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55 lines
1.6 KiB
Python
55 lines
1.6 KiB
Python
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import sqlalchemy.sql.visitors as visitors
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from pokedex.db.tables import metadata
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# stolen from sqlalchemy.sql.util.sort_tables
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def compute_dependencies(tables):
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"""Construct a reverse dependency graph for the given tables.
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Returns a dict which maps a table to the list of tables which depend on it.
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"""
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tables = list(tables)
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graph = {}
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def visit_foreign_key(fkey):
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if fkey.use_alter:
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return
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parent_table = fkey.column.table
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if parent_table in tables:
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child_table = fkey.parent.table
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if parent_table is not child_table:
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graph.setdefault(parent_table, []).append(child_table)
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for table in tables:
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visitors.traverse(table,
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{'schema_visitor': True},
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{'foreign_key': visit_foreign_key})
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graph.setdefault(table, []).extend(table._extra_dependencies)
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return graph
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#: The dependency graph for pokedex.db.tables
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_pokedex_graph = compute_dependencies(metadata.tables.values())
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def find_dependent_tables(tables, graph=None):
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"""Recursively find all tables which depend on the given tables.
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The returned set does not include the original tables.
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"""
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if graph is None:
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graph = _pokedex_graph
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tables = list(tables)
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dependents = set()
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def add_dependents_of(table):
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for dependent_table in graph.get(table, []):
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if dependent_table not in dependents:
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dependents.add(dependent_table)
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add_dependents_of(dependent_table)
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for table in tables:
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add_dependents_of(table)
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dependents -= set(tables)
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return dependents
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