Add C macro for hash table iteration

This removes some boilerplate code and further reduces dependencies on
hash table implementation internals.

* src/lisp.h (DOHASH): New.
* src/comp.c (compile_function, Fcomp__compile_ctxt_to_file):
* src/composite.c (composition_gstring_cache_clear_font):
* src/emacs-module.c (module_global_reference_p):
* src/fns.c (Fmaphash):
* src/json.c (lisp_to_json_nonscalar_1):
* src/minibuf.c (Ftest_completion):
* src/print.c (print):
Use it instead of a hand-written loop.

1 files changed, 22 insertions, 25 deletions

diff --git a/src/json.c b/src/json.c
index 266905f1c34..5434780ba13 100644
--- a/src/json.c
+++ b/src/json.c
@@ -361,33 +361,30 @@ lisp_to_json_nonscalar_1 (Lisp_Object lisp,
       json = json_check (json_object ());
       count = SPECPDL_INDEX ();
       record_unwind_protect_ptr (json_release_object, json);
-      for (ptrdiff_t i = 0; i < HASH_TABLE_SIZE (h); ++i)
+      DOHASH (h, i)
         {
           Lisp_Object key = HASH_KEY (h, i);
-          if (!hash_unused_entry_key_p (key))
-            {
-              CHECK_STRING (key);
-              Lisp_Object ekey = json_encode (key);
-              /* We can't specify the length, so the string must be
-                 null-terminated.  */
-              check_string_without_embedded_nulls (ekey);
-              const char *key_str = SSDATA (ekey);
-              /* Reject duplicate keys.  These are possible if the hash
-                 table test is not `equal'.  */
-              if (json_object_get (json, key_str) != NULL)
-                wrong_type_argument (Qjson_value_p, lisp);
-              int status
-                = json_object_set_new (json, key_str,
-                                       lisp_to_json (HASH_VALUE (h, i), conf));
-              if (status == -1)
-                {
-                  /* A failure can be caused either by an invalid key or
-                   by low memory.  */
-                  json_check_utf8 (ekey);
-                  json_out_of_memory ();
-                }
-            }
-        }
+          CHECK_STRING (key);
+          Lisp_Object ekey = json_encode (key);
+          /* We can't specify the length, so the string must be
+             null-terminated.  */
+          check_string_without_embedded_nulls (ekey);
+          const char *key_str = SSDATA (ekey);
+          /* Reject duplicate keys.  These are possible if the hash
+             table test is not `equal'.  */
+          if (json_object_get (json, key_str) != NULL)
+            wrong_type_argument (Qjson_value_p, lisp);
+          int status
+            = json_object_set_new (json, key_str,
+                                   lisp_to_json (HASH_VALUE (h, i), conf));
+          if (status == -1)
+            {
+              /* A failure can be caused either by an invalid key or
+                 by low memory.  */
+              json_check_utf8 (ekey);
+              json_out_of_memory ();
+            }
+        }
     }
   else if (NILP (lisp))
     return json_check (json_object ());