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# numdb.py - module for handling hierarchically organised numbers
#
# Copyright (C) 2010-2023 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""Query structured number format files with number properties.
This module contains functions for reading and querying a database that
stores numbers that use a hierarchical format (e.g. ISBN, IBAN, phone
numbers, etc).
To read a database from a file:
>>> with open('tests/numdb-test.dat', 'r') as f:
... dbfile = read(f)
To split a number:
>>> dbfile.split('01006')
['0', '100', '6']
>>> dbfile.split('902006')
['90', '20', '06']
>>> dbfile.split('909856')
['90', '985', '6']
To split the number and get properties for each part:
>>> import pprint
>>> pprint.pprint(dbfile.info('01006'))
[('0', {'prop1': 'foo'}), ('100', {'prop2': 'bar'}), ('6', {})]
>>> pprint.pprint(dbfile.info('02006'))
[('0', {'prop1': 'foo'}), ('200', {'prop2': 'bar', 'prop3': 'baz'}), ('6', {})]
>>> pprint.pprint(dbfile.info('03456'))
[('0', {'prop1': 'foo'}), ('345', {'prop2': 'bar', 'prop3': 'baz'}), ('6', {})]
>>> pprint.pprint(dbfile.info('902006'))
[('90', {'prop1': 'booz'}), ('20', {'prop2': 'foo'}), ('06', {})]
>>> pprint.pprint(dbfile.info('909856'))
[('90', {'prop1': 'booz'}), ('985', {'prop2': 'fooz'}), ('6', {})]
>>> pprint.pprint(dbfile.info('9889'))
[('98', {'prop1': 'booz'}), ('89', {'prop2': 'foo'})]
>>> pprint.pprint(dbfile.info('633322'))
[('6', {'prop1': 'boo'}), ('333', {'prop2': 'bar', 'prop3': 'baz', 'prop4': 'bla'}), ('22', {})]
>>> pprint.pprint(dbfile.info('1200333'))
[('1', {'prop1': 'foo'}), ('200', {'prop2': 'bar', 'prop3': 'baz'}), ('333', {'prop4': 'bax'})]
"""
import re
_line_re = re.compile(
r'^(?P<indent> *)'
r'(?P<ranges>([^-,\s]+(-[^-,\s]+)?)(,[^-,\s]+(-[^-,\s]+)?)*)\s*'
r'(?P<props>.*)$')
_prop_re = re.compile(
r'(?P<prop>[0-9a-zA-Z-_]+)="(?P<value>[^"]*)"')
# this is a cache of open databases
_open_databases = {}
# the prefixes attribute of NumDB is structured as follows:
# prefixes = [
# [ length, low, high, props, children ]
# ...
# ]
# where children is a prefixes structure in its own right
# (there is no expected ordering within the list)
class NumDB():
"""Number database."""
def __init__(self):
"""Construct an empty database."""
self.prefixes = []
@staticmethod
def _find(number, prefixes):
"""Lookup the specified number in the list of prefixes, this will
return basically what info() should return but works recursively."""
if not number:
return []
part = number
properties = {}
next_prefixes = []
# go over prefixes and find matches
for length, low, high, props, children in prefixes:
if len(part) >= length and low <= part[:length] <= high:
# only use information from the shortest match
if length < len(part):
part = part[:length]
properties = {}
next_prefixes = []
properties.update(props)
next_prefixes.extend(children)
# return first part and recursively find next matches
return [(part, properties)] + NumDB._find(number[len(part):], next_prefixes)
def info(self, number):
"""Split the provided number in components and associate properties
with each component. This returns a tuple of tuples. Each tuple
consists of a string (a part of the number) and a dict of properties.
"""
return NumDB._find(number, self.prefixes)
def split(self, number):
"""Split the provided number in components. This returns a tuple with
the number of components identified."""
return [part for part, props in self.info(number)]
def _parse(fp):
"""Read lines of text from the file pointer and generate indent, length,
low, high, properties tuples."""
for line in fp:
# ignore comments
if line[0] == '#' or line.strip() == '':
continue # pragma: no cover (optimisation takes it out)
# any other line should parse
match = _line_re.search(line)
indent = len(match.group('indent'))
ranges = match.group('ranges')
props = dict(_prop_re.findall(match.group('props')))
children = []
for rnge in ranges.split(','):
if '-' in rnge:
low, high = rnge.split('-')
else:
low, high = rnge, rnge
yield indent, len(low), low, high, props, children
def read(fp):
"""Return a new database with the data read from the specified file."""
last_indent = 0
db = NumDB()
stack = {0: db.prefixes}
for indent, length, low, high, props, children in _parse(fp):
if indent > last_indent:
# set our stack location to the last parent entry
stack[indent] = stack[last_indent][-1][4]
stack[indent].append([length, low, high, props, children])
last_indent = indent
return db
def _get_resource_stream(name):
"""Return a readable file-like object for the resource."""
try: # pragma: no cover (Python 3.9 and newer)
import importlib.resources
return importlib.resources.files(__package__).joinpath(name).open('rb')
except (ImportError, AttributeError): # pragma: no cover (older Python versions)
import pkg_resources
return pkg_resources.resource_stream(__name__, name)
def get(name):
"""Open a database with the specified name to perform queries on."""
if name not in _open_databases:
import codecs
reader = codecs.getreader('utf-8')
with reader(_get_resource_stream(name + '.dat')) as fp:
_open_databases[name] = read(fp)
return _open_databases[name]
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