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 Base class for all components.
31 */
32
33#ifndef _RE_COMPONENT_H_
34#define _RE_COMPONENT_H_
35
36#include "ComponentVisitor.h"
37#include "ConstComponentVisitor.h"
38
39#include "position.h"
40#include "ue2common.h"
41
42#include <set>
43#include <string>
44#include <vector>
45
46namespace ue2 {
47
48class GlushkovBuildState;
49class PositionInfo;
50
51enum EmptyPathType {
52 NOT_EMPTY, /**< component must consume characters */
53 EPS_ONLY_PATHS, /**< eps path with no overhanging asserts */
54 BOUNDARY_PATHS /**< eps paths some with overhanging asserts */
55};
56
57/** \brief Base class for regular expression parse tree components. */
58class Component {
59 friend class DumpVisitor;
60public:
61 /** \brief Constructor. */
62 Component();
63
64 /** \brief Destructor. */
65 virtual ~Component();
66
67 /** \brief Returns a newly-allocated deep copy of this component. */
68 virtual Component *clone() const = 0;
69
70 /** \brief Apply the given visitor functor. */
71 virtual Component *accept(ComponentVisitor &v) = 0;
72
73 /** \brief Apply the given const visitor functor. */
74 virtual void accept(ConstComponentVisitor &v) const = 0;
75
76 /** \brief Glushkov construction First() function.
77 * \return set of initial positions in this component. */
78 virtual std::vector<PositionInfo> first() const = 0;
79
80 /** \brief Glushkov construction Last() function.
81 * \return set of final positions in this component. */
82 virtual std::vector<PositionInfo> last() const = 0;
83
84 /** \brief Glushkov construction Empty() function.
85 * \return true iff the component accepts epsilon.
86 *
87 * Note: ^, $, etc are considered empty. */
88 virtual bool empty() const = 0;
89
90 /** \brief True iff epsilon can pass through the component.
91 *
92 * Note: ^, $, etc are not vacuous everywhere. */
93 virtual bool vacuous_everywhere(void) const;
94
95 /** \brief True iff the component is repeatable on its own, without being
96 * encapsulated in a sequence first.
97 *
98 * This is true for most components, but not for repeats, anchors and word
99 * boundaries. */
100 virtual bool repeatable() const;
101
102 /** \brief Optimisation pass on the component tree.
103 *
104 * Called before \ref notePositions. May modify to the component tree.
105 * Assumes no start of match information is required.
106 */
107 virtual void optimise(bool connected_to_sds);
108
109 /** \brief Informs the Glushkov build process of the positions used by this
110 * component. */
111 virtual void notePositions(GlushkovBuildState &bs) = 0;
112
113 /** \brief Glushkov construction Follow() function.
114 *
115 * Constructs (in \a bs) the set of positions in this component reachable
116 * from the positions in \a lastPos.
117 *
118 * \throw ParseError on failure
119 */
120 virtual void buildFollowSet(GlushkovBuildState &bs,
121 const std::vector<PositionInfo> &lastPos) = 0;
122
123 /** \brief Return value is used for chaining, throws if finds embedded
124 * anchor. */
125 virtual bool checkEmbeddedStartAnchor(bool at_start) const;
126
127 /* \brief Return value is used for chaining, throws if finds embedded
128 * anchor. */
129 virtual bool checkEmbeddedEndAnchor(bool at_end) const;
130
131protected:
132 /** \brief Called during \ref notePositions. */
133 void recordPosBounds(u32 b, u32 e);
134
135 u32 pos_begin;
136 u32 pos_end;
137
138 // Protected copy ctor. Use clone instead.
139 Component(const Component &other)
140 : pos_begin(other.pos_begin), pos_end(other.pos_end) {}
141};
142
143} // namespace ue2
144
145#endif
146