69 lines
1.7 KiB
Python
69 lines
1.7 KiB
Python
from collections import deque
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from cfg import config
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from db_util import get_page_id
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def prepare_dijkstra(connection):
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cursor = connection.cursor()
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if(config["use_sqlite"]):
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cursor.execute('''INSERT OR IGNORE INTO dijkstra_helper(page)
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SELECT rowid FROM pages
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''')
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else:
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cursor.execute('''INSERT IGNORE INTO dijkstra_helper(page)
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SELECT page_id FROM pages
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''')
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if(config["use_sqlite"]):
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cursor.execute("UPDATE dijkstra_helper SET value=1e1000")
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else:
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cursor.execute("UPDATE dijkstra_helper SET value=2147483647")
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connection.commit()
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def dijkstra_one(page, value, connection):
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cursor = connection.cursor()
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if(isinstance(page, tuple)):
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# Idk why this happens.
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title = title[0]
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cursor.execute('''SELECT page
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FROM dijkstra_helper
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LEFT JOIN links ON links.destination=dijkstra_helper.page
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WHERE links.source=%s
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AND dijkstra_helper.value>%s''', (page, value + 1))
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# This is the list of nodes that have to be updated
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result = cursor.fetchall()
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cursor.execute('''UPDATE dijkstra_helper
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SET value=%s
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WHERE page IN (
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SELECT destination
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FROM links
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WHERE source=%s)
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AND dijkstra_helper.value>%s''', (value + 1, page, value + 1))
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connection.commit()
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return result
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def recursive_dijkstra(titles, value, connection):
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if(not titles):
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return
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todos = deque()
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for title in titles:
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todos.extend(dijkstra_one(title, value, connection))
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recursive_dijkstra(todos, value + 1, connection)
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def dijkstra(title, connection):
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page = get_page_id(title, connection)
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cursor = connection.cursor()
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cursor.execute("UPDATE dijkstra_helper SET value=0 WHERE page=%s", (page,))
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todos = dijkstra_one(page, 1, connection)
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recursive_dijkstra(todos, 2, connection)
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