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Credit @johnhawkinson for nytimes podcasts (#10926)
[youtube-dl] / devscripts / make_lazy_extractors.py
1 from __future__ import unicode_literals, print_function
2
3 from inspect import getsource
4 import os
5 from os.path import dirname as dirn
6 import sys
7
8 print('WARNING: Lazy loading extractors is an experimental feature that may not always work', file=sys.stderr)
9
10 sys.path.insert(0, dirn(dirn((os.path.abspath(__file__)))))
11
12 lazy_extractors_filename = sys.argv[1]
13 if os.path.exists(lazy_extractors_filename):
14     os.remove(lazy_extractors_filename)
15
16 from youtube_dl.extractor import _ALL_CLASSES
17 from youtube_dl.extractor.common import InfoExtractor, SearchInfoExtractor
18
19 with open('devscripts/lazy_load_template.py', 'rt') as f:
20     module_template = f.read()
21
22 module_contents = [
23     module_template + '\n' + getsource(InfoExtractor.suitable) + '\n',
24     'class LazyLoadSearchExtractor(LazyLoadExtractor):\n    pass\n']
25
26 ie_template = '''
27 class {name}({bases}):
28     _VALID_URL = {valid_url!r}
29     _module = '{module}'
30 '''
31
32 make_valid_template = '''
33     @classmethod
34     def _make_valid_url(cls):
35         return {valid_url!r}
36 '''
37
38
39 def get_base_name(base):
40     if base is InfoExtractor:
41         return 'LazyLoadExtractor'
42     elif base is SearchInfoExtractor:
43         return 'LazyLoadSearchExtractor'
44     else:
45         return base.__name__
46
47
48 def build_lazy_ie(ie, name):
49     valid_url = getattr(ie, '_VALID_URL', None)
50     s = ie_template.format(
51         name=name,
52         bases=', '.join(map(get_base_name, ie.__bases__)),
53         valid_url=valid_url,
54         module=ie.__module__)
55     if ie.suitable.__func__ is not InfoExtractor.suitable.__func__:
56         s += '\n' + getsource(ie.suitable)
57     if hasattr(ie, '_make_valid_url'):
58         # search extractors
59         s += make_valid_template.format(valid_url=ie._make_valid_url())
60     return s
61
62 # find the correct sorting and add the required base classes so that sublcasses
63 # can be correctly created
64 classes = _ALL_CLASSES[:-1]
65 ordered_cls = []
66 while classes:
67     for c in classes[:]:
68         bases = set(c.__bases__) - set((object, InfoExtractor, SearchInfoExtractor))
69         stop = False
70         for b in bases:
71             if b not in classes and b not in ordered_cls:
72                 if b.__name__ == 'GenericIE':
73                     exit()
74                 classes.insert(0, b)
75                 stop = True
76         if stop:
77             break
78         if all(b in ordered_cls for b in bases):
79             ordered_cls.append(c)
80             classes.remove(c)
81             break
82 ordered_cls.append(_ALL_CLASSES[-1])
83
84 names = []
85 for ie in ordered_cls:
86     name = ie.__name__
87     src = build_lazy_ie(ie, name)
88     module_contents.append(src)
89     if ie in _ALL_CLASSES:
90         names.append(name)
91
92 module_contents.append(
93     '_ALL_CLASSES = [{0}]'.format(', '.join(names)))
94
95 module_src = '\n'.join(module_contents) + '\n'
96
97 with open(lazy_extractors_filename, 'wt') as f:
98     f.write(module_src)