From fe3acce2621938c033829de66c12c9d0be3a864f Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Fri, 25 Nov 2011 21:52:54 -0800
Subject: [PATCH] Some missing functions.

---
 SHAMap.cpp      | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 SHAMapNodes.cpp | 27 +++++++++++++++++++++++----
 2 files changed, 68 insertions(+), 5 deletions(-)

diff --git a/SHAMap.cpp b/SHAMap.cpp
index 63c2e37808..7b37a04c31 100644
--- a/SHAMap.cpp
+++ b/SHAMap.cpp
@@ -287,7 +287,51 @@ SHAMapItem::pointer SHAMap::peekNextItem(const uint256& id)
 
 SHAMapItem::pointer SHAMap::peekPrevItem(const uint256& id)
 {
-	// WRITEME
+	ScopedLock sl(mLock);
+
+	SHAMapLeafNode::pointer leaf=walkToLeaf(id, false, false);
+	if(!leaf) return SHAMapItem::pointer();
+
+	// is there another item in this leaf? (there almost never will be)
+	SHAMapItem::pointer prev=leaf->prevItem(id);
+	if(prev) return prev;
+
+	for(int depth=SHAMapNode::leafDepth-1; depth>=0; depth--)
+	{ // walk up the tree until we find a node with a previous child
+		SHAMapInnerNode::pointer node=mInnerNodeByID[SHAMapNode(depth, id)];
+		if(!node)
+		{
+#ifdef DEBUG
+			std::cerr << "InnerNode missing: " << SHAMapNode(depth,id).getString() << std::endl;
+#endif
+			throw SHAMapException(MissingNode);
+		}
+		for(int i=node->selectBranch(id)-1; i>=0; i--)
+			if(!!node->getChildHash(i))
+			{ // node has a subsequent child
+				SHAMapNode prevNode(node->getChildNodeID(i));
+				const uint256& prevHash(node->getChildHash(i));
+				
+				if(prevNode.isLeaf())
+				{ // this is a terminal inner node
+					leaf=getLeaf(prevNode, prevHash, false);
+					if(!leaf) throw SHAMapException(MissingNode);
+					prev=leaf->firstItem();
+					if(!prev) throw SHAMapException(InvalidNode);
+					return prev;
+				}
+
+				// the next item is the first item below this node
+				SHAMapInnerNode::pointer inner=getInner(prevNode, prevHash, false);
+				if(!inner) throw SHAMapException(MissingNode);
+				prev=lastBelow(inner);
+				if(!prev) throw SHAMapException(InvalidNode);
+				return prev;
+			}
+	}
+
+	// must be last item
+	return SHAMapItem::pointer();
 }
 
 SHAMapLeafNode::pointer SHAMap::createLeaf(const SHAMapInnerNode& lowestParent, const uint256& id)
diff --git a/SHAMapNodes.cpp b/SHAMapNodes.cpp
index fab65c2eb1..5f0806338c 100644
--- a/SHAMapNodes.cpp
+++ b/SHAMapNodes.cpp
@@ -177,11 +177,30 @@ SHAMapItem::pointer SHAMapLeafNode::firstItem(void)
 
 SHAMapItem::pointer SHAMapLeafNode::nextItem(const uint256& tag)
 {
-	bool found=false;
-	BOOST_FOREACH(SHAMapItem::pointer& it, mItems)
+	std::list<SHAMapItem::pointer>::iterator it;
+	for(it=mItems.begin(); it!=mItems.end(); ++it)
 	{
-		if(found) return it;
-		if(it->getTag() == tag) found=true;
+		if((*it)->getTag()==tag)
+		{
+			++it;
+			if(it==mItems.end()) return SHAMapItem::pointer();
+			return *it;
+		}
+	}
+	return SHAMapItem::pointer();
+}
+
+SHAMapItem::pointer SHAMapLeafNode::prevItem(const uint256& tag)
+{
+	std::list<SHAMapItem::pointer>::reverse_iterator it;
+	for(it=mItems.rbegin(); it!=mItems.rend(); ++it)
+	{
+		if((*it)->getTag()==tag)
+		{
+			++it;
+			if(it==mItems.rend()) return SHAMapItem::pointer();
+			return *it;
+		}
 	}
 	return SHAMapItem::pointer();
 }