[geary/wip/713891-traversable: 6/12] Change around the null map/filter helpers

[Charles Lindsay <clindsay src gnome org>]

commit 5b9e276bc2c7661c3089459175ff04d44ac012fa
Author: Charles Lindsay <chaz yorba org>
Date:   Wed Dec 11 17:23:01 2013 -0800

    Change around the null map/filter helpers
    
    This more accurately reflects how it seems to be used.

 src/engine/api/geary-search-folder.vala            |    3 +--
 .../conversation-monitor/app-conversation-set.vala |    3 +--
 src/engine/util/util-traversable.vala              |    8 ++++----
 3 files changed, 6 insertions(+), 8 deletions(-)
---
diff --git a/src/engine/api/geary-search-folder.vala b/src/engine/api/geary-search-folder.vala
index 2643eec..cdd7a47 100644
--- a/src/engine/api/geary-search-folder.vala
+++ b/src/engine/api/geary-search-folder.vala
@@ -152,9 +152,8 @@ public class Geary.SearchFolder : Geary.AbstractLocalFolder, Geary.FolderSupport
         try {
             Gee.ArrayList<ImapDB.SearchEmailIdentifier> relevant_ids
                 = Geary.traverse<Geary.EmailIdentifier>(ids)
-                .map<ImapDB.SearchEmailIdentifier>(
+                .map_nonnull<ImapDB.SearchEmailIdentifier>(
                     id => ImapDB.SearchEmailIdentifier.collection_get_email_identifier(search_results, id))
-                .filter_null()
                 .to_array_list();
             
             if (relevant_ids.size > 0)
diff --git a/src/engine/app/conversation-monitor/app-conversation-set.vala 
b/src/engine/app/conversation-monitor/app-conversation-set.vala
index 9e39cd2..06068d3 100644
--- a/src/engine/app/conversation-monitor/app-conversation-set.vala
+++ b/src/engine/app/conversation-monitor/app-conversation-set.vala
@@ -67,8 +67,7 @@ private class Geary.App.ConversationSet : BaseObject {
         Gee.Set<Geary.RFC822.MessageID>? ancestors = email.get_ancestors();
         if (ancestors != null) {
             return Geary.traverse<Geary.RFC822.MessageID>(ancestors)
-                .map<Conversation>(a => logical_message_id_map.get(a))
-                .filter_null()
+                .map_nonnull<Conversation>(a => logical_message_id_map.get(a))
                 .to_hash_set();
         }
         
diff --git a/src/engine/util/util-traversable.vala b/src/engine/util/util-traversable.vala
index 155eb9c..0dd65c4 100644
--- a/src/engine/util/util-traversable.vala
+++ b/src/engine/util/util-traversable.vala
@@ -48,16 +48,16 @@ public class Iterable<G> : BaseObject {
         return new Iterable<G>(i.chop(offset, length));
     }
     
-    public Iterable<G> filter_null() {
-        return new Iterable<G>(i.filter(x => x != null));
+    public Iterable<A> map_nonnull<A>(Gee.MapFunc<A, G> f) {
+        return new Iterable<A>(i.map<A>(f).filter(g => g != null));
     }
     
     public Iterable<A> cast<A>() {
         return new Iterable<G>(
             // This would be a lot simpler if valac didn't barf on the shorter,
             // more obvious syntax for each of these delegates here.
-            i.filter(x => ((Object) x).get_type().is_a(typeof(A)))
-            .map<A>(x => { return (A) x; }));
+            i.filter(g => ((Object) g).get_type().is_a(typeof(A)))
+            .map<A>(g => { return (A) g; }));
     }
     
     public G? first() {