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authorMark H Weaver <mhw@netris.org>2009-10-26 23:56:03 +0100
committerAndy Wingo <wingo@pobox.com>2009-10-27 23:25:02 +0100
commit45f4cbdf128c4d3eadcd4bf4571bcc1d61d1039a (patch)
treea9449d5a67ff928a46a800d639401d99fb9b4d89 /libguile/eval.i.c
parenta07010bf1828704edd9a40cadb0eaf820b8f3638 (diff)
downloadguile-45f4cbdf128c4d3eadcd4bf4571bcc1d61d1039a.tar.gz
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.
Diffstat (limited to 'libguile/eval.i.c')
-rw-r--r--libguile/eval.i.c13
1 files changed, 6 insertions, 7 deletions
diff --git a/libguile/eval.i.c b/libguile/eval.i.c
index 1d1c1807f..d9ec6cd5a 100644
--- a/libguile/eval.i.c
+++ b/libguile/eval.i.c
@@ -304,7 +304,7 @@ dispatch:
while (!scm_is_null (SCM_CDR (x)))
{
SCM test_result = EVALCAR (x, env);
- if (scm_is_false (test_result) || SCM_NILP (test_result))
+ if (scm_is_false_or_nil (test_result))
RETURN (SCM_BOOL_F);
else
x = SCM_CDR (x);
@@ -442,8 +442,7 @@ dispatch:
xx = SCM_CDR (clause);
proc = EVALCAR (xx, env);
guard_result = SCM_APPLY (proc, arg1, SCM_EOL);
- if (scm_is_true (guard_result)
- && !SCM_NILP (guard_result))
+ if (scm_is_true_and_not_nil (guard_result))
{
proc = SCM_CDDR (xx);
proc = EVALCAR (proc, env);
@@ -451,7 +450,7 @@ dispatch:
goto apply_proc;
}
}
- else if (scm_is_true (arg1) && !SCM_NILP (arg1))
+ else if (scm_is_true_and_not_nil (arg1))
{
x = SCM_CDR (clause);
if (scm_is_null (x))
@@ -498,7 +497,7 @@ dispatch:
SCM test_result = EVALCAR (test_form, env);
- while (scm_is_false (test_result) || SCM_NILP (test_result))
+ while (scm_is_false_or_nil (test_result))
{
{
/* Evaluate body forms. */
@@ -552,7 +551,7 @@ dispatch:
{
SCM test_result = EVALCAR (x, env);
x = SCM_CDR (x); /* then expression */
- if (scm_is_false (test_result) || SCM_NILP (test_result))
+ if (scm_is_false_or_nil (test_result))
{
x = SCM_CDR (x); /* else expression */
if (scm_is_null (x))
@@ -623,7 +622,7 @@ dispatch:
while (!scm_is_null (SCM_CDR (x)))
{
SCM val = EVALCAR (x, env);
- if (scm_is_true (val) && !SCM_NILP (val))
+ if (scm_is_true_and_not_nil (val))
RETURN (val);
else
x = SCM_CDR (x);