text: /*
   * Copyright 2021 Google LLC
   *
   * 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
   *
   *      https://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.
   */
  
  #ifndef THIRD_PARTY_CEL_CPP_EVAL_PUBLIC_CONTAINERS_CONCAT_LIST_IMPL_H_
  #define THIRD_PARTY_CEL_CPP_EVAL_PUBLIC_CONTAINERS_CONCAT_LIST_IMPL_H_
  
  #include <vector>
  
  #include "eval/public/cel_value.h"
  
  namespace google::api::expr::runtime {
  
  // Mutable CelList implementation intended to be used in the accumulation of
  // a list within a comprehension loop.
  //
  // This value should only ever be used as an intermediate result from CEL and
  // not within user code.
  class MutableListImpl : public CelList {
   public:
    // Create a list from an initial vector of CelValues.
    explicit MutableListImpl(std::vector<CelValue> values)
        : values_(std::move(values)) {}
  
    // List size.
    int size() const override { return values_.size(); }
  
    // Append a single element to the list.
    void Append(const CelValue& element) { values_.push_back(element); }
  
    // List element access operator.
    CelValue operator[](int index) const override { return values_[index]; }
  
   private:
    std::vector<CelValue> values_;
  };
  
  }  //  namespace google::api::expr::runtime
  
  #endif  // THIRD_PARTY_CEL_CPP_EVAL_PUBLIC_CONTAINERS_CONCAT_LIST_IMPL_H_
  