1 files changed, 126 insertions, 0 deletions
diff --git a/include/2geom/intervaltree/interval_tree.h b/include/2geom/intervaltree/interval_tree.h
new file mode 100644
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+++ b/include/2geom/intervaltree/interval_tree.h
@@ -0,0 +1,126 @@
+#ifndef E_INTERVAL_TREE
+#define E_INTERVAL_TREE
+
+// From Emin Martinian, licenced LGPL and MPL with permission
+
+#include <vector>
+#include <math.h>
+#include <limits>
+#include <iostream>
+
+using std::vector;
+
+//  The interval_tree.h and interval_tree.cc files contain code for 
+//  interval trees implemented using red-black-trees as described in 
+//  the book _Introduction_To_Algorithms_ by Cormen, Leisserson, 
+//  and Rivest.  
+
+//  CONVENTIONS:  
+//                Function names: Each word in a function name begins with 
+//                a capital letter.  An example funcntion name is  
+//                CreateRedTree(a,b,c). Furthermore, each function name 
+//                should begin with a capital letter to easily distinguish 
+//                them from variables. 
+//                                                                     
+//                Variable names: Each word in a variable name begins with 
+//                a capital letter EXCEPT the first letter of the variable 
+//                name.  For example, int newLongInt.  Global variables have 
+//                names beginning with "g".  An example of a global 
+//                variable name is gNewtonsConstant. 
+
+
+#ifndef MAX_INT
+#define MAX_INT INT_MAX // some architechturs define INT_MAX not MAX_INT
+#endif
+
+// The Interval class is an Abstract Base Class.  This means that no
+// instance of the Interval class can exist.  Only classes which
+// inherit from the Interval class can exist.  Furthermore any class
+// which inherits from the Interval class must define the member
+// functions GetLowPoint and GetHighPoint.
+//
+// The GetLowPoint should return the lowest point of the interval and
+// the GetHighPoint should return the highest point of the interval.  
+
+class Interval {
+public:
+  Interval();
+  virtual ~Interval();
+  virtual int GetLowPoint() const = 0;
+  virtual int GetHighPoint() const = 0;
+  virtual void Print() const;
+};
+
+class IntervalTreeNode {
+  friend class IntervalTree;
+public:
+  void Print(IntervalTreeNode*,
+	     IntervalTreeNode*) const;
+  IntervalTreeNode();
+  IntervalTreeNode(Interval *);
+  ~IntervalTreeNode();
+protected:
+  Interval * storedInterval;
+  int key;
+  int high;
+  int maxHigh;
+  bool red; /* if red=0 then the node is black */
+  IntervalTreeNode * left;
+  IntervalTreeNode * right;
+  IntervalTreeNode * parent;
+};
+
+struct it_recursion_node {
+public:
+  /*  this structure stores the information needed when we take the */
+  /*  right branch in searching for intervals but possibly come back */
+  /*  and check the left branch as well. */
+
+  IntervalTreeNode * start_node;
+  unsigned int parentIndex;
+  bool tryRightBranch;
+} ;
+
+
+class IntervalTree {
+public:
+  IntervalTree();
+  ~IntervalTree();
+  void Print() const;
+  Interval * DeleteNode(IntervalTreeNode *);
+  IntervalTreeNode * Insert(Interval *);
+  IntervalTreeNode * GetPredecessorOf(IntervalTreeNode *) const;
+  IntervalTreeNode * GetSuccessorOf(IntervalTreeNode *) const;
+  vector<void *> Enumerate(int low, int high) ;
+  void CheckAssumptions() const;
+protected:
+  /*  A sentinel is used for root and for nil.  These sentinels are */
+  /*  created when ITTreeCreate is caled.  root->left should always */
+  /*  point to the node which is the root of the tree.  nil points to a */
+  /*  node which should always be black but has arbitrary children and */
+  /*  parent and no key or info.  The point of using these sentinels is so */
+  /*  that the root and nil nodes do not require special cases in the code */
+  IntervalTreeNode * root;
+  IntervalTreeNode * nil;
+  void LeftRotate(IntervalTreeNode *);
+  void RightRotate(IntervalTreeNode *);
+  void TreeInsertHelp(IntervalTreeNode *);
+  void TreePrintHelper(IntervalTreeNode *) const;
+  void FixUpMaxHigh(IntervalTreeNode *);
+  void DeleteFixUp(IntervalTreeNode *);
+  void CheckMaxHighFields(IntervalTreeNode *) const;
+  int CheckMaxHighFieldsHelper(IntervalTreeNode * y, 
+			const int currentHigh,
+			int match) const;
+private:
+  unsigned int recursionNodeStackSize;
+  it_recursion_node * recursionNodeStack;
+  unsigned int currentParent;
+  unsigned int recursionNodeStackTop;
+};
+
+
+#endif
+
+
+