kc3-lang/kc3/libc3/cow.h

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• Hash : 593a1d6b
  Author : Thomas de Grivel
  Date : 2024-05-11T20:25:59
  

  wip cow

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• libc3/cow.h

• /* c3
   * Copyright 2022-2024 kmx.io <contact@kmx.io>
   *
   * Permission is hereby granted to use this software granted the above
   * copyright notice and this permission paragraph are included in all
   * copies and substantial portions of this software.
   *
   * THIS SOFTWARE IS PROVIDED "AS-IS" WITHOUT ANY GUARANTEE OF
   * PURPOSE AND PERFORMANCE. IN NO EVENT WHATSOEVER SHALL THE
   * AUTHOR BE CONSIDERED LIABLE FOR THE USE AND PERFORMANCE OF
   * THIS SOFTWARE.
   */
  /**
   * @file cow.h
   * @brief Copy on write is a software technique that allows you to have
   * read-only access to some memory but still be able to modify it. The
   * read-only data is copied to a writable memory area to allow for
   * modification and can then be turned into read-only memory.
   *
   * Usage :
   *   - cow_init() 
   *   - cow_rw() returns a writable tag pointer
   *   - cow_freeze() freeze the writable memory area into a read-only one
   *   - cow_ro() returns the last read-only version that was frozen
   */
  #ifndef LIBC3_COW_H
  #define LIBC3_COW_H
  
  #include "types.h"
  
  /* Stack-allocation compatible functions. Call cow_clean after use. */
  void    cow_clean (s_cow *cow);
  s_cow * cow_init (s_cow *cow, const s_sym *type);
  s_cow * cow_init_1 (s_cow *cow, const char *utf8);
  s_cow * cow_init_cast (s_cow *cow, const s_sym * const *type,
                         const s_tag *tag);
  s_cow * cow_init_copy (s_cow *cow, const s_cow *src);
  s_cow * cow_init_tag_copy (s_cow *cow, const s_sym *type,
                             const s_tag *src);
  
  /* Heap-allocation functions. Call cow_delete after use. */
  void    cow_delete (s_cow *cow);
  s_cow * cow_new (const s_sym *type);
  s_cow * cow_new_1 (const char *utf8);
  s_cow * cow_new_cast (const s_sym * const *type, const s_tag *tag);
  s_cow * cow_new_copy (const s_cow *src);
  s_cow * cow_new_tag_copy (const s_sym *type, const s_tag *src);
  
  /* Observers. */
  s_str *       cow_inspect (const s_cow *cow, s_str *dest);
  const s_tag * cow_read_only (const s_cow *cow);
  s_tag *       cow_read_write (s_cow *cow);
  const s_tag * cow_resolve (const s_cow *cow);
  
  /* Operators. */
  s_cow * cow_freeze (s_cow *cow);
  s_cow * cow_freeze_copy (s_cow *cow, const s_tag *src);
  s_cow * cow_thaw (s_cow *cow);
  s_cow * cow_thaw_copy (s_cow *cow, const s_tag *src);
  
  #endif /* LIBC3_COW_H */
  

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