[dconf-editor] Introduce KeyEditorChildEnumSingle.

[Arnaud Bonatti <arnaudb src gnome org>]

commit 711db65bb68faf88d05d7157bd11fd5ad7e639dc
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Sat Aug 13 18:29:45 2016 +0200

    Introduce KeyEditorChildEnumSingle.

 editor/ca.desrt.dconf-editor.gschema.xml |    8 ++++++++
 editor/dconf-view.vala                   |   19 +++++++++++++++++++
 editor/key-list-box-row.vala             |    2 +-
 editor/registry-info.ui                  |   26 ++++++++++++++++++++++++++
 editor/registry-info.vala                |    9 ++++++++-
 5 files changed, 62 insertions(+), 2 deletions(-)
---
diff --git a/editor/ca.desrt.dconf-editor.gschema.xml b/editor/ca.desrt.dconf-editor.gschema.xml
index f9c8d02..0071b49 100644
--- a/editor/ca.desrt.dconf-editor.gschema.xml
+++ b/editor/ca.desrt.dconf-editor.gschema.xml
@@ -83,6 +83,9 @@
     <value value="8" nick="Yellow"/>
     <value value="1" nick="Green"/>
   </flags>
+  <enum id="ca.desrt.dconf-editor.DemoWeirdEnum">
+    <value value="0" nick="only-choice"/>
+  </enum>
   <schema id="ca.desrt.dconf-editor.Demo" path="/ca/desrt/dconf-editor/demo/">
     <key name="boolean" type="b">
       <default>true</default>
@@ -209,5 +212,10 @@ If you are not interacting with D-Bus, then there is no reason to make use of th
       <summary>A nullable string, type "ms"</summary>
       <description>GSettings allows nullable types, that are similar to other types but could take a 
"nothing" value. A nullable string can take any string as value, including the empty string "''", or can be 
NULL (nothing).</description>
     </key>
+    <key name="weird-enum" enum="ca.desrt.dconf-editor.DemoWeirdEnum">
+      <default>'only-choice'</default>
+      <summary>A 1-choice enumeration</summary>
+      <description>An enumeration could contain only one item, but that's probably an error. Dconf Editor 
warns you in that case.</description>
+    </key>
   </schema>
 </schemalist>
diff --git a/editor/dconf-view.vala b/editor/dconf-view.vala
index 2e8aa70..cb7872f 100644
--- a/editor/dconf-view.vala
+++ b/editor/dconf-view.vala
@@ -27,6 +27,25 @@ public interface KeyEditorChild : Widget
     public abstract void reload (Variant gvariant);
 }
 
+private class KeyEditorChildEnumSingle : Label, KeyEditorChild
+{
+    private Variant variant;
+
+    public KeyEditorChildEnumSingle (Variant key_value)
+    {
+        variant = key_value;
+        set_label (key_value.get_string ());
+        show ();
+    }
+
+    public Variant get_variant ()
+    {
+        return variant;
+    }
+
+    public void reload (Variant gvariant) {}
+}
+
 private class KeyEditorChildEnum : MenuButton, KeyEditorChild
 {
     private Variant variant;
diff --git a/editor/key-list-box-row.vala b/editor/key-list-box-row.vala
index dba517f..f207646 100644
--- a/editor/key-list-box-row.vala
+++ b/editor/key-list-box-row.vala
@@ -534,7 +534,7 @@ private class ContextPopover : Popover
             case "<enum>":      // defined by the schema
                 Variant range = ((GSettingsKey) key).range_content;
                 uint size = (uint) range.n_children ();
-                if (size == 0)      // TODO special case also 1?
+                if (size == 0 || (size == 1 && !has_default_value))
                     assert_not_reached ();
                 for (uint index = 0; index < size; index++)
                     current_section.append (range.get_child_value (index).print (false), 
@"$group_dot_action(@mms '" + range.get_child_value (index).get_string () + "')");        // TODO use int 
settings.get_enum ()
diff --git a/editor/registry-info.ui b/editor/registry-info.ui
index 01751b1..93c7cc7 100644
--- a/editor/registry-info.ui
+++ b/editor/registry-info.ui
@@ -39,6 +39,32 @@
       </object>
     </child>
     <child>
+      <object class="GtkRevealer" id="one_choice_enum_warning">
+        <property name="visible">True</property>
+        <property name="reveal-child">False</property>
+        <child>
+          <object class="GtkInfoBar">
+            <property name="visible">True</property>
+            <property name="message-type">warning</property>
+            <child internal-child="content_area">
+              <object class="GtkBox">
+                <child>
+                  <object class="GtkLabel">
+                    <property name="visible">True</property>
+                    <property name="hexpand">True</property>
+                    <property name="max-width-chars">40</property>
+                    <property name="use-markup">True</property>
+                    <property name="wrap">True</property>
+                    <property name="label" translatable="yes">&#60;b&#62;This enumeration offers only one 
choice.&#60;/b&#62; That's probably an error of the application that installed this schema. If possible, 
please open a bug about it.</property>
+                  </object>
+                </child>
+              </object>
+            </child>
+          </object>
+        </child>
+      </object>
+    </child>
+    <child>
       <object class="GtkScrolledWindow">
         <property name="visible">True</property>
         <child>
diff --git a/editor/registry-info.vala b/editor/registry-info.vala
index df6ee42..a939ac3 100644
--- a/editor/registry-info.vala
+++ b/editor/registry-info.vala
@@ -21,6 +21,7 @@ using Gtk;
 class RegistryInfo : Grid
 {
     [GtkChild] private Revealer no_schema_warning;
+    [GtkChild] private Revealer one_choice_enum_warning;
     [GtkChild] private ListBox properties_list_box;
     [GtkChild] private Button erase_button;
 
@@ -110,6 +111,7 @@ class RegistryInfo : Grid
         add_separator ();
 
         KeyEditorChild key_editor_child = create_child (key);
+        one_choice_enum_warning.set_reveal_child (key_editor_child is KeyEditorChildEnumSingle);
 
         ulong value_has_changed_handler = key_editor_child.value_has_changed.connect ((is_valid) => {
                 if (revealer.should_delay_apply (tmp_string))
@@ -201,7 +203,12 @@ class RegistryInfo : Grid
         switch (key.type_string)
         {
             case "<enum>":
-                return (KeyEditorChild) new KeyEditorChildEnum (key);
+                switch (((GSettingsKey) key).range_content.n_children ())
+                {
+                    case 0:  assert_not_reached ();
+                    case 1:  return (KeyEditorChild) new KeyEditorChildEnumSingle (key.value);
+                    default: return (KeyEditorChild) new KeyEditorChildEnum (key);
+                }
             case "<flags>":
                 return (KeyEditorChild) new KeyEditorChildFlags ((GSettingsKey) key);
             case "b":