1 | /* |
2 | * Copyright (c) 2015-2017, 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 Literal Component Splitting. Identifies literals that span the |
31 | * graph and moves them into Rose. |
32 | */ |
33 | |
34 | #include "ng_literal_component.h" |
35 | |
36 | #include "grey.h" |
37 | #include "ng.h" |
38 | #include "ng_prune.h" |
39 | #include "ng_util.h" |
40 | #include "ue2common.h" |
41 | #include "compiler/compiler.h" |
42 | #include "rose/rose_build.h" |
43 | #include "util/container.h" |
44 | #include "util/graph.h" |
45 | #include "util/graph_range.h" |
46 | #include "util/ue2string.h" |
47 | |
48 | #include <unordered_set> |
49 | |
50 | using namespace std; |
51 | |
52 | namespace ue2 { |
53 | |
54 | static |
55 | bool isLiteralChar(const NGHolder &g, NFAVertex v, bool &nocase, |
56 | bool &casefixed) { |
57 | const CharReach &cr = g[v].char_reach; |
58 | const size_t num = cr.count(); |
59 | if (num > 2) { |
60 | return false; // char class |
61 | } |
62 | |
63 | if (!casefixed) { |
64 | if (num == 2 && cr.isCaselessChar()) { |
65 | nocase = true; |
66 | casefixed = true; |
67 | return true; |
68 | } else if (num == 1) { |
69 | if (cr.isAlpha()) { |
70 | nocase = false; |
71 | casefixed = true; |
72 | } |
73 | // otherwise, still acceptable but we can't fix caselessness yet |
74 | return true; |
75 | } |
76 | } else { |
77 | // nocase property is fixed |
78 | if (nocase) { |
79 | if ((num == 2 && cr.isCaselessChar()) || |
80 | (num == 1 && !cr.isAlpha())) { |
81 | return true; |
82 | } |
83 | } else { |
84 | return (num == 1); |
85 | } |
86 | } |
87 | |
88 | return false; |
89 | } |
90 | |
91 | static |
92 | void addToString(string &s, const NGHolder &g, NFAVertex v) { |
93 | const CharReach &cr = g[v].char_reach; |
94 | assert(cr.count() == 1 || cr.isCaselessChar()); |
95 | |
96 | char c = (char)cr.find_first(); |
97 | s.push_back(c); |
98 | } |
99 | |
100 | static |
101 | bool splitOffLiteral(NG &ng, NGHolder &g, NFAVertex v, const bool anchored, |
102 | set<NFAVertex> &dead) { |
103 | DEBUG_PRINTF("examine vertex %zu\n" , g[v].index); |
104 | bool nocase = false, casefixed = false; |
105 | |
106 | assert(!is_special(v, g)); |
107 | |
108 | size_t reqInDegree; |
109 | if (anchored) { |
110 | reqInDegree = 1; |
111 | assert(edge(g.start, v, g).second); |
112 | } else { |
113 | reqInDegree = 2; |
114 | assert(edge(g.start, v, g).second); |
115 | assert(edge(g.startDs, v, g).second); |
116 | } |
117 | if (in_degree(v, g) > reqInDegree) { |
118 | DEBUG_PRINTF("extra in-edges\n" ); |
119 | return false; |
120 | } |
121 | |
122 | if (!isLiteralChar(g, v, nocase, casefixed)) { |
123 | DEBUG_PRINTF("not literal\n" ); |
124 | return false; |
125 | } |
126 | |
127 | string literal; |
128 | addToString(literal, g, v); |
129 | |
130 | // Remaining vertices must come in a chain, each with one in-edge and one |
131 | // out-edge only. |
132 | NFAVertex u; |
133 | while (1) { |
134 | if (out_degree(v, g) != 1) { |
135 | DEBUG_PRINTF("branches, not literal\n" ); |
136 | return false; |
137 | } |
138 | |
139 | u = v; // previous vertex |
140 | v = *(adjacent_vertices(v, g).first); |
141 | |
142 | DEBUG_PRINTF("loop, v=%zu\n" , g[v].index); |
143 | |
144 | if (is_special(v, g)) { |
145 | if (v == g.accept || v == g.acceptEod) { |
146 | break; // OK |
147 | } else { |
148 | assert(0); // start? |
149 | return false; |
150 | } |
151 | } else { |
152 | // Ordinary, must be literal |
153 | if (!isLiteralChar(g, v, nocase, casefixed)) { |
154 | DEBUG_PRINTF("not literal\n" ); |
155 | return false; |
156 | } |
157 | if (in_degree(v, g) != 1) { |
158 | DEBUG_PRINTF("branches, not literal\n" ); |
159 | return false; |
160 | } |
161 | } |
162 | |
163 | addToString(literal, g, v); |
164 | } |
165 | |
166 | // Successfully found a literal; there might be multiple report IDs, in |
167 | // which case we add all the reports. |
168 | assert(!is_special(u, g)); |
169 | bool eod = v == g.acceptEod; |
170 | assert(eod || v == g.accept); |
171 | |
172 | DEBUG_PRINTF("success: found %s literal '%s'\n" , |
173 | anchored ? "anchored" : "unanchored" , |
174 | escapeString(literal).c_str()); |
175 | |
176 | // Literals of length 1 are better served going through later optimisation |
177 | // passes, where they might be combined together into a character class. |
178 | if (literal.length() == 1) { |
179 | DEBUG_PRINTF("skipping literal of length 1\n" ); |
180 | return false; |
181 | } |
182 | |
183 | ng.rose->add(anchored, eod, ue2_literal(literal, nocase), g[u].reports); |
184 | |
185 | // Remove the terminal vertex. Later, we rely on pruneUseless to remove the |
186 | // other vertices in this chain, since they'll no longer lead to an accept. |
187 | dead.insert(u); |
188 | |
189 | return true; |
190 | } |
191 | |
192 | /** \brief Split off literals. True if any changes were made to the graph. */ |
193 | bool splitOffLiterals(NG &ng, NGHolder &g) { |
194 | if (!ng.cc.grey.allowLiteral) { |
195 | return false; |
196 | } |
197 | |
198 | bool changed = false; |
199 | set<NFAVertex> dead; |
200 | |
201 | unordered_set<NFAVertex> unanchored; // for faster lookup. |
202 | insert(&unanchored, adjacent_vertices(g.startDs, g)); |
203 | |
204 | // Anchored literals. |
205 | for (auto v : adjacent_vertices_range(g.start, g)) { |
206 | if (!is_special(v, g) && !contains(unanchored, v)) { |
207 | changed |= splitOffLiteral(ng, g, v, true, dead); |
208 | } |
209 | } |
210 | |
211 | // Unanchored literals. |
212 | for (auto v : adjacent_vertices_range(g.startDs, g)) { |
213 | if (!is_special(v, g)) { |
214 | changed |= splitOffLiteral(ng, g, v, false, dead); |
215 | } |
216 | } |
217 | |
218 | if (changed) { |
219 | remove_vertices(dead, g); |
220 | pruneUseless(g); |
221 | return true; |
222 | } |
223 | |
224 | return false; |
225 | } |
226 | |
227 | } // namespace ue2 |
228 | |