So I need help in trying to compute the First/Follow functions in Python for Context Free Grammars. What I understand is that for each terminal, the FIRST for that terminal will just be the terminal itself.

But for non-terminals, it should iterate through each production rule until it finds either epsilon(null) or a terminal. I wrote code based on this understanding but I'm stuck in trying to iterate through production rules and properly update the nonterminals to their FIRST[] value. Any help would be appreciated.

This is what I've done so far. In the pseudocode I'm following, the last loop in the computeFirst function should keep executing until no changes happen anymore. I thought to implemement that I would create another variable which saves the state of FIRST[x] and keeps checking back with it to see if there was a change

#'e' is epsilon 
NONTERMS = ['S','E','E^','A','T','T^','M','F']
TERMS = [' ','-','*','(',')','n']
FIRST ={}
grammar = {'E':[['T','E^']],
           'E^':[['A','T','E^'],['e']],
           'A':[[' '],['-']],
           'T':[['F','T^']],
           'T^':[['M','F','T^'],['e']],
           'M':[['*']],
           'F':[['(','E',')'],['n']]}

def computeFirst(g):
    for a in TERMS:
        FIRST[a]=[a]

    for i in NONTERMS:
        FIRST[i]=[]

    for x in g:
        for i in g[x]:
            FIRST[i]=computeFirstOfList[i]

def computeFirstOfList(p):
    tmp=[]
    k=0
    n=len(p)


computeFirst(grammar)