beginnings of a B-tree, currently insertion has been implemented and test

git-svn-id: https://svn.musicpd.org/mpd/trunk@4487 09075e82-0dd4-0310-85a5-a0d7c8717e4f

1 files changed, 260 insertions, 0 deletions

diff --git a/src/tree.c b/src/tree.c
new file mode 100644
index 000000000..0696f4b13
--- /dev/null
+++ b/src/tree.c
@@ -0,0 +1,260 @@
+#include "tree.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+static
+TreeNode *
+_MakeNode()
+{
+	TreeNode * ret = malloc(sizeof(TreeNode));
+	memset(ret, 0, sizeof(TreeNode));
+	return ret;
+}
+
+static
+int
+_Find(TreeIterator * iter, void * data)
+{
+	while (1)
+	{
+		for (; iter->which < iter->node->dataCount; iter->which++)
+		{
+			int comp = iter->tree->
+				compareData(data,iter->node->data[iter->which]);
+
+			if (comp == 0)
+			{
+				return 1;
+			}
+			else if (comp < 0)
+			{
+				break;
+			}
+		}
+
+		assert(iter->which < CHILDREN_PER_NODE);
+
+		if (iter->node->children[iter->which])
+		{
+			iter->node = iter->node->children[iter->which];
+			iter->which = 0;
+		}
+		else
+		{
+			return 0;
+		}
+	}
+}
+
+Tree *
+MakeTree(TreeCompareDataFunction compareData, TreeFreeDataFunction freeData)
+{
+	Tree * ret = malloc(sizeof(Tree));
+	ret->compareData = compareData;
+	ret->freeData = freeData;
+	ret->rootNode = _MakeNode();
+	return ret;
+}
+
+static
+TreeNode *
+_SplitNode(TreeNode * node)
+{
+	assert(node->dataCount == DATA_PER_NODE);
+
+	TreeNode * newNode = _MakeNode();
+
+	unsigned i = DATA_PER_NODE/2;
+	unsigned j = 0;
+	for (; i < DATA_PER_NODE; i++, j++)
+	{
+		newNode->data[j] = node->data[i];
+		newNode->children[j+1] = node->children[i+1];
+		if (newNode->children[j+1])
+		{
+			newNode->children[j+1]->parent = newNode;
+		}
+		node->data[i] = NULL;
+		node->children[i+1] = NULL;
+	}
+	newNode->dataCount = j;
+	node->dataCount -= j;
+
+	return newNode;
+}
+
+static
+void
+_InsertNodeAndData(Tree * tree, 
+		   TreeNode * node, 
+		   TreeNode * newNode,
+		   void * data)
+{
+	assert(node->dataCount < DATA_PER_NODE);
+	assert(!newNode || tree->compareData(data, newNode->data[0]) < 0);
+
+	if (newNode)
+	{
+		newNode->parent = node;
+	}
+
+	int i = 0;
+	for (; 
+	     i < node->dataCount &&
+	     tree->compareData(data, node->data[i]) > 0;
+	     i++);
+
+	int j = node->dataCount;
+	for (; j > i; j--)
+	{
+		node->data[j] = node->data[j-1];
+		node->children[j+1] = node->children[j];
+	}
+
+	assert(!node->children[j] ||
+	       tree->compareData(data, node->children[j]->data[0]) > 0);
+
+	node->data[j] = data;
+	node->children[j+1] = newNode;
+	node->dataCount++;
+}
+
+static
+void *
+_AddDataToSplitNodes(Tree * tree,
+		     TreeNode * lessNode, 
+		     TreeNode * moreNode,
+		     TreeNode * newNode,
+		     void * data)
+{
+	assert(newNode == NULL ||
+	       tree->compareData(data, newNode->data[0]) < 0);
+
+	void * retData;
+
+	if (tree->compareData(data, moreNode->data[0]) < 0)
+	{
+		_InsertNodeAndData(tree, lessNode, newNode, data);
+		lessNode->dataCount--;
+		retData = lessNode->data[lessNode->dataCount];
+		lessNode->data[lessNode->dataCount] = NULL;
+	}
+	else
+	{
+		if (newNode)
+		{
+			newNode->parent = moreNode;
+		}
+
+		int i = 0;
+		for (; 
+		     i < moreNode->dataCount &&
+		     tree->compareData(data, moreNode->data[i]) > 0;
+		     i++);
+
+		if (i == 0)
+		{
+			moreNode->children[0] = newNode;
+			return data;
+		}
+		else
+		{
+			retData = moreNode->data[0];
+		}
+
+		int j = 0;
+		for (; j < i; j++)
+		{
+			moreNode->data[j] = moreNode->data[j+1];
+			moreNode->children[j] = moreNode->children[j+1];
+		}
+
+		assert(!moreNode->children[j-1] ||
+		       tree->compareData(data,
+			       		 moreNode->children[j]->data[0]) > 0);
+
+		moreNode->data[j-1] = data;
+		moreNode->children[j] = newNode;
+	}
+
+	return retData;
+}
+
+static
+void
+_InsertAt(TreeIterator * iter, void * data)
+{
+	TreeNode * node = iter->node;
+	TreeNode * insertNode = NULL;
+	
+	while (node != NULL)
+	{
+		// see if there's any NULL data in the current node
+		if (node->dataCount == DATA_PER_NODE)
+		{
+			// no open data slots, split this node!
+			TreeNode * newNode = _SplitNode(node);
+
+			// insert data in split nodes
+			data = _AddDataToSplitNodes(iter->tree,
+						    node, 
+						    newNode, 
+						    insertNode,
+						    data);
+
+			insertNode = newNode;
+
+			if (node->parent == NULL)
+			{
+				assert(node == iter->tree->rootNode);
+				iter->tree->rootNode = _MakeNode();
+				node->parent = iter->tree->rootNode;
+				newNode->parent = iter->tree->rootNode;
+				iter->tree->rootNode->data[0] = data;
+				iter->tree->rootNode->children[0] = node;
+				iter->tree->rootNode->children[1] = newNode;
+				iter->tree->rootNode->dataCount = 1;
+				return;
+			}
+
+			node = node->parent;
+		}
+		else
+		{
+			// insert the data and newNode
+			_InsertNodeAndData( iter->tree, 
+					    node, 
+					    insertNode,
+					    data );
+			node = NULL;
+		}
+	}
+
+	return;
+}
+
+void SetIteratorToBegin(TreeIterator * iter, Tree * tree)
+{
+	iter->tree = tree;
+	iter->node = tree->rootNode;
+	iter->which = 0;
+}
+
+int
+InsertIntoTree(Tree * tree, void * data)
+{
+	TreeIterator iter;
+	SetIteratorToBegin(&iter, tree);
+
+	if (_Find(&iter, data))
+	{
+		return 0;
+	}
+
+	_InsertAt(&iter, data);
+
+	return 1;
+}