text: /*
   * Copyright (c) Facebook, Inc. and its affiliates.
   *
   * 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.
   */
  
  namespace apache {
  namespace thrift {
  namespace frozen {
  namespace detail {
  
  class FixedSizeMismatchException : public std::length_error {
   public:
    FixedSizeMismatchException(size_t expected, size_t actual)
        : std::length_error(folly::to<std::string>(
              "Size mismatch. FixedSizeString specifies ",
              expected,
              ", actual size is ",
              actual)) {}
  };
  
  /**
   * Serializes a string blob with a fixed size. Similar to TrivialLayout, but
   * uses folly::ByteRange as the view. During freezing, an exception will be
   * thrown if the actual size doesn't match what's specified in the IDL schema.
   */
  template <typename T>
  struct FixedSizeStringLayout : public LayoutBase {
    using Base = LayoutBase;
    FixedSizeStringLayout() : LayoutBase(typeid(T)) {}
  
    FieldPosition maximize() {
      return FieldPosition(T::kFixedSize, 0);
    }
  
    FieldPosition layout(LayoutRoot&, const T&, LayoutPosition /* start */) {
      return maximize();
    }
  
    void freeze(FreezeRoot&, const T& o, FreezePosition self) const {
      if (o.size() == T::kFixedSize) {
        memcpy(self.start, o.data(), o.size());
      } else {
        throw FixedSizeMismatchException(T::kFixedSize, o.size());
      }
    }
  
    void thaw(ViewPosition self, T& out) const {
      if (size == T::kFixedSize) {
        out.resize(T::kFixedSize);
        memcpy(&out[0], self.start, T::kFixedSize);
      }
    }
  
    void print(std::ostream& os, int level) const override {
      LayoutBase::print(os, level);
      os << folly::demangle(type.name());
    }
  
    using View = folly::ByteRange;
    View view(ViewPosition self) const {
      return folly::ByteRange{self.start, T::kFixedSize};
    }
  
    static size_t hash(const T& value) {
      return FixedSizeStringHash<T::kFixedSize, T>::hash(value);
    }
  
    static size_t hash(const View& value) {
      return FixedSizeStringHash<T::kFixedSize, View>::hash(value);
    }
  };
  
  } // namespace detail
  
  template <size_t kSize>
  class FixedSizeString;
  
  template <size_t kSize>
  struct Layout<FixedSizeString<kSize>>
      : detail::FixedSizeStringLayout<FixedSizeString<kSize>> {};
  } // namespace frozen
  } // namespace thrift
  } // namespace apache
  