/fth/smart_if.fth

\ @(#) smart_if.fth 98/01/26 1.2

\ Smart Conditionals

\ Allow use of if, do, begin, etc.outside of colon definitions.

\

\ Thanks to Mitch Bradley for the idea.

\

\ Author: Phil Burk

\ Copyright 1994 3DO, Phil Burk, Larry Polansky, Devid Rosenboom

\

\ The pForth software code is dedicated to the public domain,

\ and any third party may reproduce, distribute and modify

\ the pForth software code or any derivative works thereof

\ without any compensation or license.  The pForth software

\ code is provided on an "as is" basis without any warranty

\ of any kind, including, without limitation, the implied

\ warranties of merchantability and fitness for a particular

\ purpose and their equivalents under the laws of any jurisdiction.



anew task-smart_if.fth



variable SMIF-XT    \ execution token for conditional code

variable SMIF-DEPTH \ depth of nested conditionals



: SMIF{   ( -- , if executing, start compiling, setup depth )

	state @ 0=

	IF

		:noname smif-xt !

		1 smif-depth !

	ELSE

		1 smif-depth +!

	THEN

;



: }SMIF  ( -- , unnest, stop compiling, execute code and forget )

	smif-xt @

	IF

		-1 smif-depth +!

		smif-depth @ 0 <=

		IF

			postpone ;             \ stop compiling

			smif-xt @ execute      \ execute conditional code

			smif-xt @ >code dp !   \ forget conditional code

			0 smif-xt !   \ clear so we don't mess up later

		THEN

	THEN

;

		

\ redefine conditionals to use smart mode

: IF      smif{   postpone if     ; immediate

: DO      smif{   postpone do     ; immediate

: ?DO     smif{   postpone ?do    ; immediate

: BEGIN   smif{   postpone begin  ; immediate

: THEN    postpone then    }smif  ; immediate

: REPEAT  postpone repeat  }smif  ; immediate

: UNTIL   postpone until   }smif  ; immediate

: LOOP    postpone loop    }smif  ; immediate

: +LOOP   postpone +loop   }smif  ; immediate