1# -*- coding: utf-8 -*- 2# 3# QAPI schema parser 4# 5# Copyright IBM, Corp. 2011 6# Copyright (c) 2013-2019 Red Hat Inc. 7# 8# Authors: 9# Anthony Liguori <aliguori@us.ibm.com> 10# Markus Armbruster <armbru@redhat.com> 11# Marc-André Lureau <marcandre.lureau@redhat.com> 12# Kevin Wolf <kwolf@redhat.com> 13# 14# This work is licensed under the terms of the GNU GPL, version 2. 15# See the COPYING file in the top-level directory. 16 17from collections import OrderedDict 18import os 19import re 20from typing import ( 21 TYPE_CHECKING, 22 Dict, 23 List, 24 Mapping, 25 Optional, 26 Set, 27 Union, 28) 29 30from .common import must_match 31from .error import QAPISemError, QAPISourceError 32from .source import QAPISourceInfo 33 34 35if TYPE_CHECKING: 36 # pylint: disable=cyclic-import 37 # TODO: Remove cycle. [schema -> expr -> parser -> schema] 38 from .schema import QAPISchemaFeature, QAPISchemaMember 39 40 41# Return value alias for get_expr(). 42_ExprValue = Union[List[object], Dict[str, object], str, bool] 43 44 45class QAPIExpression(Dict[str, object]): 46 # pylint: disable=too-few-public-methods 47 def __init__(self, 48 data: Mapping[str, object], 49 info: QAPISourceInfo, 50 doc: Optional['QAPIDoc'] = None): 51 super().__init__(data) 52 self.info = info 53 self.doc: Optional['QAPIDoc'] = doc 54 55 56class QAPIParseError(QAPISourceError): 57 """Error class for all QAPI schema parsing errors.""" 58 def __init__(self, parser: 'QAPISchemaParser', msg: str): 59 col = 1 60 for ch in parser.src[parser.line_pos:parser.pos]: 61 if ch == '\t': 62 col = (col + 7) % 8 + 1 63 else: 64 col += 1 65 super().__init__(parser.info, msg, col) 66 67 68class QAPISchemaParser: 69 """ 70 Parse QAPI schema source. 71 72 Parse a JSON-esque schema file and process directives. See 73 qapi-code-gen.txt section "Schema Syntax" for the exact syntax. 74 Grammatical validation is handled later by `expr.check_exprs()`. 75 76 :param fname: Source file name. 77 :param previously_included: 78 The absolute names of previously included source files, 79 if being invoked from another parser. 80 :param incl_info: 81 `QAPISourceInfo` belonging to the parent module. 82 ``None`` implies this is the root module. 83 84 :ivar exprs: Resulting parsed expressions. 85 :ivar docs: Resulting parsed documentation blocks. 86 87 :raise OSError: For problems reading the root schema document. 88 :raise QAPIError: For errors in the schema source. 89 """ 90 def __init__(self, 91 fname: str, 92 previously_included: Optional[Set[str]] = None, 93 incl_info: Optional[QAPISourceInfo] = None): 94 self._fname = fname 95 self._included = previously_included or set() 96 self._included.add(os.path.abspath(self._fname)) 97 self.src = '' 98 99 # Lexer state (see `accept` for details): 100 self.info = QAPISourceInfo(self._fname, incl_info) 101 self.tok: Union[None, str] = None 102 self.pos = 0 103 self.cursor = 0 104 self.val: Optional[Union[bool, str]] = None 105 self.line_pos = 0 106 107 # Parser output: 108 self.exprs: List[QAPIExpression] = [] 109 self.docs: List[QAPIDoc] = [] 110 111 # Showtime! 112 self._parse() 113 114 def _parse(self) -> None: 115 """ 116 Parse the QAPI schema document. 117 118 :return: None. Results are stored in ``.exprs`` and ``.docs``. 119 """ 120 cur_doc = None 121 122 # May raise OSError; allow the caller to handle it. 123 with open(self._fname, 'r', encoding='utf-8') as fp: 124 self.src = fp.read() 125 if self.src == '' or self.src[-1] != '\n': 126 self.src += '\n' 127 128 # Prime the lexer: 129 self.accept() 130 131 # Parse until done: 132 while self.tok is not None: 133 info = self.info 134 if self.tok == '#': 135 self.reject_expr_doc(cur_doc) 136 for cur_doc in self.get_doc(info): 137 self.docs.append(cur_doc) 138 continue 139 140 expr = self.get_expr() 141 if not isinstance(expr, dict): 142 raise QAPISemError( 143 info, "top-level expression must be an object") 144 145 if 'include' in expr: 146 self.reject_expr_doc(cur_doc) 147 if len(expr) != 1: 148 raise QAPISemError(info, "invalid 'include' directive") 149 include = expr['include'] 150 if not isinstance(include, str): 151 raise QAPISemError(info, 152 "value of 'include' must be a string") 153 incl_fname = os.path.join(os.path.dirname(self._fname), 154 include) 155 self._add_expr(OrderedDict({'include': incl_fname}), info) 156 exprs_include = self._include(include, info, incl_fname, 157 self._included) 158 if exprs_include: 159 self.exprs.extend(exprs_include.exprs) 160 self.docs.extend(exprs_include.docs) 161 elif "pragma" in expr: 162 self.reject_expr_doc(cur_doc) 163 if len(expr) != 1: 164 raise QAPISemError(info, "invalid 'pragma' directive") 165 pragma = expr['pragma'] 166 if not isinstance(pragma, dict): 167 raise QAPISemError( 168 info, "value of 'pragma' must be an object") 169 for name, value in pragma.items(): 170 self._pragma(name, value, info) 171 else: 172 if cur_doc and not cur_doc.symbol: 173 raise QAPISemError( 174 cur_doc.info, "definition documentation required") 175 self._add_expr(expr, info, cur_doc) 176 cur_doc = None 177 self.reject_expr_doc(cur_doc) 178 179 def _add_expr(self, expr: Mapping[str, object], 180 info: QAPISourceInfo, 181 doc: Optional['QAPIDoc'] = None) -> None: 182 self.exprs.append(QAPIExpression(expr, info, doc)) 183 184 @staticmethod 185 def reject_expr_doc(doc: Optional['QAPIDoc']) -> None: 186 if doc and doc.symbol: 187 raise QAPISemError( 188 doc.info, 189 "documentation for '%s' is not followed by the definition" 190 % doc.symbol) 191 192 @staticmethod 193 def _include(include: str, 194 info: QAPISourceInfo, 195 incl_fname: str, 196 previously_included: Set[str] 197 ) -> Optional['QAPISchemaParser']: 198 incl_abs_fname = os.path.abspath(incl_fname) 199 # catch inclusion cycle 200 inf: Optional[QAPISourceInfo] = info 201 while inf: 202 if incl_abs_fname == os.path.abspath(inf.fname): 203 raise QAPISemError(info, "inclusion loop for %s" % include) 204 inf = inf.parent 205 206 # skip multiple include of the same file 207 if incl_abs_fname in previously_included: 208 return None 209 210 try: 211 return QAPISchemaParser(incl_fname, previously_included, info) 212 except OSError as err: 213 raise QAPISemError( 214 info, 215 f"can't read include file '{incl_fname}': {err.strerror}" 216 ) from err 217 218 @staticmethod 219 def _pragma(name: str, value: object, info: QAPISourceInfo) -> None: 220 221 def check_list_str(name: str, value: object) -> List[str]: 222 if (not isinstance(value, list) or 223 any(not isinstance(elt, str) for elt in value)): 224 raise QAPISemError( 225 info, 226 "pragma %s must be a list of strings" % name) 227 return value 228 229 pragma = info.pragma 230 231 if name == 'doc-required': 232 if not isinstance(value, bool): 233 raise QAPISemError(info, 234 "pragma 'doc-required' must be boolean") 235 pragma.doc_required = value 236 elif name == 'command-name-exceptions': 237 pragma.command_name_exceptions = check_list_str(name, value) 238 elif name == 'command-returns-exceptions': 239 pragma.command_returns_exceptions = check_list_str(name, value) 240 elif name == 'member-name-exceptions': 241 pragma.member_name_exceptions = check_list_str(name, value) 242 else: 243 raise QAPISemError(info, "unknown pragma '%s'" % name) 244 245 def accept(self, skip_comment: bool = True) -> None: 246 """ 247 Read and store the next token. 248 249 :param skip_comment: 250 When false, return COMMENT tokens ("#"). 251 This is used when reading documentation blocks. 252 253 :return: 254 None. Several instance attributes are updated instead: 255 256 - ``.tok`` represents the token type. See below for values. 257 - ``.info`` describes the token's source location. 258 - ``.val`` is the token's value, if any. See below. 259 - ``.pos`` is the buffer index of the first character of 260 the token. 261 262 * Single-character tokens: 263 264 These are "{", "}", ":", ",", "[", and "]". 265 ``.tok`` holds the single character and ``.val`` is None. 266 267 * Multi-character tokens: 268 269 * COMMENT: 270 271 This token is not normally returned by the lexer, but it can 272 be when ``skip_comment`` is False. ``.tok`` is "#", and 273 ``.val`` is a string including all chars until end-of-line, 274 including the "#" itself. 275 276 * STRING: 277 278 ``.tok`` is "'", the single quote. ``.val`` contains the 279 string, excluding the surrounding quotes. 280 281 * TRUE and FALSE: 282 283 ``.tok`` is either "t" or "f", ``.val`` will be the 284 corresponding bool value. 285 286 * EOF: 287 288 ``.tok`` and ``.val`` will both be None at EOF. 289 """ 290 while True: 291 self.tok = self.src[self.cursor] 292 self.pos = self.cursor 293 self.cursor += 1 294 self.val = None 295 296 if self.tok == '#': 297 if self.src[self.cursor] == '#': 298 # Start of doc comment 299 skip_comment = False 300 self.cursor = self.src.find('\n', self.cursor) 301 if not skip_comment: 302 self.val = self.src[self.pos:self.cursor] 303 return 304 elif self.tok in '{}:,[]': 305 return 306 elif self.tok == "'": 307 # Note: we accept only printable ASCII 308 string = '' 309 esc = False 310 while True: 311 ch = self.src[self.cursor] 312 self.cursor += 1 313 if ch == '\n': 314 raise QAPIParseError(self, "missing terminating \"'\"") 315 if esc: 316 # Note: we recognize only \\ because we have 317 # no use for funny characters in strings 318 if ch != '\\': 319 raise QAPIParseError(self, 320 "unknown escape \\%s" % ch) 321 esc = False 322 elif ch == '\\': 323 esc = True 324 continue 325 elif ch == "'": 326 self.val = string 327 return 328 if ord(ch) < 32 or ord(ch) >= 127: 329 raise QAPIParseError( 330 self, "funny character in string") 331 string += ch 332 elif self.src.startswith('true', self.pos): 333 self.val = True 334 self.cursor += 3 335 return 336 elif self.src.startswith('false', self.pos): 337 self.val = False 338 self.cursor += 4 339 return 340 elif self.tok == '\n': 341 if self.cursor == len(self.src): 342 self.tok = None 343 return 344 self.info = self.info.next_line() 345 self.line_pos = self.cursor 346 elif not self.tok.isspace(): 347 # Show up to next structural, whitespace or quote 348 # character 349 match = must_match('[^[\\]{}:,\\s\']+', 350 self.src[self.cursor-1:]) 351 raise QAPIParseError(self, "stray '%s'" % match.group(0)) 352 353 def get_members(self) -> Dict[str, object]: 354 expr: Dict[str, object] = OrderedDict() 355 if self.tok == '}': 356 self.accept() 357 return expr 358 if self.tok != "'": 359 raise QAPIParseError(self, "expected string or '}'") 360 while True: 361 key = self.val 362 assert isinstance(key, str) # Guaranteed by tok == "'" 363 364 self.accept() 365 if self.tok != ':': 366 raise QAPIParseError(self, "expected ':'") 367 self.accept() 368 if key in expr: 369 raise QAPIParseError(self, "duplicate key '%s'" % key) 370 expr[key] = self.get_expr() 371 if self.tok == '}': 372 self.accept() 373 return expr 374 if self.tok != ',': 375 raise QAPIParseError(self, "expected ',' or '}'") 376 self.accept() 377 if self.tok != "'": 378 raise QAPIParseError(self, "expected string") 379 380 def get_values(self) -> List[object]: 381 expr: List[object] = [] 382 if self.tok == ']': 383 self.accept() 384 return expr 385 if self.tok not in tuple("{['tf"): 386 raise QAPIParseError( 387 self, "expected '{', '[', ']', string, or boolean") 388 while True: 389 expr.append(self.get_expr()) 390 if self.tok == ']': 391 self.accept() 392 return expr 393 if self.tok != ',': 394 raise QAPIParseError(self, "expected ',' or ']'") 395 self.accept() 396 397 def get_expr(self) -> _ExprValue: 398 expr: _ExprValue 399 if self.tok == '{': 400 self.accept() 401 expr = self.get_members() 402 elif self.tok == '[': 403 self.accept() 404 expr = self.get_values() 405 elif self.tok in tuple("'tf"): 406 assert isinstance(self.val, (str, bool)) 407 expr = self.val 408 self.accept() 409 else: 410 raise QAPIParseError( 411 self, "expected '{', '[', string, or boolean") 412 return expr 413 414 def get_doc(self, info: QAPISourceInfo) -> List['QAPIDoc']: 415 if self.val != '##': 416 raise QAPIParseError( 417 self, "junk after '##' at start of documentation comment") 418 419 docs = [] 420 cur_doc = QAPIDoc(self, info) 421 self.accept(False) 422 while self.tok == '#': 423 assert isinstance(self.val, str) 424 if self.val.startswith('##'): 425 # End of doc comment 426 if self.val != '##': 427 raise QAPIParseError( 428 self, 429 "junk after '##' at end of documentation comment") 430 cur_doc.end_comment() 431 docs.append(cur_doc) 432 self.accept() 433 return docs 434 if self.val.startswith('# ='): 435 if cur_doc.symbol: 436 raise QAPIParseError( 437 self, 438 "unexpected '=' markup in definition documentation") 439 if cur_doc.body.text: 440 cur_doc.end_comment() 441 docs.append(cur_doc) 442 cur_doc = QAPIDoc(self, info) 443 cur_doc.append(self.val) 444 self.accept(False) 445 446 raise QAPIParseError(self, "documentation comment must end with '##'") 447 448 449class QAPIDoc: 450 """ 451 A documentation comment block, either definition or free-form 452 453 Definition documentation blocks consist of 454 455 * a body section: one line naming the definition, followed by an 456 overview (any number of lines) 457 458 * argument sections: a description of each argument (for commands 459 and events) or member (for structs, unions and alternates) 460 461 * features sections: a description of each feature flag 462 463 * additional (non-argument) sections, possibly tagged 464 465 Free-form documentation blocks consist only of a body section. 466 """ 467 468 class Section: 469 # pylint: disable=too-few-public-methods 470 def __init__(self, parser: QAPISchemaParser, 471 name: Optional[str] = None): 472 # parser, for error messages about indentation 473 self._parser = parser 474 # optional section name (argument/member or section name) 475 self.name = name 476 # section text without section name 477 self.text = '' 478 # indentation to strip (None means indeterminate) 479 self._indent = None if self.name else 0 480 481 def append(self, line: str) -> None: 482 line = line.rstrip() 483 484 if line: 485 indent = must_match(r'\s*', line).end() 486 if self._indent is None: 487 # indeterminate indentation 488 if self.text != '': 489 # non-blank, non-first line determines indentation 490 self._indent = indent 491 elif indent < self._indent: 492 raise QAPIParseError( 493 self._parser, 494 "unexpected de-indent (expected at least %d spaces)" % 495 self._indent) 496 line = line[self._indent:] 497 498 self.text += line + '\n' 499 500 class ArgSection(Section): 501 def __init__(self, parser: QAPISchemaParser, 502 name: str): 503 super().__init__(parser, name) 504 self.member: Optional['QAPISchemaMember'] = None 505 506 def connect(self, member: 'QAPISchemaMember') -> None: 507 self.member = member 508 509 class NullSection(Section): 510 """ 511 Immutable dummy section for use at the end of a doc block. 512 """ 513 # pylint: disable=too-few-public-methods 514 def append(self, line: str) -> None: 515 assert False, "Text appended after end_comment() called." 516 517 def __init__(self, parser: QAPISchemaParser, info: QAPISourceInfo): 518 # self._parser is used to report errors with QAPIParseError. The 519 # resulting error position depends on the state of the parser. 520 # It happens to be the beginning of the comment. More or less 521 # servicable, but action at a distance. 522 self._parser = parser 523 self.info = info 524 self.symbol: Optional[str] = None 525 self.body = QAPIDoc.Section(parser) 526 # dicts mapping parameter/feature names to their ArgSection 527 self.args: Dict[str, QAPIDoc.ArgSection] = OrderedDict() 528 self.features: Dict[str, QAPIDoc.ArgSection] = OrderedDict() 529 self.sections: List[QAPIDoc.Section] = [] 530 # the current section 531 self._section = self.body 532 self._append_line = self._append_body_line 533 534 def has_section(self, name: str) -> bool: 535 """Return True if we have a section with this name.""" 536 for i in self.sections: 537 if i.name == name: 538 return True 539 return False 540 541 def append(self, line: str) -> None: 542 """ 543 Parse a comment line and add it to the documentation. 544 545 The way that the line is dealt with depends on which part of 546 the documentation we're parsing right now: 547 * The body section: ._append_line is ._append_body_line 548 * An argument section: ._append_line is ._append_args_line 549 * A features section: ._append_line is ._append_features_line 550 * An additional section: ._append_line is ._append_various_line 551 """ 552 line = line[1:] 553 if not line: 554 self._append_freeform(line) 555 return 556 557 if line[0] != ' ': 558 raise QAPIParseError(self._parser, "missing space after #") 559 line = line[1:] 560 self._append_line(line) 561 562 def end_comment(self) -> None: 563 self._switch_section(QAPIDoc.NullSection(self._parser)) 564 565 @staticmethod 566 def _match_at_name_colon(string: str): 567 return re.match(r'@([^:]*): *', string) 568 569 @staticmethod 570 def _match_section_tag(string: str): 571 return re.match(r'(Returns|Since|Notes?|Examples?|TODO): *', string) 572 573 def _append_body_line(self, line: str) -> None: 574 """ 575 Process a line of documentation text in the body section. 576 577 If this a symbol line and it is the section's first line, this 578 is a definition documentation block for that symbol. 579 580 If it's a definition documentation block, another symbol line 581 begins the argument section for the argument named by it, and 582 a section tag begins an additional section. Start that 583 section and append the line to it. 584 585 Else, append the line to the current section. 586 """ 587 # FIXME not nice: things like '# @foo:' and '# @foo: ' aren't 588 # recognized, and get silently treated as ordinary text 589 if not self.symbol and not self.body.text and line.startswith('@'): 590 if not line.endswith(':'): 591 raise QAPIParseError(self._parser, "line should end with ':'") 592 self.symbol = line[1:-1] 593 # Invalid names are not checked here, but the name provided MUST 594 # match the following definition, which *is* validated in expr.py. 595 if not self.symbol: 596 raise QAPIParseError( 597 self._parser, "name required after '@'") 598 elif self.symbol: 599 # This is a definition documentation block 600 if self._match_at_name_colon(line): 601 self._append_line = self._append_args_line 602 self._append_args_line(line) 603 elif line == 'Features:': 604 self._append_line = self._append_features_line 605 elif self._match_section_tag(line): 606 self._append_line = self._append_various_line 607 self._append_various_line(line) 608 else: 609 self._append_freeform(line) 610 else: 611 # This is a free-form documentation block 612 self._append_freeform(line) 613 614 def _append_args_line(self, line: str) -> None: 615 """ 616 Process a line of documentation text in an argument section. 617 618 A symbol line begins the next argument section, a section tag 619 section or a non-indented line after a blank line begins an 620 additional section. Start that section and append the line to 621 it. 622 623 Else, append the line to the current section. 624 625 """ 626 match = self._match_at_name_colon(line) 627 if match: 628 line = line[match.end():] 629 self._start_args_section(match.group(1)) 630 elif self._match_section_tag(line): 631 self._append_line = self._append_various_line 632 self._append_various_line(line) 633 return 634 elif (self._section.text.endswith('\n\n') 635 and line and not line[0].isspace()): 636 if line == 'Features:': 637 self._append_line = self._append_features_line 638 else: 639 self._start_section() 640 self._append_line = self._append_various_line 641 self._append_various_line(line) 642 return 643 644 self._append_freeform(line) 645 646 def _append_features_line(self, line: str) -> None: 647 match = self._match_at_name_colon(line) 648 if match: 649 line = line[match.end():] 650 self._start_features_section(match.group(1)) 651 elif self._match_section_tag(line): 652 self._append_line = self._append_various_line 653 self._append_various_line(line) 654 return 655 elif (self._section.text.endswith('\n\n') 656 and line and not line[0].isspace()): 657 self._start_section() 658 self._append_line = self._append_various_line 659 self._append_various_line(line) 660 return 661 662 self._append_freeform(line) 663 664 def _append_various_line(self, line: str) -> None: 665 """ 666 Process a line of documentation text in an additional section. 667 668 A symbol line is an error. 669 670 A section tag begins an additional section. Start that 671 section and append the line to it. 672 673 Else, append the line to the current section. 674 """ 675 match = self._match_at_name_colon(line) 676 if match: 677 raise QAPIParseError(self._parser, 678 "description of '@%s:' follows a section" 679 % match.group(1)) 680 match = self._match_section_tag(line) 681 if match: 682 line = line[match.end():] 683 self._start_section(match.group(1)) 684 685 self._append_freeform(line) 686 687 def _start_symbol_section( 688 self, 689 symbols_dict: Dict[str, 'QAPIDoc.ArgSection'], 690 name: str) -> None: 691 # FIXME invalid names other than the empty string aren't flagged 692 if not name: 693 raise QAPIParseError(self._parser, "invalid parameter name") 694 if name in symbols_dict: 695 raise QAPIParseError(self._parser, 696 "'%s' parameter name duplicated" % name) 697 assert not self.sections 698 new_section = QAPIDoc.ArgSection(self._parser, name) 699 self._switch_section(new_section) 700 symbols_dict[name] = new_section 701 702 def _start_args_section(self, name: str) -> None: 703 self._start_symbol_section(self.args, name) 704 705 def _start_features_section(self, name: str) -> None: 706 self._start_symbol_section(self.features, name) 707 708 def _start_section(self, name: Optional[str] = None) -> None: 709 if name in ('Returns', 'Since') and self.has_section(name): 710 raise QAPIParseError(self._parser, 711 "duplicated '%s' section" % name) 712 new_section = QAPIDoc.Section(self._parser, name) 713 self._switch_section(new_section) 714 self.sections.append(new_section) 715 716 def _switch_section(self, new_section: 'QAPIDoc.Section') -> None: 717 text = self._section.text = self._section.text.strip('\n') 718 719 # Only the 'body' section is allowed to have an empty body. 720 # All other sections, including anonymous ones, must have text. 721 if self._section != self.body and not text: 722 # We do not create anonymous sections unless there is 723 # something to put in them; this is a parser bug. 724 assert self._section.name 725 raise QAPIParseError( 726 self._parser, 727 "empty doc section '%s'" % self._section.name) 728 729 self._section = new_section 730 731 def _append_freeform(self, line: str) -> None: 732 match = re.match(r'(@\S+:)', line) 733 if match: 734 raise QAPIParseError(self._parser, 735 "'%s' not allowed in free-form documentation" 736 % match.group(1)) 737 self._section.append(line) 738 739 def connect_member(self, member: 'QAPISchemaMember') -> None: 740 if member.name not in self.args: 741 # Undocumented TODO outlaw 742 self.args[member.name] = QAPIDoc.ArgSection(self._parser, 743 member.name) 744 self.args[member.name].connect(member) 745 746 def connect_feature(self, feature: 'QAPISchemaFeature') -> None: 747 if feature.name not in self.features: 748 raise QAPISemError(feature.info, 749 "feature '%s' lacks documentation" 750 % feature.name) 751 self.features[feature.name].connect(feature) 752 753 def check_expr(self, expr: QAPIExpression) -> None: 754 if self.has_section('Returns') and 'command' not in expr: 755 raise QAPISemError(self.info, 756 "'Returns:' is only valid for commands") 757 758 def check(self) -> None: 759 760 def check_args_section( 761 args: Dict[str, QAPIDoc.ArgSection], what: str 762 ) -> None: 763 bogus = [name for name, section in args.items() 764 if not section.member] 765 if bogus: 766 raise QAPISemError( 767 self.info, 768 "documented %s%s '%s' %s not exist" % ( 769 what, 770 "s" if len(bogus) > 1 else "", 771 "', '".join(bogus), 772 "do" if len(bogus) > 1 else "does" 773 )) 774 775 check_args_section(self.args, 'member') 776 check_args_section(self.features, 'feature') 777