def parse_rule(rule_str):
# Example: daughter(Person, Parent) :- female(Person), parent(Parent, Person).
rule_str = rule_str.strip().rstrip('.').replace(' ', '')
sep_idx = rule_str.find(':-')
# Get conclusion (lhs) and premises (rhs) seperated by ':-'
conclusion = Fact.parse_fact(rule_str[:sep_idx])
premises = []
list_fact_str = rule_str[sep_idx + 2:].split('),')
for idx, fact_str in enumerate(list_fact_str):
if idx != len(list_fact_str) - 1:
fact_str += ')'
fact = Fact.parse_fact(fact_str)
premises.append(fact)
return Rule(conclusion, premises)
def parse_rule(rule_str):
# Example: daughter(Person, Parent) :- female(Person), parent(Parent, Person).
rule_str = rule_str.strip().rstrip('.').replace(
' ', '') # format rule to standard
sep_idx = rule_str.find(':-')
# Get conclusion (lhs) and premises (rhs) seperated by ':-'
conclusion = Fact.parse_fact(rule_str[:sep_idx])
premises = []
list_fact_str = rule_str[sep_idx + 2:].split(
'),') # get list of conditions, each condition separated by ')'
for idx, fact_str in enumerate(list_fact_str):
if idx != len(list_fact_str) - 1:
fact_str += ')' # because split by ')', some condition lost this character, we need to format it
fact = Fact.parse_fact(fact_str)
premises.append(fact)
return Rule(conclusion, premises)
def declare(kb, list_data): # initialize a knowledge database
while list_data:
current_line, list_data = Sentence.read_list(
list_data) # return a comment/fact/rule and update list
type = Sentence.classify(current_line)
if type == 'fact':
fact = Fact.parse_fact(current_line)
kb.add_fact(fact)
kb.add_fact_predicate(fact.predicate)
elif type == 'rule':
rule = Rule.parse_rule(current_line)
kb.add_rule(rule)
kb.add_rule_conclusion_predicate(rule.conclusion.predicate)
test_number = "04"
inp_file = 'test/' + test_number + '/knowledge.pl'
query_file = 'test/' + test_number + '/query.pl'
output_file = 'test/' + test_number + '/answers.txt'
kb = KnowledgeBase()
with open(inp_file, 'r') as f_in:
data_base = f_in.readlines()
KnowledgeBase.declare(kb, data_base)
print('Done initialize knowledge base from {}.'.format(inp_file))
with open(query_file, 'r') as f_query:
with open(output_file, 'w') as f_out:
for query_str in f_query.readlines():
alpha = Fact.parse_fact(query_str)
alpha_str = str(alpha) + '.'
print(alpha_str)
query_conclusion = kb.query(alpha, "backward")
if isinstance(query_conclusion, bool):
substs = query_conclusion.__str__()
else:
substs = list(query_conclusion)
substs_str = ' ;\n'.join([str(subst)
for subst in substs]) + '.\n'
print(substs_str)
f_out.write(alpha_str + '\n')
f_out.write(substs_str + '\n')
print('Results of queries from {} are written to {}.'.format(
query_file, output_file))
