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1# This file is part of daf_butler. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (http://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <http://www.gnu.org/licenses/>. 

21 

22from __future__ import annotations 

23 

24import contextlib 

25import urllib.parse 

26import posixpath 

27import copy 

28import logging 

29import re 

30 

31from pathlib import Path, PurePath, PurePosixPath 

32 

33__all__ = ('ButlerURI',) 

34 

35from typing import ( 

36 TYPE_CHECKING, 

37 Any, 

38 Iterable, 

39 Iterator, 

40 List, 

41 Optional, 

42 Tuple, 

43 Type, 

44 Union, 

45) 

46 

47from .utils import NoTransaction 

48 

49if TYPE_CHECKING: 49 ↛ 50line 49 didn't jump to line 50, because the condition on line 49 was never true

50 from ..datastore import DatastoreTransaction 

51 

52 

53log = logging.getLogger(__name__) 

54 

55# Regex for looking for URI escapes 

56ESCAPES_RE = re.compile(r"%[A-F0-9]{2}") 

57 

58# Precomputed escaped hash 

59ESCAPED_HASH = urllib.parse.quote("#") 

60 

61 

62class ButlerURI: 

63 """Convenience wrapper around URI parsers. 

64 

65 Provides access to URI components and can convert file 

66 paths into absolute path URIs. Scheme-less URIs are treated as if 

67 they are local file system paths and are converted to absolute URIs. 

68 

69 A specialist subclass is created for each supported URI scheme. 

70 

71 Parameters 

72 ---------- 

73 uri : `str` or `urllib.parse.ParseResult` 

74 URI in string form. Can be scheme-less if referring to a local 

75 filesystem path. 

76 root : `str` or `ButlerURI`, optional 

77 When fixing up a relative path in a ``file`` scheme or if scheme-less, 

78 use this as the root. Must be absolute. If `None` the current 

79 working directory will be used. Can be a file URI. 

80 forceAbsolute : `bool`, optional 

81 If `True`, scheme-less relative URI will be converted to an absolute 

82 path using a ``file`` scheme. If `False` scheme-less URI will remain 

83 scheme-less and will not be updated to ``file`` or absolute path. 

84 forceDirectory: `bool`, optional 

85 If `True` forces the URI to end with a separator, otherwise given URI 

86 is interpreted as is. 

87 isTemporary : `bool`, optional 

88 If `True` indicates that this URI points to a temporary resource. 

89 """ 

90 

91 _pathLib: Type[PurePath] = PurePosixPath 

92 """Path library to use for this scheme.""" 

93 

94 _pathModule = posixpath 

95 """Path module to use for this scheme.""" 

96 

97 transferModes: Tuple[str, ...] = ("copy", "auto", "move") 

98 """Transfer modes supported by this implementation. 

99 

100 Move is special in that it is generally a copy followed by an unlink. 

101 Whether that unlink works depends critically on whether the source URI 

102 implements unlink. If it does not the move will be reported as a failure. 

103 """ 

104 

105 transferDefault: str = "copy" 

106 """Default mode to use for transferring if ``auto`` is specified.""" 

107 

108 quotePaths = True 

109 """True if path-like elements modifying a URI should be quoted. 

110 

111 All non-schemeless URIs have to internally use quoted paths. Therefore 

112 if a new file name is given (e.g. to updatedFile or join) a decision must 

113 be made whether to quote it to be consistent. 

114 """ 

115 

116 isLocal = False 

117 """If `True` this URI refers to a local file.""" 

118 

119 # This is not an ABC with abstract methods because the __new__ being 

120 # a factory confuses mypy such that it assumes that every constructor 

121 # returns a ButlerURI and then determines that all the abstract methods 

122 # are still abstract. If they are not marked abstract but just raise 

123 # mypy is fine with it. 

124 

125 # mypy is confused without these 

126 _uri: urllib.parse.ParseResult 

127 isTemporary: bool 

128 dirLike: bool 

129 

130 def __new__(cls, uri: Union[str, urllib.parse.ParseResult, ButlerURI, Path], 

131 root: Optional[Union[str, ButlerURI]] = None, forceAbsolute: bool = True, 

132 forceDirectory: bool = False, isTemporary: bool = False) -> ButlerURI: 

133 """Create and return new specialist ButlerURI subclass.""" 

134 parsed: urllib.parse.ParseResult 

135 dirLike: bool = False 

136 subclass: Optional[Type[ButlerURI]] = None 

137 

138 if isinstance(uri, Path): 138 ↛ 139line 138 didn't jump to line 139, because the condition on line 138 was never true

139 uri = str(uri) 

140 

141 # Record if we need to post process the URI components 

142 # or if the instance is already fully configured 

143 if isinstance(uri, str): 

144 # Since local file names can have special characters in them 

145 # we need to quote them for the parser but we can unquote 

146 # later. Assume that all other URI schemes are quoted. 

147 # Since sometimes people write file:/a/b and not file:///a/b 

148 # we should not quote in the explicit case of file: 

149 if "://" not in uri and not uri.startswith("file:"): 

150 if ESCAPES_RE.search(uri): 150 ↛ 151line 150 didn't jump to line 151, because the condition on line 150 was never true

151 log.warning("Possible double encoding of %s", uri) 

152 else: 

153 uri = urllib.parse.quote(uri) 

154 # Special case hash since we must support fragments 

155 # even in schemeless URIs -- although try to only replace 

156 # them in file part and not directory part 

157 if ESCAPED_HASH in uri: 157 ↛ 158line 157 didn't jump to line 158, because the condition on line 157 was never true

158 dirpos = uri.rfind("/") 

159 # Do replacement after this / 

160 uri = uri[:dirpos+1] + uri[dirpos+1:].replace(ESCAPED_HASH, "#") 

161 

162 parsed = urllib.parse.urlparse(uri) 

163 elif isinstance(uri, urllib.parse.ParseResult): 

164 parsed = copy.copy(uri) 

165 # If we are being instantiated with a subclass, rather than 

166 # ButlerURI, ensure that that subclass is used directly. 

167 # This could lead to inconsistencies if this constructor 

168 # is used externally outside of the ButlerURI.replace() method. 

169 # ButlerS3URI(urllib.parse.urlparse("file://a/b.txt")) 

170 # will be a problem. 

171 # This is needed to prevent a schemeless absolute URI become 

172 # a file URI unexpectedly when calling updatedFile or 

173 # updatedExtension 

174 if cls is not ButlerURI: 

175 parsed, dirLike = cls._fixDirectorySep(parsed, forceDirectory) 

176 subclass = cls 

177 

178 elif isinstance(uri, ButlerURI): 178 ↛ 183line 178 didn't jump to line 183, because the condition on line 178 was never false

179 # Since ButlerURI is immutable we can return the argument 

180 # unchanged. 

181 return uri 

182 else: 

183 raise ValueError("Supplied URI must be string, Path, " 

184 f"ButlerURI, or ParseResult but got '{uri!r}'") 

185 

186 if subclass is None: 

187 # Work out the subclass from the URI scheme 

188 if not parsed.scheme: 

189 from .schemeless import ButlerSchemelessURI 

190 subclass = ButlerSchemelessURI 

191 elif parsed.scheme == "file": 191 ↛ 192line 191 didn't jump to line 192, because the condition on line 191 was never true

192 from .file import ButlerFileURI 

193 subclass = ButlerFileURI 

194 elif parsed.scheme == "s3": 194 ↛ 195line 194 didn't jump to line 195, because the condition on line 194 was never true

195 from .s3 import ButlerS3URI 

196 subclass = ButlerS3URI 

197 elif parsed.scheme.startswith("http"): 197 ↛ 198line 197 didn't jump to line 198, because the condition on line 197 was never true

198 from .http import ButlerHttpURI 

199 subclass = ButlerHttpURI 

200 elif parsed.scheme == "resource": 200 ↛ 204line 200 didn't jump to line 204, because the condition on line 200 was never false

201 # Rules for scheme names disallow pkg_resource 

202 from .packageresource import ButlerPackageResourceURI 

203 subclass = ButlerPackageResourceURI 

204 elif parsed.scheme == "mem": 

205 # in-memory datastore object 

206 from .mem import ButlerInMemoryURI 

207 subclass = ButlerInMemoryURI 

208 else: 

209 raise NotImplementedError(f"No URI support for scheme: '{parsed.scheme}'" 

210 " in {parsed.geturl()}") 

211 

212 parsed, dirLike = subclass._fixupPathUri(parsed, root=root, 

213 forceAbsolute=forceAbsolute, 

214 forceDirectory=forceDirectory) 

215 

216 # It is possible for the class to change from schemeless 

217 # to file so handle that 

218 if parsed.scheme == "file": 218 ↛ 219line 218 didn't jump to line 219, because the condition on line 218 was never true

219 from .file import ButlerFileURI 

220 subclass = ButlerFileURI 

221 

222 # Now create an instance of the correct subclass and set the 

223 # attributes directly 

224 self = object.__new__(subclass) 

225 self._uri = parsed 

226 self.dirLike = dirLike 

227 self.isTemporary = isTemporary 

228 return self 

229 

230 @property 

231 def scheme(self) -> str: 

232 """Return the URI scheme. 

233 

234 Notes 

235 ----- 

236 (``://`` is not part of the scheme). 

237 """ 

238 return self._uri.scheme 

239 

240 @property 

241 def netloc(self) -> str: 

242 """Return the URI network location.""" 

243 return self._uri.netloc 

244 

245 @property 

246 def path(self) -> str: 

247 """Return the path component of the URI.""" 

248 return self._uri.path 

249 

250 @property 

251 def unquoted_path(self) -> str: 

252 """Return path component of the URI with any URI quoting reversed.""" 

253 return urllib.parse.unquote(self._uri.path) 

254 

255 @property 

256 def ospath(self) -> str: 

257 """Return the path component of the URI localized to current OS.""" 

258 raise AttributeError(f"Non-file URI ({self}) has no local OS path.") 

259 

260 @property 

261 def relativeToPathRoot(self) -> str: 

262 """Return path relative to network location. 

263 

264 Effectively, this is the path property with posix separator stripped 

265 from the left hand side of the path. 

266 

267 Always unquotes. 

268 """ 

269 p = self._pathLib(self.path) 

270 relToRoot = str(p.relative_to(p.root)) 

271 if self.dirLike and not relToRoot.endswith("/"): 271 ↛ 272line 271 didn't jump to line 272, because the condition on line 271 was never true

272 relToRoot += "/" 

273 return urllib.parse.unquote(relToRoot) 

274 

275 @property 

276 def is_root(self) -> bool: 

277 """Return whether this URI points to the root of the network location. 

278 

279 This means that the path components refers to the top level. 

280 """ 

281 relpath = self.relativeToPathRoot 

282 if relpath == "./": 

283 return True 

284 return False 

285 

286 @property 

287 def fragment(self) -> str: 

288 """Return the fragment component of the URI.""" 

289 return self._uri.fragment 

290 

291 @property 

292 def params(self) -> str: 

293 """Return any parameters included in the URI.""" 

294 return self._uri.params 

295 

296 @property 

297 def query(self) -> str: 

298 """Return any query strings included in the URI.""" 

299 return self._uri.query 

300 

301 def geturl(self) -> str: 

302 """Return the URI in string form. 

303 

304 Returns 

305 ------- 

306 url : `str` 

307 String form of URI. 

308 """ 

309 return self._uri.geturl() 

310 

311 def root_uri(self) -> ButlerURI: 

312 """Return the base root URI. 

313 

314 Returns 

315 ------- 

316 uri : `ButlerURI` 

317 root URI. 

318 """ 

319 return self.replace(path="", forceDirectory=True) 

320 

321 def split(self) -> Tuple[ButlerURI, str]: 

322 """Split URI into head and tail. 

323 

324 Returns 

325 ------- 

326 head: `ButlerURI` 

327 Everything leading up to tail, expanded and normalized as per 

328 ButlerURI rules. 

329 tail : `str` 

330 Last `self.path` component. Tail will be empty if path ends on a 

331 separator. Tail will never contain separators. It will be 

332 unquoted. 

333 

334 Notes 

335 ----- 

336 Equivalent to `os.path.split()` where head preserves the URI 

337 components. 

338 """ 

339 head, tail = self._pathModule.split(self.path) 

340 headuri = self._uri._replace(path=head) 

341 

342 # The file part should never include quoted metacharacters 

343 tail = urllib.parse.unquote(tail) 

344 

345 # Schemeless is special in that it can be a relative path 

346 # We need to ensure that it stays that way. All other URIs will 

347 # be absolute already. 

348 forceAbsolute = self._pathModule.isabs(self.path) 

349 return ButlerURI(headuri, forceDirectory=True, forceAbsolute=forceAbsolute), tail 

350 

351 def basename(self) -> str: 

352 """Return the base name, last element of path, of the URI. 

353 

354 Returns 

355 ------- 

356 tail : `str` 

357 Last part of the path attribute. Trail will be empty if path ends 

358 on a separator. 

359 

360 Notes 

361 ----- 

362 If URI ends on a slash returns an empty string. This is the second 

363 element returned by `split()`. 

364 

365 Equivalent of `os.path.basename()``. 

366 """ 

367 return self.split()[1] 

368 

369 def dirname(self) -> ButlerURI: 

370 """Return the directory component of the path as a new `ButlerURI`. 

371 

372 Returns 

373 ------- 

374 head : `ButlerURI` 

375 Everything except the tail of path attribute, expanded and 

376 normalized as per ButlerURI rules. 

377 

378 Notes 

379 ----- 

380 Equivalent of `os.path.dirname()`. 

381 """ 

382 return self.split()[0] 

383 

384 def parent(self) -> ButlerURI: 

385 """Return a `ButlerURI` of the parent directory. 

386 

387 Returns 

388 ------- 

389 head : `ButlerURI` 

390 Everything except the tail of path attribute, expanded and 

391 normalized as per `ButlerURI` rules. 

392 

393 Notes 

394 ----- 

395 For a file-like URI this will be the same as calling `dirname()`. 

396 """ 

397 # When self is file-like, return self.dirname() 

398 if not self.dirLike: 

399 return self.dirname() 

400 # When self is dir-like, return its parent directory, 

401 # regardless of the presence of a trailing separator 

402 originalPath = self._pathLib(self.path) 

403 parentPath = originalPath.parent 

404 return self.replace(path=str(parentPath), forceDirectory=True) 

405 

406 def replace(self, forceDirectory: bool = False, **kwargs: Any) -> ButlerURI: 

407 """Return new `ButlerURI` with specified components replaced. 

408 

409 Parameters 

410 ---------- 

411 forceDirectory : `bool` 

412 Parameter passed to ButlerURI constructor to force this 

413 new URI to be dir-like. 

414 **kwargs 

415 Components of a `urllib.parse.ParseResult` that should be 

416 modified for the newly-created `ButlerURI`. 

417 

418 Returns 

419 ------- 

420 new : `ButlerURI` 

421 New `ButlerURI` object with updated values. 

422 

423 Notes 

424 ----- 

425 Does not, for now, allow a change in URI scheme. 

426 """ 

427 # Disallow a change in scheme 

428 if "scheme" in kwargs: 428 ↛ 429line 428 didn't jump to line 429, because the condition on line 428 was never true

429 raise ValueError(f"Can not use replace() method to change URI scheme for {self}") 

430 return self.__class__(self._uri._replace(**kwargs), forceDirectory=forceDirectory) 

431 

432 def updatedFile(self, newfile: str) -> ButlerURI: 

433 """Return new URI with an updated final component of the path. 

434 

435 Parameters 

436 ---------- 

437 newfile : `str` 

438 File name with no path component. 

439 

440 Returns 

441 ------- 

442 updated : `ButlerURI` 

443 

444 Notes 

445 ----- 

446 Forces the ButlerURI.dirLike attribute to be false. The new file path 

447 will be quoted if necessary. 

448 """ 

449 if self.quotePaths: 

450 newfile = urllib.parse.quote(newfile) 

451 dir, _ = self._pathModule.split(self.path) 

452 newpath = self._pathModule.join(dir, newfile) 

453 

454 updated = self.replace(path=newpath) 

455 updated.dirLike = False 

456 return updated 

457 

458 def updatedExtension(self, ext: Optional[str]) -> ButlerURI: 

459 """Return a new `ButlerURI` with updated file extension. 

460 

461 All file extensions are replaced. 

462 

463 Parameters 

464 ---------- 

465 ext : `str` or `None` 

466 New extension. If an empty string is given any extension will 

467 be removed. If `None` is given there will be no change. 

468 

469 Returns 

470 ------- 

471 updated : `ButlerURI` 

472 URI with the specified extension. Can return itself if 

473 no extension was specified. 

474 """ 

475 if ext is None: 

476 return self 

477 

478 # Get the extension 

479 current = self.getExtension() 

480 

481 # Nothing to do if the extension already matches 

482 if current == ext: 

483 return self 

484 

485 # Remove the current extension from the path 

486 # .fits.gz counts as one extension do not use os.path.splitext 

487 path = self.path 

488 if current: 

489 path = path[:-len(current)] 

490 

491 # Ensure that we have a leading "." on file extension (and we do not 

492 # try to modify the empty string) 

493 if ext and not ext.startswith("."): 

494 ext = "." + ext 

495 

496 return self.replace(path=path + ext) 

497 

498 def getExtension(self) -> str: 

499 """Return the file extension(s) associated with this URI path. 

500 

501 Returns 

502 ------- 

503 ext : `str` 

504 The file extension (including the ``.``). Can be empty string 

505 if there is no file extension. Usually returns only the last 

506 file extension unless there is a special extension modifier 

507 indicating file compression, in which case the combined 

508 extension (e.g. ``.fits.gz``) will be returned. 

509 """ 

510 special = {".gz", ".bz2", ".xz", ".fz"} 

511 

512 # Get the file part of the path so as not to be confused by 

513 # "." in directory names. 

514 basename = self.basename() 

515 extensions = self._pathLib(basename).suffixes 

516 

517 if not extensions: 517 ↛ 518line 517 didn't jump to line 518, because the condition on line 517 was never true

518 return "" 

519 

520 ext = extensions.pop() 

521 

522 # Multiple extensions, decide whether to include the final two 

523 if extensions and ext in special: 523 ↛ 524line 523 didn't jump to line 524, because the condition on line 523 was never true

524 ext = f"{extensions[-1]}{ext}" 

525 

526 return ext 

527 

528 def join(self, path: Union[str, ButlerURI]) -> ButlerURI: 

529 """Return new `ButlerURI` with additional path components. 

530 

531 Parameters 

532 ---------- 

533 path : `str`, `ButlerURI` 

534 Additional file components to append to the current URI. Assumed 

535 to include a file at the end. Will be quoted depending on the 

536 associated URI scheme. If the path looks like a URI with a scheme 

537 referring to an absolute location, it will be returned 

538 directly (matching the behavior of `os.path.join()`). It can 

539 also be a `ButlerURI`. 

540 

541 Returns 

542 ------- 

543 new : `ButlerURI` 

544 New URI with any file at the end replaced with the new path 

545 components. 

546 

547 Notes 

548 ----- 

549 Schemeless URIs assume local path separator but all other URIs assume 

550 POSIX separator if the supplied path has directory structure. It 

551 may be this never becomes a problem but datastore templates assume 

552 POSIX separator is being used. 

553 

554 If an absolute `ButlerURI` is given for ``path`` is is assumed that 

555 this should be returned directly. Giving a ``path`` of an absolute 

556 scheme-less URI is not allowed for safety reasons as it may indicate 

557 a mistake in the calling code. 

558 

559 Raises 

560 ------ 

561 ValueError 

562 Raised if the ``path`` is an absolute scheme-less URI. In that 

563 situation it is unclear whether the intent is to return a 

564 ``file`` URI or it was a mistake and a relative scheme-less URI 

565 was meant. 

566 """ 

567 # If we have a full URI in path we will use it directly 

568 # but without forcing to absolute so that we can trap the 

569 # expected option of relative path. 

570 path_uri = ButlerURI(path, forceAbsolute=False) 

571 if path_uri.scheme: 571 ↛ 574line 571 didn't jump to line 574, because the condition on line 571 was never true

572 # Check for scheme so can distinguish explicit URIs from 

573 # absolute scheme-less URIs. 

574 return path_uri 

575 

576 if path_uri.isabs(): 576 ↛ 578line 576 didn't jump to line 578, because the condition on line 576 was never true

577 # Absolute scheme-less path. 

578 raise ValueError(f"Can not join absolute scheme-less {path_uri!r} to another URI.") 

579 

580 # If this was originally a ButlerURI extract the unquoted path from it. 

581 # Otherwise we use the string we were given to allow "#" to appear 

582 # in the filename if given as a plain string. 

583 if not isinstance(path, str): 583 ↛ 584line 583 didn't jump to line 584, because the condition on line 583 was never true

584 path = path_uri.unquoted_path 

585 

586 new = self.dirname() # By definition a directory URI 

587 

588 # new should be asked about quoting, not self, since dirname can 

589 # change the URI scheme for schemeless -> file 

590 if new.quotePaths: 590 ↛ 593line 590 didn't jump to line 593, because the condition on line 590 was never false

591 path = urllib.parse.quote(path) 

592 

593 newpath = self._pathModule.normpath(self._pathModule.join(new.path, path)) 

594 

595 # normpath can strip trailing / so we force directory if the supplied 

596 # path ended with a / 

597 return new.replace(path=newpath, forceDirectory=path.endswith(self._pathModule.sep)) 

598 

599 def relative_to(self, other: ButlerURI) -> Optional[str]: 

600 """Return the relative path from this URI to the other URI. 

601 

602 Parameters 

603 ---------- 

604 other : `ButlerURI` 

605 URI to use to calculate the relative path. Must be a parent 

606 of this URI. 

607 

608 Returns 

609 ------- 

610 subpath : `str` 

611 The sub path of this URI relative to the supplied other URI. 

612 Returns `None` if there is no parent child relationship. 

613 Scheme and netloc must match. 

614 """ 

615 if self.scheme != other.scheme or self.netloc != other.netloc: 

616 return None 

617 

618 enclosed_path = self._pathLib(self.relativeToPathRoot) 

619 parent_path = other.relativeToPathRoot 

620 subpath: Optional[str] 

621 try: 

622 subpath = str(enclosed_path.relative_to(parent_path)) 

623 except ValueError: 

624 subpath = None 

625 else: 

626 subpath = urllib.parse.unquote(subpath) 

627 return subpath 

628 

629 def exists(self) -> bool: 

630 """Indicate that the resource is available. 

631 

632 Returns 

633 ------- 

634 exists : `bool` 

635 `True` if the resource exists. 

636 """ 

637 raise NotImplementedError() 

638 

639 def remove(self) -> None: 

640 """Remove the resource.""" 

641 raise NotImplementedError() 

642 

643 def isabs(self) -> bool: 

644 """Indicate that the resource is fully specified. 

645 

646 For non-schemeless URIs this is always true. 

647 

648 Returns 

649 ------- 

650 isabs : `bool` 

651 `True` in all cases except schemeless URI. 

652 """ 

653 return True 

654 

655 def abspath(self) -> ButlerURI: 

656 """Return URI using an absolute path. 

657 

658 Returns 

659 ------- 

660 abs : `ButlerURI` 

661 Absolute URI. For non-schemeless URIs this always returns itself. 

662 Schemeless URIs are upgraded to file URIs. 

663 """ 

664 return self 

665 

666 def _as_local(self) -> Tuple[str, bool]: 

667 """Return the location of the (possibly remote) resource as local file. 

668 

669 This is a helper function for `as_local` context manager. 

670 

671 Returns 

672 ------- 

673 path : `str` 

674 If this is a remote resource, it will be a copy of the resource 

675 on the local file system, probably in a temporary directory. 

676 For a local resource this should be the actual path to the 

677 resource. 

678 is_temporary : `bool` 

679 Indicates if the local path is a temporary file or not. 

680 """ 

681 raise NotImplementedError() 

682 

683 @contextlib.contextmanager 

684 def as_local(self) -> Iterator[ButlerURI]: 

685 """Return the location of the (possibly remote) resource as local file. 

686 

687 Yields 

688 ------ 

689 local : `ButlerURI` 

690 If this is a remote resource, it will be a copy of the resource 

691 on the local file system, probably in a temporary directory. 

692 For a local resource this should be the actual path to the 

693 resource. 

694 

695 Notes 

696 ----- 

697 The context manager will automatically delete any local temporary 

698 file. 

699 

700 Examples 

701 -------- 

702 Should be used as a context manager: 

703 

704 .. code-block:: py 

705 

706 with uri.as_local() as local: 

707 ospath = local.ospath 

708 """ 

709 local_src, is_temporary = self._as_local() 

710 local_uri = ButlerURI(local_src, isTemporary=is_temporary) 

711 

712 try: 

713 yield local_uri 

714 finally: 

715 # The caller might have relocated the temporary file 

716 if is_temporary and local_uri.exists(): 

717 local_uri.remove() 

718 

719 def read(self, size: int = -1) -> bytes: 

720 """Open the resource and return the contents in bytes. 

721 

722 Parameters 

723 ---------- 

724 size : `int`, optional 

725 The number of bytes to read. Negative or omitted indicates 

726 that all data should be read. 

727 """ 

728 raise NotImplementedError() 

729 

730 def write(self, data: bytes, overwrite: bool = True) -> None: 

731 """Write the supplied bytes to the new resource. 

732 

733 Parameters 

734 ---------- 

735 data : `bytes` 

736 The bytes to write to the resource. The entire contents of the 

737 resource will be replaced. 

738 overwrite : `bool`, optional 

739 If `True` the resource will be overwritten if it exists. Otherwise 

740 the write will fail. 

741 """ 

742 raise NotImplementedError() 

743 

744 def mkdir(self) -> None: 

745 """For a dir-like URI, create the directory resource if needed.""" 

746 raise NotImplementedError() 

747 

748 def isdir(self) -> bool: 

749 """Return True if this URI looks like a directory, else False.""" 

750 return self.dirLike 

751 

752 def size(self) -> int: 

753 """For non-dir-like URI, return the size of the resource. 

754 

755 Returns 

756 ------- 

757 sz : `int` 

758 The size in bytes of the resource associated with this URI. 

759 Returns 0 if dir-like. 

760 """ 

761 raise NotImplementedError() 

762 

763 def __str__(self) -> str: 

764 """Convert the URI to its native string form.""" 

765 return self.geturl() 

766 

767 def __repr__(self) -> str: 

768 """Return string representation suitable for evaluation.""" 

769 return f'ButlerURI("{self.geturl()}")' 

770 

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

772 """Compare supplied object with this `ButlerURI`.""" 

773 if not isinstance(other, ButlerURI): 

774 return NotImplemented 

775 return self.geturl() == other.geturl() 

776 

777 def __hash__(self) -> int: 

778 """Return hash of this object.""" 

779 return hash(str(self)) 

780 

781 def __copy__(self) -> ButlerURI: 

782 """Copy constructor. 

783 

784 Object is immutable so copy can return itself. 

785 """ 

786 # Implement here because the __new__ method confuses things 

787 return self 

788 

789 def __deepcopy__(self, memo: Any) -> ButlerURI: 

790 """Deepcopy the object. 

791 

792 Object is immutable so copy can return itself. 

793 """ 

794 # Implement here because the __new__ method confuses things 

795 return self 

796 

797 def __getnewargs__(self) -> Tuple: 

798 """Support pickling.""" 

799 return (str(self),) 

800 

801 @classmethod 

802 def _fixDirectorySep(cls, parsed: urllib.parse.ParseResult, 

803 forceDirectory: bool = False) -> Tuple[urllib.parse.ParseResult, bool]: 

804 """Ensure that a path separator is present on directory paths. 

805 

806 Parameters 

807 ---------- 

808 parsed : `~urllib.parse.ParseResult` 

809 The result from parsing a URI using `urllib.parse`. 

810 forceDirectory : `bool`, optional 

811 If `True` forces the URI to end with a separator, otherwise given 

812 URI is interpreted as is. Specifying that the URI is conceptually 

813 equivalent to a directory can break some ambiguities when 

814 interpreting the last element of a path. 

815 

816 Returns 

817 ------- 

818 modified : `~urllib.parse.ParseResult` 

819 Update result if a URI is being handled. 

820 dirLike : `bool` 

821 `True` if given parsed URI has a trailing separator or 

822 forceDirectory is True. Otherwise `False`. 

823 """ 

824 # assume we are not dealing with a directory like URI 

825 dirLike = False 

826 

827 # Directory separator 

828 sep = cls._pathModule.sep 

829 

830 # URI is dir-like if explicitly stated or if it ends on a separator 

831 endsOnSep = parsed.path.endswith(sep) 

832 if forceDirectory or endsOnSep: 

833 dirLike = True 

834 # only add the separator if it's not already there 

835 if not endsOnSep: 835 ↛ 838line 835 didn't jump to line 838, because the condition on line 835 was never false

836 parsed = parsed._replace(path=parsed.path+sep) 

837 

838 return parsed, dirLike 

839 

840 @classmethod 

841 def _fixupPathUri(cls, parsed: urllib.parse.ParseResult, root: Optional[Union[str, ButlerURI]] = None, 

842 forceAbsolute: bool = False, 

843 forceDirectory: bool = False) -> Tuple[urllib.parse.ParseResult, bool]: 

844 """Correct any issues with the supplied URI. 

845 

846 Parameters 

847 ---------- 

848 parsed : `~urllib.parse.ParseResult` 

849 The result from parsing a URI using `urllib.parse`. 

850 root : `str` or `ButlerURI`, ignored 

851 Not used by the this implementation since all URIs are 

852 absolute except for those representing the local file system. 

853 forceAbsolute : `bool`, ignored. 

854 Not used by this implementation. URIs are generally always 

855 absolute. 

856 forceDirectory : `bool`, optional 

857 If `True` forces the URI to end with a separator, otherwise given 

858 URI is interpreted as is. Specifying that the URI is conceptually 

859 equivalent to a directory can break some ambiguities when 

860 interpreting the last element of a path. 

861 

862 Returns 

863 ------- 

864 modified : `~urllib.parse.ParseResult` 

865 Update result if a URI is being handled. 

866 dirLike : `bool` 

867 `True` if given parsed URI has a trailing separator or 

868 forceDirectory is True. Otherwise `False`. 

869 

870 Notes 

871 ----- 

872 Relative paths are explicitly not supported by RFC8089 but `urllib` 

873 does accept URIs of the form ``file:relative/path.ext``. They need 

874 to be turned into absolute paths before they can be used. This is 

875 always done regardless of the ``forceAbsolute`` parameter. 

876 

877 AWS S3 differentiates between keys with trailing POSIX separators (i.e 

878 `/dir` and `/dir/`) whereas POSIX does not neccessarily. 

879 

880 Scheme-less paths are normalized. 

881 """ 

882 return cls._fixDirectorySep(parsed, forceDirectory) 

883 

884 def transfer_from(self, src: ButlerURI, transfer: str, 

885 overwrite: bool = False, 

886 transaction: Optional[Union[DatastoreTransaction, NoTransaction]] = None) -> None: 

887 """Transfer the current resource to a new location. 

888 

889 Parameters 

890 ---------- 

891 src : `ButlerURI` 

892 Source URI. 

893 transfer : `str` 

894 Mode to use for transferring the resource. Generically there are 

895 many standard options: copy, link, symlink, hardlink, relsymlink. 

896 Not all URIs support all modes. 

897 overwrite : `bool`, optional 

898 Allow an existing file to be overwritten. Defaults to `False`. 

899 transaction : `DatastoreTransaction`, optional 

900 A transaction object that can (depending on implementation) 

901 rollback transfers on error. Not guaranteed to be implemented. 

902 

903 Notes 

904 ----- 

905 Conceptually this is hard to scale as the number of URI schemes 

906 grow. The destination URI is more important than the source URI 

907 since that is where all the transfer modes are relevant (with the 

908 complication that "move" deletes the source). 

909 

910 Local file to local file is the fundamental use case but every 

911 other scheme has to support "copy" to local file (with implicit 

912 support for "move") and copy from local file. 

913 All the "link" options tend to be specific to local file systems. 

914 

915 "move" is a "copy" where the remote resource is deleted at the end. 

916 Whether this works depends on the source URI rather than the 

917 destination URI. Reverting a move on transaction rollback is 

918 expected to be problematic if a remote resource was involved. 

919 """ 

920 raise NotImplementedError(f"No transfer modes supported by URI scheme {self.scheme}") 

921 

922 def walk(self, file_filter: Optional[Union[str, re.Pattern]] = None) -> Iterator[Union[List, 

923 Tuple[ButlerURI, 

924 List[str], 

925 List[str]]]]: 

926 """Walk the directory tree returning matching files and directories. 

927 

928 Parameters 

929 ---------- 

930 file_filter : `str` or `re.Pattern`, optional 

931 Regex to filter out files from the list before it is returned. 

932 

933 Yields 

934 ------ 

935 dirpath : `ButlerURI` 

936 Current directory being examined. 

937 dirnames : `list` of `str` 

938 Names of subdirectories within dirpath. 

939 filenames : `list` of `str` 

940 Names of all the files within dirpath. 

941 """ 

942 raise NotImplementedError() 

943 

944 @classmethod 

945 def findFileResources(cls, candidates: Iterable[Union[str, ButlerURI]], 

946 file_filter: Optional[str] = None, 

947 grouped: bool = False) -> Iterator[Union[ButlerURI, Iterator[ButlerURI]]]: 

948 """Get all the files from a list of values. 

949 

950 Parameters 

951 ---------- 

952 candidates : iterable [`str` or `ButlerURI`] 

953 The files to return and directories in which to look for files to 

954 return. 

955 file_filter : `str`, optional 

956 The regex to use when searching for files within directories. 

957 By default returns all the found files. 

958 grouped : `bool`, optional 

959 If `True` the results will be grouped by directory and each 

960 yielded value will be an iterator over URIs. If `False` each 

961 URI will be returned separately. 

962 

963 Yields 

964 ------ 

965 found_file: `ButlerURI` 

966 The passed-in URIs and URIs found in passed-in directories. 

967 If grouping is enabled, each of the yielded values will be an 

968 iterator yielding members of the group. Files given explicitly 

969 will be returned as a single group at the end. 

970 

971 Notes 

972 ----- 

973 If a value is a file it is yielded immediately. If a value is a 

974 directory, all the files in the directory (recursively) that match 

975 the regex will be yielded in turn. 

976 """ 

977 fileRegex = None if file_filter is None else re.compile(file_filter) 

978 

979 singles = [] 

980 

981 # Find all the files of interest 

982 for location in candidates: 

983 uri = ButlerURI(location) 

984 if uri.isdir(): 

985 for found in uri.walk(fileRegex): 

986 if not found: 

987 # This means the uri does not exist and by 

988 # convention we ignore it 

989 continue 

990 root, dirs, files = found 

991 if not files: 

992 continue 

993 if grouped: 

994 yield (root.join(name) for name in files) 

995 else: 

996 for name in files: 

997 yield root.join(name) 

998 else: 

999 if grouped: 

1000 singles.append(uri) 

1001 else: 

1002 yield uri 

1003 

1004 # Finally, return any explicitly given files in one group 

1005 if grouped and singles: 

1006 yield iter(singles)