Adds label completion.

A global label hash is added, to which labels are added as they're parsed
from a mailbox file or edited manually by the user.  Reference counts are
kept in the hash table so that unused labels are removed from available
completions.  Completion is available in the label editor only, but it
may be feasible to add for search expressions if the preceding text ends
with '~y'.

1 files changed, 41 insertions, 1 deletions

diff --git a/headers.c b/headers.c
index ada4aad4..0cf3a6cc 100644
--- a/headers.c
+++ b/headers.c
@@ -212,6 +212,31 @@ void mutt_edit_headers (const char *editor,
   }
 }
 
+static void label_ref_dec(char *label)
+{
+  uintptr_t count;
+
+  count = (uintptr_t)hash_find(Labels, label);
+  if (count)
+  {
+    hash_delete(Labels, label, NULL, NULL);
+    count--;
+    if (count > 0)
+      hash_insert(Labels, label, (void *)count, 0);
+  }
+}
+
+static void label_ref_inc(char *label)
+{
+  uintptr_t count;
+
+  count = (uintptr_t)hash_find(Labels, label);
+  if (count)
+    hash_delete(Labels, label, NULL, NULL);
+  count++;  /* was zero if not found */
+  hash_insert(Labels, label, (void *)count, 0);
+}
+
 /*
  * add an X-Label: field.
  */
@@ -221,7 +246,11 @@ static int label_message(HEADER *hdr, char *new)
     return 0;
   if (mutt_strcmp (hdr->env->x_label, new) == 0)
     return 0;
+  if (hdr->env->x_label != NULL)
+    label_ref_dec(hdr->env->x_label);
   mutt_str_replace (&hdr->env->x_label, new);
+  if (hdr->env->x_label != NULL)
+    label_ref_inc(hdr->env->x_label);
   return hdr->changed = hdr->xlabel_changed = 1;
 }
 
@@ -236,7 +265,7 @@ int mutt_label_message(HEADER *hdr)
     strncpy(buf, hdr->env->x_label, LONG_STRING);
   }
 
-  if (mutt_get_field("Label: ", buf, sizeof(buf), 0 /* | MUTT_CLEAR */) != 0)
+  if (mutt_get_field("Label: ", buf, sizeof(buf), MUTT_LABEL /* | MUTT_CLEAR */) != 0)
     return 0;
 
   new = buf;
@@ -261,3 +290,14 @@ int mutt_label_message(HEADER *hdr)
 
   return changed;
 }
+
+/* scan a context (mailbox) and hash all labels we find */
+void mutt_scan_labels(CONTEXT *ctx)
+{
+  int i;
+
+  for (i = 0; i < ctx->msgcount; i++)
+    if (ctx->hdrs[i]->env->x_label)
+      label_ref_inc(ctx->hdrs[i]->env->x_label);
+}
+