/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying

   file LICENSE.rst or https://cmake.org/licensing for details.  */

#pragma once

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

#include <string>

#include <unordered_map>

#include <vector>

#include <cm/string_view>

#include "cmLinkedTree.h"

#include "cmString.hxx"

#include "cmValue.h"

/** \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

{

  using StackIter = cmLinkedTree<cmDefinitions>::iterator;

public:

  // -- Static member functions

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

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

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

  enum class UnsetKeys

  {

    Exclude,

    Include,

  };

  static std::vector<std::string> ClosureKeys(

    StackIter begin, StackIter end, UnsetKeys unsetKeys = UnsetKeys::Exclude);

  static cmDefinitions MakeClosure(StackIter begin, StackIter end);

  // -- Member functions

  /** Set a value associated with a key.  */

  void Set(std::string const& key, cm::string_view value);

  /** Unset a definition.  */

  void Unset(std::string const& key);

private:

  /** String with existence boolean.  */

  struct Def

  {

  public:

    Def() = default;

    Def(cm::string_view value)

      : Value(value)

    {

    }

    cm::String Value;

  };

  static Def NoDef;

  std::unordered_map<cm::String, Def> Map;

  static Def const& GetInternal(std::string const& key, StackIter begin,

                                StackIter end, bool raise);

};