/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
   file Copyright.txt or https://cmake.org/licensing for details.  */
#ifndef cmDefinitions_h
#define cmDefinitions_h

#include "cmConfigure.h" // IWYU pragma: keep

#include "cm_string_view.hxx"

#include "cmLinkedTree.h"

#include <string>
#include <unordered_map>
#include <vector>

/** \class cmDefinitions
 * \brief Store a scope of variable definitions for CMake language.
 *
 * This stores the state of variable definitions (set or unset) for
 * one scope.  Sets are always local.  Gets search parent scopes
 * transitively and save results locally.
 */
class cmDefinitions
{
  typedef cmLinkedTree<cmDefinitions>::iterator StackIter;

public:
  static const std::string* Get(const std::string& key, StackIter begin,
                                StackIter end);

  static void Raise(const std::string& key, StackIter begin, StackIter end);

  static bool HasKey(const std::string& key, StackIter begin, StackIter end);

  /** Set a value associated with a key.  */
  void Set(const std::string& key, cm::string_view value);

  /** Unset a definition.  */
  void Unset(const std::string& key);

  std::vector<std::string> UnusedKeys() const;

  static std::vector<std::string> ClosureKeys(StackIter begin, StackIter end);

  static cmDefinitions MakeClosure(StackIter begin, StackIter end);

private:
  /** String with existence boolean.  */
  struct Def
  {
  public:
    Def() = default;
    Def(cm::string_view value)
      : Value(value)
      , Exists(true)
    {
    }
    std::string Value;
    bool Exists = false;
    bool Used = false;
  };
  static Def NoDef;

  typedef std::unordered_map<std::string, Def> MapType;
  MapType Map;

  static Def const& GetInternal(const std::string& key, StackIter begin,
                                StackIter end, bool raise);
};

#endif