Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/rich/style.py: 45%

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1import sys 

2from functools import lru_cache 

3from marshal import dumps, loads 

4from random import randint 

5from typing import Any, Dict, Iterable, List, Optional, Type, Union, cast 

6 

7from . import errors 

8from .color import Color, ColorParseError, ColorSystem, blend_rgb 

9from .repr import Result, rich_repr 

10from .terminal_theme import DEFAULT_TERMINAL_THEME, TerminalTheme 

11 

12# Style instances and style definitions are often interchangeable 

13StyleType = Union[str, "Style"] 

14 

15 

16class _Bit: 

17 """A descriptor to get/set a style attribute bit.""" 

18 

19 __slots__ = ["bit"] 

20 

21 def __init__(self, bit_no: int) -> None: 

22 self.bit = 1 << bit_no 

23 

24 def __get__(self, obj: "Style", objtype: Type["Style"]) -> Optional[bool]: 

25 if obj._set_attributes & self.bit: 

26 return obj._attributes & self.bit != 0 

27 return None 

28 

29 

30@rich_repr 

31class Style: 

32 """A terminal style. 

33 

34 A terminal style consists of a color (`color`), a background color (`bgcolor`), and a number of attributes, such 

35 as bold, italic etc. The attributes have 3 states: they can either be on 

36 (``True``), off (``False``), or not set (``None``). 

37 

38 Args: 

39 color (Union[Color, str], optional): Color of terminal text. Defaults to None. 

40 bgcolor (Union[Color, str], optional): Color of terminal background. Defaults to None. 

41 bold (bool, optional): Enable bold text. Defaults to None. 

42 dim (bool, optional): Enable dim text. Defaults to None. 

43 italic (bool, optional): Enable italic text. Defaults to None. 

44 underline (bool, optional): Enable underlined text. Defaults to None. 

45 blink (bool, optional): Enabled blinking text. Defaults to None. 

46 blink2 (bool, optional): Enable fast blinking text. Defaults to None. 

47 reverse (bool, optional): Enabled reverse text. Defaults to None. 

48 conceal (bool, optional): Enable concealed text. Defaults to None. 

49 strike (bool, optional): Enable strikethrough text. Defaults to None. 

50 underline2 (bool, optional): Enable doubly underlined text. Defaults to None. 

51 frame (bool, optional): Enable framed text. Defaults to None. 

52 encircle (bool, optional): Enable encircled text. Defaults to None. 

53 overline (bool, optional): Enable overlined text. Defaults to None. 

54 link (str, link): Link URL. Defaults to None. 

55 

56 """ 

57 

58 _color: Optional[Color] 

59 _bgcolor: Optional[Color] 

60 _attributes: int 

61 _set_attributes: int 

62 _hash: Optional[int] 

63 _null: bool 

64 _meta: Optional[bytes] 

65 

66 __slots__ = [ 

67 "_color", 

68 "_bgcolor", 

69 "_attributes", 

70 "_set_attributes", 

71 "_link", 

72 "_link_id", 

73 "_ansi", 

74 "_style_definition", 

75 "_hash", 

76 "_null", 

77 "_meta", 

78 ] 

79 

80 # maps bits on to SGR parameter 

81 _style_map = { 

82 0: "1", 

83 1: "2", 

84 2: "3", 

85 3: "4", 

86 4: "5", 

87 5: "6", 

88 6: "7", 

89 7: "8", 

90 8: "9", 

91 9: "21", 

92 10: "51", 

93 11: "52", 

94 12: "53", 

95 } 

96 

97 STYLE_ATTRIBUTES = { 

98 "dim": "dim", 

99 "d": "dim", 

100 "bold": "bold", 

101 "b": "bold", 

102 "italic": "italic", 

103 "i": "italic", 

104 "underline": "underline", 

105 "u": "underline", 

106 "blink": "blink", 

107 "blink2": "blink2", 

108 "reverse": "reverse", 

109 "r": "reverse", 

110 "conceal": "conceal", 

111 "c": "conceal", 

112 "strike": "strike", 

113 "s": "strike", 

114 "underline2": "underline2", 

115 "uu": "underline2", 

116 "frame": "frame", 

117 "encircle": "encircle", 

118 "overline": "overline", 

119 "o": "overline", 

120 } 

121 

122 def __init__( 

123 self, 

124 *, 

125 color: Optional[Union[Color, str]] = None, 

126 bgcolor: Optional[Union[Color, str]] = None, 

127 bold: Optional[bool] = None, 

128 dim: Optional[bool] = None, 

129 italic: Optional[bool] = None, 

130 underline: Optional[bool] = None, 

131 blink: Optional[bool] = None, 

132 blink2: Optional[bool] = None, 

133 reverse: Optional[bool] = None, 

134 conceal: Optional[bool] = None, 

135 strike: Optional[bool] = None, 

136 underline2: Optional[bool] = None, 

137 frame: Optional[bool] = None, 

138 encircle: Optional[bool] = None, 

139 overline: Optional[bool] = None, 

140 link: Optional[str] = None, 

141 meta: Optional[Dict[str, Any]] = None, 

142 ): 

143 self._ansi: Optional[str] = None 

144 self._style_definition: Optional[str] = None 

145 

146 def _make_color(color: Union[Color, str]) -> Color: 

147 return color if isinstance(color, Color) else Color.parse(color) 

148 

149 self._color = None if color is None else _make_color(color) 

150 self._bgcolor = None if bgcolor is None else _make_color(bgcolor) 

151 self._set_attributes = sum( 

152 ( 

153 bold is not None, 

154 dim is not None and 2, 

155 italic is not None and 4, 

156 underline is not None and 8, 

157 blink is not None and 16, 

158 blink2 is not None and 32, 

159 reverse is not None and 64, 

160 conceal is not None and 128, 

161 strike is not None and 256, 

162 underline2 is not None and 512, 

163 frame is not None and 1024, 

164 encircle is not None and 2048, 

165 overline is not None and 4096, 

166 ) 

167 ) 

168 self._attributes = ( 

169 sum( 

170 ( 

171 bold and 1 or 0, 

172 dim and 2 or 0, 

173 italic and 4 or 0, 

174 underline and 8 or 0, 

175 blink and 16 or 0, 

176 blink2 and 32 or 0, 

177 reverse and 64 or 0, 

178 conceal and 128 or 0, 

179 strike and 256 or 0, 

180 underline2 and 512 or 0, 

181 frame and 1024 or 0, 

182 encircle and 2048 or 0, 

183 overline and 4096 or 0, 

184 ) 

185 ) 

186 if self._set_attributes 

187 else 0 

188 ) 

189 

190 self._link = link 

191 self._meta = None if meta is None else dumps(meta) 

192 self._link_id = ( 

193 f"{randint(0, 999999)}{hash(self._meta)}" if (link or meta) else "" 

194 ) 

195 self._hash: Optional[int] = None 

196 self._null = not (self._set_attributes or color or bgcolor or link or meta) 

197 

198 @classmethod 

199 def null(cls) -> "Style": 

200 """Create an 'null' style, equivalent to Style(), but more performant.""" 

201 return NULL_STYLE 

202 

203 @classmethod 

204 def from_color( 

205 cls, color: Optional[Color] = None, bgcolor: Optional[Color] = None 

206 ) -> "Style": 

207 """Create a new style with colors and no attributes. 

208 

209 Returns: 

210 color (Optional[Color]): A (foreground) color, or None for no color. Defaults to None. 

211 bgcolor (Optional[Color]): A (background) color, or None for no color. Defaults to None. 

212 """ 

213 style: Style = cls.__new__(Style) 

214 style._ansi = None 

215 style._style_definition = None 

216 style._color = color 

217 style._bgcolor = bgcolor 

218 style._set_attributes = 0 

219 style._attributes = 0 

220 style._link = None 

221 style._link_id = "" 

222 style._meta = None 

223 style._null = not (color or bgcolor) 

224 style._hash = None 

225 return style 

226 

227 @classmethod 

228 def from_meta(cls, meta: Optional[Dict[str, Any]]) -> "Style": 

229 """Create a new style with meta data. 

230 

231 Returns: 

232 meta (Optional[Dict[str, Any]]): A dictionary of meta data. Defaults to None. 

233 """ 

234 style: Style = cls.__new__(Style) 

235 style._ansi = None 

236 style._style_definition = None 

237 style._color = None 

238 style._bgcolor = None 

239 style._set_attributes = 0 

240 style._attributes = 0 

241 style._link = None 

242 style._meta = dumps(meta) 

243 style._link_id = f"{randint(0, 999999)}{hash(style._meta)}" 

244 style._hash = None 

245 style._null = not (meta) 

246 return style 

247 

248 @classmethod 

249 def on(cls, meta: Optional[Dict[str, Any]] = None, **handlers: Any) -> "Style": 

250 """Create a blank style with meta information. 

251 

252 Example: 

253 style = Style.on(click=self.on_click) 

254 

255 Args: 

256 meta (Optional[Dict[str, Any]], optional): An optional dict of meta information. 

257 **handlers (Any): Keyword arguments are translated in to handlers. 

258 

259 Returns: 

260 Style: A Style with meta information attached. 

261 """ 

262 meta = {} if meta is None else meta 

263 meta.update({f"@{key}": value for key, value in handlers.items()}) 

264 return cls.from_meta(meta) 

265 

266 bold = _Bit(0) 

267 dim = _Bit(1) 

268 italic = _Bit(2) 

269 underline = _Bit(3) 

270 blink = _Bit(4) 

271 blink2 = _Bit(5) 

272 reverse = _Bit(6) 

273 conceal = _Bit(7) 

274 strike = _Bit(8) 

275 underline2 = _Bit(9) 

276 frame = _Bit(10) 

277 encircle = _Bit(11) 

278 overline = _Bit(12) 

279 

280 @property 

281 def link_id(self) -> str: 

282 """Get a link id, used in ansi code for links.""" 

283 return self._link_id 

284 

285 def __str__(self) -> str: 

286 """Re-generate style definition from attributes.""" 

287 if self._style_definition is None: 

288 attributes: List[str] = [] 

289 append = attributes.append 

290 bits = self._set_attributes 

291 if bits & 0b0000000001111: 

292 if bits & 1: 

293 append("bold" if self.bold else "not bold") 

294 if bits & (1 << 1): 

295 append("dim" if self.dim else "not dim") 

296 if bits & (1 << 2): 

297 append("italic" if self.italic else "not italic") 

298 if bits & (1 << 3): 

299 append("underline" if self.underline else "not underline") 

300 if bits & 0b0000111110000: 

301 if bits & (1 << 4): 

302 append("blink" if self.blink else "not blink") 

303 if bits & (1 << 5): 

304 append("blink2" if self.blink2 else "not blink2") 

305 if bits & (1 << 6): 

306 append("reverse" if self.reverse else "not reverse") 

307 if bits & (1 << 7): 

308 append("conceal" if self.conceal else "not conceal") 

309 if bits & (1 << 8): 

310 append("strike" if self.strike else "not strike") 

311 if bits & 0b1111000000000: 

312 if bits & (1 << 9): 

313 append("underline2" if self.underline2 else "not underline2") 

314 if bits & (1 << 10): 

315 append("frame" if self.frame else "not frame") 

316 if bits & (1 << 11): 

317 append("encircle" if self.encircle else "not encircle") 

318 if bits & (1 << 12): 

319 append("overline" if self.overline else "not overline") 

320 if self._color is not None: 

321 append(self._color.name) 

322 if self._bgcolor is not None: 

323 append("on") 

324 append(self._bgcolor.name) 

325 if self._link: 

326 append("link") 

327 append(self._link) 

328 self._style_definition = " ".join(attributes) or "none" 

329 return self._style_definition 

330 

331 def __bool__(self) -> bool: 

332 """A Style is false if it has no attributes, colors, or links.""" 

333 return not self._null 

334 

335 def _make_ansi_codes(self, color_system: ColorSystem) -> str: 

336 """Generate ANSI codes for this style. 

337 

338 Args: 

339 color_system (ColorSystem): Color system. 

340 

341 Returns: 

342 str: String containing codes. 

343 """ 

344 

345 if self._ansi is None: 

346 sgr: List[str] = [] 

347 append = sgr.append 

348 _style_map = self._style_map 

349 attributes = self._attributes & self._set_attributes 

350 if attributes: 

351 if attributes & 1: 

352 append(_style_map[0]) 

353 if attributes & 2: 

354 append(_style_map[1]) 

355 if attributes & 4: 

356 append(_style_map[2]) 

357 if attributes & 8: 

358 append(_style_map[3]) 

359 if attributes & 0b0000111110000: 

360 for bit in range(4, 9): 

361 if attributes & (1 << bit): 

362 append(_style_map[bit]) 

363 if attributes & 0b1111000000000: 

364 for bit in range(9, 13): 

365 if attributes & (1 << bit): 

366 append(_style_map[bit]) 

367 if self._color is not None: 

368 sgr.extend(self._color.downgrade(color_system).get_ansi_codes()) 

369 if self._bgcolor is not None: 

370 sgr.extend( 

371 self._bgcolor.downgrade(color_system).get_ansi_codes( 

372 foreground=False 

373 ) 

374 ) 

375 self._ansi = ";".join(sgr) 

376 return self._ansi 

377 

378 @classmethod 

379 @lru_cache(maxsize=1024) 

380 def normalize(cls, style: str) -> str: 

381 """Normalize a style definition so that styles with the same effect have the same string 

382 representation. 

383 

384 Args: 

385 style (str): A style definition. 

386 

387 Returns: 

388 str: Normal form of style definition. 

389 """ 

390 try: 

391 return str(cls.parse(style)) 

392 except errors.StyleSyntaxError: 

393 return style.strip().lower() 

394 

395 @classmethod 

396 def pick_first(cls, *values: Optional[StyleType]) -> StyleType: 

397 """Pick first non-None style.""" 

398 for value in values: 

399 if value is not None: 

400 return value 

401 raise ValueError("expected at least one non-None style") 

402 

403 def __rich_repr__(self) -> Result: 

404 yield "color", self.color, None 

405 yield "bgcolor", self.bgcolor, None 

406 yield "bold", self.bold, None, 

407 yield "dim", self.dim, None, 

408 yield "italic", self.italic, None 

409 yield "underline", self.underline, None, 

410 yield "blink", self.blink, None 

411 yield "blink2", self.blink2, None 

412 yield "reverse", self.reverse, None 

413 yield "conceal", self.conceal, None 

414 yield "strike", self.strike, None 

415 yield "underline2", self.underline2, None 

416 yield "frame", self.frame, None 

417 yield "encircle", self.encircle, None 

418 yield "link", self.link, None 

419 if self._meta: 

420 yield "meta", self.meta 

421 

422 def __eq__(self, other: Any) -> bool: 

423 if not isinstance(other, Style): 

424 return NotImplemented 

425 return self.__hash__() == other.__hash__() 

426 

427 def __ne__(self, other: Any) -> bool: 

428 if not isinstance(other, Style): 

429 return NotImplemented 

430 return self.__hash__() != other.__hash__() 

431 

432 def __hash__(self) -> int: 

433 if self._hash is not None: 

434 return self._hash 

435 self._hash = hash( 

436 ( 

437 self._color, 

438 self._bgcolor, 

439 self._attributes, 

440 self._set_attributes, 

441 self._link, 

442 self._meta, 

443 ) 

444 ) 

445 return self._hash 

446 

447 @property 

448 def color(self) -> Optional[Color]: 

449 """The foreground color or None if it is not set.""" 

450 return self._color 

451 

452 @property 

453 def bgcolor(self) -> Optional[Color]: 

454 """The background color or None if it is not set.""" 

455 return self._bgcolor 

456 

457 @property 

458 def link(self) -> Optional[str]: 

459 """Link text, if set.""" 

460 return self._link 

461 

462 @property 

463 def transparent_background(self) -> bool: 

464 """Check if the style specified a transparent background.""" 

465 return self.bgcolor is None or self.bgcolor.is_default 

466 

467 @property 

468 def background_style(self) -> "Style": 

469 """A Style with background only.""" 

470 return Style(bgcolor=self.bgcolor) 

471 

472 @property 

473 def meta(self) -> Dict[str, Any]: 

474 """Get meta information (can not be changed after construction).""" 

475 return {} if self._meta is None else cast(Dict[str, Any], loads(self._meta)) 

476 

477 @property 

478 def without_color(self) -> "Style": 

479 """Get a copy of the style with color removed.""" 

480 if self._null: 

481 return NULL_STYLE 

482 style: Style = self.__new__(Style) 

483 style._ansi = None 

484 style._style_definition = None 

485 style._color = None 

486 style._bgcolor = None 

487 style._attributes = self._attributes 

488 style._set_attributes = self._set_attributes 

489 style._link = self._link 

490 style._link_id = f"{randint(0, 999999)}" if self._link else "" 

491 style._null = False 

492 style._meta = None 

493 style._hash = None 

494 return style 

495 

496 @classmethod 

497 @lru_cache(maxsize=4096) 

498 def parse(cls, style_definition: str) -> "Style": 

499 """Parse a style definition. 

500 

501 Args: 

502 style_definition (str): A string containing a style. 

503 

504 Raises: 

505 errors.StyleSyntaxError: If the style definition syntax is invalid. 

506 

507 Returns: 

508 `Style`: A Style instance. 

509 """ 

510 if style_definition.strip() == "none" or not style_definition: 

511 return cls.null() 

512 

513 STYLE_ATTRIBUTES = cls.STYLE_ATTRIBUTES 

514 color: Optional[str] = None 

515 bgcolor: Optional[str] = None 

516 attributes: Dict[str, Optional[Any]] = {} 

517 link: Optional[str] = None 

518 

519 words = iter(style_definition.split()) 

520 for original_word in words: 

521 word = original_word.lower() 

522 if word == "on": 

523 word = next(words, "") 

524 if not word: 

525 raise errors.StyleSyntaxError("color expected after 'on'") 

526 try: 

527 Color.parse(word) is None 

528 except ColorParseError as error: 

529 raise errors.StyleSyntaxError( 

530 f"unable to parse {word!r} as background color; {error}" 

531 ) from None 

532 bgcolor = word 

533 

534 elif word == "not": 

535 word = next(words, "") 

536 attribute = STYLE_ATTRIBUTES.get(word) 

537 if attribute is None: 

538 raise errors.StyleSyntaxError( 

539 f"expected style attribute after 'not', found {word!r}" 

540 ) 

541 attributes[attribute] = False 

542 

543 elif word == "link": 

544 word = next(words, "") 

545 if not word: 

546 raise errors.StyleSyntaxError("URL expected after 'link'") 

547 link = word 

548 

549 elif word in STYLE_ATTRIBUTES: 

550 attributes[STYLE_ATTRIBUTES[word]] = True 

551 

552 else: 

553 try: 

554 Color.parse(word) 

555 except ColorParseError as error: 

556 raise errors.StyleSyntaxError( 

557 f"unable to parse {word!r} as color; {error}" 

558 ) from None 

559 color = word 

560 style = Style(color=color, bgcolor=bgcolor, link=link, **attributes) 

561 return style 

562 

563 @lru_cache(maxsize=1024) 

564 def get_html_style(self, theme: Optional[TerminalTheme] = None) -> str: 

565 """Get a CSS style rule.""" 

566 theme = theme or DEFAULT_TERMINAL_THEME 

567 css: List[str] = [] 

568 append = css.append 

569 

570 color = self.color 

571 bgcolor = self.bgcolor 

572 if self.reverse: 

573 color, bgcolor = bgcolor, color 

574 if self.dim: 

575 foreground_color = ( 

576 theme.foreground_color if color is None else color.get_truecolor(theme) 

577 ) 

578 color = Color.from_triplet( 

579 blend_rgb(foreground_color, theme.background_color, 0.5) 

580 ) 

581 if color is not None: 

582 theme_color = color.get_truecolor(theme) 

583 append(f"color: {theme_color.hex}") 

584 append(f"text-decoration-color: {theme_color.hex}") 

585 if bgcolor is not None: 

586 theme_color = bgcolor.get_truecolor(theme, foreground=False) 

587 append(f"background-color: {theme_color.hex}") 

588 if self.bold: 

589 append("font-weight: bold") 

590 if self.italic: 

591 append("font-style: italic") 

592 if self.underline: 

593 append("text-decoration: underline") 

594 if self.strike: 

595 append("text-decoration: line-through") 

596 if self.overline: 

597 append("text-decoration: overline") 

598 return "; ".join(css) 

599 

600 @classmethod 

601 def combine(cls, styles: Iterable["Style"]) -> "Style": 

602 """Combine styles and get result. 

603 

604 Args: 

605 styles (Iterable[Style]): Styles to combine. 

606 

607 Returns: 

608 Style: A new style instance. 

609 """ 

610 iter_styles = iter(styles) 

611 return sum(iter_styles, next(iter_styles)) 

612 

613 @classmethod 

614 def chain(cls, *styles: "Style") -> "Style": 

615 """Combine styles from positional argument in to a single style. 

616 

617 Args: 

618 *styles (Iterable[Style]): Styles to combine. 

619 

620 Returns: 

621 Style: A new style instance. 

622 """ 

623 iter_styles = iter(styles) 

624 return sum(iter_styles, next(iter_styles)) 

625 

626 def copy(self) -> "Style": 

627 """Get a copy of this style. 

628 

629 Returns: 

630 Style: A new Style instance with identical attributes. 

631 """ 

632 if self._null: 

633 return NULL_STYLE 

634 style: Style = self.__new__(Style) 

635 style._ansi = self._ansi 

636 style._style_definition = self._style_definition 

637 style._color = self._color 

638 style._bgcolor = self._bgcolor 

639 style._attributes = self._attributes 

640 style._set_attributes = self._set_attributes 

641 style._link = self._link 

642 style._link_id = f"{randint(0, 999999)}" if self._link else "" 

643 style._hash = self._hash 

644 style._null = False 

645 style._meta = self._meta 

646 return style 

647 

648 @lru_cache(maxsize=128) 

649 def clear_meta_and_links(self) -> "Style": 

650 """Get a copy of this style with link and meta information removed. 

651 

652 Returns: 

653 Style: New style object. 

654 """ 

655 if self._null: 

656 return NULL_STYLE 

657 style: Style = self.__new__(Style) 

658 style._ansi = self._ansi 

659 style._style_definition = self._style_definition 

660 style._color = self._color 

661 style._bgcolor = self._bgcolor 

662 style._attributes = self._attributes 

663 style._set_attributes = self._set_attributes 

664 style._link = None 

665 style._link_id = "" 

666 style._hash = self._hash 

667 style._null = False 

668 style._meta = None 

669 return style 

670 

671 def update_link(self, link: Optional[str] = None) -> "Style": 

672 """Get a copy with a different value for link. 

673 

674 Args: 

675 link (str, optional): New value for link. Defaults to None. 

676 

677 Returns: 

678 Style: A new Style instance. 

679 """ 

680 style: Style = self.__new__(Style) 

681 style._ansi = self._ansi 

682 style._style_definition = self._style_definition 

683 style._color = self._color 

684 style._bgcolor = self._bgcolor 

685 style._attributes = self._attributes 

686 style._set_attributes = self._set_attributes 

687 style._link = link 

688 style._link_id = f"{randint(0, 999999)}" if link else "" 

689 style._hash = None 

690 style._null = False 

691 style._meta = self._meta 

692 return style 

693 

694 def render( 

695 self, 

696 text: str = "", 

697 *, 

698 color_system: Optional[ColorSystem] = ColorSystem.TRUECOLOR, 

699 legacy_windows: bool = False, 

700 ) -> str: 

701 """Render the ANSI codes for the style. 

702 

703 Args: 

704 text (str, optional): A string to style. Defaults to "". 

705 color_system (Optional[ColorSystem], optional): Color system to render to. Defaults to ColorSystem.TRUECOLOR. 

706 

707 Returns: 

708 str: A string containing ANSI style codes. 

709 """ 

710 if not text or color_system is None: 

711 return text 

712 attrs = self._ansi or self._make_ansi_codes(color_system) 

713 rendered = f"\x1b[{attrs}m{text}\x1b[0m" if attrs else text 

714 if self._link and not legacy_windows: 

715 rendered = ( 

716 f"\x1b]8;id={self._link_id};{self._link}\x1b\\{rendered}\x1b]8;;\x1b\\" 

717 ) 

718 return rendered 

719 

720 def test(self, text: Optional[str] = None) -> None: 

721 """Write text with style directly to terminal. 

722 

723 This method is for testing purposes only. 

724 

725 Args: 

726 text (Optional[str], optional): Text to style or None for style name. 

727 

728 """ 

729 text = text or str(self) 

730 sys.stdout.write(f"{self.render(text)}\n") 

731 

732 @lru_cache(maxsize=1024) 

733 def _add(self, style: Optional["Style"]) -> "Style": 

734 if style is None or style._null: 

735 return self 

736 if self._null: 

737 return style 

738 new_style: Style = self.__new__(Style) 

739 new_style._ansi = None 

740 new_style._style_definition = None 

741 new_style._color = style._color or self._color 

742 new_style._bgcolor = style._bgcolor or self._bgcolor 

743 new_style._attributes = (self._attributes & ~style._set_attributes) | ( 

744 style._attributes & style._set_attributes 

745 ) 

746 new_style._set_attributes = self._set_attributes | style._set_attributes 

747 new_style._link = style._link or self._link 

748 new_style._link_id = style._link_id or self._link_id 

749 new_style._null = style._null 

750 if self._meta and style._meta: 

751 new_style._meta = dumps({**self.meta, **style.meta}) 

752 else: 

753 new_style._meta = self._meta or style._meta 

754 new_style._hash = None 

755 return new_style 

756 

757 def __add__(self, style: Optional["Style"]) -> "Style": 

758 combined_style = self._add(style) 

759 return combined_style.copy() if combined_style.link else combined_style 

760 

761 

762NULL_STYLE = Style() 

763 

764 

765class StyleStack: 

766 """A stack of styles.""" 

767 

768 __slots__ = ["_stack"] 

769 

770 def __init__(self, default_style: "Style") -> None: 

771 self._stack: List[Style] = [default_style] 

772 

773 def __repr__(self) -> str: 

774 return f"<stylestack {self._stack!r}>" 

775 

776 @property 

777 def current(self) -> Style: 

778 """Get the Style at the top of the stack.""" 

779 return self._stack[-1] 

780 

781 def push(self, style: Style) -> None: 

782 """Push a new style on to the stack. 

783 

784 Args: 

785 style (Style): New style to combine with current style. 

786 """ 

787 self._stack.append(self._stack[-1] + style) 

788 

789 def pop(self) -> Style: 

790 """Pop last style and discard. 

791 

792 Returns: 

793 Style: New current style (also available as stack.current) 

794 """ 

795 self._stack.pop() 

796 return self._stack[-1]