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 Represents an empty regex element, like (?m)
31 */
32#include <cassert>
33
34#include "ComponentEmpty.h"
35#include "position.h"
36#include "position_info.h"
37#include "buildstate.h"
38#include "ue2common.h"
39
40using namespace std;
41
42namespace ue2 {
43
44ComponentEmpty::ComponentEmpty() {
45 // Surprise, it's EMPTY!
46}
47
48ComponentEmpty::~ComponentEmpty() {
49 // Surprise, it's EMPTY!
50}
51
52ComponentEmpty *ComponentEmpty::clone() const { return new ComponentEmpty(); }
53
54bool ComponentEmpty::empty() const {
55 return true;
56}
57
58bool ComponentEmpty::vacuous_everywhere(void) const {
59 return true;
60}
61
62bool ComponentEmpty::repeatable() const {
63 // This is the whole point of this class. Empty constructs like '(?m)' are
64 // not repeatable.
65 return false;
66}
67
68vector<PositionInfo> ComponentEmpty::first() const {
69 return vector<PositionInfo>(1, GlushkovBuildState::POS_EPSILON);
70}
71
72vector<PositionInfo> ComponentEmpty::last() const {
73 return vector<PositionInfo>();
74}
75
76void ComponentEmpty::notePositions(GlushkovBuildState &) {
77 // Nothing to do.
78}
79
80void ComponentEmpty::buildFollowSet(GlushkovBuildState &,
81 const vector<PositionInfo> &) {
82 // Nothing to do.
83}
84
85bool ComponentEmpty::checkEmbeddedStartAnchor(bool at_start) const {
86 return at_start;
87}
88
89bool ComponentEmpty::checkEmbeddedEndAnchor(bool at_end) const {
90 return at_end;
91}
92
93} // namespace ue2
94