Nominatim/nominatim/db/sqlite_functions.py

123 lines
4.2 KiB
Python

# SPDX-License-Identifier: GPL-3.0-or-later
#
# This file is part of Nominatim. (https://nominatim.org)
#
# Copyright (C) 2023 by the Nominatim developer community.
# For a full list of authors see the git log.
"""
Custom functions for SQLite.
"""
from typing import cast, Optional, Set, Any
import json
# pylint: disable=protected-access
def weigh_search(search_vector: Optional[str], rankings: str, default: float) -> float:
""" Custom weight function for search results.
"""
if search_vector is not None:
svec = [int(x) for x in search_vector.split(',')]
for rank in json.loads(rankings):
if all(r in svec for r in rank[1]):
return cast(float, rank[0])
return default
class ArrayIntersectFuzzy:
""" Compute the array of common elements of all input integer arrays.
Very large input paramenters may be ignored to speed up
computation. Therefore, the result is a superset of common elements.
Input and output arrays are given as comma-separated lists.
"""
def __init__(self) -> None:
self.first = ''
self.values: Optional[Set[int]] = None
def step(self, value: Optional[str]) -> None:
""" Add the next array to the intersection.
"""
if value is not None:
if not self.first:
self.first = value
elif len(value) < 10000000:
if self.values is None:
self.values = {int(x) for x in self.first.split(',')}
self.values.intersection_update((int(x) for x in value.split(',')))
def finalize(self) -> str:
""" Return the final result.
"""
if self.values is not None:
return ','.join(map(str, self.values))
return self.first
class ArrayUnion:
""" Compute the set of all elements of the input integer arrays.
Input and output arrays are given as strings of comma-separated lists.
"""
def __init__(self) -> None:
self.values: Optional[Set[str]] = None
def step(self, value: Optional[str]) -> None:
""" Add the next array to the union.
"""
if value is not None:
if self.values is None:
self.values = set(value.split(','))
else:
self.values.update(value.split(','))
def finalize(self) -> str:
""" Return the final result.
"""
return '' if self.values is None else ','.join(self.values)
def array_contains(container: Optional[str], containee: Optional[str]) -> Optional[bool]:
""" Is the array 'containee' completely contained in array 'container'.
"""
if container is None or containee is None:
return None
vset = container.split(',')
return all(v in vset for v in containee.split(','))
def array_pair_contains(container1: Optional[str], container2: Optional[str],
containee: Optional[str]) -> Optional[bool]:
""" Is the array 'containee' completely contained in the union of
array 'container1' and array 'container2'.
"""
if container1 is None or container2 is None or containee is None:
return None
vset = container1.split(',') + container2.split(',')
return all(v in vset for v in containee.split(','))
def install_custom_functions(conn: Any) -> None:
""" Install helper functions for Nominatim into the given SQLite
database connection.
"""
conn.create_function('weigh_search', 3, weigh_search, deterministic=True)
conn.create_function('array_contains', 2, array_contains, deterministic=True)
conn.create_function('array_pair_contains', 3, array_pair_contains, deterministic=True)
_create_aggregate(conn, 'array_intersect_fuzzy', 1, ArrayIntersectFuzzy)
_create_aggregate(conn, 'array_union', 1, ArrayUnion)
async def _make_aggregate(aioconn: Any, *args: Any) -> None:
await aioconn._execute(aioconn._conn.create_aggregate, *args)
def _create_aggregate(conn: Any, name: str, nargs: int, aggregate: Any) -> None:
try:
conn.await_(_make_aggregate(conn._connection, name, nargs, aggregate))
except Exception as error: # pylint: disable=broad-exception-caught
conn._handle_exception(error)