gatech.EDU> mlw@pyr.UUCP (Michael Williams) writes: > > This sounds like a scanner for a compiler, where you are checking for >keywords. In this case, a 'perfect' hashing function would be preferable. > >Hope this helps ... Right you are. I'm working on a simple LOGO-like language interpreter/compiler, for a programming course. Is there a better way to check for keywords/commands? Eric, tinkerer-at-large -- Eric Sheppard Georgia Tech | "Of course the US Constitution isn't Atlanta, GA | perfect; but it's a lot better than what ARPA: ce1zzes@prism.gatech.edu | we have now." uucp: ...!{allegra,amd,hplabs,seismo,ut-ngp}!gatech!prism!ce1zzes
mathrich@mthvax.cs.miami.edu (Rich Winkel) (04/14/90)
In <8001@hydra.gatech.EDU> ce1zzes@prism.gatech.EDU (Eric Sheppard) writes: >I wish to perform functions according to commands parsed into a string array. >The CASE operator only works for simple variable types. Is there an elegant way >to perform the CASE for complex (string) variables? Desired sample construct: >case Command of > '1STCOM' : FirstCommand; > '2NDCOM' : SecondCommand; > . > . >end; case ((pos(' '+Command+' ',' 1STCOM 2NDCOM QUIT 3RDCOM ...')-1) DIV 7) of 0: firstcommand; 1: secondcommand; or something similar. Not elegant, but usable. Rich