def get_follow(file_name):
follow = {}
first = get_first(file_name)
grammer_productions_list = getBNF(file_name)
production_dist = {}
for each_production in grammer_productions_list:
left, right = each_production.split('->')
if production_dist.has_key(left):
production_dist[left].append(right)
else:
production_dist[left] = [
right,
]
grammer_symbol = get_grammer_symbol(grammer_productions_list)
#print grammer_symbol
non_terminals_list = []
terminals_list = []
for each_symbol in grammer_symbol:
if each_symbol.istitle():
non_terminals_list.append(each_symbol)
else:
terminals_list.append(each_symbol)
for each_non_symbol in non_terminals_list:
if follow.has_key(each_non_symbol):
continue
else:
follow_set = get_follow_set(each_non_symbol, production_dist,
terminals_list, non_terminals_list,
follow, first)
follow[each_non_symbol] = follow_set
return follow
def get_first(file_name):
first = {}
grammer_productions_list = getBNF(file_name)
production_dist = {}
for each_production in grammer_productions_list:
left,right = each_production.split('->')
if production_dist.has_key(left):
production_dist[left].append(right)
else:
production_dist[left] = [right,]
grammer_symbol = get_grammer_symbol(grammer_productions_list)
#print grammer_symbol
non_terminals_list = []
terminals_list = []
for each_symbol in grammer_symbol:
if each_symbol.istitle():
non_terminals_list.append(each_symbol)
else:
terminals_list.append(each_symbol)
for each_symbol in non_terminals_list:
if first.has_key(each_symbol):
continue
else:
null_first_set = set()
first_set = find_first_set(each_symbol,production_dist,terminals_list,null_first_set,first)
first[each_symbol] = first_set
for each_symbol in terminals_list:
first[each_symbol] = set([each_symbol])
return first
def gen_table(file_name):
SLR1_table = {}
items_list,grammer_productions_list = getItemCollection(file_name)
gram_symbol = get_grammer_symbol(grammer_productions_list)
C_dict = get_cannonical_collection(items_list,grammer_productions_list,gram_symbol)
follow = get_follow(file_name)
non_terminals_list = []
terminals_list = []
for each_symbol in gram_symbol:
if each_symbol.istitle():
non_terminals_list.append(each_symbol)
else:
terminals_list.append(each_symbol)
terminals_list.append('#')
for each_statu in C_dict.keys():
each_statu_for_SLR1_table_key = int(each_statu.split('_')[1])
SLR1_table[each_statu_for_SLR1_table_key] = {}
for each_item in C_dict[each_statu]:
if not each_item.endswith('`'):
char_behind = each_item[each_item.index('`')+1]
for each_goto in DFA[each_statu]:
edge_end = each_goto.strip('--')
if edge_end.startswith(char_behind):
end = edge_end.split('->I_')[1]
if char_behind in terminals_list:
SLR1_table[each_statu_for_SLR1_table_key][char_behind] = 'S'+end
else:
if char_behind not in SLR1_table[each_statu_for_SLR1_table_key].keys():
SLR1_table[each_statu_for_SLR1_table_key][char_behind] = end
elif each_item.endswith('`') and each_item.split('->')[0] != non_terminals_list[0]:
left_part = each_item.split('->')[0]
if each_item.strip('`') != grammer_productions_list[0]:
for each_a in follow[left_part]:
SLR1_table[each_statu_for_SLR1_table_key][each_a] = 'r'+str(grammer_productions_list.index(each_item.strip('`')))
else:
SLR1_table[each_statu_for_SLR1_table_key]['#'] = 'acc'
return SLR1_table
flag = 1
elif generated_item is not None:
J_n = ''
for each_i in C_dict:
if C_dict[each_i] == generated_item:
J_n = each_i
break
in_flag = 0
if DFA.has_key(each_I):
for eachiii in DFA[each_I]:
if eachiii.find(J_n) != -1:
in_flag = 1
break
if in_flag == 0:
add_to_DFA(each_I, each_grammer_symbol, J_n)
if flag == 0:
break
return C_dict
if __name__ == '__main__':
items_list, grammer_productions_list = getItemCollection("grammer.txt")
gram_symbol = get_grammer_symbol(grammer_productions_list)
C_dict = get_cannonical_collection(items_list, grammer_productions_list,
gram_symbol)
# print DFA
for each, item in C_dict.items():
print(each, item)
for each, item in DFA.items():
print each, item
from cannonical_collection import DFA
from pylsy import pylsytable
if __name__ == '__main__':
file_name = raw_input('input file name which contains grammer(eg:grammer.txt):>').strip()
# file_name = 'grammer.txt'
SLR1_tabel = gen_table(file_name)
items_list,grammer_productions_list = getItemCollection(file_name)
print 'augmented grammar is:\nG\':'
for each in grammer_productions_list:
print each
non_terminals_list = []
terminals_list = []
grammer_symbol = get_grammer_symbol(grammer_productions_list)
C_dict = get_cannonical_collection(items_list,grammer_productions_list,grammer_symbol)
for each_symbol in grammer_symbol:
if each_symbol.istitle():
non_terminals_list.append(each_symbol)
else:
terminals_list.append(each_symbol)
print '==================================================='
print 'cannonical LR(0) collection:'
for key,val in C_dict.items():
print key,val
print '==================================================='
print 'DFA:'
for key,val in DFA.items():
print key,val
