[extractor] Add `_search_json`

All fetching of JSON objects should eventually be done with this function
but only `youtube` is being refactored for now

yt_dlp/extractor/archiveorg.py

@@ -442,9 +442,10 @@ class YoutubeWebArchiveIE(InfoExtractor):
             'only_matching': True
         },
     ]
-    _YT_INITIAL_DATA_RE = r'(?:(?:(?:window\s*\[\s*["\']ytInitialData["\']\s*\]|ytInitialData)\s*=\s*({.+?})\s*;)|%s)' % YoutubeBaseInfoExtractor._YT_INITIAL_DATA_RE
-    _YT_INITIAL_PLAYER_RESPONSE_RE = r'(?:(?:(?:window\s*\[\s*["\']ytInitialPlayerResponse["\']\s*\]|ytInitialPlayerResponse)\s*=[(\s]*({.+?})[)\s]*;)|%s)' % YoutubeBaseInfoExtractor._YT_INITIAL_PLAYER_RESPONSE_RE
-    _YT_INITIAL_BOUNDARY_RE = r'(?:(?:var\s+meta|</script|\n)|%s)' % YoutubeBaseInfoExtractor._YT_INITIAL_BOUNDARY_RE
+    _YT_INITIAL_DATA_RE = YoutubeBaseInfoExtractor._YT_INITIAL_DATA_RE
+    _YT_INITIAL_PLAYER_RESPONSE_RE = fr'''(?x)
+        (?:window\s*\[\s*["\']ytInitialPlayerResponse["\']\s*\]|ytInitialPlayerResponse)\s*=[(\s]*|
+        {YoutubeBaseInfoExtractor._YT_INITIAL_PLAYER_RESPONSE_RE}'''
 
     _YT_DEFAULT_THUMB_SERVERS = ['i.ytimg.com']  # thumbnails most likely archived on these servers
     _YT_ALL_THUMB_SERVERS = orderedSet(
@@ -474,11 +475,6 @@ class YoutubeWebArchiveIE(InfoExtractor):
         elif not isinstance(res, list) or len(res) != 0:
             self.report_warning('Error while parsing CDX API response' + bug_reports_message())
 
-    def _extract_yt_initial_variable(self, webpage, regex, video_id, name):
-        return self._parse_json(self._search_regex(
-            (fr'{regex}\s*{self._YT_INITIAL_BOUNDARY_RE}',
-             regex), webpage, name, default='{}'), video_id, fatal=False)
-
     def _extract_webpage_title(self, webpage):
         page_title = self._html_extract_title(webpage, default='')
         # YouTube video pages appear to always have either 'YouTube -' as prefix or '- YouTube' as suffix.
@@ -488,10 +484,11 @@ class YoutubeWebArchiveIE(InfoExtractor):
 
     def _extract_metadata(self, video_id, webpage):
         search_meta = ((lambda x: self._html_search_meta(x, webpage, default=None)) if webpage else (lambda x: None))
-        player_response = self._extract_yt_initial_variable(
-            webpage, self._YT_INITIAL_PLAYER_RESPONSE_RE, video_id, 'initial player response') or {}
-        initial_data = self._extract_yt_initial_variable(
-            webpage, self._YT_INITIAL_DATA_RE, video_id, 'initial player response') or {}
+        player_response = self._search_json(
+            self._YT_INITIAL_PLAYER_RESPONSE_RE, webpage, 'initial player response',
+            video_id, fatal=False)
+        initial_data = self._search_json(
+            self._YT_INITIAL_DATA_RE, webpage, 'initial data', video_id, fatal=False)
 
         initial_data_video = traverse_obj(
             initial_data, ('contents', 'twoColumnWatchNextResults', 'results', 'results', 'contents', ..., 'videoPrimaryInfoRenderer'),

yt_dlp/extractor/common.py

@@ -35,6 +35,7 @@ from ..utils import (
     ExtractorError,
     GeoRestrictedError,
     GeoUtils,
+    LenientJSONDecoder,
     RegexNotFoundError,
     UnsupportedError,
     age_restricted,
@@ -930,19 +931,10 @@ class InfoExtractor:
             else:
                 self.report_warning(errmsg + str(ve))
 
-    def _parse_json(self, json_string, video_id, transform_source=None, fatal=True, lenient=False):
-        if transform_source:
-            json_string = transform_source(json_string)
+    def _parse_json(self, json_string, video_id, transform_source=None, fatal=True, **parser_kwargs):
         try:
-            try:
-                return json.loads(json_string, strict=False)
-            except json.JSONDecodeError as e:
-                if not lenient:
-                    raise
-                try:
-                    return json.loads(json_string[:e.pos], strict=False)
-                except ValueError:
-                    raise e
+            return json.loads(
+                json_string, cls=LenientJSONDecoder, strict=False, transform_source=transform_source, **parser_kwargs)
         except ValueError as ve:
             errmsg = f'{video_id}: Failed to parse JSON'
             if fatal:
@@ -1196,6 +1188,14 @@ class InfoExtractor:
             self.report_warning('unable to extract %s' % _name + bug_reports_message())
             return None
 
+    def _search_json(self, start_pattern, string, name, video_id, *, end_pattern='', fatal=True, **kwargs):
+        """Searches string for the JSON object specified by start_pattern"""
+        # NB: end_pattern is only used to reduce the size of the initial match
+        return self._parse_json(
+            self._search_regex(rf'{start_pattern}\s*(?P<json>{{.+}})\s*{end_pattern}',
+                               string, name, group='json', fatal=fatal) or '{}',
+            video_id, fatal=fatal, ignore_extra=True, **kwargs) or {}
+
     def _html_search_regex(self, pattern, string, name, default=NO_DEFAULT, fatal=True, flags=0, group=None):
         """
         Like _search_regex, but strips HTML tags and unescapes entities.

yt_dlp/extractor/youtube.py

@@ -397,9 +397,8 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
         if self._LOGIN_REQUIRED and not self._cookies_passed:
             self.raise_login_required('Login details are needed to download this content', method='cookies')
 
-    _YT_INITIAL_DATA_RE = r'(?:window\s*\[\s*["\']ytInitialData["\']\s*\]|ytInitialData)\s*=\s*({.+})\s*;'
-    _YT_INITIAL_PLAYER_RESPONSE_RE = r'ytInitialPlayerResponse\s*=\s*({.+})\s*;'
-    _YT_INITIAL_BOUNDARY_RE = r'(?:var\s+meta|</script|\n)'
+    _YT_INITIAL_DATA_RE = r'(?:window\s*\[\s*["\']ytInitialData["\']\s*\]|ytInitialData)\s*='
+    _YT_INITIAL_PLAYER_RESPONSE_RE = r'ytInitialPlayerResponse\s*='
 
     def _get_default_ytcfg(self, client='web'):
         return copy.deepcopy(INNERTUBE_CLIENTS[client])
@@ -476,12 +475,8 @@ class YoutubeBaseInfoExtractor(InfoExtractor):
             data=json.dumps(data).encode('utf8'), headers=real_headers,
             query={'key': api_key or self._extract_api_key(), 'prettyPrint': 'false'})
 
-    def extract_yt_initial_data(self, item_id, webpage, fatal=True):
-        data = self._search_regex(
-            (fr'{self._YT_INITIAL_DATA_RE}\s*{self._YT_INITIAL_BOUNDARY_RE}',
-             self._YT_INITIAL_DATA_RE), webpage, 'yt initial data', fatal=fatal)
-        if data:
-            return self._parse_json(data, item_id, fatal=fatal)
+    def extract_yt_initial_data(self, item_id, webpage):
+        return self._search_json(self._YT_INITIAL_DATA_RE, webpage, 'yt initial data', item_id, fatal=True)
 
     def _extract_yt_initial_variable(self, webpage, regex, video_id, name):
         return self._parse_json(self._search_regex(
@@ -3052,9 +3047,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
     def _extract_player_responses(self, clients, video_id, webpage, master_ytcfg):
         initial_pr = None
         if webpage:
-            initial_pr = self._extract_yt_initial_variable(
-                webpage, self._YT_INITIAL_PLAYER_RESPONSE_RE,
-                video_id, 'initial player response')
+            initial_pr = self._search_json(
+                self._YT_INITIAL_PLAYER_RESPONSE_RE, webpage, 'initial player response', video_id, fatal=False)
 
         all_clients = set(clients)
         clients = clients[::-1]
@@ -3678,9 +3672,8 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
 
         initial_data = None
         if webpage:
-            initial_data = self._extract_yt_initial_variable(
-                webpage, self._YT_INITIAL_DATA_RE, video_id,
-                'yt initial data')
+            initial_data = self._search_json(
+                self._YT_INITIAL_DATA_RE, webpage, 'yt initial data', video_id, fatal=False)
         if not initial_data:
             query = {'videoId': video_id}
             query.update(self._get_checkok_params())

yt_dlp/utils.py

@@ -594,6 +594,19 @@ def clean_html(html):
     return html.strip()
 
 
+class LenientJSONDecoder(json.JSONDecoder):
+    def __init__(self, *args, transform_source=None, ignore_extra=False, **kwargs):
+        self.transform_source, self.ignore_extra = transform_source, ignore_extra
+        super().__init__(*args, **kwargs)
+
+    def decode(self, s):
+        if self.transform_source:
+            s = self.transform_source(s)
+        if self.ignore_extra:
+            return self.raw_decode(s.lstrip())[0]
+        return super().decode(s)
+
+
 def sanitize_open(filename, open_mode):
     """Try to open the given filename, and slightly tweak it if this fails.