summaryrefslogtreecommitdiff
path: root/Userland/Libraries/LibRegex/RegexMatcher.cpp
blob: 970db6bf1c4b5b3f281a08610d35bf0d8de2b24a (plain)
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
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
/*
 * Copyright (c) 2020, Emanuel Sprung <emanuel.sprung@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "RegexMatcher.h"
#include "RegexDebug.h"
#include "RegexParser.h"
#include <AK/Debug.h>
#include <AK/ScopedValueRollback.h>
#include <AK/String.h>
#include <AK/StringBuilder.h>

namespace regex {

#if REGEX_DEBUG
static RegexDebug s_regex_dbg(stderr);
#endif

template<class Parser>
Regex<Parser>::Regex(StringView pattern, typename ParserTraits<Parser>::OptionsType regex_options)
{
    pattern_value = pattern.to_string();
    regex::Lexer lexer(pattern);

    Parser parser(lexer, regex_options);
    parser_result = parser.parse();

    if (parser_result.error == regex::Error::NoError)
        matcher = make<Matcher<Parser>>(*this, regex_options);
}

template<class Parser>
typename ParserTraits<Parser>::OptionsType Regex<Parser>::options() const
{
    if (parser_result.error != Error::NoError)
        return {};

    return matcher->options();
}

template<class Parser>
String Regex<Parser>::error_string(Optional<String> message) const
{
    StringBuilder eb;
    eb.appendf("Error during parsing of regular expression:\n");
    eb.appendf("    %s\n    ", pattern_value.characters());
    for (size_t i = 0; i < parser_result.error_token.position(); ++i)
        eb.append(" ");

    eb.appendf("^---- %s", message.value_or(get_error_string(parser_result.error)).characters());
    return eb.build();
}

template<typename Parser>
RegexResult Matcher<Parser>::match(const RegexStringView& view, Optional<typename ParserTraits<Parser>::OptionsType> regex_options) const
{
    AllOptions options = m_regex_options | regex_options.value_or({}).value();

    if (options.has_flag_set(AllFlags::Multiline))
        return match(view.lines(), regex_options); // FIXME: how do we know, which line ending a line has (1char or 2char)? This is needed to get the correct match offsets from start of string...

    Vector<RegexStringView> views;
    views.append(view);
    return match(views, regex_options);
}

template<typename Parser>
RegexResult Matcher<Parser>::match(const Vector<RegexStringView> views, Optional<typename ParserTraits<Parser>::OptionsType> regex_options) const
{
    // If the pattern *itself* isn't stateful, reset any changes to start_offset.
    if (!((AllFlags)m_regex_options.value() & AllFlags::Internal_Stateful))
        m_pattern.start_offset = 0;

    size_t match_count { 0 };

    MatchInput input;
    MatchState state;
    MatchOutput output;

    input.regex_options = m_regex_options | regex_options.value_or({}).value();
    input.start_offset = m_pattern.start_offset;
    output.operations = 0;

    if (input.regex_options.has_flag_set(AllFlags::Internal_Stateful))
        VERIFY(views.size() == 1);

    if (c_match_preallocation_count) {
        output.matches.ensure_capacity(c_match_preallocation_count);
        output.capture_group_matches.ensure_capacity(c_match_preallocation_count);
        output.named_capture_group_matches.ensure_capacity(c_match_preallocation_count);

        auto& capture_groups_count = m_pattern.parser_result.capture_groups_count;
        auto& named_capture_groups_count = m_pattern.parser_result.named_capture_groups_count;

        for (size_t j = 0; j < c_match_preallocation_count; ++j) {
            output.matches.empend();
            output.capture_group_matches.unchecked_append({});
            output.capture_group_matches.at(j).ensure_capacity(capture_groups_count);
            for (size_t k = 0; k < capture_groups_count; ++k)
                output.capture_group_matches.at(j).unchecked_append({});

            output.named_capture_group_matches.unchecked_append({});
            output.named_capture_group_matches.at(j).ensure_capacity(named_capture_groups_count);
        }
    }

    auto append_match = [](auto& input, auto& state, auto& output, auto& start_position) {
        if (output.matches.size() == input.match_index)
            output.matches.empend();

        VERIFY(start_position + state.string_position - start_position <= input.view.length());
        if (input.regex_options.has_flag_set(AllFlags::StringCopyMatches)) {
            output.matches.at(input.match_index) = { input.view.substring_view(start_position, state.string_position - start_position).to_string(), input.line, start_position, input.global_offset + start_position };
        } else { // let the view point to the original string ...
            output.matches.at(input.match_index) = { input.view.substring_view(start_position, state.string_position - start_position), input.line, start_position, input.global_offset + start_position };
        }
    };

#if REGEX_DEBUG
    s_regex_dbg.print_header();
#endif

    bool continue_search = input.regex_options.has_flag_set(AllFlags::Global) || input.regex_options.has_flag_set(AllFlags::Multiline);
    if (input.regex_options.has_flag_set(AllFlags::Internal_Stateful))
        continue_search = false;

    for (auto& view : views) {
        input.view = view;
        dbgln_if(REGEX_DEBUG, "[match] Starting match with view ({}): _{}_", view.length(), view);

        auto view_length = view.length();
        size_t view_index = m_pattern.start_offset;
        state.string_position = view_index;

        if (view_index == view_length && m_pattern.parser_result.match_length_minimum == 0) {
            // Run the code until it tries to consume something.
            // This allows non-consuming code to run on empty strings, for instance
            // e.g. "Exit"
            MatchOutput temp_output { output };

            input.column = match_count;
            input.match_index = match_count;

            state.string_position = view_index;
            state.instruction_position = 0;

            auto success = execute(input, state, temp_output, 0);
            // This success is acceptable only if it doesn't read anything from the input (input length is 0).
            if (state.string_position <= view_index) {
                if (success.value()) {
                    output = move(temp_output);
                    if (!match_count) {
                        // Nothing was *actually* matched, so append an empty match.
                        append_match(input, state, output, view_index);
                        ++match_count;
                    }
                }
            }
        }

        for (; view_index < view_length; ++view_index) {
            auto& match_length_minimum = m_pattern.parser_result.match_length_minimum;
            // FIXME: More performant would be to know the remaining minimum string
            //        length needed to match from the current position onwards within
            //        the vm. Add new OpCode for MinMatchLengthFromSp with the value of
            //        the remaining string length from the current path. The value though
            //        has to be filled in reverse. That implies a second run over bytecode
            //        after generation has finished.
            if (match_length_minimum && match_length_minimum > view_length - view_index)
                break;

            input.column = match_count;
            input.match_index = match_count;

            state.string_position = view_index;
            state.instruction_position = 0;

            auto success = execute(input, state, output, 0);
            if (!success.has_value())
                return { false, 0, {}, {}, {}, output.operations };

            if (success.value()) {

                if (input.regex_options.has_flag_set(AllFlags::MatchNotEndOfLine) && state.string_position == input.view.length()) {
                    if (!continue_search)
                        break;
                    continue;
                }
                if (input.regex_options.has_flag_set(AllFlags::MatchNotBeginOfLine) && view_index == 0) {
                    if (!continue_search)
                        break;
                    continue;
                }

                if constexpr (REGEX_DEBUG) {
                    dbgln("state.string_position={}, view_index={}", state.string_position, view_index);
                    dbgln("[match] Found a match (length={}): '{}'", state.string_position - view_index, input.view.substring_view(view_index, state.string_position - view_index));
                }

                ++match_count;

                if (continue_search) {
                    append_match(input, state, output, view_index);

                    bool has_zero_length = state.string_position == view_index;
                    view_index = state.string_position - (has_zero_length ? 0 : 1);
                    continue;

                } else if (input.regex_options.has_flag_set(AllFlags::Internal_Stateful)) {
                    append_match(input, state, output, view_index);
                    break;

                } else if (state.string_position < view_length) {
                    return { false, 0, {}, {}, {}, output.operations };
                }

                append_match(input, state, output, view_index);
                break;
            }

            if (!continue_search && !input.regex_options.has_flag_set(AllFlags::Internal_Stateful))
                break;
        }

        ++input.line;
        input.global_offset += view.length() + 1; // +1 includes the line break character

        if (input.regex_options.has_flag_set(AllFlags::Internal_Stateful))
            m_pattern.start_offset = state.string_position;
    }

    MatchOutput output_copy;
    if (match_count) {
        auto capture_groups_count = min(output.capture_group_matches.size(), output.matches.size());
        for (size_t i = 0; i < capture_groups_count; ++i) {
            if (input.regex_options.has_flag_set(AllFlags::SkipTrimEmptyMatches)) {
                output_copy.capture_group_matches.append(output.capture_group_matches.at(i));
            } else {
                Vector<Match> capture_group_matches;
                for (size_t j = 0; j < output.capture_group_matches.at(i).size(); ++j) {
                    if (!output.capture_group_matches.at(i).at(j).view.is_null())
                        capture_group_matches.append(output.capture_group_matches.at(i).at(j));
                }
                output_copy.capture_group_matches.append(capture_group_matches);
            }
        }

        auto named_capture_groups_count = min(output.named_capture_group_matches.size(), output.matches.size());
        for (size_t i = 0; i < named_capture_groups_count; ++i) {
            if (output.matches.at(i).view.length())
                output_copy.named_capture_group_matches.append(output.named_capture_group_matches.at(i));
        }

        for (size_t i = 0; i < match_count; ++i)
            output_copy.matches.append(output.matches.at(i));

    } else {
        output_copy.capture_group_matches.clear_with_capacity();
        output_copy.named_capture_group_matches.clear_with_capacity();
    }

    return {
        match_count ? true : false,
        match_count,
        move(output_copy.matches),
        move(output_copy.capture_group_matches),
        move(output_copy.named_capture_group_matches),
        output.operations,
        m_pattern.parser_result.capture_groups_count,
        m_pattern.parser_result.named_capture_groups_count,
    };
}

template<class Parser>
Optional<bool> Matcher<Parser>::execute(const MatchInput& input, MatchState& state, MatchOutput& output, size_t recursion_level) const
{
    if (recursion_level > c_max_recursion)
        return false;

    Vector<MatchState> fork_low_prio_states;
    MatchState fork_high_prio_state;
    Optional<bool> success;

    auto& bytecode = m_pattern.parser_result.bytecode;

    for (;;) {
        ++output.operations;
        auto* opcode = bytecode.get_opcode(state);

        if (!opcode) {
            dbgln("Wrong opcode... failed!");
            return {};
        }

#if REGEX_DEBUG
        s_regex_dbg.print_opcode("VM", *opcode, state, recursion_level, false);
#endif

        ExecutionResult result;
        if (input.fail_counter > 0) {
            --input.fail_counter;
            result = ExecutionResult::Failed_ExecuteLowPrioForks;
        } else {
            result = opcode->execute(input, state, output);
        }

#if REGEX_DEBUG
        s_regex_dbg.print_result(*opcode, bytecode, input, state, result);
#endif

        state.instruction_position += opcode->size();

        switch (result) {
        case ExecutionResult::Fork_PrioLow:
            fork_low_prio_states.prepend(state);
            continue;
        case ExecutionResult::Fork_PrioHigh:
            fork_high_prio_state = state;
            fork_high_prio_state.instruction_position = fork_high_prio_state.fork_at_position;
            success = execute(input, fork_high_prio_state, output, ++recursion_level);
            if (!success.has_value())
                return {};

            if (success.value()) {
                state = fork_high_prio_state;
                return true;
            }

            continue;
        case ExecutionResult::Continue:
            continue;
        case ExecutionResult::Succeeded:
            return true;
        case ExecutionResult::Failed:
            return false;
        case ExecutionResult::Failed_ExecuteLowPrioForks:
            return execute_low_prio_forks(input, state, output, fork_low_prio_states, recursion_level + 1);
        }
    }

    VERIFY_NOT_REACHED();
}

template<class Parser>
ALWAYS_INLINE Optional<bool> Matcher<Parser>::execute_low_prio_forks(const MatchInput& input, MatchState& original_state, MatchOutput& output, Vector<MatchState> states, size_t recursion_level) const
{
    for (auto& state : states) {

        state.instruction_position = state.fork_at_position;
#if REGEX_DEBUG
        fprintf(stderr, "Forkstay... ip = %lu, sp = %lu\n", state.instruction_position, state.string_position);
#endif
        auto success = execute(input, state, output, recursion_level);
        if (!success.has_value())
            return {};
        if (success.value()) {
#if REGEX_DEBUG
            fprintf(stderr, "Forkstay succeeded... ip = %lu, sp = %lu\n", state.instruction_position, state.string_position);
#endif
            original_state = state;
            return true;
        }
    }

    original_state.string_position = 0;
    return false;
}

template class Matcher<PosixExtendedParser>;
template class Regex<PosixExtendedParser>;

template class Matcher<ECMA262Parser>;
template class Regex<ECMA262Parser>;
}