text: // Copyright (c) 2014-2018 Thomas Fussell
  // Copyright (c) 2010-2015 openpyxl
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, WRISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE
  //
  // @license: http://www.opensource.org/licenses/mit-license.php
  // @author: see AUTHORS file
  
  #pragma once
  
  #include <string>
  
  #include <xlnt/xlnt_config.hpp>
  #include <xlnt/packaging/uri.hpp>
  #include <xlnt/utils/path.hpp>
  
  namespace xlnt {
  
  /// <summary>
  /// Specifies whether the target of a relationship is inside or outside the Package.
  /// </summary>
  enum class XLNT_API target_mode
  {
      /// <summary>
      /// The relationship references a resource that is external to the package.
      /// </summary>
      internal,
      /// <summary>
      /// The relationship references a part that is inside the package.
      /// </summary>
      external
  };
  
  /// <summary>
  /// All package relationships must be one of these defined types.
  /// </summary>
  enum class XLNT_API relationship_type
  {
      unknown,
  
      // Package parts
      core_properties,
      extended_properties,
      custom_properties,
      office_document,
      thumbnail,
      printer_settings,
  
      // SpreadsheetML parts
      calculation_chain,
      chartsheet,
      comments,
      connections,
      custom_property,
      custom_xml_mappings,
      dialogsheet,
      drawings,
      external_workbook_references,
      pivot_table,
      pivot_table_cache_definition,
      pivot_table_cache_records,
      query_table,
      shared_string_table,
      shared_workbook_revision_headers,
      shared_workbook,
      theme,
      revision_log,
      shared_workbook_user_data,
      single_cell_table_definitions,
      stylesheet,
      table_definition,
      vml_drawing,
      volatile_dependencies,
      worksheet,
  
      // Worksheet parts
      hyperlink,
      image
  };
  
  /// <summary>
  /// Represents an association between a source Package or part, and a target object which can be a part or external
  /// resource.
  /// </summary>
  class XLNT_API relationship
  {
  public:
      /// <summary>
      /// Constructs a new empty relationship.
      /// </summary>
      relationship();
  
      /// <summary>
      /// Constructs a new relationship by specifying all of its properties.
      /// </summary>
      relationship(const std::string &id, relationship_type t, const uri &source,
          const uri &target, xlnt::target_mode mode);
  
      /// <summary>
      /// Returns a string of the form rId# that identifies the relationship.
      /// </summary>
      const std::string& id() const;
  
      /// <summary>
      /// Returns the type of this relationship.
      /// </summary>
      relationship_type type() const;
  
      /// <summary>
      /// Returns whether the target of the relationship is internal or external to the package.
      /// </summary>
      xlnt::target_mode target_mode() const;
  
      /// <summary>
      /// Returns the URI of the package part this relationship points to.
      /// </summary>
      const uri &source() const;
  
      /// <summary>
      /// Returns the URI of the package part this relationship points to.
      /// </summary>
      const uri &target() const;
  
      /// <summary>
      /// Returns true if and only if rhs is equal to this relationship.
      /// </summary>
      bool operator==(const relationship &rhs) const;
  
      /// <summary>
      /// Returns true if and only if rhs is not equal to this relationship.
      /// </summary>
      bool operator!=(const relationship &rhs) const;
  
  private:
      /// <summary>
      /// The id of this relationship in the format "rId#"
      /// </summary>
      std::string id_;
  
      /// <summary>
      /// The type of this relationship.
      /// </summary>
      relationship_type type_;
  
      /// <summary>
      /// The URI of the source of this relationship.
      /// </summary>
      uri source_;
  
      /// <summary>
      /// The URI of the target of this relationshp.
      /// </summary>
      uri target_;
  
      /// <summary>
      /// Whether the target of this relationship is internal or external.
      /// </summary>
      xlnt::target_mode mode_;
  };
  
  } // namespace xlnt
  