From 5dc31d3d2dc3486cf17cdf8f511d6e9ae000326e Mon Sep 17 00:00:00 2001
From: Jukka Zitting <jukka@adobe.com>
Date: Thu, 18 Apr 2013 16:15:13 +0300
Subject: [PATCH] OAK-781: Clarify / fix effects of MISSING_NODE as base state
 of NodeBuilder

Add exists(), getChild() and addChild() methods to NodeBuilder
---
 .../oak/plugins/memory/MemoryNodeBuilder.java      | 17 +++++++++++-
 .../jackrabbit/oak/spi/state/NodeBuilder.java      | 31 ++++++++++++++++++++++
 .../jackrabbit/oak/spi/state/ReadOnlyBuilder.java  | 15 +++++++++++
 3 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/memory/MemoryNodeBuilder.java b/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/memory/MemoryNodeBuilder.java
index 9faa23f..281e788 100644
--- a/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/memory/MemoryNodeBuilder.java
+++ b/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/memory/MemoryNodeBuilder.java
@@ -41,6 +41,7 @@ import org.apache.jackrabbit.oak.spi.state.ChildNodeEntry;
 import org.apache.jackrabbit.oak.spi.state.NodeBuilder;
 import org.apache.jackrabbit.oak.spi.state.NodeState;
 import org.apache.jackrabbit.oak.spi.state.NodeStateDiff;
+import org.apache.jackrabbit.oak.spi.state.ReadOnlyBuilder;
 
 /**
  * In-memory node state builder.
@@ -191,7 +192,8 @@ public class MemoryNodeBuilder implements NodeBuilder {
      * Determine whether this child exists at its direct parent.
      * @return {@code true} iff this child exists at its direct parent.
      */
-    private boolean exists() {
+    @Override
+    public boolean exists() {
         if (isRoot()) {
             return true;
         } else if (parent.writeState == null) {
@@ -502,6 +504,19 @@ public class MemoryNodeBuilder implements NodeBuilder {
         return builder;
     }
 
+    @Override @Nonnull
+    public NodeBuilder getChild(@Nonnull String name) {
+        read();
+        return createChildBuilder(name);
+    }
+
+    @Override @Nonnull
+    public NodeBuilder addChild(@Nonnull String name) {
+        NodeBuilder builder = child(name);
+        builder.reset(EMPTY_NODE);
+        return builder;
+    }
+
     /**
      * The <em>mutable</em> state being built. Instances of this class
      * are never passed beyond the containing {@code MemoryNodeBuilder},
diff --git a/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/NodeBuilder.java b/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/NodeBuilder.java
index 29a950e..b2fd1b8 100644
--- a/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/NodeBuilder.java
+++ b/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/NodeBuilder.java
@@ -47,6 +47,13 @@ public interface NodeBuilder {
     NodeState getBaseState();
 
     /**
+     * Checks whether this builder represents a node that exists.
+     *
+     * @return {@code true} if the node exists, {@code false} otherwise
+     */
+    boolean exists();
+
+    /**
      * Check whether this builder represents a new node, which is not present in the base state.
      * @return  {@code true} for a new node
      */
@@ -277,4 +284,28 @@ public interface NodeBuilder {
     @Nonnull
     NodeBuilder child(@Nonnull String name);
 
+    /**
+     * Returns a builder for constructing changes to the named child node.
+     * If the named child node does not already exist, the returned builder
+     * will refer to a non-existent node and trying to modify it will cause
+     * {@link IllegalStateException}s to be thrown.
+     *
+     * @since Oak 0.7
+     * @param name name of the child node
+     * @return child builder, possibly non-existent
+     */
+    @Nonnull
+    NodeBuilder getChild(@Nonnull String name);
+
+    /**
+     * Adds the named child node and returns a builder for modifying it.
+     * Possible previous content in the named subtree is removed.
+     *
+     * @since Oak 0.7
+     * @param name name of the child node
+     * @return child builder
+     */
+    @Nonnull
+    NodeBuilder addChild(@Nonnull String name);
+
 }
diff --git a/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/ReadOnlyBuilder.java b/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/ReadOnlyBuilder.java
index 4f964d6..408fb0c 100644
--- a/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/ReadOnlyBuilder.java
+++ b/oak-core/src/main/java/org/apache/jackrabbit/oak/spi/state/ReadOnlyBuilder.java
@@ -39,6 +39,11 @@ public class ReadOnlyBuilder implements NodeBuilder {
     }
 
     @Override
+    public boolean exists() {
+        return state.exists();
+    }
+
+    @Override
     public boolean isNew() {
         return false;
     }
@@ -158,4 +163,14 @@ public class ReadOnlyBuilder implements NodeBuilder {
         }
     }
 
+    @Override @Nonnull
+    public NodeBuilder getChild(@Nonnull String name) {
+        return new ReadOnlyBuilder(state.getChildNode(name));
+    }
+
+    @Override @Nonnull
+    public NodeBuilder addChild(@Nonnull String name) {
+        throw unsupported();
+    }
+
 }
-- 
1.8.0.msysgit.0