def get_grammar(string):
'''
function takes in lines of the grammar rules as input
returns a Grammar instance initialized with as per given grammar rules.
'''
G = Grammar()
string = string.split('\n')
#This loop reads every line for rules
for line in string:
line = line.split(" : ")
#n_term is non terminal symbol for the rule in particular line
n_term = line[0]
#add the non terminal to the set of non-terminals in G
G.add_V(n_term)
#line contains list of possble right hand productions for the n_term
line = line[1].split("|")
#remove leading-trailing whitespaces
line = map(str.strip, line)
for p in line:
#for each possible production of n_term
#add the production to the grammar
G.add_P(n_term, p)
p = p.split(" ")
for t in p:
#for every term in the production
#if term is not a non termianl, add it to the set of terminals for G
if t not in G.variables:
G.add_T(t)
#above does not ensure that all added term is not a non terminal,
#so this func below will ensure correctness
for i in G.variables:
if i in G.terminals:
G.terminals.remove(i)
G.start = G.variables[0]
return G
def get_grammar(string):
"""
function takes in lines of the grammar rules as input
returns a Grammar instance initialized with as per given grammar rules.
"""
G = Grammar()
string = string.split("\n")
# This loop reads every line for rules
for line in string:
line = line.split(" : ")
# n_term is non terminal symbol for the rule in particular line
n_term = line[0]
# add the non terminal to the set of non-terminals in G
G.add_V(n_term)
# line contains list of possble right hand productions for the n_term
line = line[1].split("|")
# remove leading-trailing whitespaces
line = map(str.strip, line)
for p in line:
# for each possible production of n_term
# add the production to the grammar
G.add_P(n_term, p)
p = p.split(" ")
for t in p:
# for every term in the production
# if term is not a non termianl, add it to the set of terminals for G
if t not in G.variables:
G.add_T(t)
# above does not ensure that all added term is not a non terminal,
# so this func below will ensure correctness
for i in G.variables:
if i in G.terminals:
G.terminals.remove(i)
G.start = G.variables[0]
return G
