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Diffstat (limited to 'tensorflow/python/autograph/converters/slices.py')
-rw-r--r-- | tensorflow/python/autograph/converters/slices.py | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/tensorflow/python/autograph/converters/slices.py b/tensorflow/python/autograph/converters/slices.py new file mode 100644 index 0000000000..11cea6de5b --- /dev/null +++ b/tensorflow/python/autograph/converters/slices.py @@ -0,0 +1,85 @@ +# Copyright 2016 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. +# ============================================================================== +"""Converter for slice operations.""" + +from __future__ import absolute_import +from __future__ import division +from __future__ import print_function + +import gast + +from tensorflow.python.autograph.core import converter +from tensorflow.python.autograph.lang import directives +from tensorflow.python.autograph.pyct import templates + + +class SliceTransformer(converter.Base): + """Converts slicing operations to their TF counterpart. + + Currently, relying on the default slice operator that Tensor uses is + insufficient, because TensorArray and tensor lists use dedicated index read + and write functions. + """ + + def _process_single_assignment(self, target, value): + if not isinstance(target, gast.Subscript): + return None + if not isinstance(target.slice, gast.Index): + return None + + template = """ + target = ag__.set_item(target, key, item) + """ + return templates.replace( + template, target=target.value, key=target.slice.value, item=value) + + def visit_Assign(self, node): + node = self.generic_visit(node) + # TODO(mdan): Support unpackings and multiple assignments. + if len(node.targets) != 1: + raise NotImplementedError('multiple assignment') + replacement = self._process_single_assignment(node.targets[0], node.value) + if replacement is not None: + return replacement + return node + + def visit_Subscript(self, node): + node = self.generic_visit(node) + if not isinstance(node.slice, gast.Index): + return node + + if not isinstance(node.ctx, gast.Load): + # Index writes are handled at a higher level, one at which the rvalue is + # also available. + return node + + dtype = self.get_definition_directive( + node.value, + directives.set_element_type, + 'dtype', + default=templates.replace_as_expression('None')) + + template = """ + ag__.get_item( + target, + key, + opts=ag__.GetItemOpts(element_dtype=dtype)) + """ + return templates.replace_as_expression( + template, target=node.value, key=node.slice.value, dtype=dtype) + + +def transform(node, ctx): + return SliceTransformer(ctx).visit(node) |