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
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
|
# Production rules:
# stream ::= implicit_document? explicit_document* END
# explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END?
# implicit_document ::= block_node DOCUMENT-END?
# block_node ::= ALIAS | properties? block_content
# flow_node ::= ALIAS | properties? flow_content
# properties ::= TAG ANCHOR? | ANCHOR TAG?
# block_content ::= block_collection | flow_collection | SCALAR
# flow_content ::= flow_collection | SCALAR
# block_collection ::= block_sequence | block_mapping
# block_sequence ::= BLOCK-SEQUENCE-START (ENTRY block_node?)* BLOCK-END
# block_mapping ::= BLOCK-MAPPING_START ((KEY block_node_or_indentless_sequence?)? (VALUE block_node_or_indentless_sequence?)?)* BLOCK-END
# block_node_or_indentless_sequence ::= ALIAS | properties? (block_content | indentless_block_sequence)
# indentless_block_sequence ::= (ENTRY block_node?)+
# flow_collection ::= flow_sequence | flow_mapping
# flow_sequence ::= FLOW-SEQUENCE-START (flow_sequence_entry ENTRY)* flow_sequence_entry? FLOW-SEQUENCE-END
# flow_mapping ::= FLOW-MAPPING-START flow_mapping_entry ENTRY)* flow_mapping_entry? FLOW-MAPPING-END
# flow_sequence_entry ::= flow_node | KEY flow_node (VALUE flow_node?)?
# flow_mapping_entry ::= flow_node | KEY flow_node (VALUE flow_node?)?
# FIRST(rule) sets:
# stream: {}
# explicit_document: { DIRECTIVE DOCUMENT-START }
# implicit_document: block_node
# block_node: { ALIAS TAG ANCHOR SCALAR BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START }
# flow_node: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START }
# block_content: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
# flow_content: { FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
# block_collection: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START }
# flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
# block_sequence: { BLOCK-SEQUENCE-START }
# block_mapping: { BLOCK-MAPPING-START }
# block_node_or_indentless_sequence: { ALIAS ANCHOR TAG SCALAR BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START ENTRY }
# indentless_sequence: { ENTRY }
# flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
# flow_sequence: { FLOW-SEQUENCE-START }
# flow_mapping: { FLOW-MAPPING-START }
# flow_sequence_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START KEY }
# flow_mapping_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START KEY }
from error import YAMLError
from tokens import *
class ParserError(YAMLError):
pass
class Node:
def __repr__(self):
args = []
for attribute in ['anchor', 'tag', 'value']:
if hasattr(self, attribute):
args.append(repr(getattr(self, attribute)))
return "%s(%s)" % (self.__class__.__name__, ', '.join(args))
class AliasNode(Node):
def __init__(self, anchor):
self.anchor = anchor
class ScalarNode(Node):
def __init__(self, anchor, tag, value):
self.anchor = anchor
self.tag = tag
self.value = value
class SequenceNode(Node):
def __init__(self, anchor, tag, value):
self.anchor = anchor
self.tag = tag
self.value = value
class MappingNode(Node):
def __init__(self, anchor, tag, value):
self.anchor = anchor
self.tag = tag
self.value = value
class Parser:
def __init__(self, scanner):
self.scanner = scanner
def is_token(self, *choices):
token = self.scanner.peek_token()
for choice in choices:
if isinstance(token, choices):
return True
return False
def get_token(self):
return self.scanner.get_token()
def parse(self):
return self.parse_stream()
def parse_stream(self):
documents = []
if not self.is_token(DirectiveToken, DocumentStartToken, StreamEndToken):
documents.append(self.parse_block_node())
while not self.is_token(StreamEndToken):
while self.is_token(DirectiveToken):
self.get_token()
if not self.is_token(DocumentStartToken):
self.fail('DOCUMENT-START is expected')
self.get_token()
if self.is_token(DirectiveToken,
DocumentStartToken, DocumentEndToken, StreamEndToken):
documents.append(None)
else:
documents.append(self.parse_block_node())
while self.is_token(DocumentEndToken):
self.get_token()
if not self.is_token(StreamEndToken):
self.fail("STREAM-END is expected")
return documents
def parse_block_node(self):
return self.parse_node(block=True)
def parse_flow_node(self):
return self.parse_node()
def parse_block_node_or_indentless_sequence(self):
return self.parse_node(block=True, indentless_sequence=True)
def parse_node(self, block=False, indentless_sequence=False):
if self.is_token(AliasToken):
token = self.get_token()
return AliasNode(token.value)
anchor = None
tag = None
if self.is_token(AnchorToken):
anchor = self.get_token().value
if self.is_token(TagToken):
tag = self.get_token().value
elif self.is_token(TagToken):
tag = self.get_token().value
if self.is_token(AnchorToken):
anchor = self.get_token().value
if indentless_sequence and self.is_token(EntryToken):
NodeClass = SequenceNode
value = self.parse_indentless_sequence()
else:
if self.is_token(ScalarToken):
NodeClass = ScalarNode
elif self.is_token(BlockSequenceStartToken, FlowSequenceStartToken):
NodeClass = SequenceNode
elif self.is_token(BlockMappingStartToken, FlowMappingStartToken):
NodeClass = MappingNode
if block:
value = self.parse_block_content()
else:
value = self.parse_flow_content()
return NodeClass(anchor, tag, value)
def parse_block_content(self):
if self.is_token(ScalarToken):
return self.get_token().value
elif self.is_token(BlockSequenceStartToken):
return self.parse_block_sequence()
elif self.is_token(BlockMappingStartToken):
return self.parse_block_mapping()
elif self.is_token(FlowSequenceStartToken):
return self.parse_flow_sequence()
elif self.is_token(FlowMappingStartToken):
return self.parse_flow_mapping()
else:
self.fail('block content is expected')
def parse_flow_content(self):
if self.is_token(ScalarToken):
return self.get_token().value
elif self.is_token(FlowSequenceStartToken):
return self.parse_flow_sequence()
elif self.is_token(FlowMappingStartToken):
return self.parse_flow_mapping()
else:
self.fail('flow content is expected')
def parse_block_sequence(self):
sequence = []
if not self.is_token(BlockSequenceStartToken):
self.fail('BLOCK-SEQUENCE-START is expected')
self.get_token()
while self.is_token(EntryToken):
self.get_token()
if not self.is_token(EntryToken, BlockEndToken):
sequence.append(self.parse_block_node())
else:
sequence.append(None)
if not self.is_token(BlockEndToken):
self.fail('BLOCK-END is expected')
self.get_token()
return sequence
def parse_indentless_sequence(self):
sequence = []
while self.is_token(EntryToken):
self.get_token()
if not self.is_token(EntryToken):
sequence.append(self.parse_block_node())
else:
sequence.append(None)
return sequence
def parse_block_mapping(self):
mapping = []
if not self.is_token(BlockMappingStartToken):
self.fail('BLOCK-MAPPING-START is expected')
self.get_token()
while self.is_token(KeyToken, ValueToken):
key = None
value = None
if self.is_token(KeyToken):
self.get_token()
if not self.is_token(KeyToken, ValueToken, BlockEndToken):
key = self.parse_block_node_or_indentless_sequence()
if self.is_token(ValueToken):
self.get_token()
if not self.is_token(KeyToken, ValueToken, BlockEndToken):
value = self.parse_block_node_or_indentless_sequence()
mapping.append((key, value))
if not self.is_token(BlockEndToken):
self.fail('BLOCK-END is expected')
self.get_token()
return mapping
def parse_flow_sequence(self):
sequence = []
if not self.is_token(FlowSequenceStartToken):
self.fail('FLOW-SEQUENCE-START is expected')
self.get_token()
while not self.is_token(FlowSequenceEndToken):
if self.is_token(KeyToken):
self.get_token()
key = None
value = None
if not self.is_token(ValueToken):
key = self.parse_flow_node()
if self.is_token(ValueToken):
self.get_token()
if not self.is_token(EntryToken, FlowSequenceEndToken):
value = self.parse_flow_node()
node = MappingNode(None, None, [(key, value)])
sequence.append(node)
else:
sequence.append(self.parse_flow_node())
if not self.is_token(EntryToken, FlowSequenceEndToken):
self.fail("ENTRY or FLOW-SEQUENCE-END are expected")
if self.is_token(EntryToken):
self.get_token()
if not self.is_token(FlowSequenceEndToken):
self.fail('FLOW-SEQUENCE-END is expected')
self.get_token()
return sequence
def parse_flow_mapping(self):
mapping = []
if not self.is_token(FlowMappingStartToken):
self.fail('FLOW-MAPPING-START is expected')
self.get_token()
while not self.is_token(FlowMappingEndToken):
if self.is_token(KeyToken):
self.get_token()
key = None
value = None
if not self.is_token(ValueToken):
key = self.parse_flow_node()
if self.is_token(ValueToken):
self.get_token()
if not self.is_token(EntryToken, FlowMappingEndToken):
value = self.parse_flow_node()
mapping.append((key, value))
else:
mapping.append((self.parse_flow_node(), None))
if not self.is_token(EntryToken, FlowMappingEndToken):
self.fail("ENTRY or FLOW-MAPPING-END are expected")
if self.is_token(EntryToken):
self.get_token()
if not self.is_token(FlowMappingEndToken):
self.fail('FLOW-MAPPING-END is expected')
self.get_token()
return mapping
def fail(self, message):
marker = self.scanner.peek_token().start_marker
raise ParserError(message+':\n'+marker.get_snippet())
|
