// file      : build2/target-type -*- C++ -*-
// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#ifndef BUILD2_TARGET_TYPE
#define BUILD2_TARGET_TYPE

#include <map>
#include <string>
#include <ostream>

#include <build2/types>
#include <build2/utility>

namespace build2
{
  class scope;
  class target;
  class target_key;
  class prerequisite_key;

  // Target type.
  //
  // Note that we assume there is always a single instance of this class for
  // any target type. As a result, we can use address comparison to determine
  // if two target types are the same.
  //
  // If the extension derivation function is NULL, then it means this target
  // type does not use extensions. Note that this is relied upon when deciding
  // whether to print the extension; if the target does use extensions but the
  // defaults could not (and its ok), could not (and its not ok), or should not
  // (logically) be obtained, then use target_extension_{null,fail,assert}(),
  // respectively. If the extension function returns NULL, then that means the
  // default extension for this target could not be derived.
  //
  // The extension function is used in two places: search_existing_file() and
  // in target::derive_path(); see their implementations for details.
  //
  struct target_type
  {
    const char* name;
    const target_type* base;
    target* (*factory) (const target_type&, dir_path, string, const string*);
    const string* (*extension) (const target_key&, scope&);
    void (*print) (ostream&, const target_key&);
    target* (*search) (const prerequisite_key&);
    bool see_through; // A group with the default "see through" semantics.

    bool
    is_a (const target_type&) const; // Defined in target.cxx

    template <typename T>
    bool
    is_a () const {return is_a (T::static_type);}
  };

  inline bool
  operator< (const target_type& x, const target_type& y) {return &x < &y;}

  inline bool
  operator== (const target_type& x, const target_type& y) {return &x == &y;}

  inline bool
  operator!= (const target_type& x, const target_type& y) {return &x != &y;}

  inline std::ostream&
  operator<< (std::ostream& os, const target_type& tt) {return os << tt.name;}

  // Target type map.
  //
  struct target_type_ref
  {
    // Like reference_wrapper except it sometimes deletes the target type.
    //
    explicit
    target_type_ref (const target_type& r): p_ (&r), d_ (false) {}

    explicit
    target_type_ref (unique_ptr<target_type>&& p)
        : p_ (p.release ()), d_ (true) {}

    target_type_ref (target_type_ref&& r)
        : p_ (r.p_), d_ (r.d_) {r.p_ = nullptr;}

    ~target_type_ref () {if (p_ != nullptr && d_) delete p_;}

    explicit operator const target_type& () const {return *p_;}
    const target_type& get () const {return *p_;}

  private:
    const target_type* p_;
    bool d_;
  };

  using target_type_map_base = std::map<string, target_type_ref>;

  class target_type_map: public target_type_map_base
  {
  public:
    void
    insert (const target_type& tt) {emplace (tt.name, target_type_ref (tt));}

    template <typename T>
    void
    insert () {insert (T::static_type);}
  };
}

#endif // BUILD2_TARGET_TYPE