1		% minimize ProB AST sequence expressions for shrinking stage
2
3		minimize_seq_expr(b(sequence_extension(Seq),seq(Type),Info),b(sequence_extension(ShrunkenSeq),seq(Type),Info)) :-
4		is_list(Seq) ,
5		shrink(list(_),Seq,ShrunkenSeq).
6
7		minimize_seq_expr(b(value(Seq),seq(Type),Info),Shrunken) :-
8		shrink(prob_value_seq,Seq,ShrunkenSeq) ,
9		Shrunken = b(value(ShrunkenSeq),seq(Type),Info).
10
11		minimize_seq_expr(b(sequence_extension([]),seq(Inner),Info),b(sequence_extension([]),seq(Inner),Info)).
12
13		minimize_seq_expr(b(general_concat(SeqOfSeq),seq(Type),Info),Shrunken) :-
14		(prob_is_ground(SeqOfSeq,true)
15		-> seqint_avl(b(general_concat(SeqOfSeq),seq(Type),Info),ValueAvl) ,
16		Shrunken = b(value(ValueAvl),seq(Type),Info)
17		; SeqOfSeq = b(sequence_extension(Seq),seq(OutterType),OutterInfo) ,
18		maplist(minimize_seq_expr,Seq,ShrunkenSeq) ,
19		Shrunken = b(general_concat(b(sequence_extension(ShrunkenSeq),seq(OutterType),OutterInfo)),seq(Type),Info)).
20
21		minimize_seq_expr(b(Expression,seq(Type),Info),Shrunken) :-
22		Expression =.. [Expr,Arg] ,
23		member(Expr,[front,tail,rev]) ,
24		(prob_is_ground(Arg,true)
25		-> seqint_avl(b(Expression,seq(Type),Info),ValueAvl) ,
26		(ValueAvl = avl_set(empty) ->
27		% no empty set for well-definedness
28		Shrunken = b(Expression,seq(Type),Info)
29		; Shrunken = b(value(ValueAvl),seq(Type),Info))
30		; minimize_seq_expr(Arg,NewArg) ,
31		NewExpr =.. [Expr,NewArg] ,
32		Shrunken = b(NewExpr,seq(Type),Info)).
33
34		minimize_seq_expr(b(Expression,seq(Type),Info),Shrunken) :-
35		Expression =.. [Expr,Seq,Value] ,
36		member(Expr,[restrict_front,restrict_tail]) ,
37		(prob_is_ground(Seq,true)
38		-> seqint_avl(b(Expression,seq(Type),Info),ValueAvl) ,
39		Shrunken = b(value(ValueAvl),seq(Type),Info)
40		; minimize_seq_expr(Seq,NewArg) ,
41		% decrease restriction value by one after every shrinking call
42		% to keep well-definedness
43		Value = b(integer(Val),integer,IntInfo) ,
44		(Val = 0 -> NVal = Val ; NVal is Val - 1) ,
45		NewValue = b(integer(NVal),integer,IntInfo) ,
46		NewExpr =.. [Expr,NewArg,NewValue] ,
47		Shrunken = b(NewExpr,seq(Type),Info)).
48
49		minimize_seq_expr(b(concat(Seq1,Seq2),seq(Type),Info),b(value(ValueSeq),seq(Type),Info)) :-
50		prob_is_ground(Seq1,true) ,
51		prob_is_ground(Seq2,true) ,
52		seqint_avl(b(concat(Seq1,Seq2),seq(Type),Info),ValueSeq).
53		minimize_seq_expr(b(concat(Seq1,Seq2),seq(Type),Info),b(concat(NewSeq1,NewSeq2),seq(Type),Info)) :-
54		prob_is_ground(Seq1,Res1) ,
55		prob_is_ground(Seq2,Res2) ,
56		( Res1 = true , Res2 = false
57		-> minimize_seq_expr(Seq2,NewSeq2) ,
58		NewSeq1 = Seq1
59		; Res1 = false , Res2 = true
60		-> minimize_seq_expr(Seq1,NewSeq1) ,
61		NewSeq2 = Seq2
62		; minimize_seq_expr(Seq1,NewSeq1) ,
63		minimize_seq_expr(Seq2,NewSeq2)).
64
65		minimize_seq_expr(b(insert_front(Value,Seq),seq(Type),Info),Shrunken) :-
66		(prob_is_ground(Seq,true)
67		-> seqint_avl(b(insert_front(Value,Seq),seq(Type),Info),ValueAvl) ,
68		Shrunken = b(value(ValueAvl),seq(Type),Info)
69		; minimize_seq_expr(Seq,NewSeq) ,
70		NewExpr =.. [insert_front,Value,NewSeq] ,
71		Shrunken = b(NewExpr,seq(Type),Info)).
72
73		minimize_seq_expr(b(insert_tail(Seq,Value),seq(Type),Info),Shrunken) :-
74		(prob_is_ground(Seq,true)
75		-> seqint_avl(b(insert_tail(Value,Seq),seq(Type),Info),ValueAvl) ,
76		Shrunken = b(value(ValueAvl),seq(Type),Info)
77		; minimize_seq_expr(Seq,NewSeq) ,
78		NewExpr =.. [insert_tail,NewSeq,Value] ,
79		Shrunken = b(NewExpr,seq(Type),Info)).
80
81		% skip identifier
82		minimize_seq_expr(b(identifier(Name),Type,Info),b(identifier(Name),Type,Info)).