1		% minimize ProB AST integer expressions for shrinking stage
2
3		minimize_int_expr(b(integer(Value),integer,[]),b(integer(Value),integer,[])).
4
5		% add, minus, multiplication, div, power_of, modulo
6		% shrink expression to its value when both arguments are integer values
7		minimize_int_expr(b(Expression,integer,Info),Shrunken) :-
8		Expression =.. [Type,Arg1,Arg2] ,
9		member(Type,[add,minus,multiplication,div,power_of,modulo]) ,
10		prob_is_ground(Arg1,true) ,
11		prob_is_ground(Arg2,true) ,
12		int(b(Expression,integer,Info),Value) ,
13		Shrunken = b(integer(Value),integer,Info).
14		minimize_int_expr(b(Expression,integer,Info),Shrunken) :-
15		Expression =.. [Type,Arg1,Arg2] ,
16		member(Type,[add,minus,multiplication,div,power_of,modulo]) ,
17		% hold integer value and minimize expression
18		(prob_is_ground(Arg1,true) , prob_is_ground(Arg2,false)
19		-> minimize_int_expr(Arg2,NewArg2) ,
20		NewExpr =.. [Type,Arg1,NewArg2] ,
21		Shrunken = b(NewExpr,integer,Info)
22		; prob_is_ground(Arg1,false) , prob_is_ground(Arg2,true)
23		-> minimize_int_expr(Arg1,NewArg1) ,
24		NewExpr =.. [Type,NewArg1,Arg2] ,
25		Shrunken = b(NewExpr,integer,Info)
26		; % minimize both expressions
27		minimize_int_expr(Arg1,NewArg1) ,
28		minimize_int_expr(Arg2,NewArg2) ,
29		NewExpr =.. [Type,NewArg1,NewArg2] ,
30		Shrunken = b(NewExpr,integer,Info)).
31
32		% unary_minus
33		minimize_int_expr(b(unary_minus(Expression),integer,Info),Shrunken) :-
34		(Expression = b(integer(Value),integer,_)
35		-> Temp is -(Value) ,
36		Shrunken = b(integer(Temp),integer,Info)
37		; minimize_int_expr(Expression,Temp) ,
38		Shrunken = b(unary_minus(Temp),integer,Info)).
39
40		% card
41		/*minimize_int_expr(b(card(Set),integer,Info),Shrunken) :-
42		(prob_is_ground(Set,true) ->
43		int(b(card(Set),integer,Info),Value) ,
44		Shrunken = b(integer(Value),integer,Info)
45		;
46		minimize_set_expr(Set,ShrunkenSet) ,
47		Shrunken = b(card(ShrunkenSet),integer,Info)).*/
48
49		% max_int, min_int
50		minimize_int_expr(b(Expression,integer,Info),Shrunken) :-
51		member(Expression,[max_int,min_int]) ,
52		int(b(Expression,integer,Info),Value) ,
53		Shrunken = b(integer(Value),integer,Info).
54
55		% max, min
56		minimize_int_expr(b(Expression,integer,Info),Shrunken) :-
57		Expression =.. [Type,Set] ,
58		member(Type,[max,min]) ,
59		(prob_is_ground(Set,true)
60		-> int(b(Expression,integer,Info),Val) ,
61		Shrunken = b(integer(Val),integer,[])
62		; minimize_set_expr(Set,Temp) ,
63		% no empty set in max, min for well-definedness
64		((Temp = [] ; Temp = avl_set(empty))
65		-> ShrunkenSet = Set
66		; ShrunkenSet = Temp) ,
67		NewExpr =.. [Type,ShrunkenSet] ,
68		Shrunken = b(NewExpr,integer,Info)).
69
70		% skip identifier
71		minimize_int_expr(b(identifier(Name),Type,Info),b(identifier(Name),Type,Info)).
72
73		% get the deepest value or expression of an prob ast expression
74		get_inner_expr(b(Expression,Type,Info),Shrunken) :-
75		Expression =.. [_,Arg1,Arg2] ,
76		prob_is_ground(Arg1,Res1) , prob_is_ground(Arg2,Res2) ,
77		( Res1 = true , Res2 = true
78		-> % done
79		Shrunken = b(Expression,Type,Info)
80		; % get inner expression of second argument
81		Res1 = true , Res2 = false
82		-> get_inner_expr(Arg2,Shrunken)
83		; % both arguments are expressions
84		Res1 = false , Res2 = false
85		-> % random choice heuristic
86		random_member(Argument,[Arg1,Arg2]) ,
87		get_inner_expr(Argument,Shrunken)
88		; % get inner expression of first argument
89		get_inner_expr(Arg1,Shrunken)).
90
91		get_inner_expr(Expr,Expr).