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ex2.py
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ex2.py
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inp = "((e+a).b*)*"#input("")
"""
Give your input in the above variable
a and b are the only terminals accepted by this script
e denotes epsilon
. is used for "and" operation Eg. ab = a.b
+ is used for "or" operation Eg. a|b = a+b
* is the Kleene's Closure operator. You can give star operator after any closing brackets and terminals
"""
_="-"
start = 1 # denotes start of e-nfa table
end = 1 # denotes end of our table which is initially same as start
cur = 1 # denotes current position of our pointer
# this is intitial e-nfa table with only one state which is start and end both
table = [["state","epsilon","a","b"],
[1,_,_,_]]
def print_t(table):
"""
This function prints the e-nfa table
"""
i = table[0]
print(f'{i[0]: <10}'+f'| {i[1]: <10}'+f'| {i[2]: <10}'+f'| {i[3]: <10}')
print("-"*46)
for i in table[1:]:
try:
x = " ".join([str(j) for j in i[1]])
except:
x = ""
try:
y = " ".join([str(j) for j in i[2]])
except:
y = ""
try:
z = " ".join([str(j) for j in i[3]])
except:
z = ""
print(f'{i[0]: <10}'+f'| {x: <10}'+f'| {y: <10}'+f'| {z: <10}')
def e_(cur,ed=end):
"""
this fuction adds epsilon to the table
"""
temp = table[cur]
try:
table[cur] = [cur,temp[1].append(cur+1),temp[2],temp[3]]
except:
table[cur] = [cur,[cur+1],temp[2],temp[3]]
try:
nv = table([cur+1])
except:
table.append([ed+1,_,_,_])
ed+=1
return ed
def a_(cur,ed=end):
temp = table[cur]
try:
table[cur] = [cur,temp[1],temp[2].append(cur+1),temp[3]]
except:
table[cur] = [cur,temp[1],[cur+1],temp[3]]
try:
nv = table([cur+1])
except:
table.append([ed+1,_,_,_])
ed+=1
return ed
def b_(cur,ed=end):
temp = table[cur]
try:
table[cur] = [cur,temp[1],temp[2],temp[3].append(cur+1)]
except:
table[cur] = [cur,temp[1],temp[2],[cur+1]]
try:
nv = table([cur+1])
except:
table.append([ed+1,_,_,_])
ed+=1
return ed
def or_b(cur,ed=end):
temp = table[cur]
try:
table[cur] = [cur,temp[1],temp[2],temp[3].append(cur+1)]
except:
table[cur] = [cur,temp[1],temp[2],[cur+1]]
def or_a(cur,ed=end):
temp = table[cur]
try:
table[cur] = [cur,temp[1],temp[2].append(cur+1),temp[3]]
except:
table[cur] = [cur,temp[1],[cur+1],temp[3]]
def and_a(cur,ed=end):
cur+=1
temp = table[cur]
try:
table[cur] = [cur,temp[1],temp[2].append(cur+1),temp[3]]
except:
table[cur] = [cur,temp[1],[cur+1],temp[3]]
try:
nv = table([cur+1])
except:
table.append([cur+1,_,_,_])
ed+=1
return cur,ed
def and_b(cur,ed=end):
cur+=1
temp = table[cur]
try:
table[cur] = [cur,temp[1],temp[2],temp[3].append(cur+1)]
except:
table[cur] = [cur,temp[1],temp[2],[cur+1]]
try:
nv = table([cur+1])
except:
table.append([cur+1,_,_,_])
ed+=1
return cur,ed
def star(cur,ed=end):
table.append([ed+1,_,_,_])
table.append([ed+2,_,_,_])
ed+=2
for i in range(cur,ed):
temp = [table[ed-i+cur][0]]+table[ed-i+cur-1][1:4]
for j in [1,2,3]:
try:
temp[j] = [x+1 for x in table[ed-i+cur-1][j]]
except:
pass
table[ed-i+cur] = temp
table[cur]=[cur,_,_,_]
temp = table[cur]
try:
table[cur] = [temp[0],temp[1]+[cur+1,ed],temp[2],temp[3]]
except:
table[cur] = [temp[0],[cur+1,ed],temp[2],temp[3]]
temp = table[ed-1]
try:
table[ed-1] = [temp[0],temp[1]+[cur+1,ed],temp[2],temp[3]]
except:
table[ed-1] = [temp[0],[cur+1,ed],temp[2],temp[3]]
return ed-1,ed
def mod_table(inp,start,cur,end,table):
#print(inp)
k = 0
while k<len(inp):
#print(start,cur,end,k,inp[k:],len(table)-1)
if inp[k]=="a":
end = a_(cur,end)
#print("in a_")
elif inp[k]=="b":
end = b_(cur,end)
#print("in b_")
elif inp[k]=="e":
end = e_(cur,end)
elif inp[k]==".":
k+=1
if inp[k]=="a":
#k-=1
cur,end = and_a(cur,end)
elif inp[k]=="b":
cur,end = and_b(cur,end)
#k-=1
elif inp[k]=="(":
li = ["("]
l = k
for i in inp[k+1:]:
if i == "(":
li.append("(")
if i == ")":
try:
del li[-1]
except:
break
if len(li)==0:
break
l+=1
m = k
k=l+1
cur+=1
start,cur,end,table = mod_table(inp[m+1:l+1],start,cur,end,table)
elif inp[k]=="+":
k+=1
if inp[k]=="a":
or_a(cur,end)
#print("in or_a")
elif inp[k]=="b":
or_b(cur,end)
#print("in or_b")
else:
print(f"ERROR at{k }Done:{inp[:k+1]}Rem{inp[k+1:]}")
elif inp[k]=="*":
#print("in star")
cur,end = star(cur,end)
elif inp[k]=="(":
li = ["("]
l = k
for i in inp[k+1:]:
if i == "(":
li.append("(")
if i == ")":
try:
del li[-1]
except:
break
if len(li)==0:
break
l+=1
m = k
k=l+1
try:
if inp[k+1]=="*":
cur_ = cur
except:
pass
#print(inp[m+1:l+1])
start,cur,end,table = mod_table(inp[m+1:l+1],start,cur,end,table)
try:
if inp[k+1]=="*":
cur = cur_
except:
pass
else:
print(f'error{k}{inp[k]}')
k+=1
return start,cur,end,table
start,cur,end,table = mod_table(inp,start,cur,end,table)
print_t(table)