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69bec673 | 1 | import collections.abc |
2 | import contextlib | |
3 | import inspect | |
4 | import itertools | |
5 | import re | |
6 | ||
7 | from ._utils import ( | |
8 | IDENTITY, | |
9 | NO_DEFAULT, | |
10 | LazyList, | |
0b6f829b | 11 | deprecation_warning, |
69bec673 | 12 | is_iterable_like, |
13 | try_call, | |
14 | variadic, | |
15 | ) | |
16 | ||
17 | ||
18 | def traverse_obj( | |
19 | obj, *paths, default=NO_DEFAULT, expected_type=None, get_all=True, | |
0b6f829b | 20 | casesense=True, is_user_input=NO_DEFAULT, traverse_string=False): |
69bec673 | 21 | """ |
22 | Safely traverse nested `dict`s and `Iterable`s | |
23 | ||
24 | >>> obj = [{}, {"key": "value"}] | |
25 | >>> traverse_obj(obj, (1, "key")) | |
f9fb3ce8 | 26 | 'value' |
69bec673 | 27 | |
28 | Each of the provided `paths` is tested and the first producing a valid result will be returned. | |
29 | The next path will also be tested if the path branched but no results could be found. | |
30 | Supported values for traversal are `Mapping`, `Iterable` and `re.Match`. | |
31 | Unhelpful values (`{}`, `None`) are treated as the absence of a value and discarded. | |
32 | ||
33 | The paths will be wrapped in `variadic`, so that `'key'` is conveniently the same as `('key', )`. | |
34 | ||
35 | The keys in the path can be one of: | |
36 | - `None`: Return the current object. | |
37 | - `set`: Requires the only item in the set to be a type or function, | |
38 | like `{type}`/`{func}`. If a `type`, returns only values | |
39 | of this type. If a function, returns `func(obj)`. | |
40 | - `str`/`int`: Return `obj[key]`. For `re.Match`, return `obj.group(key)`. | |
41 | - `slice`: Branch out and return all values in `obj[key]`. | |
42 | - `Ellipsis`: Branch out and return a list of all values. | |
43 | - `tuple`/`list`: Branch out and return a list of all matching values. | |
44 | Read as: `[traverse_obj(obj, branch) for branch in branches]`. | |
45 | - `function`: Branch out and return values filtered by the function. | |
46 | Read as: `[value for key, value in obj if function(key, value)]`. | |
47 | For `Iterable`s, `key` is the index of the value. | |
48 | For `re.Match`es, `key` is the group number (0 = full match) | |
49 | as well as additionally any group names, if given. | |
50 | - `dict` Transform the current object and return a matching dict. | |
51 | Read as: `{key: traverse_obj(obj, path) for key, path in dct.items()}`. | |
52 | ||
53 | `tuple`, `list`, and `dict` all support nested paths and branches. | |
54 | ||
55 | @params paths Paths which to traverse by. | |
56 | @param default Value to return if the paths do not match. | |
57 | If the last key in the path is a `dict`, it will apply to each value inside | |
58 | the dict instead, depth first. Try to avoid if using nested `dict` keys. | |
59 | @param expected_type If a `type`, only accept final values of this type. | |
60 | If any other callable, try to call the function on each result. | |
61 | If the last key in the path is a `dict`, it will apply to each value inside | |
62 | the dict instead, recursively. This does respect branching paths. | |
63 | @param get_all If `False`, return the first matching result, otherwise all matching ones. | |
64 | @param casesense If `False`, consider string dictionary keys as case insensitive. | |
65 | ||
0b6f829b | 66 | `traverse_string` is only meant to be used by YoutubeDL.prepare_outtmpl and is not part of the API |
69bec673 | 67 | |
69bec673 | 68 | @param traverse_string Whether to traverse into objects as strings. |
69 | If `True`, any non-compatible object will first be | |
70 | converted into a string and then traversed into. | |
71 | The return value of that path will be a string instead, | |
72 | not respecting any further branching. | |
73 | ||
74 | ||
75 | @returns The result of the object traversal. | |
76 | If successful, `get_all=True`, and the path branches at least once, | |
77 | then a list of results is returned instead. | |
78 | If no `default` is given and the last path branches, a `list` of results | |
79 | is always returned. If a path ends on a `dict` that result will always be a `dict`. | |
80 | """ | |
0b6f829b SS |
81 | if is_user_input is not NO_DEFAULT: |
82 | deprecation_warning('The is_user_input parameter is deprecated and no longer works') | |
83 | ||
69bec673 | 84 | casefold = lambda k: k.casefold() if isinstance(k, str) else k |
85 | ||
86 | if isinstance(expected_type, type): | |
87 | type_test = lambda val: val if isinstance(val, expected_type) else None | |
88 | else: | |
89 | type_test = lambda val: try_call(expected_type or IDENTITY, args=(val,)) | |
90 | ||
91 | def apply_key(key, obj, is_last): | |
92 | branching = False | |
93 | result = None | |
94 | ||
95 | if obj is None and traverse_string: | |
96 | if key is ... or callable(key) or isinstance(key, slice): | |
97 | branching = True | |
98 | result = () | |
99 | ||
100 | elif key is None: | |
101 | result = obj | |
102 | ||
103 | elif isinstance(key, set): | |
104 | assert len(key) == 1, 'Set should only be used to wrap a single item' | |
105 | item = next(iter(key)) | |
106 | if isinstance(item, type): | |
107 | if isinstance(obj, item): | |
108 | result = obj | |
109 | else: | |
110 | result = try_call(item, args=(obj,)) | |
111 | ||
112 | elif isinstance(key, (list, tuple)): | |
113 | branching = True | |
114 | result = itertools.chain.from_iterable( | |
115 | apply_path(obj, branch, is_last)[0] for branch in key) | |
116 | ||
117 | elif key is ...: | |
118 | branching = True | |
119 | if isinstance(obj, collections.abc.Mapping): | |
120 | result = obj.values() | |
121 | elif is_iterable_like(obj): | |
122 | result = obj | |
123 | elif isinstance(obj, re.Match): | |
124 | result = obj.groups() | |
125 | elif traverse_string: | |
126 | branching = False | |
127 | result = str(obj) | |
128 | else: | |
129 | result = () | |
130 | ||
131 | elif callable(key): | |
132 | branching = True | |
133 | if isinstance(obj, collections.abc.Mapping): | |
134 | iter_obj = obj.items() | |
135 | elif is_iterable_like(obj): | |
136 | iter_obj = enumerate(obj) | |
137 | elif isinstance(obj, re.Match): | |
138 | iter_obj = itertools.chain( | |
139 | enumerate((obj.group(), *obj.groups())), | |
140 | obj.groupdict().items()) | |
141 | elif traverse_string: | |
142 | branching = False | |
143 | iter_obj = enumerate(str(obj)) | |
144 | else: | |
145 | iter_obj = () | |
146 | ||
147 | result = (v for k, v in iter_obj if try_call(key, args=(k, v))) | |
148 | if not branching: # string traversal | |
149 | result = ''.join(result) | |
150 | ||
151 | elif isinstance(key, dict): | |
152 | iter_obj = ((k, _traverse_obj(obj, v, False, is_last)) for k, v in key.items()) | |
153 | result = { | |
154 | k: v if v is not None else default for k, v in iter_obj | |
155 | if v is not None or default is not NO_DEFAULT | |
156 | } or None | |
157 | ||
158 | elif isinstance(obj, collections.abc.Mapping): | |
159 | result = (try_call(obj.get, args=(key,)) if casesense or try_call(obj.__contains__, args=(key,)) else | |
160 | next((v for k, v in obj.items() if casefold(k) == key), None)) | |
161 | ||
162 | elif isinstance(obj, re.Match): | |
163 | if isinstance(key, int) or casesense: | |
164 | with contextlib.suppress(IndexError): | |
165 | result = obj.group(key) | |
166 | ||
167 | elif isinstance(key, str): | |
168 | result = next((v for k, v in obj.groupdict().items() if casefold(k) == key), None) | |
169 | ||
170 | elif isinstance(key, (int, slice)): | |
171 | if is_iterable_like(obj, collections.abc.Sequence): | |
172 | branching = isinstance(key, slice) | |
173 | with contextlib.suppress(IndexError): | |
174 | result = obj[key] | |
175 | elif traverse_string: | |
176 | with contextlib.suppress(IndexError): | |
177 | result = str(obj)[key] | |
178 | ||
179 | return branching, result if branching else (result,) | |
180 | ||
181 | def lazy_last(iterable): | |
182 | iterator = iter(iterable) | |
183 | prev = next(iterator, NO_DEFAULT) | |
184 | if prev is NO_DEFAULT: | |
185 | return | |
186 | ||
187 | for item in iterator: | |
188 | yield False, prev | |
189 | prev = item | |
190 | ||
191 | yield True, prev | |
192 | ||
193 | def apply_path(start_obj, path, test_type): | |
194 | objs = (start_obj,) | |
195 | has_branched = False | |
196 | ||
197 | key = None | |
198 | for last, key in lazy_last(variadic(path, (str, bytes, dict, set))): | |
69bec673 | 199 | if not casesense and isinstance(key, str): |
200 | key = key.casefold() | |
201 | ||
202 | if __debug__ and callable(key): | |
203 | # Verify function signature | |
204 | inspect.signature(key).bind(None, None) | |
205 | ||
206 | new_objs = [] | |
207 | for obj in objs: | |
208 | branching, results = apply_key(key, obj, last) | |
209 | has_branched |= branching | |
210 | new_objs.append(results) | |
211 | ||
212 | objs = itertools.chain.from_iterable(new_objs) | |
213 | ||
214 | if test_type and not isinstance(key, (dict, list, tuple)): | |
215 | objs = map(type_test, objs) | |
216 | ||
217 | return objs, has_branched, isinstance(key, dict) | |
218 | ||
219 | def _traverse_obj(obj, path, allow_empty, test_type): | |
220 | results, has_branched, is_dict = apply_path(obj, path, test_type) | |
221 | results = LazyList(item for item in results if item not in (None, {})) | |
222 | if get_all and has_branched: | |
223 | if results: | |
224 | return results.exhaust() | |
225 | if allow_empty: | |
226 | return [] if default is NO_DEFAULT else default | |
227 | return None | |
228 | ||
229 | return results[0] if results else {} if allow_empty and is_dict else None | |
230 | ||
231 | for index, path in enumerate(paths, 1): | |
232 | result = _traverse_obj(obj, path, index == len(paths), True) | |
233 | if result is not None: | |
234 | return result | |
235 | ||
236 | return None if default is NO_DEFAULT else default | |
237 | ||
238 | ||
239 | def get_first(obj, *paths, **kwargs): | |
240 | return traverse_obj(obj, *((..., *variadic(keys)) for keys in paths), **kwargs, get_all=False) | |
241 | ||
242 | ||
243 | def dict_get(d, key_or_keys, default=None, skip_false_values=True): | |
244 | for val in map(d.get, variadic(key_or_keys)): | |
245 | if val is not None and (val or not skip_false_values): | |
246 | return val | |
247 | return default |