/usr/lib/gcc-cross/powerpc64-linux-gnu/7/plugin/include/spellcheck.h is in gcc-7-plugin-dev-powerpc64-linux-gnu 7.3.0-16ubuntu3cross1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 | /* Find near-matches for strings and identifiers.
Copyright (C) 2015-2017 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#ifndef GCC_SPELLCHECK_H
#define GCC_SPELLCHECK_H
typedef unsigned int edit_distance_t;
const edit_distance_t MAX_EDIT_DISTANCE = UINT_MAX;
/* spellcheck.c */
extern edit_distance_t
levenshtein_distance (const char *s, int len_s,
const char *t, int len_t);
extern edit_distance_t
levenshtein_distance (const char *s, const char *t);
extern const char *
find_closest_string (const char *target,
const auto_vec<const char *> *candidates);
/* A traits class for describing a string-like type usable by
class best_match.
Specializations should provide the implementations of the following:
static size_t get_length (TYPE);
static const char *get_string (TYPE);
get_string should return a non-NULL ptr, which does not need to be
0-terminated. */
template <typename TYPE>
struct edit_distance_traits {};
/* Specialization of edit_distance_traits for C-style strings. */
template <>
struct edit_distance_traits<const char *>
{
static size_t get_length (const char *str)
{
gcc_assert (str);
return strlen (str);
}
static const char *get_string (const char *str)
{
gcc_assert (str);
return str;
}
};
/* A type for use when determining the best match against a string,
expressed as a template so that we can match against various
string-like types (const char *, frontend identifiers, and preprocessor
macros).
This type accumulates the best possible match against GOAL_TYPE for
a sequence of elements of CANDIDATE_TYPE, whilst minimizing the
number of calls to levenshtein_distance and to
edit_distance_traits<T>::get_length. */
template <typename GOAL_TYPE, typename CANDIDATE_TYPE>
class best_match
{
public:
typedef GOAL_TYPE goal_t;
typedef CANDIDATE_TYPE candidate_t;
typedef edit_distance_traits<goal_t> goal_traits;
typedef edit_distance_traits<candidate_t> candidate_traits;
/* Constructor. */
best_match (GOAL_TYPE goal,
edit_distance_t best_distance_so_far = MAX_EDIT_DISTANCE)
: m_goal (goal_traits::get_string (goal)),
m_goal_len (goal_traits::get_length (goal)),
m_best_candidate (NULL),
m_best_distance (best_distance_so_far)
{}
/* Compare the edit distance between CANDIDATE and m_goal,
and if it's the best so far, record it. */
void consider (candidate_t candidate)
{
size_t candidate_len = candidate_traits::get_length (candidate);
/* Calculate a lower bound on the candidate's distance to the goal,
based on the difference in lengths; it will require at least
this many insertions/deletions. */
edit_distance_t min_candidate_distance
= abs ((ssize_t)candidate_len - (ssize_t)m_goal_len);
/* If the candidate's length is sufficiently different to that
of the goal string, then the number of insertions/deletions
may be >= the best distance so far. If so, we can reject
the candidate immediately without needing to compute
the exact distance, since it won't be an improvement. */
if (min_candidate_distance >= m_best_distance)
return;
/* If the candidate will be unable to beat the criterion in
get_best_meaningful_candidate, reject it without computing
the exact distance. */
unsigned int cutoff = MAX (m_goal_len, candidate_len) / 2;
if (min_candidate_distance > cutoff)
return;
/* Otherwise, compute the distance and see if the candidate
has beaten the previous best value. */
edit_distance_t dist
= levenshtein_distance (m_goal, m_goal_len,
candidate_traits::get_string (candidate),
candidate_len);
if (dist < m_best_distance)
{
m_best_distance = dist;
m_best_candidate = candidate;
m_best_candidate_len = candidate_len;
}
}
/* Assuming that BEST_CANDIDATE is known to be better than
m_best_candidate, update (without recomputing the edit distance to
the goal). */
void set_best_so_far (CANDIDATE_TYPE best_candidate,
edit_distance_t best_distance,
size_t best_candidate_len)
{
gcc_assert (best_distance < m_best_distance);
m_best_candidate = best_candidate;
m_best_distance = best_distance;
m_best_candidate_len = best_candidate_len;
}
/* Get the best candidate so far, but applying a filter to ensure
that we return NULL if none of the candidates are close to the goal,
to avoid offering nonsensical suggestions to the user. */
candidate_t get_best_meaningful_candidate () const
{
/* If more than half of the letters were misspelled, the suggestion is
likely to be meaningless. */
if (m_best_candidate)
{
unsigned int cutoff = MAX (m_goal_len, m_best_candidate_len) / 2;
if (m_best_distance > cutoff)
return NULL;
}
/* If the goal string somehow makes it into the candidate list, offering
it as a suggestion will be nonsensical e.g.
'constexpr' does not name a type; did you mean 'constexpr'?
Ultimately such suggestions are due to bugs in constructing the
candidate list, but as a band-aid, do not offer suggestions for
distance == 0 (where candidate == goal). */
if (m_best_distance == 0)
return NULL;
return m_best_candidate;
}
edit_distance_t get_best_distance () const { return m_best_distance; }
size_t get_best_candidate_length () const { return m_best_candidate_len; }
private:
const char *m_goal;
size_t m_goal_len;
candidate_t m_best_candidate;
edit_distance_t m_best_distance;
size_t m_best_candidate_len;
};
#endif /* GCC_SPELLCHECK_H */
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