def main():
rules, goal = parse_grammar(stdin)
nonterminals, terminals = classify_terms(rules)
table = build(rules, goal)
rules = label(rules)
item_sets = label(table['item_sets'])
print({
'start': item_sets[table['start']],
'finish': item_sets[table['finish']],
'shifts': {
(item_sets[state[0]], state[1]): item_sets[transition[1]] \
for state, transition in table['shifts'].items() \
if state[1] in terminals
},
'reductions': {
item_sets[state]: (rule[0], len(rule[1]), rules[rule]) \
for state, rule in table['reductions'].items()
},
'gotos': {
(item_sets[state[0]], state[1]): item_sets[transition[1]] \
for state, transition in table['shifts'].items() \
if state[1] in nonterminals
},
})
def main():
rules, goal = parse_grammar(stdin)
nonterminals, terminals = classify_terms(rules)
symbols = label(chain(nonterminals, terminals))
table = build(rules, goal)
rules = label(rules)
item_sets = label(table['item_sets'])
print('Given a grammar with the following production rules:')
print()
for rule, index in rules.items():
print('r{}. {} → {}'.format(index, rule[0], ' '.join(rule[1])))
print()
print('We can produce the following item sets, along with their transitions:')
print()
cols = [[] for i in range(5)]
for item_set, index in item_sets.items():
if item_set in table['reductions']:
reduction = table['reductions'][item_set]
rule = rules[reduction]
cols[0].append(index)
cols[1].append('. ')
cols[2].append('[' + format_reduction(reduction) + ']')
cols[3].append(' → ')
cols[4].append('r' + str(rule))
for symbol in symbols:
if (item_set, symbol) in table['shifts']:
shift = table['shifts'][(item_set, symbol)]
for item in shift[0]:
cols[0].append(index)
cols[1].append('. ')
cols[2].append('[' + str(item) + ']')
cols[3].append(' → ')
cols[4].append(item_sets[shift[1]])
tabulate(cols, lambda l: print('' + l))
print()
print('Using the transitions, we can produce the following shift-reduce table:')
print()
cols = [[None, 'State', None]] + [[None, symbol, None] for symbol in symbols]
for item_set, index in item_sets.items():
cols[0].append(index)
for symbol, symbol_index in symbols.items():
if item_set in table['reductions'] and symbol in terminals:
rule = rules[table['reductions'][item_set]]
cell = 'r' + str(rule)
elif (item_set, symbol) in table['shifts']:
transition = item_sets[table['shifts'][(item_set, symbol)][1]]
cell = ('s' if symbol in terminals else '') + str(transition)
else:
cell = ''
cols[1 + symbol_index].append(cell)
for col in cols:
col.append(None)
tabulate(cols, lambda l: print('| ' + l + ' |'), ' | ')
print()
def main():
rules, goal = parse_grammar(stdin)
nonterminals, terminals = classify_terms(rules)
symbols = label(chain(nonterminals, terminals))
table = build(rules, goal)
rules = label(rules)
item_sets = label(table["item_sets"])
print("Given a grammar with the following production rules:")
print()
for rule, index in rules.items():
print("r{}. {} → {}".format(index, rule[0], " ".join(rule[1])))
print()
print("We can produce the following item sets, along with their transitions:")
print()
cols = [[] for i in range(5)]
for item_set, index in item_sets.items():
if item_set in table["reductions"]:
reduction = table["reductions"][item_set]
rule = rules[reduction]
cols[0].append(index)
cols[1].append(". ")
cols[2].append("[" + format_reduction(reduction) + "]")
cols[3].append(" → ")
cols[4].append("r" + str(rule))
for symbol in symbols:
if (item_set, symbol) in table["shifts"]:
shift = table["shifts"][(item_set, symbol)]
for item in shift[0]:
cols[0].append(index)
cols[1].append(". ")
cols[2].append("[" + str(item) + "]")
cols[3].append(" → ")
cols[4].append(item_sets[shift[1]])
tabulate(cols, lambda l: print("" + l))
print()
print("Using the transitions, we can produce the following shift-reduce table:")
print()
cols = [[None, "State", None]] + [[None, symbol, None] for symbol in symbols]
for item_set, index in item_sets.items():
cols[0].append(index)
for symbol, symbol_index in symbols.items():
if item_set in table["reductions"] and symbol in terminals:
rule = rules[table["reductions"][item_set]]
cell = "r" + str(rule)
elif (item_set, symbol) in table["shifts"]:
transition = item_sets[table["shifts"][(item_set, symbol)][1]]
cell = ("s" if symbol in terminals else "") + str(transition)
else:
cell = ""
cols[1 + symbol_index].append(cell)
for col in cols:
col.append(None)
tabulate(cols, lambda l: print("| " + l + " |"), " | ")
print()