1 | /* |
2 | * Copyright (c) 2015, Intel Corporation |
3 | * |
4 | * Redistribution and use in source and binary forms, with or without |
5 | * modification, are permitted provided that the following conditions are met: |
6 | * |
7 | * * Redistributions of source code must retain the above copyright notice, |
8 | * this list of conditions and the following disclaimer. |
9 | * * Redistributions in binary form must reproduce the above copyright |
10 | * notice, this list of conditions and the following disclaimer in the |
11 | * documentation and/or other materials provided with the distribution. |
12 | * * Neither the name of Intel Corporation nor the names of its contributors |
13 | * may be used to endorse or promote products derived from this software |
14 | * without specific prior written permission. |
15 | * |
16 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
17 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
20 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
26 | * POSSIBILITY OF SUCH DAMAGE. |
27 | */ |
28 | |
29 | /** \file |
30 | * \brief Short Exhaustible Passthroughs. |
31 | * |
32 | * Analysis code for determining whether a graph should be treated specially |
33 | * because it is short and contains exhaustible reports; typically we turn |
34 | * these into outfixes rather than risk them becoming Rose literals. |
35 | * |
36 | * For example, the pattern: |
37 | * |
38 | * /[a-f]/H |
39 | * |
40 | * ... is far better suited to becoming a small outfix that generates one match |
41 | * and goes dead than being split into six one-byte Rose literals that end up |
42 | * in the literal matcher. |
43 | */ |
44 | #include "ng_sep.h" |
45 | |
46 | #include "grey.h" |
47 | #include "ng_holder.h" |
48 | #include "ng_reports.h" |
49 | #include "ng_util.h" |
50 | #include "ue2common.h" |
51 | #include "util/graph_range.h" |
52 | |
53 | using namespace std; |
54 | |
55 | namespace ue2 { |
56 | |
57 | static |
58 | bool checkFromVertex(const NGHolder &g, NFAVertex start) { |
59 | for (auto v : adjacent_vertices_range(start, g)) { |
60 | if (v == g.startDs) { |
61 | continue; |
62 | } |
63 | |
64 | assert(!is_special(v, g)); /* should not be vacuous */ |
65 | |
66 | if (!edge(g.startDs, v, g).second) { /* only floating starts */ |
67 | return false; |
68 | } else if (out_degree(v, g) == 1 |
69 | && edge(v, g.accept, g).second) { /* only floating end */ |
70 | ; /* possible sep */ |
71 | } else { |
72 | return false; |
73 | } |
74 | } |
75 | return true; |
76 | } |
77 | |
78 | bool isSEP(const NGHolder &g, const ReportManager &rm, const Grey &grey) { |
79 | if (!grey.mergeSEP || !can_exhaust(g, rm)) { |
80 | return false; |
81 | } |
82 | |
83 | if (!checkFromVertex(g, g.start) || !checkFromVertex(g, g.startDs)) { |
84 | return false; |
85 | } |
86 | |
87 | assert(out_degree(g.start, g) || proper_out_degree(g.startDs, g)); |
88 | |
89 | DEBUG_PRINTF("graph is an SEP\n" ); |
90 | return true; |
91 | } |
92 | |
93 | } // namespace ue2 |
94 | |