1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
from __future__ import absolute_import
import unittest
from lark import Lark
from lark.lexer import Token
from lark.tree import Tree
from lark.visitors import Visitor, Transformer, Discard
from lark.parsers.earley_forest import TreeForestTransformer, handles_ambiguity
class TestTreeForestTransformer(unittest.TestCase):
grammar = """
start: ab bc cd
!ab: "A" "B"?
!bc: "B"? "C"?
!cd: "C"? "D"
"""
parser = Lark(grammar, parser='earley', ambiguity='forest')
forest = parser.parse("ABCD")
def test_identity_resolve_ambiguity(self):
l = Lark(self.grammar, parser='earley', ambiguity='resolve')
tree1 = l.parse("ABCD")
tree2 = TreeForestTransformer(resolve_ambiguity=True).transform(self.forest)
self.assertEqual(tree1, tree2)
def test_identity_explicit_ambiguity(self):
l = Lark(self.grammar, parser='earley', ambiguity='explicit')
tree1 = l.parse("ABCD")
tree2 = TreeForestTransformer(resolve_ambiguity=False).transform(self.forest)
self.assertEqual(tree1, tree2)
def test_tree_class(self):
class CustomTree(Tree):
pass
class TreeChecker(Visitor):
def __default__(self, tree):
assert isinstance(tree, CustomTree)
tree = TreeForestTransformer(resolve_ambiguity=False, tree_class=CustomTree).transform(self.forest)
TreeChecker().visit(tree)
def test_token_calls(self):
visited = [False] * 4
class CustomTransformer(TreeForestTransformer):
def A(self, node):
assert node.type == 'A'
visited[0] = True
def B(self, node):
assert node.type == 'B'
visited[1] = True
def C(self, node):
assert node.type == 'C'
visited[2] = True
def D(self, node):
assert node.type == 'D'
visited[3] = True
tree = CustomTransformer(resolve_ambiguity=False).transform(self.forest)
assert visited == [True] * 4
def test_default_token(self):
token_count = [0]
class CustomTransformer(TreeForestTransformer):
def __default_token__(self, node):
token_count[0] += 1
assert isinstance(node, Token)
tree = CustomTransformer(resolve_ambiguity=True).transform(self.forest)
self.assertEqual(token_count[0], 4)
def test_rule_calls(self):
visited_start = [False]
visited_ab = [False]
visited_bc = [False]
visited_cd = [False]
class CustomTransformer(TreeForestTransformer):
def start(self, data):
visited_start[0] = True
def ab(self, data):
visited_ab[0] = True
def bc(self, data):
visited_bc[0] = True
def cd(self, data):
visited_cd[0] = True
tree = CustomTransformer(resolve_ambiguity=False).transform(self.forest)
self.assertTrue(visited_start[0])
self.assertTrue(visited_ab[0])
self.assertTrue(visited_bc[0])
self.assertTrue(visited_cd[0])
def test_default_rule(self):
rule_count = [0]
class CustomTransformer(TreeForestTransformer):
def __default__(self, name, data):
rule_count[0] += 1
tree = CustomTransformer(resolve_ambiguity=True).transform(self.forest)
self.assertEqual(rule_count[0], 4)
def test_default_ambig(self):
ambig_count = [0]
class CustomTransformer(TreeForestTransformer):
def __default_ambig__(self, name, data):
if len(data) > 1:
ambig_count[0] += 1
tree = CustomTransformer(resolve_ambiguity=False).transform(self.forest)
self.assertEqual(ambig_count[0], 1)
def test_handles_ambiguity(self):
class CustomTransformer(TreeForestTransformer):
@handles_ambiguity
def start(self, data):
assert isinstance(data, list)
assert len(data) == 4
for tree in data:
assert tree.data == 'start'
return 'handled'
@handles_ambiguity
def ab(self, data):
assert isinstance(data, list)
assert len(data) == 1
assert data[0].data == 'ab'
tree = CustomTransformer(resolve_ambiguity=False).transform(self.forest)
self.assertEqual(tree, 'handled')
def test_discard(self):
class CustomTransformer(TreeForestTransformer):
def bc(self, data):
return Discard
def D(self, node):
return Discard
class TreeChecker(Transformer):
def bc(self, children):
assert False
def D(self, token):
assert False
tree = CustomTransformer(resolve_ambiguity=False).transform(self.forest)
TreeChecker(visit_tokens=True).transform(tree)
def test_aliases(self):
visited_ambiguous = [False]
visited_full = [False]
class CustomTransformer(TreeForestTransformer):
@handles_ambiguity
def start(self, data):
for tree in data:
assert tree.data == 'ambiguous' or tree.data == 'full'
def ambiguous(self, data):
visited_ambiguous[0] = True
assert len(data) == 3
assert data[0].data == 'ab'
assert data[1].data == 'bc'
assert data[2].data == 'cd'
return self.tree_class('ambiguous', data)
def full(self, data):
visited_full[0] = True
assert len(data) == 1
assert data[0].data == 'abcd'
return self.tree_class('full', data)
grammar = """
start: ab bc cd -> ambiguous
| abcd -> full
!ab: "A" "B"?
!bc: "B"? "C"?
!cd: "C"? "D"
!abcd: "ABCD"
"""
l = Lark(grammar, parser='earley', ambiguity='forest')
forest = l.parse('ABCD')
tree = CustomTransformer(resolve_ambiguity=False).transform(forest)
self.assertTrue(visited_ambiguous[0])
self.assertTrue(visited_full[0])
def test_transformation(self):
class CustomTransformer(TreeForestTransformer):
def __default__(self, name, data):
result = []
for item in data:
if isinstance(item, list):
result += item
else:
result.append(item)
return result
def __default_token__(self, node):
return node.lower()
def __default_ambig__(self, name, data):
return data[0]
result = CustomTransformer(resolve_ambiguity=False).transform(self.forest)
expected = ['a', 'b', 'c', 'd']
self.assertEqual(result, expected)
if __name__ == '__main__':
unittest.main()
|
