class RDP(object):
def __init__(self, filename, grammar):
self.attempted_matches = 0
self.matched_then_discarded = 0
self.correctly_matched = 0
self.grammar = grammar
self.token_stream = TokenStream(filename)
def parse(self, nt, start_pos=0):
result = ""
if self.recursive_parse(nt, start_pos=0)[0]:
result += "Success input is valid"
else:
result += "Fail input is not valid"
result += self.display_metrics()
return result
def recursive_parse(self, nt, start_pos=0):
sub_count = 0 #counter for number of succesfull matched rhs (used to count discarded matches)
for production in self.grammar.grammar_productions:
next_pos = start_pos
if production.lhs == nt:
valid = True
for symbol in production.rhs:
valid = False
self.attempted_matches += 1
if symbol in self.grammar.get_terminals():
if self.token_stream.get_token(next_pos) == symbol:
next_pos += 1
valid = True
else:
break
else:
temp = self.recursive_parse(symbol, next_pos)
if temp[0]:
valid = True
next_pos = temp[1]
sub_count += temp[2] + 1
else:
break
if valid:
self.correctly_matched += 1
#print production #uncomment to display correcly matched productions
return [True, next_pos, sub_count]
self.matched_then_discarded += sub_count
self.correctly_matched -= sub_count
return [False, 0, sub_count]
def display_metrics(self):
metrics = "\nNumber of RHS matches attempted: " + str(self.attempted_matches) +\
"\nNumber of RHS matched then later discarded: " + str(self.matched_then_discarded)+\
"\nNumber of RHS matched in final result: " + str(self.correctly_matched)
self.attempted_matches = 0
self.matched_then_discarded = 0
self.correctly_matched = 0
return metrics
class NBTP(object):
def __init__(self, filename, grammar):
self.token_stream = TokenStream(filename)
self.grammar = grammar
temp = ParsingTable(grammar, sentence_symbol)
self.parse_table = temp.get_table()
def parse(self):
start_symbol = ll1_grammar.grammar_productions[0].lhs
output = ""
position = 0
sentinel = 99
match_count = 0
stack = list()
stack.append(sentinel)
stack.append(start_symbol)
a = self.token_stream.get_token(position)
t = stack[-1]
while t != sentinel:
if t == a:
stack.pop()
position += 1
a = self.token_stream.get_token(position)
elif t in self.grammar.get_terminals():
return "Input invalid Error occured"
elif self.parse_table[t][a] == []:
return "Input invalid Error occured"
else:
match_count += 1
output += "\n" + str(self.parse_table[t][a])
stack.pop()
for symbol in reversed((self.parse_table[t][a]).rhs):
stack.append(symbol)
t = stack[-1]
return "Input is valid.\nThere were " + str(match_count) +\
" matched productions.(which are shown below)\n\n" + output
class NBTP(object):
def __init__(self, filename, grammar):
self.token_stream = TokenStream(filename)
self.grammar = grammar
temp = ParsingTable(grammar, sentence_symbol)
self.parse_table = temp.get_table()
def parse(self):
start_symbol = ll1_grammar.grammar_productions[0].lhs
output = ""
position = 0
sentinel = 99
match_count = 0
stack = list()
stack.append(sentinel)
stack.append(start_symbol)
a = self.token_stream.get_token(position)
t = stack[-1]
while t != sentinel:
if t == a:
stack.pop()
position +=1
a = self.token_stream.get_token(position)
elif t in self.grammar.get_terminals(): return "Input invalid Error occured"
elif self.parse_table[t][a] == []: return "Input invalid Error occured"
else:
match_count += 1
output += "\n" + str(self.parse_table[t][a])
stack.pop()
for symbol in reversed((self.parse_table[t][a]).rhs):
stack.append(symbol)
t = stack[-1]
return "Input is valid.\nThere were " + str(match_count) +\
" matched productions.(which are shown below)\n\n" + output
def __init__(self, filename, grammar):
self.attempted_matches = 0
self.matched_then_discarded = 0
self.correctly_matched = 0
self.grammar = grammar
self.token_stream = TokenStream(filename)
def __init__(self, filename, grammar):
self.token_stream = TokenStream(filename)
self.grammar = grammar
temp = ParsingTable(grammar, sentence_symbol)
self.parse_table = temp.get_table()
def __init__(self, filename, grammar):
self.token_stream = TokenStream(filename)
self.grammar = grammar
temp = ParsingTable(grammar, sentence_symbol)
self.parse_table = temp.get_table()
