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author | Mark H Weaver <mhw@netris.org> | 2009-10-26 23:56:03 +0100 |
---|---|---|
committer | Andy Wingo <wingo@pobox.com> | 2009-10-27 23:25:02 +0100 |
commit | 45f4cbdf128c4d3eadcd4bf4571bcc1d61d1039a (patch) | |
tree | a9449d5a67ff928a46a800d639401d99fb9b4d89 /libguile/eval.i.c | |
parent | a07010bf1828704edd9a40cadb0eaf820b8f3638 (diff) | |
download | guile-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.c | 13 |
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); |