def demo():
from en.parser.nltk_lite.parse import cfg
nonterminals = 'S VP NP PP P N Name V Det'
(S, VP, NP, PP, P, N, Name, V,
Det) = [cfg.Nonterminal(s) for s in nonterminals.split()]
grammar = cfg.parse_grammar("""
S -> NP VP
PP -> P NP
PP -> 'up' 'over' NP
NP -> Det N
NP -> NP PP
VP -> V NP
VP -> VP PP
Det -> 'a'
Det -> 'the'
Det -> 'my'
NP -> 'I'
N -> 'dog'
N -> 'man'
N -> 'park'
N -> 'statue'
V -> 'saw'
P -> 'in'
P -> 'with'
""")
def cb(grammar):
print(grammar)
top = Tk()
editor = CFGEditor(top, grammar, cb)
Label(top, text='\nTesting CFG Editor\n').pack()
Button(top, text='Quit', command=top.destroy).pack()
top.mainloop()
def demo2():
from en.parser.nltk_lite.parse import cfg
nonterminals = 'S VP NP PP P N Name V Det'
(S, VP, NP, PP, P, N, Name, V,
Det) = [cfg.Nonterminal(s) for s in nonterminals.split()]
productions = (
# Syntactic Productions
cfg.Production(S, [NP, VP]),
cfg.Production(NP, [Det, N]),
cfg.Production(NP, [NP, PP]),
cfg.Production(VP, [VP, PP]),
cfg.Production(VP, [V, NP, PP]),
cfg.Production(VP, [V, NP]),
cfg.Production(PP, [P, NP]),
cfg.Production(PP, []),
cfg.Production(PP, ['up', 'over', NP]),
# Lexical Productions
cfg.Production(NP, ['I']),
cfg.Production(Det, ['the']),
cfg.Production(Det, ['a']),
cfg.Production(N, ['man']),
cfg.Production(V, ['saw']),
cfg.Production(P, ['in']),
cfg.Production(P, ['with']),
cfg.Production(N, ['park']),
cfg.Production(N, ['dog']),
cfg.Production(N, ['statue']),
cfg.Production(Det, ['my']),
)
grammar = cfg.Grammar(S, productions)
text = 'I saw a man in the park'.split()
d = CFGDemo(grammar, text)
d.mainloop()
def _child_names(tree):
names = []
for child in tree:
if isinstance(child, Tree):
names.append(cfg.Nonterminal(child.node))
else:
names.append(child)
return names
def _trace_stack(self, stack, remaining_text, marker=' '):
"""
Print trace output displaying the given stack and text.
@rtype: C{None}
@param marker: A character that is printed to the left of the
stack. This is used with trace level 2 to print 'S'
before shifted stacks and 'R' before reduced stacks.
"""
str = ' ' + marker + ' [ '
for elt in stack:
if isinstance(elt, Tree):
str += ` cfg.Nonterminal(elt.node) ` + ' '
else:
str += ` elt ` + ' '
str += '* ' + ' '.join(remaining_text) + ']'
print str
def grammar(terminals):
(S, Star, Plus, Qmk, Paren) = [cfg.Nonterminal(s) for s in 'S*+?(']
rules = [pcfg.Production(S, [Star], prob=0.2),
pcfg.Production(S, [Plus], prob=0.2),
pcfg.Production(S, [Qmk], prob=0.2),
pcfg.Production(S, [Paren], prob=0.2),
pcfg.Production(S, [S, S], prob=0.1),
pcfg.Production(Star, [S, '*'], prob=1),
pcfg.Production(Plus, [S, '+'], prob=1),
pcfg.Production(Qmk, [S, '?'], prob=1),
pcfg.Production(Paren, ['(', S, ')'], prob=1)]
prob_term = 0.1/len(terminals) # divide remaining pr. mass
for terminal in terminals:
rules.append(pcfg.Production(S, [terminal], prob=prob_term))
return pcfg.Grammar(S, rules)
def _trace_fringe(self, tree, treeloc=None):
"""
Print trace output displaying the fringe of C{tree}. The
fringe of C{tree} consists of all of its leaves and all of
its childless subtrees.
@rtype: C{None}
"""
if treeloc == (): print "*",
if isinstance(tree, Tree):
if len(tree) == 0: print `cfg.Nonterminal(tree.node)`,
for i in range(len(tree)):
if treeloc is not None and i == treeloc[0]:
self._trace_fringe(tree[i], treeloc[1:])
else:
self._trace_fringe(tree[i])
else:
print `tree`,
def productions(self):
"""
Generate the productions that correspond to the non-terminal nodes of the tree.
For each subtree of the form (P: C1 C2 ... Cn) this produces a production of the
form P -> C1 C2 ... Cn.
@rtype: list of C{cfg.Production}s
"""
if not isinstance(self.node, str):
raise TypeError, 'Productions can only be generated from trees having node labels that are strings'
prods = [
cfg.Production(cfg.Nonterminal(self.node), _child_names(self))
]
for child in self:
if isinstance(child, Tree):
prods += child.productions()
return prods
def demo():
"""
Create a shift reduce parser demo, using a simple grammar and
text.
"""
from en.parser.nltk_lite.parse import cfg
nonterminals = 'S VP NP PP P N Name V Det'
(S, VP, NP, PP, P, N, Name, V,
Det) = [cfg.Nonterminal(s) for s in nonterminals.split()]
productions = (
# Syntactic Productions
cfg.Production(S, [NP, VP]),
cfg.Production(NP, [Det, N]),
cfg.Production(NP, [NP, PP]),
cfg.Production(VP, [VP, PP]),
cfg.Production(VP, [V, NP, PP]),
cfg.Production(VP, [V, NP]),
cfg.Production(PP, [P, NP]),
# Lexical Productions
cfg.Production(NP, ['I']),
cfg.Production(Det, ['the']),
cfg.Production(Det, ['a']),
cfg.Production(N, ['man']),
cfg.Production(V, ['saw']),
cfg.Production(P, ['in']),
cfg.Production(P, ['with']),
cfg.Production(N, ['park']),
cfg.Production(N, ['dog']),
cfg.Production(N, ['statue']),
cfg.Production(Det, ['my']),
)
grammar = cfg.Grammar(S, productions)
# tokenize the sentence
sent = list(
tokenize.whitespace('my dog saw a man in the park with a statue'))
ShiftReduceDemo(grammar, sent).mainloop()
