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45f4cbdf12
* 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.
99 lines
2.7 KiB
C
99 lines
2.7 KiB
C
/* Copyright (C) 1995, 1996, 2000, 2001, 2006, 2008, 2009 Free Software Foundation, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation; either version 3 of
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* the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301 USA
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*/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "libguile/_scm.h"
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#include "libguile/validate.h"
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#include "libguile/boolean.h"
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#include "libguile/lang.h"
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#include "libguile/tags.h"
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#include "verify.h"
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/*
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* These compile-time tests verify the properties needed for the
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* efficient test macros defined in boolean.h, which are defined in
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* terms of the SCM_MATCHES_BITS_IN_COMMON macro.
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*
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* See the comments preceeding the definitions of SCM_BOOL_F and
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* SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
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*/
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verify (SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
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(SCM_BOOL_F, SCM_BOOL_T));
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verify (SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
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(SCM_ELISP_NIL, SCM_BOOL_F));
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verify (SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
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(SCM_ELISP_NIL, SCM_EOL));
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verify (SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
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(SCM_ELISP_NIL, SCM_BOOL_F, SCM_BOOL_T, \
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SCM_XXX_ANOTHER_BOOLEAN_DONT_USE));
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verify (SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
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(SCM_ELISP_NIL, SCM_BOOL_F, SCM_EOL, \
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SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE));
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SCM_DEFINE (scm_not, "not", 1, 0, 0,
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(SCM x),
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"Return @code{#t} iff @var{x} is @code{#f}, else return @code{#f}.")
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#define FUNC_NAME s_scm_not
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{
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return scm_from_bool (scm_is_false_or_nil (x));
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}
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#undef FUNC_NAME
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SCM_DEFINE (scm_boolean_p, "boolean?", 1, 0, 0,
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(SCM obj),
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"Return @code{#t} iff @var{obj} is either @code{#t} or @code{#f}.")
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#define FUNC_NAME s_scm_boolean_p
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{
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return scm_from_bool (scm_is_bool_or_nil (obj));
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}
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#undef FUNC_NAME
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int
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scm_to_bool (SCM x)
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{
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/* XXX Should this first test use scm_is_false_or_nil instead? */
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if (scm_is_eq (x, SCM_BOOL_F))
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return 0;
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else if (scm_is_eq (x, SCM_BOOL_T))
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return 1;
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else
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scm_wrong_type_arg (NULL, 0, x);
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}
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void
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scm_init_boolean ()
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{
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#include "libguile/boolean.x"
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}
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/*
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Local Variables:
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c-file-style: "gnu"
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End:
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*/
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