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// 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.
package op
import (
"fmt"
"runtime/debug"
tf "github.com/tensorflow/tensorflow/tensorflow/go"
)
// Scope encapsulates common operation properties when building a Graph.
//
// A Scope object (and its derivates, e.g., obtained from Scope.SubScope)
// act as a builder for graphs. They allow common properties (such as
// a name prefix) to be specified for multiple operations being added
// to the graph.
//
// A Scope object and all its derivates (e.g., obtained from Scope.SubScope)
// are not safe for concurrent use by multiple goroutines.
type Scope struct {
graph *tf.Graph
namemap map[string]int
namespace string
err *scopeErr
}
// scopeErr is used to share errors between all derivatives of a root scope.
type scopeErr struct {
err error
}
// NewScope creates a Scope initialized with an empty Graph.
func NewScope() *Scope {
return &Scope{graph: tf.NewGraph(), namemap: make(map[string]int), err: new(scopeErr)}
}
// Finalize returns the Graph on which this scope operates on and renders s
// unusable. If there was an error during graph construction, that error is
// returned instead.
func (s *Scope) Finalize() (*tf.Graph, error) {
if err := s.Err(); err != nil {
return nil, err
}
s.err.err = fmt.Errorf("Scope has been finalized and is no longer usable")
return s.graph, nil
}
// AddOperation adds the operation to the Graph managed by s.
//
// If there is a name prefix associated with s (such as if s was created
// by a call to SubScope), then this prefix will be applied to the name
// of the operation being added. See also Graph.AddOperation.
func (s *Scope) AddOperation(args tf.OpSpec) *tf.Operation {
if s.Err() != nil {
return nil
}
if args.Name == "" {
args.Name = args.Type
}
if s.namespace != "" {
args.Name = s.namespace + "/" + args.Name
}
op, err := s.graph.AddOperation(args)
if err != nil {
s.UpdateErr(args.Type, err)
}
return op
}
// SubScope returns a new Scope which will cause all operations added to the
// graph to be namespaced with 'namespace'. If namespace collides with an
// existing namespace within the scope, then a suffix will be added.
func (s *Scope) SubScope(namespace string) *Scope {
namespace = s.uniqueName(namespace)
if s.namespace != "" {
namespace = s.namespace + "/" + namespace
}
return &Scope{
graph: s.graph,
namemap: make(map[string]int),
namespace: namespace,
err: s.err,
}
}
// Err returns the error, if any, encountered during the construction
// of the Graph managed by s.
//
// Once Err returns a non-nil error, all future calls will do the same,
// indicating that the scope should be discarded as the graph could not
// be constructed.
func (s *Scope) Err() error {
return s.err.err
}
// UpdateErr is used to notify Scope of any graph construction errors
// while creating the operation op.
func (s *Scope) UpdateErr(op string, err error) {
if s.err.err == nil {
s.err.err = fmt.Errorf("failed to add operation %q: %v (Stacktrace: %s)", op, err, debug.Stack())
}
}
func (s *Scope) uniqueName(name string) string {
count := s.namemap[name]
s.namemap[name]++
if count == 0 {
return name
}
return fmt.Sprint(name, "_", count)
}
func (s *Scope) opName(typ string) string {
if s.namespace == "" {
return typ
}
return s.namespace + "/" + typ
}
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