yt-dlp/devscripts/make_lazy_extractors.py

#!/usr/bin/env python3

# Allow direct execution
import os
import shutil
import sys

sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))


from inspect import getsource

from devscripts.utils import get_filename_args, read_file, write_file

NO_ATTR = object()
STATIC_CLASS_PROPERTIES = [
    'IE_NAME', '_ENABLED', '_VALID_URL',  # Used for URL matching
    '_WORKING', 'IE_DESC', '_NETRC_MACHINE', 'SEARCH_KEY',  # Used for --extractor-descriptions
    'age_limit',  # Used for --age-limit (evaluated)
    '_RETURN_TYPE',  # Accessed in CLI only with instance (evaluated)
]
CLASS_METHODS = [
    'ie_key', 'suitable', '_match_valid_url',  # Used for URL matching
    'working', 'get_temp_id', '_match_id',  # Accessed just before instance creation
    'description',  # Used for --extractor-descriptions
    'is_suitable',  # Used for --age-limit
    'supports_login', 'is_single_video',  # Accessed in CLI only with instance
]
IE_TEMPLATE = '''
class {name}({bases}):
    _module = {module!r}
'''
MODULE_TEMPLATE = read_file('devscripts/lazy_load_template.py')


def main():
    lazy_extractors_filename = get_filename_args(default_outfile='yt_dlp/extractor/lazy_extractors.py')
    if os.path.exists(lazy_extractors_filename):
        os.remove(lazy_extractors_filename)

    _ALL_CLASSES = get_all_ies()  # Must be before import

    import yt_dlp.plugins
    from yt_dlp.extractor.common import InfoExtractor, SearchInfoExtractor

    # Filter out plugins
    _ALL_CLASSES = [cls for cls in _ALL_CLASSES if not cls.__module__.startswith(f'{yt_dlp.plugins.PACKAGE_NAME}.')]

    DummyInfoExtractor = type('InfoExtractor', (InfoExtractor,), {'IE_NAME': NO_ATTR})
    module_src = '\n'.join((
        MODULE_TEMPLATE,
        '    _module = None',
        *extra_ie_code(DummyInfoExtractor),
        '\nclass LazyLoadSearchExtractor(LazyLoadExtractor):\n    pass\n',
        *build_ies(_ALL_CLASSES, (InfoExtractor, SearchInfoExtractor), DummyInfoExtractor),
    ))

    write_file(lazy_extractors_filename, f'{module_src}\n')


def get_all_ies():
    PLUGINS_DIRNAME = 'ytdlp_plugins'
    BLOCKED_DIRNAME = f'{PLUGINS_DIRNAME}_blocked'
    if os.path.exists(PLUGINS_DIRNAME):
        # os.rename cannot be used, e.g. in Docker. See https://github.com/yt-dlp/yt-dlp/pull/4958
        shutil.move(PLUGINS_DIRNAME, BLOCKED_DIRNAME)
    try:
        from yt_dlp.extractor.extractors import _ALL_CLASSES
    finally:
        if os.path.exists(BLOCKED_DIRNAME):
            shutil.move(BLOCKED_DIRNAME, PLUGINS_DIRNAME)
    return _ALL_CLASSES


def extra_ie_code(ie, base=None):
    for var in STATIC_CLASS_PROPERTIES:
        val = getattr(ie, var)
        if val != (getattr(base, var) if base else NO_ATTR):
            yield f'    {var} = {val!r}'
    yield ''

    for name in CLASS_METHODS:
        f = getattr(ie, name)
        if not base or f.__func__ != getattr(base, name).__func__:
            yield getsource(f)


def build_ies(ies, bases, attr_base):
    names = []
    for ie in sort_ies(ies, bases):
        yield build_lazy_ie(ie, ie.__name__, attr_base)
        if ie in ies:
            names.append(ie.__name__)

    yield f'\n_ALL_CLASSES = [{", ".join(names)}]'


def sort_ies(ies, ignored_bases):
    """find the correct sorting and add the required base classes so that subclasses can be correctly created"""
    classes, returned_classes = ies[:-1], set()
    assert ies[-1].__name__ == 'GenericIE', 'Last IE must be GenericIE'
    while classes:
        for c in classes[:]:
            bases = set(c.__bases__) - {object, *ignored_bases}
            restart = False
            for b in sorted(bases, key=lambda x: x.__name__):
                if b not in classes and b not in returned_classes:
                    assert b.__name__ != 'GenericIE', 'Cannot inherit from GenericIE'
                    classes.insert(0, b)
                    restart = True
            if restart:
                break
            if bases <= returned_classes:
                yield c
                returned_classes.add(c)
                classes.remove(c)
                break
    yield ies[-1]


def build_lazy_ie(ie, name, attr_base):
    bases = ', '.join({
        'InfoExtractor': 'LazyLoadExtractor',
        'SearchInfoExtractor': 'LazyLoadSearchExtractor',
    }.get(base.__name__, base.__name__) for base in ie.__bases__)

    s = IE_TEMPLATE.format(name=name, module=ie.__module__, bases=bases)
    return s + '\n'.join(extra_ie_code(ie, attr_base))


if __name__ == '__main__':
    main()