[geary] Tighten up parent refs in ListParameters

[Jim Nelson <jnelson src gnome org>]

commit 513c6d8c0dfea6264a9f99242a686704e27b1500
Author: Jim Nelson <jim yorba org>
Date:   Thu Sep 18 17:36:41 2014 -0700

    Tighten up parent refs in ListParameters
    
    While working on another bug, I discovered some issues with the
    maintenance of parent references for IMAP Parameters being held in
    ListParameters (of which every Parameter is held).  This patch not
    only tightens up references, it also verifies references are accurate
    when the ListParameter is destroyed.

 src/engine/imap/parameter/imap-list-parameter.vala |   37 ++++++++++++--------
 1 files changed, 22 insertions(+), 15 deletions(-)
---
diff --git a/src/engine/imap/parameter/imap-list-parameter.vala 
b/src/engine/imap/parameter/imap-list-parameter.vala
index 1df02be..e742752 100644
--- a/src/engine/imap/parameter/imap-list-parameter.vala
+++ b/src/engine/imap/parameter/imap-list-parameter.vala
@@ -43,14 +43,15 @@ public class Geary.Imap.ListParameter : Geary.Imap.Parameter {
     }
     
     ~ListParameter() {
-        // Although every attempt is made to make sure the parent-child relationship is maintained,
-        // be lenient here and only drop it if coherent ... this is done because, although it's
-        // a weak ref, sometimes ListParameters are temporarily made and current Vala doesn't
-        // reset weak refs
+        // Drop back links because, although it's a weak ref, sometimes ListParameters are temporarily
+        // made and current Vala doesn't reset weak refs
         foreach (Parameter param in list) {
             ListParameter? listp = param as ListParameter;
-            if (listp != null && listp.parent == this)
+            if (listp != null) {
+                assert(listp.parent == this);
+                
                 listp.parent = null;
+            }
         }
     }
     
@@ -68,8 +69,12 @@ public class Geary.Imap.ListParameter : Geary.Imap.Parameter {
     public bool add(Parameter param) {
         // if adding a ListParameter, set its parent
         ListParameter? listp = param as ListParameter;
-        if (listp != null)
+        if (listp != null) {
+            if (listp.parent != null)
+                listp.parent.list.remove(listp);
+            
             listp.parent = this;
+        }
         
         return list.add(param);
     }
@@ -129,6 +134,8 @@ public class Geary.Imap.ListParameter : Geary.Imap.Parameter {
     
     /**
      * Clears the { link ListParameter} of all its children.
+     *
+     * This also clears (sets to null) the parents of all { link ListParamater} children.
      */
     public void clear() {
         // sever ties to ListParameter children
@@ -448,8 +455,12 @@ public class Geary.Imap.ListParameter : Geary.Imap.Parameter {
         
         // add parent to new Parameter if a list
         ListParameter? listp = parameter as ListParameter;
-        if (listp != null)
+        if (listp != null) {
+            if (listp.parent != null)
+                listp.parent.list.remove(listp);
+            
             listp.parent = this;
+        }
         
         // clear parent of old Parameter if a list
         listp = old as ListParameter;
@@ -468,15 +479,11 @@ public class Geary.Imap.ListParameter : Geary.Imap.Parameter {
     public void adopt_children(ListParameter src) {
         clear();
         
-        foreach (Parameter param in src.list) {
-            ListParameter? listp = param as ListParameter;
-            if (listp != null)
-                listp.parent = this;
-            
-            list.add(param);
-        }
-        
+        Gee.List<Parameter> src_children = new Gee.ArrayList<Parameter>();
+        src_children.add_all(src.list);
         src.clear();
+        
+        add_all(src_children);
     }
     
     protected string stringize_list() {