def demo():
from 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 demo():
"""
A demonstration showing how C{Grammar}s can be created and used.
"""
from nltk_lite.parse import cfg
# Create some nonterminals
S, NP, VP, PP = cfg.nonterminals('S, NP, VP, PP')
N, V, P, Det = cfg.nonterminals('N, V, P, Det')
VP_slash_NP = VP/NP
print 'Some nonterminals:', [S, NP, VP, PP, N, V, P, Det, VP/NP]
print ' S.symbol() =>', `S.symbol()`
print
print cfg.Production(S, [NP])
# Create some Grammar Productions
grammar = cfg.parse_grammar("""
S -> NP VP
PP -> P NP
NP -> Det N
NP -> NP PP
VP -> V NP
VP -> VP PP
Det -> 'a'
Det -> 'the'
N -> 'dog'
N -> 'cat'
V -> 'chased'
V -> 'sat'
P -> 'on'
P -> 'in'
""")
print 'A Grammar:', `grammar`
print ' grammar.start() =>', `grammar.start()`
print ' grammar.productions() =>',
# Use string.replace(...) is to line-wrap the output.
print `grammar.productions()`.replace(',', ',\n'+' '*25)
print
def demo():
"""
A demonstration showing how C{Grammar}s can be created and used.
"""
from nltk_lite.parse import cfg
# Create some nonterminals
S, NP, VP, PP = cfg.nonterminals('S, NP, VP, PP')
N, V, P, Det = cfg.nonterminals('N, V, P, Det')
VP_slash_NP = VP / NP
print 'Some nonterminals:', [S, NP, VP, PP, N, V, P, Det, VP / NP]
print ' S.symbol() =>', ` S.symbol() `
print
print cfg.Production(S, [NP])
# Create some Grammar Productions
grammar = cfg.parse_grammar("""
S -> NP VP
PP -> P NP
NP -> Det N
NP -> NP PP
VP -> V NP
VP -> VP PP
Det -> 'a'
Det -> 'the'
N -> 'dog'
N -> 'cat'
V -> 'chased'
V -> 'sat'
P -> 'on'
P -> 'in'
""")
print 'A Grammar:', ` grammar `
print ' grammar.start() =>', ` grammar.start() `
print ' grammar.productions() =>',
# Use string.replace(...) is to line-wrap the output.
print ` grammar.productions() `.replace(',', ',\n' + ' ' * 25)
print
from nltk_lite import tokenize
from nltk_lite.parse import cfg
from nltk_lite.draw.rdparser import RecursiveDescentDemo
productions = """
NP -> NP AND NP
NP -> N
N -> "cabbages"
N -> "kings"
AND -> "and"
"""
grammar = cfg.parse_grammar(productions)
text = list(tokenize.whitespace('cabbages and kings'))
RecursiveDescentDemo(grammar, text).mainloop()
