def exp_probabilities(expansions, nonterminal="<symbol>"):
probabilities = [exp_prob(expansion) for expansion in expansions]
prob_dist = prob_distribution(probabilities, nonterminal)
prob_mapping = {}
for i in range(len(expansions)):
expansion = exp_string(expansions[i])
prob_mapping[expansion] = prob_dist[i]
return prob_mapping
def find_expansion(self, tree):
symbol, children = tree
applied_expansion = \
"".join([child_symbol for child_symbol, _ in children])
for expansion in self.grammar[symbol]:
if exp_string(expansion) == applied_expansion:
return expansion
raise KeyError(symbol + ": did not find expansion " +
repr(applied_expansion))
def expansion_to_children(expansion):
# print("Converting " + repr(expansion))
# strings contains all substrings -- both terminals and nonterminals such
# that ''.join(strings) == expansion
expansion = exp_string(expansion)
assert isinstance(expansion, str)
if expansion == "": # Special case: epsilon expansion
return [("", [])]
strings = re.split(RE_NONTERMINAL, expansion)
return [(s, None) if is_nonterminal(s) else (s, []) for s in strings
if len(s) > 0]
def replace_symbol(grammar, old_symbol, new_symbol):
"""Return a grammar in which all occurrences of `old_symbol` are replaced by `new_symbol`"""
new_grammar = {}
for symbol in grammar:
new_expansions = []
for expansion in grammar[symbol]:
new_expansion_string = exp_string(expansion).replace(old_symbol, new_symbol)
if len(exp_opts(expansion)) > 0:
new_expansion = (new_expansion_string, exp_opts(expansion))
else:
new_expansion = new_expansion_string
new_expansions.append(new_expansion)
new_grammar[symbol] = new_expansions
# Remove unused parts
for nonterminal in unreachable_nonterminals(new_grammar):
del new_grammar[nonterminal]
return new_grammar
"<digit>": ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"],
}
if __name__ == "__main__":
assert is_valid_grammar(PROBABILISTIC_EXPR_GRAMMAR,
supported_opts={'prob'})
if __name__ == "__main__":
PROBABILISTIC_EXPR_GRAMMAR["<leaddigit>"]
if __name__ == "__main__":
leaddigit_expansion = PROBABILISTIC_EXPR_GRAMMAR["<leaddigit>"][0]
leaddigit_expansion
if __name__ == "__main__":
exp_string(leaddigit_expansion)
def exp_prob(expansion):
"""Return the options of an expansion"""
return exp_opt(expansion, 'prob')
if __name__ == "__main__":
exp_prob(leaddigit_expansion)
if __name__ == "__main__":
f = GrammarFuzzer(PROBABILISTIC_EXPR_GRAMMAR)
f.fuzz()
if __package__ is None or __package__ == "":
