[PATCH 1/1] scm_set_source_properties_x: optimize if only name, line, and/or col

[Rob Browning]

* libguile/srcprop.c (scm_set_source_properties_x): When only a subset
  of file, line, and column fields are specified, store the data as a
  srcprops object (tc16_srcprops) rather than an alist.
---

 Proposed for at least 3.x.  If we want some additional tests, then
 one option might be a public or private predicate to test for a
 srcprops object (at least for scheme level testing).

 libguile/srcprop.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/libguile/srcprop.c b/libguile/srcprop.c
index 0ebbfc301..fea68e031 100644
--- a/libguile/srcprop.c
+++ b/libguile/srcprop.c
@@ -168,8 +168,6 @@ SCM_DEFINE (scm_source_properties, "source-properties", 1, 
0, 0,
 #define SCM_VALIDATE_NIM(pos, scm) \
   SCM_MAKE_VALIDATE_MSG (pos, scm, NIMP, "non-immediate")
 
-/* Perhaps this procedure should look through an alist
-   and try to make a srcprops-object...? */
 SCM_DEFINE (scm_set_source_properties_x, "set-source-properties!", 2, 0, 0,
             (SCM obj, SCM alist),
            "Install the association list @var{alist} as the source property\n"
@@ -177,9 +175,17 @@ SCM_DEFINE (scm_set_source_properties_x, 
"set-source-properties!", 2, 0, 0,
 #define FUNC_NAME s_scm_set_source_properties_x
 {
   SCM_VALIDATE_NIM (1, obj);
-
-  scm_weak_table_putq_x (scm_source_whash, obj, alist);
-
+  SCM fname = scm_assq_ref (alist, scm_sym_filename);
+  SCM col = scm_assq_ref (alist, scm_sym_column);
+  SCM line = scm_assq_ref (alist, scm_sym_line);
+  const int n = ((fname == SCM_BOOL_F) ? 0 : 1)
+    + ((col == SCM_BOOL_F) ? 0 : 1)
+    + ((line == SCM_BOOL_F) ? 0 : 1);
+
+  if (scm_ilength (alist) == n)
+    scm_i_set_source_properties_x (obj, line, col, fname);
+  else
+    scm_weak_table_putq_x (scm_source_whash, obj, alist);
   return alist;
 }
 #undef FUNC_NAME
-- 
2.29.2