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-rw-r--r--libguile/boolean.c112
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diff --git a/libguile/boolean.c b/libguile/boolean.c
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--- /dev/null
+++ b/libguile/boolean.c
@@ -0,0 +1,112 @@
+/* Copyright 1995-1996,2000-2001,2006,2008-2011,2018
+ Free Software Foundation, Inc.
+
+ This file is part of Guile.
+
+ Guile 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.
+
+ Guile 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 Guile. If not, see
+ <https://www.gnu.org/licenses/>. */
+
+
+
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "error.h"
+#include "gsubr.h"
+#include "verify.h"
+
+#include "boolean.h"
+
+
+
+
+/*
+ * These compile-time tests verify the properties needed for the
+ * efficient test macros defined in boolean.h, which are defined in
+ * terms of the SCM_MATCHES_BITS_IN_COMMON macro.
+ *
+ * See the comments preceeding the definitions of SCM_BOOL_F and
+ * SCM_MATCHES_BITS_IN_COMMON in scm.h for more information.
+ */
+verify (SCM_BITS_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
+ (SCM_BOOL_F_BITS, SCM_BOOL_T_BITS));
+verify (SCM_BITS_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
+ (SCM_ELISP_NIL_BITS, SCM_BOOL_F_BITS));
+verify (SCM_BITS_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
+ (SCM_ELISP_NIL_BITS, SCM_EOL_BITS));
+verify (SCM_BITS_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
+ (SCM_ELISP_NIL_BITS, SCM_BOOL_F_BITS, SCM_BOOL_T_BITS, \
+ SCM_XXX_ANOTHER_BOOLEAN_DONT_USE_0));
+verify (SCM_BITS_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
+ (SCM_ELISP_NIL_BITS, SCM_BOOL_F_BITS, SCM_EOL_BITS, \
+ SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE));
+
+SCM_DEFINE (scm_not, "not", 1, 0, 0,
+ (SCM x),
+ "Return @code{#t} iff @var{x} is false, else return @code{#f}.")
+#define FUNC_NAME s_scm_not
+{
+ return scm_from_bool (scm_is_false (x));
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_nil_p, "nil?", 1, 0, 0,
+ (SCM x),
+ "Return @code{#t} iff @var{x} is nil, else return @code{#f}.")
+#define FUNC_NAME s_scm_nil_p
+{
+ return scm_from_bool (scm_is_lisp_false (x));
+}
+#undef FUNC_NAME
+
+SCM_DEFINE (scm_boolean_p, "boolean?", 1, 0, 0,
+ (SCM obj),
+ "Return @code{#t} iff @var{obj} is @code{#t} or false.")
+#define FUNC_NAME s_scm_boolean_p
+{
+ return scm_from_bool (scm_is_bool (obj));
+}
+#undef FUNC_NAME
+
+int
+scm_to_bool (SCM x)
+{
+ if (scm_is_false (x))
+ return 0;
+ else if (scm_is_eq (x, SCM_BOOL_T))
+ return 1;
+ else
+ scm_wrong_type_arg (NULL, 0, x);
+}
+
+/* We keep this primitive as a function in addition to the same-named macro
+ because some applications (e.g., GNU LilyPond 2.13.9) expect it to be a
+ function. */
+#undef scm_is_bool
+int
+scm_is_bool (SCM obj)
+{
+ /* This must match the macro definition of `scm_is_bool ()'. */
+ return scm_is_bool_or_nil (obj);
+}
+
+
+void
+scm_init_boolean ()
+{
+#include "boolean.x"
+}
+