Source code for contracts.library.lists
from ..interface import Contract, ContractNotRespected
from ..syntax import (add_contract, W, contract_expression, O, S, add_keyword,
Keyword)
[docs]class List(Contract):
def __init__(self, length_contract=None,
elements_contract=None, where=None):
Contract.__init__(self, where)
self.length_contract = length_contract
self.elements_contract = elements_contract
[docs] def check_contract(self, context, value, silent):
if not isinstance(value, list):
error = 'Expected a list, got %r.' % value.__class__.__name__
raise ContractNotRespected(self, error, value, context)
if self.length_contract is not None:
self.length_contract._check_contract(context, len(value), silent)
if self.elements_contract is not None:
for element in value:
self.elements_contract._check_contract(context, element, silent)
def __str__(self):
s = 'list'
if self.length_contract is not None:
s += '[%s]' % self.length_contract
if self.elements_contract is not None:
s += '(%s)' % self.elements_contract
return s
def __repr__(self):
s = 'List(%r,%r)' % (self.length_contract, self.elements_contract)
return s
[docs] @staticmethod
def parse_action(s, loc, tokens):
where = W(s, loc)
length_contract = tokens.get('length_contract', None)
elements_contract = tokens.get('elements_contract', None)
return List(length_contract, elements_contract, where=where)
list_contract = (Keyword('list') -
O(S('[') - contract_expression('length_contract') - S(']')) +
O(S('(') - contract_expression('elements_contract') - S(')')))
list_contract.setParseAction(List.parse_action)
list_contract.setName('List contract')
add_keyword('list')
add_contract(list_contract)