28 case ALT(r1, r2) => ALT(der(c, r1), der(c, r2)) |
28 case ALT(r1, r2) => ALT(der(c, r1), der(c, r2)) |
29 case SEQ(r1, r2) => |
29 case SEQ(r1, r2) => |
30 if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2)) |
30 if (nullable(r1)) ALT(SEQ(der(c, r1), r2), der(c, r2)) |
31 else SEQ(der(c, r1), r2) |
31 else SEQ(der(c, r1), r2) |
32 case STAR(r1) => SEQ(der(c, r1), STAR(r1)) |
32 case STAR(r1) => SEQ(der(c, r1), STAR(r1)) |
33 case NTIMES(r, i) => |
33 case NTIMES(r1, i) => |
34 if (i == 0) ZERO else SEQ(der(c, r), NTIMES(r, i - 1)) |
34 if (i == 0) ZERO else der(c, SEQ(r1, NTIMES(r1, i - 1))) |
35 } |
35 } |
36 |
36 |
37 def simp(r: Rexp) : Rexp = r match { |
37 def simp(r: Rexp) : Rexp = r match { |
38 case ALT(r1, r2) => (simp(r1), simp(r2)) match { |
38 case ALT(r1, r2) => (simp(r1), simp(r2)) match { |
39 case (ZERO, r2s) => r2s |
39 case (ZERO, r2s) => r2s |
44 case (ZERO, _) => ZERO |
44 case (ZERO, _) => ZERO |
45 case (_, ZERO) => ZERO |
45 case (_, ZERO) => ZERO |
46 case (ONE, r2s) => r2s |
46 case (ONE, r2s) => r2s |
47 case (r1s, ONE) => r1s |
47 case (r1s, ONE) => r1s |
48 case (r1s, r2s) => SEQ(r1s, r2s) |
48 case (r1s, r2s) => SEQ(r1s, r2s) |
49 } |
|
50 case NTIMES(r1, n) => simp(r1) match { |
|
51 case ZERO => ZERO |
|
52 case ONE => ONE |
|
53 case r1s => NTIMES(r1s, n) |
|
54 } |
49 } |
55 case r => r |
50 case r => r |
56 } |
51 } |
57 |
52 |
58 // derivative w.r.t. a string (iterates der) |
53 // derivative w.r.t. a string (iterates der) |