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//===- DeltaTree.h - B-Tree for Rewrite Delta tracking ----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the DeltaTree class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_REWRITE_CORE_DELTATREE_H
#define LLVM_CLANG_REWRITE_CORE_DELTATREE_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 *"
public:
DeltaTree();
// Note: Currently we only support copying when the RHS is empty.
DeltaTree(const DeltaTree &RHS);
DeltaTree &operator=(const DeltaTree &) = delete;
~DeltaTree();
/// 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);
};
} // namespace clang
#endif // LLVM_CLANG_REWRITE_CORE_DELTATREE_H
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