-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathcsx.py
More file actions
executable file
·1189 lines (931 loc) · 36.4 KB
/
csx.py
File metadata and controls
executable file
·1189 lines (931 loc) · 36.4 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
#!/usr/bin/env python3
# csx.py - Extended Cascading Stylesheets.
# Copyright (C) 2009 Zero Piraeus
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""csx - Create, manipulate and convert CSX stylesheets.
CSX is a style language based on `CSS 2.1`_, with two improvements:
1. Rules may be nested inside other rules.
2. There are no at-rules (like @media or @import).
CSX is also somewhat stricter than CSS (for example, you can't split a
quoted string over more than one line, and comments must be terminated).
See the file `README.txt` provided with this module for a complete description
of the differences between CSS and CSX.
.. _CSS 2.1: http://www.w3.org/TR/CSS21
"""
import collections
import copy
import re
__author__ = "Zero Piraeus <z@etiol.net>"
__version__ = "1.0.0"
DEFAULT_STYLE = "pretty"
STYLES = ("bare", "compact", "pretty")
TAB = " "
WIDTH = 80
class Error(Exception):
"""An error which may usefully be displayed by the csx utility."""
# Allows incorporation of filename and line no. for output to end-users
# by the csx utility - see doc/lib/error.txt for details.
def __init__(self, msg:str="", line:int=0, source:str=""):
self.msg = msg
self.line = line
self.source = source
def __str__(self):
if self.source == "-":
source = "<stdin>"
elif self.source:
source = repr(self.source)
else:
source = ""
if self.line:
line = "line {0}".format(self.line)
else:
line = ""
location = ", ".join(x for x in (source, line) if x)
return ": ".join(x for x in (location, self.msg) if x)
class _Comparable(object):
"""Base class for objects with sane comparison behaviour."""
# The following methods define comparisons other than `__lt__` in terms of
# `__lt__`, which is not otherwise the case for subclasses of e.g. `set`.
def __ge__(self, other):
less_than = (self < other)
return NotImplemented if less_than is NotImplemented else not less_than
def __gt__(self, other):
return other < self
def __le__(self, other):
more_than = (other < self)
return NotImplemented if more_than is NotImplemented else not more_than
class _Renderable(object):
"""Base class for renderable objects.
Example::
>>> class Chars(_Renderable, list): pass
>>> Chars("squee")
Chars('s,q,u,e,e')
"""
SEP = {s: "," for s in STYLES}
def __repr__(self):
return "{0}({1!r})".format(self.__class__.__name__, str(self))
def __str__(self):
return self.render("compact", level=1) # `level=1` to prevent newlines.
def render(self, style:str=DEFAULT_STYLE, level:int=0) -> str:
"""Return a textual representation of `self`.
Arguments:
:`style`: One of `STYLES`.
:`level`: Indentation level of "pretty" output.
Example::
>>> selector = Selector("ol li a")
>>> print(selector.render())
ol li a
"""
return self.SEP[style].join(self)
class _Renderable_Recursive(_Renderable):
"""Base class for recursively renderable objects."""
def render(self, style:str=DEFAULT_STYLE, level:int=0) -> str:
"""Return a textual representation of `self`.
Arguments:
:`style`: One of `STYLES`.
:`level`: Indentation level of "pretty" output.
Example::
>>> ds = Declarations("color: red; font-family: serif")
>>> print(ds.render())
color: red;
font-family: serif;
"""
# `SEP` is defined by the subclass.
return self.SEP[style].join(x.render(style, level) for x in self)
class Declaration(_Renderable, tuple):
"""A CSX declaration; e.g. "color: red".
Examples::
>>> d1 = Declaration("color: red")
>>> d2 = Declaration(["color", "red"])
>>> assert d1 == d2
"""
SEP = {
"bare": ":",
"compact": ": ",
"pretty": ": ",
}
def __new__(cls, arg:collections.Sequence):
if isinstance(arg, str):
try:
key, value = Text(arg).iterate_as(cls)
except ValueError as cause:
raise Error("invalid declaration {0!r}".format(arg)) from cause
else:
return tuple.__new__(cls, (key.lower(), value))
else:
return tuple.__new__(cls, arg)
def render(self, style:str=DEFAULT_STYLE, level:int=0) -> str:
"""Return a textual representation of `self`.
Arguments:
:`style`: One of `STYLES`.
:`level`: Indentation level of "pretty" output.
Example::
>>> declaration = Declaration("color: red")
>>> print(declaration.render())
color: red;
"""
if style == "pretty":
return (TAB * level) + super().render(style, level) + ";"
else:
return super().render(style, level)
class Declarations(_Renderable_Recursive, _Comparable, dict):
"""A CSX declaration block; e.g. "color: red; font-family: serif".
Examples::
>>> ds1 = Declarations("color: red; font-family: serif")
>>> ds2 = Declarations({
... "color": "red",
... "font-family": "serif",
... })
>>> ds3 = Declarations([
... Declaration("color: red"),
... Declaration("font-family: serif"),
... ])
Underscores are replaced by hyphens in keyword arguments::
>>> ds4 = Declarations(color="red", font_family="serif")
>>> assert ds1 == ds2 == ds3 == ds4
Iterating over a `Declarations` instance returns `Declaration`
instances, in order::
>>> [d for d in ds1]
[Declaration('color: red'), Declaration('font-family: serif')]
Unlike `dict`, `Declarations` is orderable::
>>> ds5 = Declarations("color: blue; font-family: serif")
>>> assert ds1 > ds5
"""
SEP = {
"bare": ";",
"compact": "; ",
"pretty": "\n",
}
def __init__(self, arg:collections.Iterable=(), **kwargs):
if isinstance(arg, str):
arg = (Declaration(s) for s in Text(arg).iterate_as(Declarations))
elif isinstance(arg, collections.Mapping):
arg = arg.items()
kwargs = {k.replace("_", "-"): v for k, v in kwargs.items()}
self.update(dict(arg, **kwargs))
def __iter__(self):
return iter(sorted(self.items()))
def __lt__(self, other):
return sorted(self.items()) < sorted(other.items())
def items(self) -> set:
"""Extend `dict.items` to return a set of `Declaration` instances.
Example::
>>> ds = Declarations("color: red; font-family: serif")
>>> d1 = Declaration("color: red")
>>> d2 = Declaration("font-family: serif")
>>> assert ds.items() == {d1, d2}
"""
return {Declaration(x) for x in super().items()}
class Rule(_Renderable, _Comparable):
"""A CSX rule; e.g. "dt, dd { color: red; a { color: blue } }".
Attributes:
:`selectors`: A `Selectors` instance.
:`declarations`: A `Declarations` instance.
:`rules`: A `Rules` instance.
Examples::
>>> r1 = Rule("dt, dd { color: red; a { color: blue } }")
>>> ss = Selectors("dt, dd")
>>> ds = Declarations("color: red")
>>> rs = Rules("a { color: blue }")
>>> r2 = Rule(selectors=ss, declarations=ds, rules=rs)
>>> assert r1 == r2
If declarations specified in string and keyword arguments conflict,
the string argument takes precedence::
>>> ds = Declarations("background: yellow; color: red")
>>> Rule("dl { background: aqua }", declarations=ds)
Rule('dl { background: aqua; color: red }')
"""
SEP = {
"bare": ";",
"compact": "; ",
"pretty": "\n",
}
FORMAT = {
"bare": "{selectors}{{{block}}}",
"compact": "{selectors} {{ {block} }}",
"pretty": "{selectors} {{\n{block}\n{indent}}}",
}
def __init__(self, text:str="", **kwargs):
self.selectors = kwargs.pop("selectors", Selectors())
self.declarations = kwargs.pop("declarations", Declarations())
self.rules = kwargs.pop("rules", Rules())
if kwargs:
invalid = kwargs.keys().pop()
raise TypeError("invalid keyword argument {0!r}".format(invalid))
text_rules = Text(text).extract()
if len(text_rules) > 1:
raise ValueError("string argument describes multiple rules")
elif text_rules:
rule = text_rules.pop()
self.selectors.update(rule.selectors)
self.declarations.update(rule.declarations)
self.rules.extend(rule.rules)
def __eq__(self, other):
return (
(self.selectors == other.selectors)
and (self.declarations == other.declarations)
and (self.rules == other.rules)
)
def __lt__(self, other):
if self.selectors != other.selectors:
return self.selectors < other.selectors
elif self.declarations != other.declarations:
return self.declarations < other.declarations
elif self.rules != other.rules:
return self.rules < other.rules
else:
return False
def collapse(self):
"""Remove redundant nesting from `self`.
Example::
>>> rule = Rule("ol { li { a { color: blue } } }")
>>> rule.collapse()
>>> print(rule.render())
ol li a {
color: blue;
}
"""
while (
(not self.declarations)
and (len(self.selectors) == 1)
and (len(self.rules) == 1)
and (len(self.rules[0].selectors) == 1)
):
child = self.rules.pop()
self.selectors = child.selectors.prefix(self.selectors)
self.declarations = child.declarations
self.rules = child.rules
for rule in self.rules:
rule.collapse()
def render(self, style:str=DEFAULT_STYLE, level:int=0) -> str:
"""Return a textual representation of `self`.
Arguments:
:`style`: One of `STYLES`.
:`level`: Indentation level of "pretty" output.
Example::
>>> rule = Rule("dt, dd { color: red; a { color: blue } }")
>>> print(rule.render())
dt, dd {
color: red;
a {
color: blue;
}
}
"""
selectors = self.selectors.render(style, level)
if self.declarations and self.rules:
block = self.SEP[style].join((
self.declarations.render(style, level + 1),
self.rules.render(style, level + 1),
))
elif self.declarations:
block = self.declarations.render(style, level + 1)
elif self.rules:
block = self.rules.render(style, level + 1)
else:
block = ""
indent = TAB * level
return self.FORMAT[style].format(**locals())
class Rules(_Renderable_Recursive, list):
"""A CSX rule block; e.g. "ol { background: aqua }; li { color: red }".
Examples::
>>> rs1 = Rules('''
... ol { background: aqua }
... li { color: red }
... ''')
>>> rs2 = Rules([
... Rule("ol { background: aqua }"),
... Rule("li { color: red }"),
... ])
>>> assert rs1 == rs2
"""
SEP = {
"bare": "",
"compact": "\n",
"pretty": "\n\n",
}
# Nested rules are delimited differently to top-level rules - see
# `Rules.render`.
ALT_SEP = {
"bare": ";",
"compact": "; ",
"pretty": "\n",
}
def __init__(self, arg:collections.Iterable=()):
if isinstance(arg, str):
self[:] = Text(arg).extract()
else:
self[:] = arg
def _graft(self, tree:"Rules") -> list:
"""Merge `tree` into `self` and return a list of leaf rules.
Arguments:
:`tree`: As returned by `Selectors._sprout`.
Example::
>>> rules = Rules('''
... dl, ol, ul { margin: 1em; padding: 1em }
... dl { background: yellow }
... ol, ul { background: aqua }
... ''')
>>> tree = Selectors("dl dt, dl dd, ol li, ul li")._sprout()
>>> leaves = rules._graft(tree)
>>> sorted(leaves)
[Rule('dt, dd { }'), Rule('li { }')]
>>> print(rules.render("compact"))
dl, ol, ul { margin: 1em; padding: 1em }
dl { background: yellow; dt, dd { } }
ol, ul { background: aqua; li { } }
"""
# Used by `_merge_optimized` - somewhat voodoo, but the examples above
# should make it clear *what* is happening, if not *how*. Essentially
# we search for nodes in `self` that, in traditional CSS, would
# have the same selectors as those in `tree`, so we can insert
# declarations from `tree` at those nodes as appropriate. This is
# tricky stuff, though, and can only really be properly understood by
# reading `_merge_optimized` as well. Action by side-effect is not
# ideal, admittedly, but I can't see an easier way to do it.
leaves = []
target_selectors = [r.selectors for r in self]
for rule in tree:
if rule.selectors in target_selectors:
target = self[target_selectors.index(rule.selectors)]
else:
self.append(rule)
target = rule
if ("$", "leaf") in rule.declarations.items():
leaves.append(target)
del rule.declarations["$"]
if rule.rules:
leaves += target.rules._graft(rule.rules)
return leaves
def _merge_normalized(self, rule:Rule, _prefixes:set=set()):
"""Merge a rule into `self` for each declaration in `rule`.
Arguments:
:`rule`: Rule to be merged into `self`.
:`_prefixes`: Used internally - ***DO NOT SET***.
Example::
>>> normalized = Rules('''
... dl { background: yellow }
... dl { margin: 1em }
... dl { padding: 1em }
... dl dt, dl dd { color: red }
... ''')
>>> rule = Rule('''
... ol, ul {
... background: aqua;
... margin: 1em;
... padding: 1em;
... li { color: red }
... }
... ''')
>>> normalized._merge_normalized(rule)
>>> print(normalized.render("compact"))
dl { background: yellow }
dl, ol, ul { margin: 1em }
dl, ol, ul { padding: 1em }
dl dt, dl dd, ol li, ul li { color: red }
ol, ul { background: aqua }
"""
# Used by `Rules.optimize`.
selectors = rule.selectors.prefix(_prefixes)
for dec in (Declarations({d}) for d in rule.declarations):
for candidate in self:
if dec == candidate.declarations:
candidate.selectors.update(selectors)
break
else:
self.append(Rule(selectors=selectors.copy(), declarations=dec))
for subrule in rule.rules:
self._merge_normalized(subrule, selectors)
def _merge_optimized(self, rule:Rule):
"""Merge an optimized rule tree based on `rule` into `self`.
Arguments:
:`rule`: Rule to be merged into `self`.
Example::
>>> optimized = Rules('''
... dl { background: yellow }
... ol, ul { background: aqua }
... ''')
>>> rule = Rule("dl dt, dl dd, ol li, ul li { color: red }")
>>> optimized._merge_optimized(rule)
>>> print(optimized.render("compact"))
dl { background: yellow; dt, dd { color: red } }
ol, ul { background: aqua; li { color: red } }
"""
# Used by `Rules.optimize`.
for leaf in self._graft(rule.selectors._sprout()):
leaf.declarations.update(rule.declarations)
for subrule in rule.rules:
leaf.rules._merge_optimized(subrule)
def flatten(self, _prefixes:set=set()):
"""Convert `self` to un-nested rules.
Arguments:
:`_prefixes`: Used internally - ***DO NOT SET***.
Example::
>>> rules = Rules('''
...
... dl, ol, ul {
... margin: 1em;
... padding: 1em;
... }
...
... ol, ul {
... background: aqua;
... li { color: red }
... }
...
... dl {
... background: yellow;
... dt, dd { color: red }
... }
...
... ''')
>>> rules.flatten()
>>> print(rules.render("compact"))
dl, ol, ul { margin: 1em; padding: 1em }
ol, ul { background: aqua }
ol li, ul li { color: red }
dl { background: yellow }
dl dt, dl dd { color: red }
"""
flattened = []
for rule in self:
selectors = rule.selectors.prefix(_prefixes)
if rule.declarations:
new = Rule(selectors=selectors, declarations=rule.declarations)
flattened.append(new)
rule.rules.flatten(selectors)
flattened += rule.rules
self[:] = flattened
def optimize(self, collapse:bool=True, normalize:bool=False):
"""Optimize `self`.
Arguments:
:`collapse`: If True, collapse redundant nesting.
:`normalize`: If True, normalize `self` before optimizing
(dramatically alters rule order).
Example::
>>> rules = Rules('''
... dl { background: yellow }
... dl, ol, ul { margin: 1em }
... dl, ol, ul { padding: 1em }
... dl dt, dl dd, ol li, ul li { color: red }
... ol, ul { background: aqua }
... ''')
>>> rules.optimize()
>>> print(rules.render("compact"))
dl, ol, ul { margin: 1em; padding: 1em }
dl { background: yellow; dt, dd { color: red } }
ol, ul { background: aqua; li { color: red } }
"""
if normalize:
normalized = Rules()
for rule in self:
normalized._merge_normalized(rule)
rules = normalized
else:
rules = self
optimized = Rules()
for rule in rules:
optimized._merge_optimized(rule)
if collapse:
for rule in optimized:
rule.collapse()
optimized.sort()
self[:] = optimized
def render(self, style:str=DEFAULT_STYLE, level:int=0) -> str:
"""Return a textual representation of `self`.
Arguments:
:`style`: One of `STYLES`.
:`level`: Indentation level of "pretty" output.
Example::
>>> rules = Rules('''
...
... dl, ol, ul {
... margin: 1em;
... padding: 1em;
... }
...
... ol, ul {
... background: aqua;
... li { color: red }
... }
...
... dl {
... background: yellow;
... dt, dd { color: red }
... }
...
... ''')
>>> print(rules.render("compact"))
dl, ol, ul { margin: 1em; padding: 1em }
ol, ul { background: aqua; li { color: red } }
dl { background: yellow; dt, dd { color: red } }
"""
if (level == 0) or (self.SEP is self.ALT_SEP):
return super().render(style, level)
else:
self.SEP, cache = self.ALT_SEP, self.SEP
try:
return super().render(style, level)
finally:
self.SEP = cache
def sort(self, key=None, reverse=False):
"""Extend `list.sort` to recursively sort `self`.
Example::
>>> rules = Rules('''
... ol li, ul li { a { color: blue }; b { color: black } }
... dl dt, dl dd { b { color: black }; a { color: blue } }
... ''')
>>> rules.sort()
>>> print(rules.render("compact"))
dl dt, dl dd { a { color: blue }; b { color: black } }
ol li, ul li { a { color: blue }; b { color: black } }
"""
for rule in self:
rule.rules.sort(key, reverse)
super().sort(key=key, reverse=reverse)
class Selector(_Renderable, _Comparable, tuple):
"""A CSX selector; e.g. "ol > li a[lang|='en']".
Example::
>>> Selector("ol > li a[lang|='en']")
Selector("ol > li a[lang|='en']")
"""
# Match and retain:
# > or + (possibly followed by whitespace), followed by any sequence
# of characters except whitespace, > or +
# Match and discard:
# whitespace (where not part of a match as detailed above)
ITER = re.compile("([>+]\s*[^\s>+]+)|\s+")
SEP = {s: " " for s in STYLES}
# Both `SORT_ATTRIBUTES` and `SORT_ELEMENTS` are used to create
# substitutions so that lexicographical sorting produces output in a more
# useful order; i.e `:link` before `:visited`, `dt` before `dd` etc.
SORT_ATTRIBUTES = tuple((x, "~{0:02d} ".format(n)) for n, x in enumerate((
":link",
":visited",
":focus",
":hover",
":active",
":", "[", ".", "#",
)))
# Not a dict, because order is important.
SORT_ELEMENTS = (
("*", " *"),
("html", " * ~"),
("body", " * ~~"),
("dd", "dt ~"),
("input", "label ~"),
("td", "th ~"),
("tfoot", "thead ~"),
("tbody", "thead ~~"),
)
__SORT_ELEMENT_KEYS = tuple(e[0] for e in SORT_ELEMENTS) # for speed
__lt_cache = {}
def __new__(cls, arg:collections.Iterable):
if isinstance(arg, str):
self = tuple.__new__(cls, Text(arg).iterate_as(Selector))
else:
self = tuple.__new__(cls, arg)
return self
def __lt__(self, other):
# This comparison is expensive and frequently performed, so we
# optimize it by caching the result.
try:
return self.__lt_cache[(self, other)]
except KeyError:
for self_item, other_item in zip(self._sort_key, other._sort_key):
if self_item != other_item:
result = self_item < other_item
break
else:
result = len(self) < len(other)
self.__lt_cache[(self, other)] = result
return result
@property
def _sort_key(self) -> collections.Iterator:
"""An ordering key for `self`.
Example::
>>> selector = Selector("body dl[lang='en'] dt + dd a:link")
>>> list(selector._sort_key)
[' * ~~', "dl~06 lang='en']", 'dt', ' dt ~', 'a~00 ']
"""
# See `SORT_ATTRIBUTES`, `SORT_ELEMENTS` to better understand what's
# going on above.
for item in self:
# Sibling and child combinators sort before type selectors.
if item[0] == "+":
item = " " + item[1:].lstrip()
if item[0] == ">":
item = " " + item[1:].lstrip()
# Bare class, id etc. selectors sort after type selectors.
for target, replacement in self.SORT_ATTRIBUTES:
item = item.replace(target, replacement)
# Conceptually related type selectors sort in the "right" order.
if item.lstrip().startswith(self.__SORT_ELEMENT_KEYS):
for target, replacement in self.SORT_ELEMENTS:
if item.lstrip().startswith(target):
item = item.replace(target, replacement, 1)
break
yield item
class Selectors(_Renderable_Recursive, _Comparable, set):
"""A CSX selector block; e.g. "dl dd, dl dt, ol li, ul li".
Example::
>>> Selectors("dl dd, dl dt, ol li, ul li")
Selectors('dl dt, dl dd, ol li, ul li')
"""
SEP = {
"bare": ",",
"compact": ", ",
"pretty": ", ",
}
def __init__(self, arg:collections.Iterable=()):
if isinstance(arg, str):
arg = Text(arg).iterate_as(Selectors)
set.__init__(self, (Selector(x) for x in arg))
def __iter__(self):
return iter(sorted(set(self)))
def __lt__(self, other):
# This comparison is expensive and frequently performed, so we
# optimize it by caching the result.
for self_item, other_item in zip(self, other):
if self_item != other_item:
return self_item < other_item
else: # indentation is correct! This is the else of the for loop.
return len(self) > len(other)
def _sprout(self, _prefix:collections.Iterable=()) -> {Rule, Rules}:
"""Return a graftable tree of optimized rules for `self`.
Arguments:
:`_prefix`: Used internally - ***DO NOT SET***.
Example::
>>> example = Selectors("ul, ol, ul ul, ol ol, ol ul, ul ol")
>>> print(example._sprout().render())
ol, ul {
$: leaf;
ol, ul {
$: leaf;
}
}
"""
# Used by `Rules._graft` - turns a selector block into an
# optimally-nested `Rules` object with place-markers for where any
# declarations for those selectors should go. This was murder to write,
# but I *think* it now works in all cases. No line-by-line comments
# because they just padded out the code and made it even harder to
# understand - you just have to read it very very carefully.
tree = Rule(selectors=Selectors({_prefix}))
for node in {s[:1] for s in self}:
if node:
branches = {s[1:] for s in self if s[:1] == node}
rule = Selectors(branches)._sprout(node)
rule_spec = (rule.rules, rule.declarations)
tree_specs = [(r.rules, r.declarations) for r in tree.rules]
if rule_spec in tree_specs:
target = tree.rules[tree_specs.index(rule_spec)]
target.selectors.add(Selector(node))
else:
tree.rules.append(rule)
else:
tree.declarations["$"] = "leaf"
if _prefix:
return tree
else:
tree.rules.sort()
return tree.rules
def copy(self) -> "Selectors":
"""Extend `set.copy` to return a `Selectors` instance."""
# set.copy() returns a set, which isn't what we want.
return copy.copy(self)
def prefix(self, prefixes:set) -> "Selectors":
"""Prefix `self` with `prefixes`.
Arguments:
:`prefixes`: Selectors with which to prefix `self`.
Example::
>>> prefixed = Selectors("b, i").prefix(Selectors("p, a"))
>>> Selectors(prefixed)
Selectors('a b, a i, p b, p i')
"""
if prefixes:
return Selectors({Selector(p + s) for p in prefixes for s in self})
else:
return self.copy()
def render(self, style:str=DEFAULT_STYLE, level:int=0) -> str:
"""Return a textual representation of `self`.
Arguments:
:`style`: One of `STYLES`.
:`level`: Indentation level of "pretty" output.
Example::
>>> selectors = Selectors("ol li, ul li, dl dd, dl dt")
>>> print(selectors.render("compact"))
dl dt, dl dd, ol li, ul li
>>> table = Selectors('''
...
... table tbody tr td, table tbody tr th,
... table tfoot tr td, table tfoot tr th,
... table thead tr td, table thead tr th,
...
... ''')
>>> print(table.render(level=1))
table thead tr th,
table thead tr td,
table tfoot tr th,
table tfoot tr td,
table tbody tr th,
table tbody tr td
"""
if style == "pretty":
indent = TAB * level
result = indent + super().render(style, level)
if len(result) <= WIDTH:
return result
else:
cache = self.SEP["pretty"]
try:
self.SEP["pretty"] = ",\n" + indent
return indent + super().render(style, level)
finally:
self.SEP["pretty"] = cache
else:
return super().render(style, level)
class Text(str):
r"""An escaped string.
Attributes:
:`subs`: A list of quoted substrings extracted from input.
Instantiated by passing a string to the constructor.