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
# -*- coding: utf-8 -*-
__author__ = 'SkywalkerAtlas'
from BNF import getBNF
def get_grammer_symbol(grammer_productions_list):
grammer_symbol = []
for each_production in grammer_productions_list:
symbols = each_production.split('->',)
if symbols[0] not in grammer_symbol:
grammer_symbol.append(symbols[0])
for symbol in symbols[1]:
if symbol not in grammer_symbol:
grammer_symbol.append(symbol)
return grammer_symbol
if __name__ == '__main__':
grammer_productions_list = getBNF('grammer.txt')
grammer_symbol = get_grammer_symbol(grammer_productions_list)
print grammer_symbol
# -*- coding: utf-8 -*-
__author__ = 'SkywalkerAtlas'
from BNF import getBNF
def get_grammer_symbol(grammer_productions_list):
grammer_symbol = []
for each_production in grammer_productions_list:
symbols = each_production.split('->', )
if symbols[0] not in grammer_symbol:
grammer_symbol.append(symbols[0])
for symbol in symbols[1]:
if symbol not in grammer_symbol:
grammer_symbol.append(symbol)
return grammer_symbol
if __name__ == '__main__':
grammer_productions_list = getBNF('grammer.txt')
grammer_symbol = get_grammer_symbol(grammer_productions_list)
print grammer_symbol
