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- /* classes: h_files */
- /* Copyright (C) 1995,1996,2000, 2006, 2008, 2009, 2010, 2013 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
- */
- /* Boolean Values. Obviously there are
- * with. We choose to treat nil as a false boolean. All options might silently
- * break existing code, but this one seems most responsible.
- *
- */
- /*
- * Use these macros if it's important (for correctness)
- * that
- */
- /*
- * Use these macros if
- * for increased efficiency.
- */
- /*
- * 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.
- */
- (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_ELISP_NIL, SCM_BOOL_F))
- /*
- /*
- * Since we know SCM_BOOL_F and SCM_BOOL_T differ by exactly one bit,
- * and that SCM_BOOL_F and SCM_ELISP_NIL differ by exactly one bit,
- * and that they of course can't be the same bit (or else SCM_BOOL_T
- * and SCM_ELISP_NIL be would equal), it follows that SCM_BOOL_T and
- * SCM_ELISP_NIL differ by exactly two bits, and these are the bits
- * which will be ignored by SCM_MATCHES_BITS_IN_COMMON below.
- *
- * See the comments preceeding the definitions of SCM_BOOL_F and
- * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
- *
- * If SCM_ENABLE_ELISP is true, then scm_is_bool_or_nil(x)
- * returns 1 if and only if x is one of the following: SCM_BOOL_F,
- * SCM_BOOL_T, SCM_ELISP_NIL, or SCM_XXX_ANOTHER_BOOLEAN_DONT_USE_0.
- * Otherwise, it returns 0.
- */
- (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_BOOL_T, SCM_ELISP_NIL))
- (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_BOOL_F, SCM_BOOL_T))
- SCM_API int scm_is_bool (SCM);
- SCM_API int scm_to_bool (SCM x);
- /* Older spellings for the above routines, kept around for
- compatibility. */
- /*
- * The following macros efficiently implement boolean truth testing as
- * expected by most lisps, which treat '() aka SCM_EOL as false.
- *
- * Since we know SCM_ELISP_NIL and SCM_BOOL_F differ by exactly one
- * bit, and that SCM_ELISP_NIL and SCM_EOL differ by exactly one bit,
- * and that they of course can't be the same bit (or else SCM_BOOL_F
- * and SCM_EOL be would equal), it follows that SCM_BOOL_F and SCM_EOL
- * differ by exactly two bits, and these are the bits which will be
- * ignored by SCM_MATCHES_BITS_IN_COMMON below.
- *
- * See the comments preceeding the definitions of SCM_BOOL_F and
- * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
- *
- * scm_is_lisp_false(x) returns 1 if and only if x is one of the
- * following: SCM_BOOL_F, SCM_ELISP_NIL, SCM_EOL or
- * SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE. Otherwise, it returns 0.
- */
- (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_BOOL_F, SCM_EOL))
- SCM_API SCM scm_not (SCM x);
- SCM_API SCM scm_boolean_p (SCM obj);
- SCM_API SCM scm_nil_p (SCM obj);
- SCM_INTERNAL void scm_init_boolean (void);
- /*
- Local Variables:
- c-file-style: "gnu"
- End:
- */
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