EVOLUTION-MANAGER

Edit File: feature_util.h

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
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==============================================================================*/

// A set of lightweight wrappers which simplify access to Feature protos.
//
// TensorFlow Example proto uses associative maps on top of oneof fields.
// SequenceExample proto uses associative map of FeatureList.
// So accessing feature values is not very convenient.
//
// For example, to read a first value of integer feature "tag":
//   int id = example.features().feature().at("tag").int64_list().value(0);
//
// to add a value:
//   auto features = example->mutable_features();
//   (*features->mutable_feature())["tag"].mutable_int64_list()->add_value(id);
//
// For float features you have to use float_list, for string - bytes_list.
//
// To do the same with this library:
//   int id = GetFeatureValues<int64>("tag", example).Get(0);
//   GetFeatureValues<int64>("tag", &example)->Add(id);
//
// Modification of bytes features is slightly different:
//   auto tag = GetFeatureValues<string>("tag", &example);
//   *tag->Add() = "lorem ipsum";
//
// To copy multiple values into a feature:
//   AppendFeatureValues({1,2,3}, "tag", &example);
//
// GetFeatureValues gives you access to underlying data - RepeatedField object
// (RepeatedPtrField for byte list). So refer to its documentation of
// RepeatedField for full list of supported methods.
//
// NOTE: Due to the nature of oneof proto fields setting a feature of one type
// automatically clears all values stored as another type with the same feature
// key.
//
// This library also has tools to work with SequenceExample protos.
//
// To get a value from SequenceExample.context:
//   int id = GetFeatureValues<protobuf_int64>("tag", se.context()).Get(0);
// To add a value to the context:
//   GetFeatureValues<protobuf_int64>("tag", se.mutable_context())->Add(42);
//
// To add values to feature_lists:
//   AppendFeatureValues({4.0},
//                       GetFeatureList("images", &se)->Add());
//   AppendFeatureValues({5.0, 3.0},
//                       GetFeatureList("images", &se)->Add());
// This will create a feature list keyed as "images" with two features:
//   feature_lists {
//     feature_list {
//       key: "images"
//       value {
//         feature { float_list { value: [4.0] } }
//         feature { float_list { value: [5.0, 3.0] } }
//       }
//     }
//   }
//
// Functions exposed by this library:
//   HasFeature<[FeatureType]>(key, proto) -> bool
//     Returns true if a feature with the specified key, and optionally
//     FeatureType, belongs to the Features or Example proto.
//   HasFeatureList(key, sequence_example) -> bool
//     Returns true if SequenceExample has a feature_list with the key.
//
//   GetFeatureValues<FeatureType>(key, proto) -> RepeatedField<FeatureType>
//     Returns values for the specified key and the FeatureType.
//     Supported types for the proto: Example, Features.
//   GetFeatureList(key, sequence_example) -> RepeatedPtrField<Feature>
//     Returns Feature protos associated with a key.
//
//   AppendFeatureValues(begin, end, feature)
//   AppendFeatureValues(container or initializer_list, feature)
//     Copies values into a Feature.
//   AppendFeatureValues(begin, end, key, proto)
//   AppendFeatureValues(container or initializer_list, key, proto)
//     Copies values into Features and Example protos with the specified key.
//
//   ClearFeatureValues<FeatureType>(feature)
//     Clears the feature's repeated field of the given type.
//
//   SetFeatureValues(begin, end, feature)
//   SetFeatureValues(container or initializer_list, feature)
//     Clears a Feature, then copies values into it.
//   SetFeatureValues(begin, end, key, proto)
//   SetFeatureValues(container or initializer_list, key, proto)
//     Clears Features or Example protos with the specified key,
//     then copies values into them.
//
// Auxiliary functions, it is unlikely you'll need to use them directly:
//   GetFeatures(proto) -> Features
//     A convenience function to get Features proto.
//     Supported types for the proto: Example, Features.
//   GetFeature(key, proto) -> Feature
//     Returns a Feature proto for the specified key.
//     Supported types for the proto: Example, Features.
//   GetFeatureValues<FeatureType>(feature) -> RepeatedField<FeatureType>
//     Returns values of the feature for the FeatureType.

#ifndef TENSORFLOW_CORE_EXAMPLE_FEATURE_UTIL_H_
#define TENSORFLOW_CORE_EXAMPLE_FEATURE_UTIL_H_

#include <iterator>
#include <type_traits>

#include "absl/base/macros.h"
#include "tensorflow/core/example/example.pb.h"
#include "tensorflow/core/example/feature.pb.h"
#include "tensorflow/core/platform/protobuf.h"
#include "tensorflow/core/platform/stringpiece.h"
#include "tensorflow/core/platform/types.h"

namespace tensorflow {

namespace internal {

// TODO(gorban): Update all clients in a followup CL.
// Returns a reference to a feature corresponding to the name.
// Note: it will create a new Feature if it is missing in the example.
ABSL_DEPRECATED("Use GetFeature instead.")
Feature& ExampleFeature(const string& name, Example* example);

// Specializations of RepeatedFieldTrait define a type of RepeatedField
// corresponding to a selected feature type.
template <typename FeatureType>
struct RepeatedFieldTrait;

template <>
struct RepeatedFieldTrait<protobuf_int64> {
  using Type = protobuf::RepeatedField<protobuf_int64>;
};

template <>
struct RepeatedFieldTrait<float> {
  using Type = protobuf::RepeatedField<float>;
};

template <>
struct RepeatedFieldTrait<tstring> {
  using Type = protobuf::RepeatedPtrField<string>;
};

template <>
struct RepeatedFieldTrait<string> {
  using Type = protobuf::RepeatedPtrField<string>;
};

// Specializations of FeatureTrait define a type of feature corresponding to a
// selected value type.
template <typename ValueType, class Enable = void>
struct FeatureTrait;

template <typename ValueType>
struct FeatureTrait<ValueType, typename std::enable_if<
                                   std::is_integral<ValueType>::value>::type> {
  using Type = protobuf_int64;
};

template <typename ValueType>
struct FeatureTrait<
    ValueType,
    typename std::enable_if<std::is_floating_point<ValueType>::value>::type> {
  using Type = float;
};

template <typename T>
struct is_string
    : public std::integral_constant<
          bool,
          std::is_same<char*, typename std::decay<T>::type>::value ||
              std::is_same<const char*, typename std::decay<T>::type>::value> {
};

template <>
struct is_string<string> : std::true_type {};

template <>
struct is_string<::tensorflow::StringPiece> : std::true_type {};

template <>
struct is_string<tstring> : std::true_type {};

template <typename ValueType>
struct FeatureTrait<
    ValueType, typename std::enable_if<is_string<ValueType>::value>::type> {
  using Type = string;
};

}  //  namespace internal

// Returns true if sequence_example has a feature_list with the specified key.
bool HasFeatureList(const string& key, const SequenceExample& sequence_example);

template <typename T>
struct TypeHasFeatures : std::false_type {};

template <>
struct TypeHasFeatures<Example> : std::true_type {};

template <>
struct TypeHasFeatures<Features> : std::true_type {};

// A family of template functions to return mutable Features proto from a
// container proto. Supported ProtoTypes: Example, Features.
template <typename ProtoType>
typename std::enable_if<TypeHasFeatures<ProtoType>::value, Features*>::type
GetFeatures(ProtoType* proto);

template <typename ProtoType>
typename std::enable_if<TypeHasFeatures<ProtoType>::value,
                        const Features&>::type
GetFeatures(const ProtoType& proto);

// Base declaration of a family of template functions to return a read only
// repeated field of feature values.
template <typename FeatureType>
const typename internal::RepeatedFieldTrait<FeatureType>::Type&
GetFeatureValues(const Feature& feature);

// Returns a read only repeated field corresponding to a feature with the
// specified name and FeatureType. Supported ProtoTypes: Example, Features.
template <typename FeatureType, typename ProtoType>
const typename internal::RepeatedFieldTrait<FeatureType>::Type&
GetFeatureValues(const string& key, const ProtoType& proto) {
  return GetFeatureValues<FeatureType>(GetFeatures(proto).feature().at(key));
}

// Returns a mutable repeated field of a feature values.
template <typename FeatureType>
typename internal::RepeatedFieldTrait<FeatureType>::Type* GetFeatureValues(
    Feature* feature);

// Returns a mutable repeated field corresponding to a feature with the
// specified name and FeatureType. Supported ProtoTypes: Example, Features.
template <typename FeatureType, typename ProtoType>
typename internal::RepeatedFieldTrait<FeatureType>::Type* GetFeatureValues(
    const string& key, ProtoType* proto) {
  ::tensorflow::Feature& feature =
      (*GetFeatures(proto)->mutable_feature())[key];
  return GetFeatureValues<FeatureType>(&feature);
}

// Returns a read-only Feature proto for the specified key, throws
// std::out_of_range if the key is not found. Supported types for the proto:
// Example, Features.
template <typename ProtoType>
const Feature& GetFeature(const string& key, const ProtoType& proto) {
  return GetFeatures(proto).feature().at(key);
}

// Returns a mutable Feature proto for the specified key, creates a new if
// necessary. Supported types for the proto: Example, Features.
template <typename ProtoType>
Feature* GetFeature(const string& key, ProtoType* proto) {
  return &(*GetFeatures(proto)->mutable_feature())[key];
}

// Returns a repeated field with features corresponding to a feature_list key.
const protobuf::RepeatedPtrField<Feature>& GetFeatureList(
    const string& key, const SequenceExample& sequence_example);

// Returns a mutable repeated field with features corresponding to a
// feature_list key. It will create a new FeatureList if necessary.
protobuf::RepeatedPtrField<Feature>* GetFeatureList(
    const string& feature_list_key, SequenceExample* sequence_example);

template <typename IteratorType>
void AppendFeatureValues(IteratorType first, IteratorType last,
                         Feature* feature) {
  using FeatureType = typename internal::FeatureTrait<
      typename std::iterator_traits<IteratorType>::value_type>::Type;
  std::copy(first, last,
            protobuf::RepeatedFieldBackInserter(
                GetFeatureValues<FeatureType>(feature)));
}

template <typename ValueType>
void AppendFeatureValues(std::initializer_list<ValueType> container,
                         Feature* feature) {
  AppendFeatureValues(container.begin(), container.end(), feature);
}

template <typename ContainerType>
void AppendFeatureValues(const ContainerType& container, Feature* feature) {
  using IteratorType = typename ContainerType::const_iterator;
  AppendFeatureValues<IteratorType>(container.begin(), container.end(),
                                    feature);
}

// Copies elements from the range, defined by [first, last) into the feature
// obtainable from the (proto, key) combination.
template <typename IteratorType, typename ProtoType>
void AppendFeatureValues(IteratorType first, IteratorType last,
                         const string& key, ProtoType* proto) {
  AppendFeatureValues(first, last, GetFeature(key, GetFeatures(proto)));
}

// Copies all elements from the container into a feature.
template <typename ContainerType, typename ProtoType>
void AppendFeatureValues(const ContainerType& container, const string& key,
                         ProtoType* proto) {
  using IteratorType = typename ContainerType::const_iterator;
  AppendFeatureValues<IteratorType>(container.begin(), container.end(), key,
                                    proto);
}

// Copies all elements from the initializer list into a Feature contained by
// Features or Example proto.
template <typename ValueType, typename ProtoType>
void AppendFeatureValues(std::initializer_list<ValueType> container,
                         const string& key, ProtoType* proto) {
  using IteratorType =
      typename std::initializer_list<ValueType>::const_iterator;
  AppendFeatureValues<IteratorType>(container.begin(), container.end(), key,
                                    proto);
}

// Clears the feature's repeated field (int64, float, or string).
template <typename... FeatureType>
void ClearFeatureValues(Feature* feature);

// Clears the feature's repeated field (int64, float, or string). Copies
// elements from the range, defined by [first, last) into the feature's repeated
// field.
template <typename IteratorType>
void SetFeatureValues(IteratorType first, IteratorType last, Feature* feature) {
  using FeatureType = typename internal::FeatureTrait<
      typename std::iterator_traits<IteratorType>::value_type>::Type;
  ClearFeatureValues<FeatureType>(feature);
  AppendFeatureValues(first, last, feature);
}

// Clears the feature's repeated field (int64, float, or string). Copies all
// elements from the initializer list into the feature's repeated field.
template <typename ValueType>
void SetFeatureValues(std::initializer_list<ValueType> container,
                      Feature* feature) {
  SetFeatureValues(container.begin(), container.end(), feature);
}

// Clears the feature's repeated field (int64, float, or string). Copies all
// elements from the container into the feature's repeated field.
template <typename ContainerType>
void SetFeatureValues(const ContainerType& container, Feature* feature) {
  using IteratorType = typename ContainerType::const_iterator;
  SetFeatureValues<IteratorType>(container.begin(), container.end(), feature);
}

// Clears the feature's repeated field (int64, float, or string). Copies
// elements from the range, defined by [first, last) into the feature's repeated
// field.
template <typename IteratorType, typename ProtoType>
void SetFeatureValues(IteratorType first, IteratorType last, const string& key,
                      ProtoType* proto) {
  SetFeatureValues(first, last, GetFeature(key, GetFeatures(proto)));
}

// Clears the feature's repeated field (int64, float, or string). Copies all
// elements from the container into the feature's repeated field.
template <typename ContainerType, typename ProtoType>
void SetFeatureValues(const ContainerType& container, const string& key,
                      ProtoType* proto) {
  using IteratorType = typename ContainerType::const_iterator;
  SetFeatureValues<IteratorType>(container.begin(), container.end(), key,
                                 proto);
}

// Clears the feature's repeated field (int64, float, or string). Copies all
// elements from the initializer list into the feature's repeated field.
template <typename ValueType, typename ProtoType>
void SetFeatureValues(std::initializer_list<ValueType> container,
                      const string& key, ProtoType* proto) {
  using IteratorType =
      typename std::initializer_list<ValueType>::const_iterator;
  SetFeatureValues<IteratorType>(container.begin(), container.end(), key,
                                 proto);
}

// Returns true if a feature with the specified key belongs to the Features.
// The template parameter pack accepts zero or one template argument - which
// is FeatureType. If the FeatureType not specified (zero template arguments)
// the function will not check the feature type. Otherwise it will return false
// if the feature has a wrong type.
template <typename... FeatureType>
bool HasFeature(const string& key, const Features& features);

// Returns true if a feature with the specified key belongs to the Example.
// Doesn't check feature type if used without FeatureType, otherwise the
// specialized versions return false if the feature has a wrong type.
template <typename... FeatureType>
bool HasFeature(const string& key, const Example& example) {
  return HasFeature<FeatureType...>(key, GetFeatures(example));
}

// TODO(gorban): update all clients in a followup CL.
template <typename... FeatureType>
ABSL_DEPRECATED("Use HasFeature instead.")
bool ExampleHasFeature(const string& key, const Example& example) {
  return HasFeature<FeatureType...>(key, example);
}

}  // namespace tensorflow
#endif  // TENSORFLOW_CORE_EXAMPLE_FEATURE_UTIL_H_