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-rw-r--r--srfi/srfi-1.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/srfi/srfi-1.c b/srfi/srfi-1.c
index 79701b0b5..74df5a96e 100644
--- a/srfi/srfi-1.c
+++ b/srfi/srfi-1.c
@@ -63,6 +63,40 @@ equal_trampoline (SCM proc, SCM arg1, SCM arg2)
}
+SCM_DEFINE (scm_srfi1_alist_copy, "alist-copy", 1, 0, 0,
+ (SCM alist),
+ "Return a copy of @var{alist}, copying both the pairs comprising\n"
+ "the list and those making the associations.")
+#define FUNC_NAME s_scm_srfi1_alist_copy
+{
+ SCM ret, *p, elem, c;
+
+ /* ret is the list to return. p is where to append to it, initially &ret
+ then SCM_CDRLOC of the last pair. */
+ ret = SCM_EOL;
+ p = &ret;
+
+ for ( ; scm_is_pair (alist); alist = SCM_CDR (alist))
+ {
+ elem = SCM_CAR (alist);
+
+ /* each element of alist must be a pair */
+ SCM_ASSERT_TYPE (scm_is_pair (elem), alist, SCM_ARG1, FUNC_NAME,
+ "association list");
+
+ c = scm_cons (scm_cons (SCM_CAR (elem), SCM_CDR (elem)), SCM_EOL);
+ *p = c;
+ p = SCM_CDRLOC (c);
+ }
+
+ /* alist must be a proper list */
+ SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (alist), alist, SCM_ARG1, FUNC_NAME,
+ "association list");
+ return ret;
+}
+#undef FUNC_NAME
+
+
/* scm_append and scm_append_x don't modify their list argument (only the
lists within that list in the case of scm_append_x), hence making them
suitable for direct use for concatentate. */