| 1 | #!/usr/bin/env python3 |
| 2 | # SPDX-License-Identifier: GPL-2.0 |
| 3 | # Copyright(c) 2025: Mauro Carvalho Chehab <mchehab@kernel.org>. |
| 4 | |
| 5 | """ |
| 6 | Regular expression ancillary classes. |
| 7 | |
| 8 | Those help caching regular expressions and do matching for kernel-doc. |
| 9 | """ |
| 10 | |
| 11 | import re |
| 12 | |
| 13 | # Local cache for regular expressions |
| 14 | re_cache = {} |
| 15 | |
| 16 | |
| 17 | class KernRe: |
| 18 | """ |
| 19 | Helper class to simplify regex declaration and usage. |
| 20 | |
| 21 | It calls re.compile for a given pattern. It also allows adding |
| 22 | regular expressions and define sub at class init time. |
| 23 | |
| 24 | Regular expressions can be cached via an argument, helping to speedup |
| 25 | searches. |
| 26 | """ |
| 27 | |
| 28 | def _add_regex(self, string, flags): |
| 29 | """ |
| 30 | Adds a new regex or reuses it from the cache. |
| 31 | """ |
| 32 | self.regex = re_cache.get(string, None) |
| 33 | if not self.regex: |
| 34 | self.regex = re.compile(string, flags=flags) |
| 35 | if self.cache: |
| 36 | re_cache[string] = self.regex |
| 37 | |
| 38 | def __init__(self, string, cache=True, flags=0): |
| 39 | """ |
| 40 | Compile a regular expression and initialize internal vars. |
| 41 | """ |
| 42 | |
| 43 | self.cache = cache |
| 44 | self.last_match = None |
| 45 | |
| 46 | self._add_regex(string, flags) |
| 47 | |
| 48 | def __str__(self): |
| 49 | """ |
| 50 | Return the regular expression pattern. |
| 51 | """ |
| 52 | return self.regex.pattern |
| 53 | |
| 54 | def __add__(self, other): |
| 55 | """ |
| 56 | Allows adding two regular expressions into one. |
| 57 | """ |
| 58 | |
| 59 | return KernRe(str(self) + str(other), cache=self.cache or other.cache, |
| 60 | flags=self.regex.flags | other.regex.flags) |
| 61 | |
| 62 | def match(self, string): |
| 63 | """ |
| 64 | Handles a re.match storing its results |
| 65 | """ |
| 66 | |
| 67 | self.last_match = self.regex.match(string) |
| 68 | return self.last_match |
| 69 | |
| 70 | def search(self, string): |
| 71 | """ |
| 72 | Handles a re.search storing its results |
| 73 | """ |
| 74 | |
| 75 | self.last_match = self.regex.search(string) |
| 76 | return self.last_match |
| 77 | |
| 78 | def findall(self, string): |
| 79 | """ |
| 80 | Alias to re.findall |
| 81 | """ |
| 82 | |
| 83 | return self.regex.findall(string) |
| 84 | |
| 85 | def split(self, string): |
| 86 | """ |
| 87 | Alias to re.split |
| 88 | """ |
| 89 | |
| 90 | return self.regex.split(string) |
| 91 | |
| 92 | def sub(self, sub, string, count=0): |
| 93 | """ |
| 94 | Alias to re.sub |
| 95 | """ |
| 96 | |
| 97 | return self.regex.sub(sub, string, count=count) |
| 98 | |
| 99 | def group(self, num): |
| 100 | """ |
| 101 | Returns the group results of the last match |
| 102 | """ |
| 103 | |
| 104 | return self.last_match.group(num) |
| 105 | |
| 106 | |
| 107 | class NestedMatch: |
| 108 | """ |
| 109 | Finding nested delimiters is hard with regular expressions. It is |
| 110 | even harder on Python with its normal re module, as there are several |
| 111 | advanced regular expressions that are missing. |
| 112 | |
| 113 | This is the case of this pattern: |
| 114 | |
| 115 | '\\bSTRUCT_GROUP(\\(((?:(?>[^)(]+)|(?1))*)\\))[^;]*;' |
| 116 | |
| 117 | which is used to properly match open/close parentheses of the |
| 118 | string search STRUCT_GROUP(), |
| 119 | |
| 120 | Add a class that counts pairs of delimiters, using it to match and |
| 121 | replace nested expressions. |
| 122 | |
| 123 | The original approach was suggested by: |
| 124 | https://stackoverflow.com/questions/5454322/python-how-to-match-nested-parentheses-with-regex |
| 125 | |
| 126 | Although I re-implemented it to make it more generic and match 3 types |
| 127 | of delimiters. The logic checks if delimiters are paired. If not, it |
| 128 | will ignore the search string. |
| 129 | """ |
| 130 | |
| 131 | # TODO: make NestedMatch handle multiple match groups |
| 132 | # |
| 133 | # Right now, regular expressions to match it are defined only up to |
| 134 | # the start delimiter, e.g.: |
| 135 | # |
| 136 | # \bSTRUCT_GROUP\( |
| 137 | # |
| 138 | # is similar to: STRUCT_GROUP\((.*)\) |
| 139 | # except that the content inside the match group is delimiter-aligned. |
| 140 | # |
| 141 | # The content inside parentheses is converted into a single replace |
| 142 | # group (e.g. r`\1'). |
| 143 | # |
| 144 | # It would be nice to change such definition to support multiple |
| 145 | # match groups, allowing a regex equivalent to: |
| 146 | # |
| 147 | # FOO\((.*), (.*), (.*)\) |
| 148 | # |
| 149 | # it is probably easier to define it not as a regular expression, but |
| 150 | # with some lexical definition like: |
| 151 | # |
| 152 | # FOO(arg1, arg2, arg3) |
| 153 | |
| 154 | DELIMITER_PAIRS = { |
| 155 | '{': '}', |
| 156 | '(': ')', |
| 157 | '[': ']', |
| 158 | } |
| 159 | |
| 160 | RE_DELIM = re.compile(r'[\{\}\[\]\(\)]') |
| 161 | |
| 162 | def _search(self, regex, line): |
| 163 | """ |
| 164 | Finds paired blocks for a regex that ends with a delimiter. |
| 165 | |
| 166 | The suggestion of using finditer to match pairs came from: |
| 167 | https://stackoverflow.com/questions/5454322/python-how-to-match-nested-parentheses-with-regex |
| 168 | but I ended using a different implementation to align all three types |
| 169 | of delimiters and seek for an initial regular expression. |
| 170 | |
| 171 | The algorithm seeks for open/close paired delimiters and places them |
| 172 | into a stack, yielding a start/stop position of each match when the |
| 173 | stack is zeroed. |
| 174 | |
| 175 | The algorithm should work fine for properly paired lines, but will |
| 176 | silently ignore end delimiters that precede a start delimiter. |
| 177 | This should be OK for kernel-doc parser, as unaligned delimiters |
| 178 | would cause compilation errors. So, we don't need to raise exceptions |
| 179 | to cover such issues. |
| 180 | """ |
| 181 | |
| 182 | stack = [] |
| 183 | |
| 184 | for match_re in regex.finditer(line): |
| 185 | start = match_re.start() |
| 186 | offset = match_re.end() |
| 187 | |
| 188 | d = line[offset - 1] |
| 189 | if d not in self.DELIMITER_PAIRS: |
| 190 | continue |
| 191 | |
| 192 | end = self.DELIMITER_PAIRS[d] |
| 193 | stack.append(end) |
| 194 | |
| 195 | for match in self.RE_DELIM.finditer(line[offset:]): |
| 196 | pos = match.start() + offset |
| 197 | |
| 198 | d = line[pos] |
| 199 | |
| 200 | if d in self.DELIMITER_PAIRS: |
| 201 | end = self.DELIMITER_PAIRS[d] |
| 202 | |
| 203 | stack.append(end) |
| 204 | continue |
| 205 | |
| 206 | # Does the end delimiter match what is expected? |
| 207 | if stack and d == stack[-1]: |
| 208 | stack.pop() |
| 209 | |
| 210 | if not stack: |
| 211 | yield start, offset, pos + 1 |
| 212 | break |
| 213 | |
| 214 | def search(self, regex, line): |
| 215 | """ |
| 216 | This is similar to re.search: |
| 217 | |
| 218 | It matches a regex that it is followed by a delimiter, |
| 219 | returning occurrences only if all delimiters are paired. |
| 220 | """ |
| 221 | |
| 222 | for t in self._search(regex, line): |
| 223 | |
| 224 | yield line[t[0]:t[2]] |
| 225 | |
| 226 | def sub(self, regex, sub, line, count=0): |
| 227 | """ |
| 228 | This is similar to re.sub: |
| 229 | |
| 230 | It matches a regex that it is followed by a delimiter, |
| 231 | replacing occurrences only if all delimiters are paired. |
| 232 | |
| 233 | if r'\1' is used, it works just like re: it places there the |
| 234 | matched paired data with the delimiter stripped. |
| 235 | |
| 236 | If count is different than zero, it will replace at most count |
| 237 | items. |
| 238 | """ |
| 239 | out = "" |
| 240 | |
| 241 | cur_pos = 0 |
| 242 | n = 0 |
| 243 | |
| 244 | for start, end, pos in self._search(regex, line): |
| 245 | out += line[cur_pos:start] |
| 246 | |
| 247 | # Value, ignoring start/end delimiters |
| 248 | value = line[end:pos - 1] |
| 249 | |
| 250 | # replaces \1 at the sub string, if \1 is used there |
| 251 | new_sub = sub |
| 252 | new_sub = new_sub.replace(r'\1', value) |
| 253 | |
| 254 | out += new_sub |
| 255 | |
| 256 | # Drop end ';' if any |
| 257 | if line[pos] == ';': |
| 258 | pos += 1 |
| 259 | |
| 260 | cur_pos = pos |
| 261 | n += 1 |
| 262 | |
| 263 | if count and count >= n: |
| 264 | break |
| 265 | |
| 266 | # Append the remaining string |
| 267 | l = len(line) |
| 268 | out += line[cur_pos:l] |
| 269 | |
| 270 | return out |