gcc/diagnostics/lazy-paths.h

/* Helper class for deferring path creation until a diagnostic is emitted.
   Copyright (C) 2024-2025 Free Software Foundation, Inc.
   Contributed by David Malcolm <dmalcolm@redhat.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#ifndef GCC_DIAGNOSTICS_LAZY_PATHS_H
#define GCC_DIAGNOSTICS_LAZY_PATHS_H

#include "diagnostics/paths.h"

namespace diagnostics {
namespace paths {

/* An implementation of diagnostics::paths::path which has a trivial ctor
   and lazily creates another path the first time the path
   is queried, deferring to this inner path for all queries.

   Use this to avoid expensive path creation logic when creating
   rich_location instances, so that expense can be deferred until the path
   is actually used by a diagnostic, and thus avoided for warnings that
   are disabled.  */

class lazy_path : public path
{
 public:
  virtual ~lazy_path () {}

  unsigned num_events () const final override;
  const event & get_event (int idx) const final override;
  unsigned num_threads () const final override;
  const thread &
  get_thread (thread_id_t) const final override;
  bool
  same_function_p (int event_idx_a,
		   int event_idx_b) const final override;

  bool generated_p () const { return m_inner_path != nullptr; }

protected:
  lazy_path (const logical_locations::manager &logical_loc_mgr)
  : path (logical_loc_mgr)
  {
  }

 private:
  void lazily_generate_path () const;
  virtual std::unique_ptr<path> make_inner_path () const = 0;

  mutable std::unique_ptr<path> m_inner_path;
};

} // namespace paths
} // namespace diagnostics

#endif /* ! GCC_DIAGNOSTICS_LAZY_PATHS_H */