Repository: yt-dlp/yt-dlp
File: yt_dlp/extractor/lastfm.py (Python)

Code before:
# coding: utf-8
from __future__ import unicode_literals

import re

from .common import InfoExtractor
from ..utils import int_or_none


class LastFMPlaylistBaseIE(InfoExtractor):
    def _extract_current_page(self, url):
        return int_or_none(self._search_regex(
            r'\bpage=(\d+)', url, 'page', default=None))

    def _extract_last_page(self, webpage):
        last_page = None
        pagination_list = self._search_regex(
            r'(?s)class="[^"]*pagination-list[^"]*"[^>]*>(.+?)</ul>', webpage, 'pagination_list', fatal=False,
            default=None)

        if pagination_list:
            last_page = max(map(int_or_none, re.findall(r'(\d+)', pagination_list)))

        return last_page

    def _extract_entries(self, webpage):
        tbody = self._search_regex(
            r'(?s)tbody\s+data-playlisting-add-entries[^>]*>(.+?)</tbody>', webpage, 'tbody')
        return [
            self.url_result(player_url, 'Youtube')
            for player_url in re.findall(r'href="([^"]+youtube.com/watch[^"]+)"', tbody)
        ]

    def _download_page(self, url, current_page_number, last_page_number, playlist_id):
        note = 'Downloading page'
        query = {}

        if last_page_number:
            note = '%s %d of %d' % (note, current_page_number, last_page_number)
            query['page'] = current_page_number

        return self._download_webpage(url, playlist_id, note, query=query)

    def _entries(self, url, playlist_id):
        webpage = self._download_webpage(url, playlist_id)
        last_page_number = self._extract_last_page(webpage)
        start_page_number = self._extract_current_page(url) or 1

        for page_number in range(start_page_number, (last_page_number or start_page_number) + 1):

Review comment (suggestion):
isn't it better to directly match
```py
r'>(\d+)</a></li><li[^>]+class="pagination-next"'
```

Code after:
# coding: utf-8
from __future__ import unicode_literals

import re

from .common import InfoExtractor
from ..utils import int_or_none, format_field


class LastFMPlaylistBaseIE(InfoExtractor):
    def _entries(self, url, playlist_id):
        webpage = self._download_webpage(url, playlist_id)
        start_page_number = int_or_none(self._search_regex(
            r'\bpage=(\d+)', url, 'page', default=None)) or 1
        last_page_number = int_or_none(self._search_regex(
            r'>(\d+)</a>[^<]*</li>[^<]*<li[^>]+class="pagination-next', webpage, 'last_page', default=None))

        for page_number in range(start_page_number, (last_page_number or start_page_number) + 1):
            webpage = self._download_webpage(
                url, playlist_id,
                note='Downloading page %d%s' % (page_number, format_field(last_page_number, template=' of %d')),
                query={'page': page_number})
            page_entries = [
                self.url_result(player_url, 'Youtube')
                for player_url in set(re.findall(r'data-youtube-url="([^"]+)"', webpage))
            ]

            for e in page_entries:
                yield e

    def _real_extract(self, url):
        playlist_id = self._match_id(url)
        return self.playlist_result(self._entries(url, playlist_id), playlist_id)


class LastFMPlaylistIE(LastFMPlaylistBaseIE):
    _VALID_URL = r'https?://(?:www\.)?last\.fm/(music|tag)/(?P<id>[^/]+)(?:/[^/]+)?/?(?:[?#]|$)'
    _TESTS = [{
        'url': 'https://www.last.fm/music/Oasis/(What%27s+the+Story)+Morning+Glory%3F',
        'info_dict': {
            'id': 'Oasis',
        },
        'playlist_count': 11,
    }, {
        'url': 'https://www.last.fm/music/Oasis',
        'only_matching': True,
    }, {
        'url': 'https://www.last.fm/music/Oasis/',
        'only_matching': True,