;;;;;;;;;;;;;;;;;;; -*- Mode: Lisp; Package: Macsyma -*- ;;;;;;;;;;;;;;;;;;;
;;;     (c) Copyright 1980 Massachusetts Institute of Technology         ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(macsyma-module char)


;;; hacks for character manipulation.


(DEFMFUN $GETCHARN (SYMBOL INDEX)
	 (OR (SYMBOLP SYMBOL)
	     (MERROR "First arg to GETCHARN: ~A, was not a symbol."
		     (implode (mstring symbol))))
	 (OR (AND (FIXP INDEX)
		  (> INDEX 0))
	     (MERROR "Second arg to GETCHARN: ~A, was not a positive fixnum."
		     (implode (mstring index))))
	 ; what happens next is debateable.
	 ; one thing I don't want to do call mstring and take nthcdr.
	 ; what to returns depends on what you would see printed.
	 ; well, or read in.
	 ; the main use for this is to check symbol name conventions,
	 ; so $FOO and &FOO might be the same, same with %FOO I guess,
	 ; but FOO (i.e. ?FOO is different.) poo, all these things
	 ; depend on the setting of global switches. screw it.
	 (LET ((C1 (GETCHARN SYMBOL 1)))
	      (COND ((OR (= C1 #/$) (= C1 #/%) (= C1 #/&))
		     (GETCHARN SYMBOL (1+ INDEX)))
		    ((= INDEX 1) #/?)
		    (T (GETCHARN SYMBOL (1- INDEX))))))