def test_empty_words(self):
grammar = gmr.Grammar(gmr.Rule('N', ['Nothing'], preterminal=True))
words = []
parser = psr.EarleyParser(grammar)
trees = parser.parse(words)
self.assertEqual(0, len(trees))
self.assertEqual([], trees)
def test_empty_grammar(self):
grammar = gmr.Grammar()
words = ['Something']
parser = psr.EarleyParser(grammar)
trees = parser.parse(words)
self.assertEqual(0, len(trees))
self.assertEqual([], trees)
def test_regex_rule(self):
grammar = gmr.Grammar(
gmr.Rule('S', [gmr.Regex(r'[a-z]')], preterminal=True))
words = ['hello']
parser = psr.EarleyParser(grammar)
trees = parser.parse(words)
self.assertEqual(1, len(trees))
self.assertEqual([['S', 'hello']], trees)
def test_ambiguity(self):
grammar = gmr.Grammar(
gmr.Rule('S', ['NP', 'VP']), gmr.Rule('NP', ['Det', 'Nominal']),
gmr.Rule('NP', ['Det', 'Nominal', 'PP']),
gmr.Rule('NP', ['Nominal']), gmr.Rule('VP', ['VP', 'PP']),
gmr.Rule('VP', ['V', 'NP']), gmr.Rule('PP', ['Prep', 'NP']),
gmr.Rule('Det', ['a'], preterminal=True),
gmr.Rule('Nominal', ['I'], preterminal=True),
gmr.Rule('Nominal', ['man'], preterminal=True),
gmr.Rule('Nominal', ['telescope'], preterminal=True),
gmr.Rule('V', ['saw'], preterminal=True),
gmr.Rule('Prep', ['with'], preterminal=True))
words = ['I', 'saw', 'a', 'man', 'with', 'a', 'telescope']
parser = psr.EarleyParser(grammar)
trees = parser.parse(words)
self.assertEqual(2, len(trees))
self.assertEqual(
[
# ... saw ... with a telescope
[
'S', ['NP', ['Nominal', 'I']],
[
'VP',
[
'VP', ['V', 'saw'],
['NP', ['Det', 'a'], ['Nominal', 'man']]
],
[
'PP', ['Prep', 'with'],
['NP', ['Det', 'a'], ['Nominal', 'telescope']]
]
]
],
# ... man with a telescope
[
'S', ['NP', ['Nominal', 'I']],
[
'VP', ['V', 'saw'],
[
'NP', ['Det', 'a'], ['Nominal', 'man'],
[
'PP', ['Prep', 'with'],
['NP', ['Det', 'a'], ['Nominal', 'telescope']]
]
]
]
]
],
trees)
def test_multiple_parses(self):
grammar = gmr.Grammar(gmr.Rule('N', ['I'], preterminal=True),
gmr.Rule('V', ['made'], preterminal=True),
gmr.Rule('N', ['her'], preterminal=True),
gmr.Rule('V', ['duck'], preterminal=True),
gmr.Rule('N', ['duck'], preterminal=True),
gmr.Rule('S', ['N', 'V', 'N', 'V']),
gmr.Rule('S', ['N', 'V', 'N', 'N']))
words = ['I', 'made', 'her', 'duck']
parser = psr.EarleyParser(grammar)
trees = parser.parse(words)
self.assertEqual(2, len(trees))
self.assertEqual(
[['S', ['N', 'I'], ['V', 'made'], ['N', 'her'], ['V', 'duck']],
['S', ['N', 'I'], ['V', 'made'], ['N', 'her'], ['N', 'duck']]],
trees)
def test_programming_language_parsing(self):
grammar = gmr.Grammar(gmr.Rule('program',
['variable', 'operator', 'value']),
gmr.Rule('variable', [gmr.Regex(r'x')],
preterminal=True),
gmr.Rule('operator', [gmr.Regex(r'[+\-=*/]')],
preterminal=True),
gmr.Rule('value', [gmr.Regex(r'\d+')],
preterminal=True),
distinguished_symbol='program')
words = ['x', '=', '599993949']
parser = psr.EarleyParser(grammar)
trees = parser.parse(words)
self.assertEqual([[
'program', ['variable', 'x'], ['operator', '='],
['value', '599993949']
]], trees)
def test_parse(self):
grammar = gmr.Grammar(
gmr.Rule('S', ['VP']), gmr.Rule('VP', ['V', 'NP']),
gmr.Rule('NP', ['Det', 'Nominal']),
gmr.Rule('Det', ['that'], preterminal=True),
gmr.Rule('Nominal', ['flight'], preterminal=True),
gmr.Rule('V', ['Book'], preterminal=True))
words = ['Book', 'that', 'flight']
parser = psr.EarleyParser(grammar)
trees = parser.parse(words)
self.assertEqual([[
'S',
[
'VP', ['V', 'Book'],
['NP', ['Det', 'that'], ['Nominal', 'flight']]
]
]], trees)