def generate(self):
""" Generate the expansion of the context free grammar.
Under the hood it starts from the <start> nonterminal and returns the
expansion. A production is chosen randomly from the multiproduction
non terminal.
"""
utility.debug_print(self.grammar["start"][0], "start=")
return self.__rgenerate(self.get_random_production("start"))
def generate(self):
""" Generate the expansion of the context free grammar.
Under the hood it starts from the <start> nonterminal and returns the
expansion. A production is chosen randomly from the multiproduction
non terminal.
"""
utility.debug_print(self.grammar["start"][0], "start=")
return self.__rgenerate(self.get_random_production("start"))
def __init__(self, nonterminal_start, nonterminal_end, cfgGrammar):
""" Inititalize the CFG instance.
The method takes three arguments:
nonterminal_start -- the starting delimiter of the non terminal
nonterminal_end -- the ending delimiter of the non terminal
cfgGrammar -- recieves a grammar as dictionary object. Program exits
if not not provided
"""
if not cfgGrammar:
print "Grammar not provided."
sys.exit(0)
self.grammar = cfgGrammar
self.nonterminal_start = nonterminal_start
self.nonterminal_end = nonterminal_end
utility.debug_print(self.grammar, "grammar")
def __init__(self, nonterminal_start, nonterminal_end, cfgGrammar):
""" Inititalize the CFG instance.
The method takes three arguments:
nonterminal_start -- the starting delimiter of the non terminal
nonterminal_end -- the ending delimiter of the non terminal
cfgGrammar -- recieves a grammar as dictionary object. Program exits
if not not provided
"""
if not cfgGrammar:
print "Grammar not provided."
sys.exit(0)
self.grammar = cfgGrammar
self.nonterminal_start = nonterminal_start
self.nonterminal_end = nonterminal_end
utility.debug_print(self.grammar, "grammar")
def __rgenerate(self, production):
pattern_string = (self.nonterminal_start +
'(?P<nonterminal>\\b.+?\\b)' + self.nonterminal_end)
utility.debug_print(pattern_string, "pattern")
pattern_nt = re.compile(pattern_string)
#find a match for a not terminal in the given production
match = pattern_nt.search(production)
matched_nonterminal = match.group('nonterminal')
utility.debug_print(match.group('nonterminal'),
"matched non terminal = ")
#get a random production for the matched non terminal
substitution = self.get_random_production(matched_nonterminal)
utility.debug_print(substitution, "substitution")
#split the string around found non terminal
lst = pattern_nt.split(production, 1)
# substitute the random production for non terminal
new_production = lst[0] + substitution + lst[2]
utility.debug_print(new_production, "new_production")
# if new production still has more non terminals
if not pattern_nt.search(new_production):
return new_production
return self.__rgenerate(new_production)
def __rgenerate(self, production):
pattern_string = (self.nonterminal_start +
'(?P<nonterminal>\\b.+?\\b)' +
self.nonterminal_end)
utility.debug_print(pattern_string, "pattern")
pattern_nt = re.compile(pattern_string)
#find a match for a not terminal in the given production
match = pattern_nt.search(production)
matched_nonterminal = match.group('nonterminal')
utility.debug_print(match.group('nonterminal'),
"matched non terminal = ")
#get a random production for the matched non terminal
substitution = self. get_random_production(matched_nonterminal)
utility.debug_print(substitution, "substitution")
#split the string around found non terminal
lst = pattern_nt.split(production, 1)
# substitute the random production for non terminal
new_production = lst[0] + substitution + lst[2]
utility.debug_print(new_production, "new_production")
# if new production still has more non terminals
if not pattern_nt.search(new_production):
return new_production
return self.__rgenerate(new_production)
