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guile/libguile/pairs.h
Mark H Weaver 45f4cbdf12 the cube of lisp booleans (#f nil () #t) 
* Renumbers the IFLAG constants.

 * Adds several macros related to boolean type tests, null tests, and
   boolean-truth testing (including lisp-style boolean-truth tests).

 * Adds compile-time checks to verify the necessary IFLAG numbering
   properties needed for the checks to work properly.

 * Changes some existing code to use the new optimized macros, without
   changing the semantics of the code at all (except that scm_is_bool
   is changed from a function to a macro).

I added the following macros, whose names explicitly state how %nil
should be handled.  See the comments in the patch for more information
about these.

  scm_is_false_assume_not_lisp_nil  scm_is_true_assume_not_lisp_nil
  scm_is_false_and_not_lisp_nil     scm_is_true_or_lisp_nil
  scm_is_false_or_lisp_nil          scm_is_true_and_not_lisp_nil

  scm_is_lisp_false                 scm_is_lisp_true

  scm_is_null_assume_not_lisp_nil
  scm_is_null_and_not_lisp_nil
  scm_is_null_or_lisp_nil

  scm_is_bool_and_not_lisp_nil
  scm_is_bool_or_lisp_nil

The following already-existing macros are defined as aliases, such
that their semantics is unchanged (although scm_is_bool used to be a
function and is now a macro).

  scm_is_null   -->  scm_is_null_and_not_lisp_nil
  scm_is_false  -->  scm_is_false_and_not_lisp_nil
  scm_is_true   -->  scm_is_true_or_lisp_nil
  scm_is_bool   -->  scm_is_bool_and_not_lisp_nil

(I still believe that these should be changed to versions that handle
 %nil properly, but await approval on that point, so these patches do
 not make those changes)

Also, if the preprocessor macro SCM_ENABLE_ELISP is not true (this
macro already existed and was used in lang.h), all overheads
associated with %nil handling are eliminated from the above macros.

* libguile/tags.h (SCM_BOOL_F, SCM_BOOL_T, SCM_UNSPECIFIED)
  (SCM_UNDEFINED, SCM_UNBOUND, SCM_ELISP_NIL): Renumber, so that a
  number of important distinctions (false versus true, end-of-list, etc)
  can be made by masking a single bit. Also define a number of
  build-time tests to assert that this condition holds.

* libguile/boolean.h (scm_is_false_and_not_nil, scm_is_true_or_nil)
  (scm_is_false_assume_not_nil, scm_is_true_assume_not_nil):
  (scm_is_false_or_nil, scm_is_true_and_not_nil)
  (scm_is_bool_or_nil, scm_is_bool_and_not_nil): New exciting macros to
  test certain boolean/end-of-list properties.
  (scm_is_false, scm_is_true): Use a restrictive definition, where only
  SCM_BOOL_F is false. Should probably change in the future.
  (scm_is_bool): Incompatible change: changed to be a macro. Was a
  function before. Probably should allow nil as a boolean, but that will
  be for a later patch.
  (scm_is_lisp_false, scm_is_lisp_true): New macros, implementing the
  standard Lisp boolean predicates, where '() is actually false.

* libguile/eval.i.c (CEVAL): Fix a number of false-or-nil and similar
  tests to use the new macros.

* libguile/lang.h (SCM_NULL_OR_NIL_P): Use scm_is_null_or_nil.

* libguile/pairs.c: Add a compile-time check that null and nil differ by
  only one bit.

* libguile/pairs.h (scm_is_null_and_not_nil, scm_is_null_assume_not_nil)
  (scm_is_null_or_nil): New exciting macros!
  (scm_is_null): Just be scm_is_null_and_not_nil, for now.

* libguile/print.c: Adapt to the reordering, and print suitably nasty
  things for the not-to-be-used values.
2009-10-27 23:25:02 +01:00

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/* classes: h_files */
#ifndef SCM_PAIRS_H
#define SCM_PAIRS_H
/* Copyright (C) 1995,1996,2000,2001, 2004, 2006, 2008, 2009 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include "libguile/__scm.h"
#if (SCM_DEBUG_PAIR_ACCESSES == 1)
# define SCM_VALIDATE_PAIR(cell, expr) \
((!scm_is_pair (cell) ? scm_error_pair_access (cell), 0 : 0), (expr))
#else
# define SCM_VALIDATE_PAIR(cell, expr) (expr)
#endif
/*
* Use scm_is_null_and_not_nil if it's important (for correctness)
* that %nil must NOT be considered null.
*/
#define scm_is_null_and_not_nil(x) (scm_is_eq ((x), SCM_EOL))
/*
* Use scm_is_null_assume_not_nil if %nil will never be tested,
* for increased efficiency.
*/
#define scm_is_null_assume_not_nil(x) (scm_is_eq ((x), SCM_EOL))
/*
* See the comments preceeding the definitions of SCM_BOOL_F and
* SCM_MATCHES_BITS_IN_COMMON in tags.h for more information on
* how the following macro works.
*/
#if SCM_ENABLE_ELISP
# define scm_is_null_or_nil(x) \
(SCM_MATCHES_BITS_IN_COMMON ((x), SCM_ELISP_NIL, SCM_EOL))
#else
# define scm_is_null_or_nil(x) (scm_is_null_assume_not_nil (x))
#endif
/* XXX Should scm_is_null treat %nil as null by default? */
#define scm_is_null(x) (scm_is_null_and_not_nil(x))
#define SCM_CAR(x) (SCM_VALIDATE_PAIR (x, SCM_CELL_OBJECT_0 (x)))
#define SCM_CDR(x) (SCM_VALIDATE_PAIR (x, SCM_CELL_OBJECT_1 (x)))
#define SCM_SETCAR(x, v) (SCM_VALIDATE_PAIR (x, SCM_SET_CELL_OBJECT_0 ((x), (v))))
#define SCM_SETCDR(x, v) (SCM_VALIDATE_PAIR (x, SCM_SET_CELL_OBJECT_1 ((x), (v))))
#define SCM_CAAR(OBJ) SCM_CAR (SCM_CAR (OBJ))
#define SCM_CDAR(OBJ) SCM_CDR (SCM_CAR (OBJ))
#define SCM_CADR(OBJ) SCM_CAR (SCM_CDR (OBJ))
#define SCM_CDDR(OBJ) SCM_CDR (SCM_CDR (OBJ))
#define SCM_CAAAR(OBJ) SCM_CAR (SCM_CAR (SCM_CAR (OBJ)))
#define SCM_CDAAR(OBJ) SCM_CDR (SCM_CAR (SCM_CAR (OBJ)))
#define SCM_CADAR(OBJ) SCM_CAR (SCM_CDR (SCM_CAR (OBJ)))
#define SCM_CDDAR(OBJ) SCM_CDR (SCM_CDR (SCM_CAR (OBJ)))
#define SCM_CAADR(OBJ) SCM_CAR (SCM_CAR (SCM_CDR (OBJ)))
#define SCM_CDADR(OBJ) SCM_CDR (SCM_CAR (SCM_CDR (OBJ)))
#define SCM_CADDR(OBJ) SCM_CAR (SCM_CDR (SCM_CDR (OBJ)))
#define SCM_CDDDR(OBJ) SCM_CDR (SCM_CDR (SCM_CDR (OBJ)))
#define SCM_CAAAAR(OBJ) SCM_CAR (SCM_CAR (SCM_CAR (SCM_CAR (OBJ))))
#define SCM_CDAAAR(OBJ) SCM_CDR (SCM_CAR (SCM_CAR (SCM_CAR (OBJ))))
#define SCM_CADAAR(OBJ) SCM_CAR (SCM_CDR (SCM_CAR (SCM_CAR (OBJ))))
#define SCM_CDDAAR(OBJ) SCM_CDR (SCM_CDR (SCM_CAR (SCM_CAR (OBJ))))
#define SCM_CAADAR(OBJ) SCM_CAR (SCM_CAR (SCM_CDR (SCM_CAR (OBJ))))
#define SCM_CDADAR(OBJ) SCM_CDR (SCM_CAR (SCM_CDR (SCM_CAR (OBJ))))
#define SCM_CADDAR(OBJ) SCM_CAR (SCM_CDR (SCM_CDR (SCM_CAR (OBJ))))
#define SCM_CDDDAR(OBJ) SCM_CDR (SCM_CDR (SCM_CDR (SCM_CAR (OBJ))))
#define SCM_CAAADR(OBJ) SCM_CAR (SCM_CAR (SCM_CAR (SCM_CDR (OBJ))))
#define SCM_CDAADR(OBJ) SCM_CDR (SCM_CAR (SCM_CAR (SCM_CDR (OBJ))))
#define SCM_CADADR(OBJ) SCM_CAR (SCM_CDR (SCM_CAR (SCM_CDR (OBJ))))
#define SCM_CDDADR(OBJ) SCM_CDR (SCM_CDR (SCM_CAR (SCM_CDR (OBJ))))
#define SCM_CAADDR(OBJ) SCM_CAR (SCM_CAR (SCM_CDR (SCM_CDR (OBJ))))
#define SCM_CDADDR(OBJ) SCM_CDR (SCM_CAR (SCM_CDR (SCM_CDR (OBJ))))
#define SCM_CADDDR(OBJ) SCM_CAR (SCM_CDR (SCM_CDR (SCM_CDR (OBJ))))
#define SCM_CDDDDR(OBJ) SCM_CDR (SCM_CDR (SCM_CDR (SCM_CDR (OBJ))))
#if (SCM_DEBUG_PAIR_ACCESSES == 1)
SCM_API void scm_error_pair_access (SCM);
#endif
SCM_API SCM scm_cons (SCM x, SCM y);
SCM_API SCM scm_cons2 (SCM w, SCM x, SCM y);
SCM_API SCM scm_pair_p (SCM x);
SCM_API SCM scm_car (SCM x);
SCM_API SCM scm_cdr (SCM x);
SCM_API SCM scm_set_car_x (SCM pair, SCM value);
SCM_API SCM scm_set_cdr_x (SCM pair, SCM value);
#define SCM_I_D_PAT 0x02 /* 00000010 */
#define SCM_I_A_PAT 0x03 /* 00000011 */
#define SCM_I_DD_PAT 0x0a /* 00001010 */
#define SCM_I_DA_PAT 0x0b /* 00001011 */
#define SCM_I_AD_PAT 0x0e /* 00001110 */
#define SCM_I_AA_PAT 0x0f /* 00001111 */
#define SCM_I_DDD_PAT 0x2a /* 00101010 */
#define SCM_I_DDA_PAT 0x2b /* 00101011 */
#define SCM_I_DAD_PAT 0x2e /* 00101110 */
#define SCM_I_DAA_PAT 0x2f /* 00101111 */
#define SCM_I_ADD_PAT 0x3a /* 00111010 */
#define SCM_I_ADA_PAT 0x3b /* 00111011 */
#define SCM_I_AAD_PAT 0x3e /* 00111110 */
#define SCM_I_AAA_PAT 0x3f /* 00111111 */
#define SCM_I_DDDD_PAT 0xaa /* 10101010 */
#define SCM_I_DDDA_PAT 0xab /* 10101011 */
#define SCM_I_DDAD_PAT 0xae /* 10101110 */
#define SCM_I_DDAA_PAT 0xaf /* 10101111 */
#define SCM_I_DADD_PAT 0xba /* 10111010 */
#define SCM_I_DADA_PAT 0xbb /* 10111011 */
#define SCM_I_DAAD_PAT 0xbe /* 10111110 */
#define SCM_I_DAAA_PAT 0xbf /* 10111111 */
#define SCM_I_ADDD_PAT 0xea /* 11101010 */
#define SCM_I_ADDA_PAT 0xeb /* 11101011 */
#define SCM_I_ADAD_PAT 0xee /* 11101110 */
#define SCM_I_ADAA_PAT 0xef /* 11101111 */
#define SCM_I_AADD_PAT 0xfa /* 11111010 */
#define SCM_I_AADA_PAT 0xfb /* 11111011 */
#define SCM_I_AAAD_PAT 0xfe /* 11111110 */
#define SCM_I_AAAA_PAT 0xff /* 11111111 */
SCM_API SCM scm_i_chase_pairs (SCM x, scm_t_uint32 pattern);
#define scm_cddr(x) scm_i_chase_pairs ((x), SCM_I_DD_PAT)
#define scm_cdar(x) scm_i_chase_pairs ((x), SCM_I_DA_PAT)
#define scm_cadr(x) scm_i_chase_pairs ((x), SCM_I_AD_PAT)
#define scm_caar(x) scm_i_chase_pairs ((x), SCM_I_AA_PAT)
#define scm_cdddr(x) scm_i_chase_pairs ((x), SCM_I_DDD_PAT)
#define scm_cddar(x) scm_i_chase_pairs ((x), SCM_I_DDA_PAT)
#define scm_cdadr(x) scm_i_chase_pairs ((x), SCM_I_DAD_PAT)
#define scm_cdaar(x) scm_i_chase_pairs ((x), SCM_I_DAA_PAT)
#define scm_caddr(x) scm_i_chase_pairs ((x), SCM_I_ADD_PAT)
#define scm_cadar(x) scm_i_chase_pairs ((x), SCM_I_ADA_PAT)
#define scm_caadr(x) scm_i_chase_pairs ((x), SCM_I_AAD_PAT)
#define scm_caaar(x) scm_i_chase_pairs ((x), SCM_I_AAA_PAT)
#define scm_cddddr(x) scm_i_chase_pairs ((x), SCM_I_DDDD_PAT)
#define scm_cdddar(x) scm_i_chase_pairs ((x), SCM_I_DDDA_PAT)
#define scm_cddadr(x) scm_i_chase_pairs ((x), SCM_I_DDAD_PAT)
#define scm_cddaar(x) scm_i_chase_pairs ((x), SCM_I_DDAA_PAT)
#define scm_cdaddr(x) scm_i_chase_pairs ((x), SCM_I_DADD_PAT)
#define scm_cdadar(x) scm_i_chase_pairs ((x), SCM_I_DADA_PAT)
#define scm_cdaadr(x) scm_i_chase_pairs ((x), SCM_I_DAAD_PAT)
#define scm_cdaaar(x) scm_i_chase_pairs ((x), SCM_I_DAAA_PAT)
#define scm_cadddr(x) scm_i_chase_pairs ((x), SCM_I_ADDD_PAT)
#define scm_caddar(x) scm_i_chase_pairs ((x), SCM_I_ADDA_PAT)
#define scm_cadadr(x) scm_i_chase_pairs ((x), SCM_I_ADAD_PAT)
#define scm_cadaar(x) scm_i_chase_pairs ((x), SCM_I_ADAA_PAT)
#define scm_caaddr(x) scm_i_chase_pairs ((x), SCM_I_AADD_PAT)
#define scm_caadar(x) scm_i_chase_pairs ((x), SCM_I_AADA_PAT)
#define scm_caaadr(x) scm_i_chase_pairs ((x), SCM_I_AAAD_PAT)
#define scm_caaaar(x) scm_i_chase_pairs ((x), SCM_I_AAAA_PAT)
SCM_INTERNAL void scm_init_pairs (void);
#endif /* SCM_PAIRS_H */
/*
Local Variables:
c-file-style: "gnu"
End:
*/
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