83 lines
2.6 KiB
Python
83 lines
2.6 KiB
Python
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# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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"""Converter for slice operations."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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import gast
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from tensorflow.contrib.autograph.core import converter
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from tensorflow.contrib.autograph.pyct import anno
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from tensorflow.contrib.autograph.pyct import templates
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class SliceTransformer(converter.Base):
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"""Converts slicing operations to their TF counterpart.
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Currently, relying on the default slice operator that Tensor uses is
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insufficient, because TensorArray and tensor lists use dedicated index read
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and write functions.
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"""
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def _process_single_assignment(self, target, value):
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if not isinstance(target, gast.Subscript):
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return None
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template = """
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target = ag__.set_item(target, key, item)
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"""
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return templates.replace(
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template, target=target.value, key=target.slice, item=value)
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def visit_Assign(self, node):
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node = self.generic_visit(node)
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# TODO(mdan): Support unpackings and multiple assignments.
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if len(node.targets) != 1:
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raise NotImplementedError('multiple assignment')
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replacement = self._process_single_assignment(node.targets[0], node.value)
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if replacement is not None:
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return replacement
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return node
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def visit_Subscript(self, node):
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node = self.generic_visit(node)
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if not isinstance(node.slice, gast.Index):
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return node
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if not isinstance(node.ctx, gast.Load):
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# Index writes are handled at a higher level, one at which the rvalue is
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# also available.
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return node
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dtype = anno.getanno(
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node.value,
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'element_type',
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default=templates.replace_as_expression('None'))
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template = """
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ag__.get_item(
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target,
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key,
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opts=ag__.GetItemOpts(element_dtype=dtype))
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"""
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return templates.replace_as_expression(
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template, target=node.value, key=node.slice, dtype=dtype)
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def transform(node, ctx):
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return SliceTransformer(ctx).visit(node)
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