Remove redundant initialization of `sub'.

[mLib] / atom.h

/* -*-c-*-
 *
 * $Id: atom.h,v 1.1 2001/01/20 11:50:16 mdw Exp $
 *
 * Atom management
 *
 * (c) 2000 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of the mLib utilities library.
 *
 * mLib is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * mLib 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 Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with mLib; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: atom.h,v $
 * Revision 1.1  2001/01/20 11:50:16  mdw
 * Implementation of atom tables (for example, as found in X11).
 *
 */

#ifndef MLIB_ATOM_H
#define MLIB_ATOM_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Header files ------------------------------------------------------*/

#ifndef MLIB_SYM_H
#  include "sym.h"
#endif

/*----- Data structures ---------------------------------------------------*/

typedef struct atom_table {
  sym_table t;				/* Symbol table of interned atoms */
  hash_base *g;				/* List of uninterned atoms */
  unsigned long gseq;			/* Sequence number for @gensym@ */
} atom_table;

typedef struct atom {
  sym_base b;				/* Base structure for symbol table */
  unsigned f;				/* Various useful flags */
} atom;

#define ATOMF_GENSYM 1u			/* Atom is uninterned */

typedef struct { sym_iter i; } atom_iter;

/*----- Global magic ------------------------------------------------------*/

#define ATOM_GLOBAL 0

/*----- Functions provided ------------------------------------------------*/

/* --- @atom_createtable@ --- *
 *
 * Arguments:	@atom_table *t@ = pointer to an atom table
 *
 * Returns:	---
 *
 * Use:		Initializes an atom table.
 */

extern void atom_createtable(atom_table */*t*/);

/* --- @atom_destroytable@ --- *
 *
 * Arguments:	@atom_table *t@ = pointer to an atom table
 *
 * Returns:	---
 *
 * Use:		Destroys all of the atoms in an atom table.  All of the atoms
 *		(including uninterned atoms) are freed.  Any references to
 *		atoms from the table become invalid, and any association
 *		tables dependent on the atom table are unusable, except that
 *		they may be destroyed safely.
 */

extern void atom_destroytable(atom_table */*t*/);

/* --- @atom_intern@ --- *
 *
 * Arguments:	@atom_table *t@ = pointer to an atom table
 *		@const char *p@ = pointer to the string to intern
 *
 * Returns:	A pointer to the atom block for the given symbol string.
 *
 * Use:		Interns an atom, returning the atom block.  The string can be
 *		extracted from the atom by means of the @ATOM_NAME@ macro.
 */

#define INTERN(p) atom_intern(ATOM_GLOBAL, (p))

extern atom *atom_intern(atom_table */*t*/, const char */*p*/);

/* --- @atom_gensym@ --- *
 *
 * Arguments:	@atom_table *t@ = pointer to a symbol table
 *
 * Returns:	A pointer to a new atom block, not previously interned.
 *
 * Use:		Creates a new, uninterned atom.  This atom will never be
 *		returned by either @atom_intern@ or any other call to
 *		@atom_gensym@, while the symbol table exists.
 */

#define GENSYM atom_gensym(ATOM_GLOBAL)

extern atom *atom_gensym(atom_table */*t*/);

/* --- @atom_name@ --- *
 *
 * Arguments:	@atom *a@ = pointer to an atom
 *
 * Returns:	The atom's textual name.
 *
 * Use:		Given an atom, returns the name with which it was interned
 *		(or a made-up name if it was created using @gensym@.
 */

#define ATOM_NAME(a) SYM_NAME(a)

extern const char *atom_name(const atom */*a*/);

/* --- @atom_len@ --- *
 *
 * Arguments:	@atom *a@ = pointer to an atom
 *
 * Returns:	The atom string's length.
 *
 * Use:		Given an atom, return the length of its textual
 *		representation.
 */

#define ATOM_LEN(a) (SYM_LEN(a) - 1)

extern size_t atom_len(const atom */*a*/);

/* --- @atom_hash@ --- *
 *
 * Arguments:	@atom *a@ = pointer to an atom
 *
 * Returns:	The atom's hash.
 *
 * Use:		Given an atom, returns its hash.
 */

#define ATOM_HASH(a) SYM_HASH(a)

extern uint32 atom_hash(const atom */*a*/);

/* --- @atom_mkiter@ , @atom_next@ --- *
 *
 * Arguments:	@atom_table *t@ = pointer to an atom table
 *		@atom_iter *i@ = pointer to an iterator structure
 *
 * Returns:	Next atom, for @atom_next@; nothing for @atom_mkiter@.
 *
 * Use:		Iterates over atoms (both interned and uninterned).
 */

extern void atom_mkiter(atom_iter */*i*/, atom_table */*t*/);
extern atom *atom_next(atom_iter */*i*/);

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif