forget-cancellare-vecchi-toot/libforget/known_instances.py

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import json
def find(predicate, iterator, default=None):
"""
returns the first element of iterator that matches predicate
or default if none is found
"""
try:
return next((el for el in iterator if predicate(el)))
except StopIteration:
return default
class KnownInstances(object):
def __init__(self, serialised=None, top_slots=5):
self.instances = list()
self.top_slots = top_slots
try:
unserialised = json.loads(serialised)
if not isinstance(unserialised, list):
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self.__default()
return
for instance in unserialised:
if 'instance' in instance and 'hits' in instance:
self.instances.append(dict(
instance=instance['instance'],
hits=instance['hits']
))
except (json.JSONDecodeError, TypeError):
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self.__default()
return
def __default(self):
self.instances = [{
"instance": "mastodon.social",
"hits": 0
}]
def clear(self):
self.instances = []
def bump(self, instance_name, bump_by=1):
instance = find(
lambda i: i['instance'] == instance_name,
self.instances)
if not instance:
instance = dict(instance=instance_name, hits=0)
self.instances.append(instance)
instance['hits'] += bump_by
def normalize(self):
"""
raises the top `top_slots` instances to the top,
making sure not to move instances that were already at
the top
"""
top_slots = self.top_slots
head = self.instances[:top_slots]
tail = self.instances[top_slots:]
if len(tail) == 0:
return
def key(instance):
return instance['hits']
for _ in range(top_slots):
head_min = min(head, key=key)
tail_max = max(tail, key=key)
if tail_max['hits'] > head_min['hits']:
# swap them
i = head.index(head_min)
j = tail.index(tail_max)
buf = head[i]
head[i] = tail[j]
tail[j] = buf
else:
break
self.instances = head + tail
def top(self):
head = self.instances[:self.top_slots]
return tuple((i['instance'] for i in head))
def serialize(self):
return json.dumps(self.instances)