# This is a simple example of the expected TL-Delta Grammar derivative. 
# This TM takes an input string and replaces all 0's with 1's.

# Note:  The ~ is the symbol for a space, this may change in the future,
# but for now, it was simpler than parsing ' ', because whitespace is 
# being stripped.  Also note that the label names need to adhere to the 
# C standard, i.e., they must start with an Alpha character and be at
# at least one character long and cannot contain special characters
# or white space. 
 
# pointer(>) means to move the tape head to the right
# pointer(<) means to move the tape head to the left
# pointer(^) means to leave the tape head in its current position. 

# scan=0 is a comparison on the symbol where the tape head is currently
# and the character 0.

# scan:=0 is an assignment, it tells the machine to write a 0 where the
# tape head is currently.

# ACCEPT tells the machine to accept.
# REJECT tells the machine to reject.

# either upper or lowercase may be used for keywords. 

BEGIN
	L0: IF ( scan=0 ) then
		begin 
			scan:=1; pointer(>); goto L0;
		end
	L1: if ( scan=1 ) then
		begin
			scan:=1; pointer(>); goto L0; 
		end
	L2: if ( scan= ~ ) then 
		begin
			scan:=~; pointer(>); goto REWIND;
		end
	REWIND: if ( scan = 1 ) then
		begin
			scan:=1; pointer(<); goto REWIND; 
		end
	L3: if (scan = ~ ) then
		begin
			scan:=~; pointer(>); GOTO FINISH;
		end
	FINISH: ACCEPT;
END.