1/*
2 * Copyright (c) 2015-2018, Intel Corporation
3 *
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5 * modification, are permitted provided that the following conditions are met:
6 *
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8 * this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
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15 *
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27 */
28
29/** \file
30 * \brief Stop Alphabet calculation.
31 */
32
33#ifndef NG_STOP_H
34#define NG_STOP_H
35
36#include "ue2common.h"
37#include "som/som.h"
38
39#include <vector>
40
41namespace ue2 {
42
43struct CastleProto;
44class CharReach;
45class NGHolder;
46
47/** Find the set of characters that are not present in the reachability of
48 * graph \p g after a certain depth (currently 8). If a character in this set
49 * is encountered, it means that the NFA is either dead or has not progressed
50 * more than 8 characters from its start states.
51 *
52 * This is only used to guide merging heuristics, use
53 * findLeftOffsetStopAlphabet for real uses.
54 */
55CharReach findStopAlphabet(const NGHolder &g, som_type som);
56
57/** Calculate the stop alphabet for each depth from 0 to MAX_STOP_DEPTH. Then
58 * build an eight-bit mask per character C, with each bit representing the
59 * depth before the location of character C (if encountered) that the NFA would
60 * be in a predictable start state. */
61std::vector<u8> findLeftOffsetStopAlphabet(const NGHolder &g, som_type som);
62std::vector<u8> findLeftOffsetStopAlphabet(const CastleProto &c, som_type som);
63
64} // namespace ue2
65
66#endif
67