Source code for sqlalchemy_utils.primitives.ltree

import re

from ..utils import str_coercible

path_matcher = re.compile(r'^[A-Za-z0-9_]+(\.[A-Za-z0-9_]+)*$')

[docs]@str_coercible class Ltree: """ Ltree class wraps a valid string label path. It provides various convenience properties and methods. :: from sqlalchemy_utils import Ltree Ltree('1.2.3').path # '1.2.3' Ltree always validates the given path. :: Ltree(None) # raises TypeError Ltree('..') # raises ValueError Validator is also available as class method. :: Ltree.validate('1.2.3') Ltree.validate(None) # raises TypeError Ltree supports equality operators. :: Ltree('Countries.Finland') == Ltree('Countries.Finland') Ltree('Countries.Germany') != Ltree('Countries.Finland') Ltree objects are hashable. :: assert hash(Ltree('Finland')) == hash('Finland') Ltree objects have length. :: assert len(Ltree('1.2')) == 2 assert len(Ltree('')) # 4 You can easily find subpath indexes. :: assert Ltree('1.2.3').index('2.3') == 1 assert Ltree('').index('3.4') == 2 Ltree objects can be sliced. :: assert Ltree('1.2.3')[0:2] == Ltree('1.2') assert Ltree('1.2.3')[1:] == Ltree('2.3') Finding longest common ancestor. :: assert Ltree('').lca('1.2.3', '', '1.2.3') == '1.2' assert Ltree('').lca('1.2', '1.2.3') == '1' Ltree objects can be concatenated. :: assert Ltree('1.2') + Ltree('1.2') == Ltree('') """ def __init__(self, path_or_ltree): if isinstance(path_or_ltree, Ltree): self.path = path_or_ltree.path elif isinstance(path_or_ltree, str): self.validate(path_or_ltree) self.path = path_or_ltree else: raise TypeError( "Ltree() argument must be a string or an Ltree, not '{}'" .format( type(path_or_ltree).__name__ ) ) @classmethod def validate(cls, path): if path_matcher.match(path) is None: raise ValueError( f"'{path}' is not a valid ltree path." ) def __len__(self): return len(self.path.split('.')) def index(self, other): subpath = Ltree(other).path.split('.') parts = self.path.split('.') for index, _ in enumerate(parts): if parts[index:len(subpath) + index] == subpath: return index raise ValueError('subpath not found') def descendant_of(self, other): """ is left argument a descendant of right (or equal)? :: assert Ltree('').descendant_of('1.2.3') """ subpath = self[:len(Ltree(other))] return subpath == other def ancestor_of(self, other): """ is left argument an ancestor of right (or equal)? :: assert Ltree('1.2.3').ancestor_of('') """ subpath = Ltree(other)[:len(self)] return subpath == self def __getitem__(self, key): if isinstance(key, int): return Ltree(self.path.split('.')[key]) elif isinstance(key, slice): return Ltree('.'.join(self.path.split('.')[key])) raise TypeError( 'Ltree indices must be integers, not {}'.format( key.__class__.__name__ ) ) def lca(self, *others): """ Lowest common ancestor, i.e., longest common prefix of paths :: assert Ltree('').lca('1.2.3', '', '1.2.3') == '1.2' """ other_parts = [Ltree(other).path.split('.') for other in others] parts = self.path.split('.') for index, element in enumerate(parts): if any( other[index] != element or len(other) <= index + 1 or len(parts) == index + 1 for other in other_parts ): if index == 0: return None return Ltree('.'.join(parts[0:index])) def __add__(self, other): return Ltree(self.path + '.' + Ltree(other).path) def __radd__(self, other): return Ltree(other) + self def __eq__(self, other): if isinstance(other, Ltree): return self.path == other.path elif isinstance(other, str): return self.path == other else: return NotImplemented def __hash__(self): return hash(self.path) def __ne__(self, other): return not (self == other) def __repr__(self): return f'{self.__class__.__name__}({self.path!r})' def __unicode__(self): return self.path def __contains__(self, label): return label in self.path.split('.') def __gt__(self, other): return self.path > other.path def __lt__(self, other): return self.path < other.path def __ge__(self, other): return self.path >= other.path def __le__(self, other): return self.path <= other.path