204 lines
6.4 KiB
Python
204 lines
6.4 KiB
Python
# numdb.py - module for handling hierarchically organised numbers
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#
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# Copyright (C) 2010, 2011, 2012, 2013 Arthur de Jong
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301 USA
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"""Query structured number format files with number properties.
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This module contains functions for reading and querying a database that
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stores numbers that use a hierarchical format (e.g. ISBN, IBAN, phone
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numbers, etc).
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To read a database from a file:
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>>> dbfile = read(open('tests/numdb-test.dat', 'r'))
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To split a number:
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>>> dbfile.split('01006')
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['0', '100', '6']
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>>> dbfile.split('902006')
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['90', '20', '06']
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>>> dbfile.split('909856')
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['90', '985', '6']
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To split the number and get properties for each part:
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>>> dbfile.info('01006') == [
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... ('0', {'prop1': 'foo'}),
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... ('100', {'prop2': 'bar'}),
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... ('6', {}),
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... ]
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True
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>>> dbfile.info('02006') == [
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... ('0', {'prop1': 'foo'}),
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... ('200', {'prop2': 'bar', 'prop3': 'baz'}),
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... ('6', {}),
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... ]
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True
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>>> dbfile.info('03456') == [
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... ('0', {'prop1': 'foo'}),
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... ('345', {'prop2': 'bar', 'prop3': 'baz'}),
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... ('6', {}),
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... ]
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True
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>>> dbfile.info('902006') == [
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... ('90', {'prop1': 'booz'}),
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... ('20', {'prop2': 'foo'}),
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... ('06', {}),
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... ]
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True
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>>> dbfile.info('909856') == [
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... ('90', {'prop1': 'booz'}),
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... ('985', {'prop2': 'fooz'}),
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... ('6', {}),
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... ]
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True
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>>> dbfile.info('9889') == [
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... ('98', {'prop1': 'booz'}),
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... ('89', {'prop2': 'foo'}),
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... ]
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True
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>>> dbfile.info('633322') == [
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... ('6', {'prop1': 'boo'}),
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... ('333', {'prop2': 'bar', 'prop3': 'baz'}),
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... ('22', {}),
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... ]
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True
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"""
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import re
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from pkg_resources import resource_stream
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_line_re = re.compile(
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r'^(?P<indent> *)'
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r'(?P<ranges>([^-,\s]+(-[^-,\s]+)?)(,[^-,\s]+(-[^-,\s]+)?)*)\s*'
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r'(?P<props>.*)$')
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_prop_re = re.compile(
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r'(?P<prop>[0-9a-zA-Z-_]+)="(?P<value>[^"]*)"')
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# this is a cache of open databases
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_open_databases = {}
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# the prefixes attribute of NumDB is structured as follows:
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# prefixes = [
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# [ length, low, high, props, children ]
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# ...
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# ]
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# where children is a prefixes structure in its own right
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# (there is no expected ordering within the list)
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class NumDB(object):
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def __init__(self):
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self.prefixes = []
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@staticmethod
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def _merge(results):
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"""Merge the provided list of possible results into a single result
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list (this is a generator)."""
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# expand the results to all have the same length
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ml = max(len(x) for x in results)
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results = [x + (ml - len(x)) * [None]
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for x in results]
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# go over each part
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for parts in zip(*results):
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# regroup parts into parts list and properties list
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partlist, proplist = list(zip(*(x for x in parts if x)))
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part = min(partlist, key=len)
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props = {}
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for p in proplist:
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props.update(p)
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yield part, props
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@staticmethod
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def _find(number, prefixes):
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"""Lookup the specified number in the list of prefixes, this will
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return basically what info() should return but works recursively."""
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if not number:
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return []
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results = []
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if prefixes:
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for length, low, high, props, children in prefixes:
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if low <= number[:length] <= high and len(number) >= length:
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results.append([(number[:length], props)] +
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NumDB._find(number[length:], children))
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# not-found fallback
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if not results:
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return [(number, {})]
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# merge the results into a single result
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return list(NumDB._merge(results))
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def info(self, number):
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"""Split the provided number in components and associate properties
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with each component. This returns a tuple of tuples. Each tuple
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consists of a string (a part of the number) and a dict of properties.
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"""
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return NumDB._find(number, self.prefixes)
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def split(self, number):
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"""Split the provided number in components. This returns a tuple with
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the number of components identified."""
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return [part for part, props in self.info(number)]
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def _parse(fp):
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"""Read lines of text from the file pointer and generate indent, length,
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low, high, properties tuples."""
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for line in fp:
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# ignore comments
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if line[0] == '#' or line.strip() == '':
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continue # pragma: no cover (optimisation takes it out)
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# any other line should parse
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match = _line_re.search(line)
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indent = len(match.group('indent'))
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ranges = match.group('ranges')
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props = dict(_prop_re.findall(match.group('props')))
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for rnge in ranges.split(','):
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if '-' in rnge:
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low, high = rnge.split('-')
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else:
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low, high = rnge, rnge
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yield indent, len(low), low, high, props
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def read(fp):
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"""Return a new database with the data read from the specified file."""
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last_indent = 0
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db = NumDB()
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stack = {0: db.prefixes}
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for indent, length, low, high, props in _parse(fp):
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if indent > last_indent:
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# populate the children field of the last indent
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if stack[last_indent][-1][4] is None:
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stack[last_indent][-1][4] = []
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stack[indent] = stack[last_indent][-1][4]
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stack[indent].append([length, low, high, props, None])
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last_indent = indent
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return db
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def get(name):
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"""Opens a database with the specified name to perform queries on."""
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if name not in _open_databases:
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import codecs
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reader = codecs.getreader('utf-8')
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db = read(reader(resource_stream(__name__, name + '.dat')))
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_open_databases[name] = db
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return _open_databases[name]
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