def test_parse_with_ambiguity(self):
# Define new rules
rules = ['S->NP | VP', 'NP->book', 'VP->book']
earley = EarleyParser(Grammar(rules))
earley.parse('book')
self.assertIn(State(earley.DUMMY_CHAR,['S'],1,0,1), earley.chart[1])
self.assertIn(State('S',['NP'],1,0,1), earley.chart[1])
self.assertIn(State('S',['VP'],1,0,1), earley.chart[1])
self.assertItemsEqual([Tree('S', [Tree('NP', ['book'])]), Tree('S', [Tree('VP', ['book'])])], earley.tree())
print earley.tree()
class TestEarleyParser(TestCase):
def setUp(self):
rules = [
'S -> NP VP',
'NP -> Det N',
'VP -> VT NP',
'VP -> VI PP',
'PP -> P NP',
'Det -> a',
'N -> circle | square | triangle',
'VT -> touches',
'VI -> is',
'P -> above | below'
]
grammar = Grammar(rules)
self.earley = EarleyParser(grammar)
self.earley.words = 'a circle touches a triangle'.split(' ')
self.earley.chart = [[] for _ in range(5)]
def test_parse(self):
"""A complete parse"""
self.earley.parse('a circle touches a triangle')
chart = []
chart.append([State(self.earley.DUMMY_CHAR,['S'],0,0,0),State('S',['NP','VP'],0,0,0),State('NP',['Det','N'],0,0,0)])
chart.append([State('Det',['a'],1,0,1),State('NP', ['Det','N'],1,0,1)])
chart.append([State('N', ['circle'],1,1,2),State('NP',['Det','N'],2,0,2),State('S',['NP','VP'],1,0,2),State('VP',['VT','NP'],0,2,2),State('VP',['VI','PP'],0,2,2)])
chart.append([State('VT', ['touches'],1,2,3),State('VP',['VT','NP'],1,2,3),State('NP', ['Det','N'],0,3,3)])
chart.append([State('Det',['a'],1,3,4),State('NP',['Det','N'],1,3,4)])
chart.append([State('N',['triangle'],1,4,5),State('NP',['Det','N'],2,3,5),State('VP',['VT','NP'],2,2,5),State('S',['NP','VP'],2,0,5),State(self.earley.DUMMY_CHAR,['S'],1,0,5)])
self.assertItemsEqual(chart,self.earley.chart)
def test_predictor(self):
self.assertEqual(len(self.earley.chart[0]), 0)
# Call predictor
state = State('S', ['VP'], 0, 0, 0)
self.earley.predictor(state)
self.assertEqual(len(self.earley.chart[0]), 2)
self.assertIn(State('VP', ['VT', 'NP'], 0, 0, 0), self.earley.chart[0])
self.assertIn(State('VP', ['VI', 'PP'], 0, 0, 0), self.earley.chart[0])
def test_scanner(self):
state1 = State('NP', ['Det', 'N'], 1, 0, 1)
state2 = State('VP', ['VT', 'NP'], 1, 0, 1)
# Scan these states
self.earley.scanner(state1)
self.earley.scanner(state2)
# Expect only `state1` to have added a new state
self.assertIn(State('N', ['circle'], 1, 1, 2), self.earley.chart[2])
self.assertEqual(1, len(self.earley.chart[2]))
def test_completer(self):
state1 = State('NP', ['Det', 'N'], 0, 0, 0)
self.earley.chart[0].append(state1)
state2 = State('Det', ['a'], 1, 0, 1)
self.earley.completer(state2)
self.assertIn(State('NP', ['Det', 'N'], 1, 0, 1), self.earley.chart[1])
def test_enqueue(self):
state = State('S', ['VP'], 0, 0, 0)
self.earley.enqueue(state, 0)
self.earley.enqueue(state, 1)
self.assertEqual(len(self.earley.chart[0]), 1)
self.assertEqual(len(self.earley.chart[1]), 1, "Doesn't add duplicates")
self.assertEqual(len(self.earley.chart[2]), 0)
self.earley.enqueue(State('VP', ['V'], 0, 0, 0), 1)
self.assertEqual(len(self.earley.chart[1]), 2)
def test_tree(self):
# No parse for sentence
self.earley.parse('Not valid')
self.assertEqual('Not valid', self.earley.tree())
# Sentence has parse
self.earley.parse('a circle touches a triangle')
actual = self.earley.tree()
expected = Tree('S', [Tree('NP', [Tree('Det', ['a']), Tree('N', ['circle'])]), Tree('VP', [Tree('VT', ['touches']), Tree('NP', [Tree('Det', ['a']), Tree('N', ['triangle'])])])])
self.assertEqual([expected], actual)
def test_parse_with_ambiguity(self):
# Define new rules
rules = ['S->NP | VP', 'NP->book', 'VP->book']
earley = EarleyParser(Grammar(rules))
earley.parse('book')
self.assertIn(State(earley.DUMMY_CHAR,['S'],1,0,1), earley.chart[1])
self.assertIn(State('S',['NP'],1,0,1), earley.chart[1])
self.assertIn(State('S',['VP'],1,0,1), earley.chart[1])
self.assertItemsEqual([Tree('S', [Tree('NP', ['book'])]), Tree('S', [Tree('VP', ['book'])])], earley.tree())
print earley.tree()