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
|
# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Canonicalizes continue statements by de-sugaring into a control boolean."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from tensorflow.python.autograph.core import converter
from tensorflow.python.autograph.pyct import anno
from tensorflow.python.autograph.pyct import templates
from tensorflow.python.autograph.pyct.static_analysis.annos import NodeAnno
# Tags for local state.
CONTROL_VAR_NAME = 'control_var_name'
CONTINUE_USED = 'continue_used'
GUARD_CREATED = 'guard_created'
CREATE_GUARD_NEXT = 'create_guard_next'
class ContinueCanonicalizationTransformer(converter.Base):
"""Canonicalizes continue statements into additional conditionals."""
def visit_Continue(self, node):
self.set_local(CONTINUE_USED, True)
template = """
var_name = tf.constant(True)
"""
return templates.replace(
template, var_name=self.get_local(CONTROL_VAR_NAME))
def _postprocess_statement(self, node):
# Example of how the state machine below works:
#
# 1| stmt # State: CONTINUE_USED = False
# | # Action: none
# 2| if cond:
# 3| continue # State: CONTINUE_USED = True,
# | # GUARD_CREATED = False,
# | # CREATE_GUARD_NEXT = False
# | # Action: set CREATE_GUARD_NEXT = True
# 4| stmt # State: CONTINUE_USED = True,
# | # GUARD_CREATED = False,
# | # CREATE_GUARD_NEXT = True
# | # Action: create `if not continue_used`,
# | # set GUARD_CREATED = True
# 5| stmt # State: CONTINUE_USED = True, GUARD_CREATED = True
# | # Action: none (will be wrapped under previously
# | # created if node)
if self.get_local(CONTINUE_USED, False):
if self.get_local(GUARD_CREATED, False):
return node, None
elif not self.get_local(CREATE_GUARD_NEXT, False):
self.set_local(CREATE_GUARD_NEXT, True)
return node, None
else:
self.set_local(GUARD_CREATED, True)
template = """
if not var_name:
original_node
"""
cond, = templates.replace(
template,
var_name=self.get_local(CONTROL_VAR_NAME),
original_node=node)
return cond, cond.body
return node, None
def _visit_loop_body(self, node, nodes):
self.enter_local_scope()
scope = anno.getanno(node, NodeAnno.BODY_SCOPE)
continue_var = self.ctx.namer.new_symbol('continue_', scope.referenced)
self.set_local(CONTROL_VAR_NAME, continue_var)
nodes = self.visit_block(nodes, after_visit=self._postprocess_statement)
if self.get_local(CONTINUE_USED, False):
template = """
var_name = tf.constant(False)
"""
control_var_init = templates.replace(template, var_name=continue_var)
nodes = control_var_init + nodes
self.exit_local_scope()
return nodes
def _visit_non_loop_body(self, nodes):
self.enter_local_scope(inherit=(CONTROL_VAR_NAME,))
nodes = self.visit_block(nodes, after_visit=self._postprocess_statement)
continue_used = self.get_local(CONTINUE_USED, False)
self.exit_local_scope(keep=(CONTINUE_USED,))
return nodes, continue_used
def visit_While(self, node):
node.test = self.visit(node.test)
node.body = self._visit_loop_body(node, node.body)
# A continue in the else clause applies to the containing scope.
node.orelse, _ = self._visit_non_loop_body(node.orelse)
return node
def visit_For(self, node):
node.target = self.generic_visit(node.target)
node.iter = self.generic_visit(node.iter)
node.body = self._visit_loop_body(node, node.body)
# A continue in the else clause applies to the containing scope.
node.orelse, _ = self._visit_non_loop_body(node.orelse)
return node
def visit_If(self, node):
node.test = self.generic_visit(node.test)
node.body, continue_used_body = self._visit_non_loop_body(node.body)
node.orelse, continue_used_orelse = self._visit_non_loop_body(node.orelse)
self.set_local(CONTINUE_USED, continue_used_body or continue_used_orelse)
return node
def visit_With(self, node):
node.items = self.visit_block(node.items)
node.body, _ = self._visit_non_loop_body(node.body)
return node
def transform(node, ctx):
return ContinueCanonicalizationTransformer(ctx).visit(node)
|
