From a6a148c6244cc1748b10cc0a365582b327f5241a Mon Sep 17 00:00:00 2001
From: Kohsuke Kawaguchi <kk@kohsuke.org>
Date: Fri, 11 Mar 2011 14:17:02 -0800
Subject: [PATCH] Added a visitor to walk the tree structure of Item&ItemGroup

---
 core/src/main/java/hudson/model/Item.java     |  1 +
 .../main/java/hudson/model/ItemVisitor.java   | 59 +++++++++++++++++++
 .../java/hudson/model/ViewDescriptor.java     | 30 +++++-----
 3 files changed, 74 insertions(+), 16 deletions(-)
 create mode 100644 core/src/main/java/hudson/model/ItemVisitor.java

diff --git a/core/src/main/java/hudson/model/Item.java b/core/src/main/java/hudson/model/Item.java
index d35476dc43..f4f2e17002 100644
--- a/core/src/main/java/hudson/model/Item.java
+++ b/core/src/main/java/hudson/model/Item.java
@@ -60,6 +60,7 @@ import hudson.security.AccessControlled;
  *
  * @author Kohsuke Kawaguchi
  * @see Items
+ * @see ItemVisitor
  */
 public interface Item extends PersistenceRoot, SearchableModelObject, AccessControlled {
     /**
diff --git a/core/src/main/java/hudson/model/ItemVisitor.java b/core/src/main/java/hudson/model/ItemVisitor.java
new file mode 100644
index 0000000000..f63ba1ecc2
--- /dev/null
+++ b/core/src/main/java/hudson/model/ItemVisitor.java
@@ -0,0 +1,59 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2011, CloudBees, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package hudson.model;
+
+/**
+ * Walks the tree structure that consists of {@link ItemGroup} and {@link Item}.
+ *
+ * @author Kohsuke Kawaguchi
+ * @since 1.402
+ */
+public abstract class ItemVisitor {
+    /**
+     * Visits an {@link ItemGroup} by visits the member items.
+     */
+    public void onItemGroup(ItemGroup<?> group) {
+        for (Item i : group.getItems())
+            if (i.hasPermission(Item.READ))
+                onItem(i);
+    }
+
+    /**
+     * Visits an {@link Item}. If it is a group,
+     * visits the children.
+     */
+    public void onItem(Item i) {
+        if(i instanceof ItemGroup)
+            onItemGroup((ItemGroup)i);
+    }
+
+    /**
+     * Visits the entire tree rooted at {@code Hudson.getInstance()}.
+     * <p>
+     * To walk a subtree, call {@link #onItemGroup(ItemGroup)} or {@link #onItem(Item)}
+     */
+    public final void walk() {
+        onItemGroup(Hudson.getInstance());
+    }
+}
diff --git a/core/src/main/java/hudson/model/ViewDescriptor.java b/core/src/main/java/hudson/model/ViewDescriptor.java
index cdf4705adb..d02155dbc9 100644
--- a/core/src/main/java/hudson/model/ViewDescriptor.java
+++ b/core/src/main/java/hudson/model/ViewDescriptor.java
@@ -25,8 +25,6 @@ package hudson.model;
 
 import org.kohsuke.stapler.QueryParameter;
 
-import java.util.Stack;
-
 /**
  * {@link Descriptor} for {@link View}.
  *
@@ -66,24 +64,24 @@ public abstract class ViewDescriptor extends Descriptor<View> {
     /**
      * Auto-completion for the "copy from" field in the new job page.
      */
-    public AutoCompletionCandidates doAutoCompleteCopyNewItemFrom(@QueryParameter String value) {
-        AutoCompletionCandidates r = new AutoCompletionCandidates();
-
-        Stack<ItemGroup> q = new Stack<ItemGroup>();
-        q.push(Hudson.getInstance());
-
-        while(!q.isEmpty()) {
-            ItemGroup<?> parent = q.pop();
-            for (Item i : parent.getItems()) {
-                if (i.hasPermission(Item.READ))
-                    r.add(i.getFullName());
+    public AutoCompletionCandidates doAutoCompleteCopyNewItemFrom(@QueryParameter final String value) {
+        final AutoCompletionCandidates r = new AutoCompletionCandidates();
 
+        new ItemVisitor() {
+            @Override
+            public void onItemGroup(ItemGroup<?> group) {
                 // only dig deep when the path matches what's typed.
                 // for example, if 'foo/bar' is typed, we want to show 'foo/barcode'
-                if(i instanceof ItemGroup && value.startsWith(i.getFullName()))
-                    q.push((ItemGroup)i);
+                if (value.startsWith(group.getFullName()))
+                    super.onItemGroup(group);
+            }
+
+            @Override
+            public void onItem(Item i) {
+                r.add(i.getFullName());
+                super.onItem(i);
             }
-        }
+        }.onItemGroup(Hudson.getInstance());
 
         return r;
     }
-- 
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