paul@32 | 1 | #!/usr/bin/env python |
paul@32 | 2 | |
paul@32 | 3 | """ |
paul@32 | 4 | Moin wiki parsing functionality. |
paul@32 | 5 | |
paul@32 | 6 | Copyright (C) 2017 Paul Boddie <paul@boddie.org.uk> |
paul@32 | 7 | |
paul@32 | 8 | This program is free software; you can redistribute it and/or modify it under |
paul@32 | 9 | the terms of the GNU General Public License as published by the Free Software |
paul@32 | 10 | Foundation; either version 3 of the License, or (at your option) any later |
paul@32 | 11 | version. |
paul@32 | 12 | |
paul@32 | 13 | This program is distributed in the hope that it will be useful, but WITHOUT |
paul@32 | 14 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS |
paul@32 | 15 | FOR A PARTICULAR PURPOSE. See the GNU General Public License for more |
paul@32 | 16 | details. |
paul@32 | 17 | |
paul@32 | 18 | You should have received a copy of the GNU General Public License along with |
paul@32 | 19 | this program. If not, see <http://www.gnu.org/licenses/>. |
paul@32 | 20 | """ |
paul@32 | 21 | |
paul@43 | 22 | from collections import defaultdict |
paul@32 | 23 | from moinformat.tree import Block, Region, Text |
paul@33 | 24 | import re |
paul@33 | 25 | |
paul@33 | 26 | # Pattern management. |
paul@33 | 27 | |
paul@36 | 28 | ws_excl_nl = r"[ \f\r\t\v]" |
paul@36 | 29 | |
paul@33 | 30 | def get_patterns(syntax): |
paul@33 | 31 | |
paul@36 | 32 | """ |
paul@36 | 33 | Define patterns for the regular expressions in the 'syntax' mapping. In each |
paul@36 | 34 | pattern, replace \N with a pattern for matching whitespace excluding |
paul@36 | 35 | newlines. |
paul@36 | 36 | """ |
paul@33 | 37 | |
paul@33 | 38 | patterns = {} |
paul@33 | 39 | for name, value in syntax.items(): |
paul@36 | 40 | value = value.replace(r"\N", ws_excl_nl) |
paul@33 | 41 | patterns[name] = re.compile(value, re.UNICODE | re.MULTILINE) |
paul@33 | 42 | return patterns |
paul@33 | 43 | |
paul@37 | 44 | def get_subset(d, keys): |
paul@33 | 45 | |
paul@37 | 46 | "Return a subset of 'd' having the given 'keys'." |
paul@36 | 47 | |
paul@37 | 48 | subset = {} |
paul@37 | 49 | for key in keys: |
paul@37 | 50 | subset[key] = d[key] |
paul@37 | 51 | return subset |
paul@36 | 52 | |
paul@36 | 53 | |
paul@32 | 54 | |
paul@32 | 55 | # Tokenising functions. |
paul@32 | 56 | |
paul@32 | 57 | class TokenStream: |
paul@32 | 58 | |
paul@32 | 59 | "A stream of tokens taken from a string." |
paul@32 | 60 | |
paul@37 | 61 | def __init__(self, s, pos=0): |
paul@32 | 62 | self.s = s |
paul@36 | 63 | self.pos = pos |
paul@32 | 64 | self.match = None |
paul@32 | 65 | self.matching = None |
paul@32 | 66 | |
paul@32 | 67 | def rewind(self, length): |
paul@32 | 68 | |
paul@32 | 69 | "Rewind in the string by 'length'." |
paul@32 | 70 | |
paul@32 | 71 | self.pos -= min(length, self.pos) |
paul@32 | 72 | |
paul@37 | 73 | def read_until(self, patterns, remaining=True): |
paul@32 | 74 | |
paul@32 | 75 | """ |
paul@37 | 76 | Find the first match for the given 'patterns'. Return the text preceding |
paul@37 | 77 | any match, the remaining text if no match was found, or None if no match |
paul@37 | 78 | was found and 'remaining' is given as a false value. |
paul@32 | 79 | """ |
paul@32 | 80 | |
paul@32 | 81 | first = None |
paul@32 | 82 | self.matching = None |
paul@32 | 83 | |
paul@32 | 84 | # Find the first matching pattern. |
paul@32 | 85 | |
paul@37 | 86 | for pattern_name, pattern in patterns.items(): |
paul@37 | 87 | match = pattern.search(self.s, self.pos) |
paul@32 | 88 | if match: |
paul@32 | 89 | start, end = match.span() |
paul@32 | 90 | if self.matching is None or start < first: |
paul@32 | 91 | first = start |
paul@32 | 92 | self.matching = pattern_name |
paul@32 | 93 | self.match = match |
paul@32 | 94 | |
paul@32 | 95 | if self.matching is None: |
paul@32 | 96 | if remaining: |
paul@32 | 97 | return self.s[self.pos:] |
paul@32 | 98 | else: |
paul@32 | 99 | return None |
paul@32 | 100 | else: |
paul@32 | 101 | return self.s[self.pos:first] |
paul@32 | 102 | |
paul@32 | 103 | def read_match(self, group=1): |
paul@32 | 104 | |
paul@32 | 105 | """ |
paul@32 | 106 | Return the matched text, updating the position in the stream. If 'group' |
paul@32 | 107 | is specified, the indicated group in a match will be returned. |
paul@32 | 108 | Typically, group 1 should contain all pertinent data, but groups defined |
paul@32 | 109 | within group 1 can provide sections of the data. |
paul@32 | 110 | """ |
paul@32 | 111 | |
paul@32 | 112 | if self.match: |
paul@32 | 113 | _start, self.pos = self.match.span() |
paul@32 | 114 | try: |
paul@32 | 115 | return self.match.group(group) |
paul@32 | 116 | except IndexError: |
paul@32 | 117 | return "" |
paul@32 | 118 | else: |
paul@32 | 119 | self.pos = len(self.s) |
paul@32 | 120 | return None |
paul@32 | 121 | |
paul@32 | 122 | |
paul@32 | 123 | |
paul@32 | 124 | # Parser abstractions. |
paul@32 | 125 | |
paul@32 | 126 | class ParserBase: |
paul@32 | 127 | |
paul@32 | 128 | "Common parsing methods." |
paul@32 | 129 | |
paul@37 | 130 | region_pattern_names = None |
paul@37 | 131 | |
paul@32 | 132 | def __init__(self, formats=None): |
paul@32 | 133 | |
paul@32 | 134 | """ |
paul@32 | 135 | Initialise the parser with any given 'formats' mapping from region type |
paul@32 | 136 | names to parser objects. |
paul@32 | 137 | """ |
paul@32 | 138 | |
paul@32 | 139 | self.formats = formats |
paul@43 | 140 | self.queued = defaultdict(list) |
paul@37 | 141 | |
paul@37 | 142 | def get_parser(self, format_type): |
paul@37 | 143 | |
paul@37 | 144 | """ |
paul@37 | 145 | Return a parser for 'format_type' or None if no suitable parser is found. |
paul@37 | 146 | """ |
paul@37 | 147 | |
paul@37 | 148 | if not self.formats: |
paul@37 | 149 | return None |
paul@37 | 150 | |
paul@37 | 151 | cls = self.formats.get(format_type) |
paul@37 | 152 | if cls: |
paul@37 | 153 | return cls(self.formats) |
paul@37 | 154 | else: |
paul@37 | 155 | return None |
paul@37 | 156 | |
paul@37 | 157 | def get_patterns(self, pattern_names): |
paul@37 | 158 | |
paul@37 | 159 | "Return a mapping of the given 'pattern_names' to patterns." |
paul@37 | 160 | |
paul@37 | 161 | return get_subset(self.patterns, pattern_names) |
paul@32 | 162 | |
paul@36 | 163 | def get_items(self, s, pos=0): |
paul@32 | 164 | |
paul@36 | 165 | "Return a sequence of token items for 's' and 'pos'." |
paul@32 | 166 | |
paul@37 | 167 | return TokenStream(s, pos) |
paul@37 | 168 | |
paul@37 | 169 | def set_region(self, items, region): |
paul@37 | 170 | |
paul@37 | 171 | "Set the 'items' used to populate the given 'region'." |
paul@32 | 172 | |
paul@37 | 173 | self.items = items |
paul@37 | 174 | self.region = region |
paul@37 | 175 | |
paul@37 | 176 | def read_until(self, pattern_names, remaining=True): |
paul@36 | 177 | |
paul@37 | 178 | """ |
paul@37 | 179 | Read the next portion of input, matching using 'pattern_names'. Return |
paul@37 | 180 | the text preceding any match, the remaining text if no match was found, |
paul@37 | 181 | or None if no match was found and 'remaining' is given as a false value. |
paul@37 | 182 | """ |
paul@36 | 183 | |
paul@37 | 184 | return self.items.read_until(self.get_patterns(pattern_names)) |
paul@37 | 185 | |
paul@37 | 186 | def read_match(self, group=1): |
paul@37 | 187 | |
paul@37 | 188 | """ |
paul@37 | 189 | Return the group of the matching pattern with the given 'group' number. |
paul@37 | 190 | """ |
paul@36 | 191 | |
paul@37 | 192 | return self.items.read_match(group) |
paul@37 | 193 | |
paul@37 | 194 | def read_matching(self): |
paul@36 | 195 | |
paul@37 | 196 | "Return the name of the matching pattern." |
paul@36 | 197 | |
paul@37 | 198 | return self.items.matching |
paul@37 | 199 | |
paul@37 | 200 | # Parser methods invoked from other objects. |
paul@36 | 201 | |
paul@32 | 202 | def parse(self, s): |
paul@32 | 203 | |
paul@32 | 204 | """ |
paul@32 | 205 | Parse page text 's'. Pages consist of regions delimited by markers. |
paul@32 | 206 | """ |
paul@32 | 207 | |
paul@37 | 208 | self.items = self.get_items(s) |
paul@37 | 209 | self.region = self.parse_region() |
paul@37 | 210 | return self.region |
paul@37 | 211 | |
paul@37 | 212 | def parse_region_content(self, items, region): |
paul@37 | 213 | |
paul@37 | 214 | "Parse the data provided by 'items' to populate a 'region'." |
paul@37 | 215 | |
paul@37 | 216 | self.set_region(items, region) |
paul@32 | 217 | |
paul@37 | 218 | # Define a block to hold text and start parsing. |
paul@37 | 219 | |
paul@43 | 220 | self.new_block(region) |
paul@37 | 221 | |
paul@37 | 222 | if self.region_pattern_names: |
paul@37 | 223 | self.parse_region_details(region, self.region_pattern_names) |
paul@37 | 224 | |
paul@37 | 225 | # Top-level parser handler methods. |
paul@37 | 226 | |
paul@37 | 227 | def parse_region(self, level=0, indent=0): |
paul@32 | 228 | |
paul@32 | 229 | """ |
paul@37 | 230 | Parse the data to populate a region with the given 'level' at the given |
paul@37 | 231 | 'indent'. |
paul@32 | 232 | """ |
paul@32 | 233 | |
paul@32 | 234 | region = Region([], level, indent) |
paul@32 | 235 | |
paul@32 | 236 | # Parse section headers, then parse according to region type. |
paul@32 | 237 | |
paul@37 | 238 | self.parse_region_header(region) |
paul@37 | 239 | self.parse_region_type(region) |
paul@32 | 240 | |
paul@32 | 241 | return region |
paul@32 | 242 | |
paul@37 | 243 | def parse_region_type(self, region): |
paul@32 | 244 | |
paul@32 | 245 | """ |
paul@37 | 246 | Use configured parsers to parse 'region' based on its type. |
paul@32 | 247 | """ |
paul@32 | 248 | |
paul@32 | 249 | # Find an appropriate parser given the type. |
paul@32 | 250 | |
paul@37 | 251 | parser = self.get_parser(region.type) |
paul@37 | 252 | |
paul@37 | 253 | if parser: |
paul@37 | 254 | parser.parse_region_content(self.items, region) |
paul@32 | 255 | |
paul@32 | 256 | # Otherwise, treat the section as opaque. |
paul@32 | 257 | |
paul@32 | 258 | else: |
paul@37 | 259 | self.parse_region_opaque(region) |
paul@32 | 260 | |
paul@37 | 261 | def parse_region_header(self, region): |
paul@32 | 262 | |
paul@32 | 263 | """ |
paul@37 | 264 | Parse the region header, setting it on the 'region' object. |
paul@32 | 265 | """ |
paul@32 | 266 | |
paul@37 | 267 | if self.read_until(["header"], False) == "": # None means no header |
paul@37 | 268 | region.type = self.read_match() |
paul@32 | 269 | |
paul@37 | 270 | def parse_region_opaque(self, region): |
paul@32 | 271 | |
paul@37 | 272 | "Parse the data to populate an opaque 'region'." |
paul@32 | 273 | |
paul@32 | 274 | region.transparent = False |
paul@37 | 275 | self.parse_region_details(region, ["regionend"]) |
paul@32 | 276 | |
paul@32 | 277 | # Parsing utilities. |
paul@32 | 278 | |
paul@43 | 279 | def parse_region_details(self, region, pattern_names, strict=False): |
paul@32 | 280 | |
paul@43 | 281 | """ |
paul@43 | 282 | Search 'region' using the 'pattern_names'. If 'strict' is set to a true |
paul@43 | 283 | value, forbid the accumulation of additional textual padding. |
paul@43 | 284 | """ |
paul@32 | 285 | |
paul@32 | 286 | try: |
paul@32 | 287 | while True: |
paul@32 | 288 | |
paul@32 | 289 | # Obtain text before any marker or the end of the input. |
paul@32 | 290 | |
paul@37 | 291 | preceding = self.read_until(pattern_names) |
paul@32 | 292 | if preceding: |
paul@43 | 293 | if not strict: |
paul@43 | 294 | region.append_inline(Text(preceding)) |
paul@43 | 295 | else: |
paul@43 | 296 | break |
paul@32 | 297 | |
paul@32 | 298 | # End of input. |
paul@32 | 299 | |
paul@37 | 300 | if not self.read_matching(): |
paul@32 | 301 | break |
paul@32 | 302 | |
paul@32 | 303 | # Obtain any feature. |
paul@32 | 304 | |
paul@37 | 305 | feature = self.read_match() |
paul@37 | 306 | handler = self.handlers.get(self.read_matching()) |
paul@32 | 307 | |
paul@32 | 308 | # Handle each feature or add text to the region. |
paul@32 | 309 | |
paul@32 | 310 | if handler: |
paul@37 | 311 | handler(self, region) |
paul@43 | 312 | elif not strict: |
paul@43 | 313 | region.append_inline(Text(feature)) |
paul@32 | 314 | else: |
paul@43 | 315 | break |
paul@32 | 316 | |
paul@32 | 317 | except StopIteration: |
paul@32 | 318 | pass |
paul@32 | 319 | |
paul@32 | 320 | region.normalise() |
paul@32 | 321 | |
paul@43 | 322 | def add_node(self, region, node): |
paul@43 | 323 | |
paul@43 | 324 | "Add to 'region' the given 'node'." |
paul@43 | 325 | |
paul@43 | 326 | region.add(node) |
paul@43 | 327 | self.unqueue_region(region, node) |
paul@43 | 328 | |
paul@43 | 329 | def append_node(self, region, node): |
paul@43 | 330 | |
paul@43 | 331 | "Append to 'region' the given 'node'." |
paul@43 | 332 | |
paul@43 | 333 | region.append(node) |
paul@43 | 334 | self.unqueue_region(region, node) |
paul@43 | 335 | |
paul@37 | 336 | def end_region(self, region): |
paul@32 | 337 | |
paul@32 | 338 | "End the parsing of 'region', breaking out of the parsing loop." |
paul@32 | 339 | |
paul@32 | 340 | raise StopIteration |
paul@32 | 341 | |
paul@43 | 342 | def queue_region(self, region, current): |
paul@43 | 343 | |
paul@43 | 344 | "Queue 'region' for appending after the 'current' region is ended." |
paul@43 | 345 | |
paul@43 | 346 | self.queued[current].append(region) |
paul@43 | 347 | |
paul@43 | 348 | def unqueue_region(self, region, ended): |
paul@43 | 349 | |
paul@43 | 350 | "Unqueue any queued region, adding it to 'region' after 'ended'." |
paul@43 | 351 | |
paul@43 | 352 | nodes = self.queued.get(ended) |
paul@43 | 353 | |
paul@43 | 354 | while nodes: |
paul@43 | 355 | node = nodes.pop() |
paul@43 | 356 | region.add(node) |
paul@43 | 357 | self.unqueue_region(region, node) |
paul@43 | 358 | |
paul@43 | 359 | if self.queued.has_key(ended): |
paul@43 | 360 | del self.queued[ended] |
paul@43 | 361 | |
paul@43 | 362 | def new_block(self, region): |
paul@43 | 363 | |
paul@43 | 364 | "Start a new block in 'region'." |
paul@43 | 365 | |
paul@43 | 366 | self.add_node(region, Block([])) |
paul@43 | 367 | |
paul@32 | 368 | # vim: tabstop=4 expandtab shiftwidth=4 |