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//===--- DeltaTree.h - B-Tree for Rewrite Delta tracking --------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file defines the DeltaTree class.
#include "llvm/Support/Compiler.h"
namespace clang {
/// DeltaTree - a multiway search tree (BTree) structure with some fancy
/// features. B-Trees are generally more memory and cache efficient than
/// binary trees, because they store multiple keys/values in each node. This
/// implements a key/value mapping from index to delta, and allows fast lookup
/// on index. However, an added (important) bonus is that it can also
/// efficiently tell us the full accumulated delta for a specific file offset
/// as well, without traversing the whole tree.
class DeltaTree {
void *Root; // "DeltaTreeNode *"
void operator=(const DeltaTree &) = delete;
// Note: Currently we only support copying when the RHS is empty.
DeltaTree(const DeltaTree &RHS);
/// getDeltaAt - Return the accumulated delta at the specified file offset.
/// This includes all insertions or delections that occurred *before* the
/// specified file index.
int getDeltaAt(unsigned FileIndex) const;
/// AddDelta - When a change is made that shifts around the text buffer,
/// this method is used to record that info. It inserts a delta of 'Delta'
/// into the current DeltaTree at offset FileIndex.
void AddDelta(unsigned FileIndex, int Delta);
} // end namespace clang