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* libguile/eval.c (scm_m_case): Allow empty lists of case labels.

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* test-suite/tests/syntax.test: Fixed and activated test of empty case
        label support.
This commit is contained in:
Dirk Herrmann 2003-10-11 01:52:25 +00:00
parent 2a6f7afe04
commit 58a2510b07
4 changed files with 19 additions and 5 deletions
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4
libguile/ChangeLog
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@ -1,3 +1,7 @@
2003-10-11 Dirk Herrmann <D.Herrmann@tu-bs.de>
* eval.c (scm_m_case): Allow empty lists of case labels.
2003-10-11 Dirk Herrmann <D.Herrmann@tu-bs.de>
* tags.h (SCM_IM_ELSE, SCM_IM_ARROW): New memoizer codes.

7
libguile/eval.c
View file

@ -741,6 +741,13 @@ scm_m_case (SCM expr, SCM env)
s_bad_case_labels, labels, expr);
all_labels = scm_append_x (scm_list_2 (labels, all_labels));
}
else if (SCM_NULLP (labels))
{
/* The list of labels is empty. According to R5RS this is allowed.
* It means that the sequence of expressions will never be executed.
* Therefore, as an optimization, we could remove the whole
* clause. */
}
else
{
ASSERT_SYNTAX_2 (SCM_EQ_P (labels, scm_sym_else) && else_literal_p,

5
test-suite/ChangeLog
View file

@ -1,3 +1,8 @@
2003-10-11 Dirk Herrmann <D.Herrmann@tu-bs.de>
* tests/syntax.test: Fixed and activated test of empty case label
support.
2003-10-11 Dirk Herrmann <D.Herrmann@tu-bs.de>
* tests/syntax.test (exception:bad-expression,

8
test-suite/tests/syntax.test
View file

@ -509,6 +509,9 @@
(with-test-prefix "case"
(pass-if "clause with empty labels list"
(case 1 (() #f) (else #t)))
(with-test-prefix "case is hygienic"
(pass-if-exception "bound 'else is handled correctly"
@ -558,11 +561,6 @@
(eval '(case 1 ("foo" "bar"))
(interaction-environment)))
;; According to R5RS, the following one is syntactically correct.
;; (pass-if-exception "(case 1 (() \"bar\"))"
;; exception:bad/missing-clauses
;; (case 1 (() "bar")))
(pass-if-exception "(case 1 ((2) \"bar\") . \"foo\")"
exception:bad-expression
(eval '(case 1 ((2) "bar") . "foo")