| 1 | //===- DeltaTree.h - B-Tree for Rewrite Delta tracking ----------*- C++ -*-===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | // |
| 9 | // This file defines the DeltaTree class. |
| 10 | // |
| 11 | //===----------------------------------------------------------------------===// |
| 12 | |
| 13 | #ifndef LLVM_CLANG_REWRITE_CORE_DELTATREE_H |
| 14 | #define LLVM_CLANG_REWRITE_CORE_DELTATREE_H |
| 15 | |
| 16 | namespace clang { |
| 17 | |
| 18 | /// DeltaTree - a multiway search tree (BTree) structure with some fancy |
| 19 | /// features. B-Trees are generally more memory and cache efficient than |
| 20 | /// binary trees, because they store multiple keys/values in each node. This |
| 21 | /// implements a key/value mapping from index to delta, and allows fast lookup |
| 22 | /// on index. However, an added (important) bonus is that it can also |
| 23 | /// efficiently tell us the full accumulated delta for a specific file offset |
| 24 | /// as well, without traversing the whole tree. |
| 25 | class DeltaTree { |
| 26 | void *Root; // "DeltaTreeNode *" |
| 27 | |
| 28 | public: |
| 29 | DeltaTree(); |
| 30 | |
| 31 | // Note: Currently we only support copying when the RHS is empty. |
| 32 | DeltaTree(const DeltaTree &RHS); |
| 33 | |
| 34 | DeltaTree &operator=(const DeltaTree &) = delete; |
| 35 | ~DeltaTree(); |
| 36 | |
| 37 | /// getDeltaAt - Return the accumulated delta at the specified file offset. |
| 38 | /// This includes all insertions or delections that occurred *before* the |
| 39 | /// specified file index. |
| 40 | int getDeltaAt(unsigned FileIndex) const; |
| 41 | |
| 42 | /// AddDelta - When a change is made that shifts around the text buffer, |
| 43 | /// this method is used to record that info. It inserts a delta of 'Delta' |
| 44 | /// into the current DeltaTree at offset FileIndex. |
| 45 | void AddDelta(unsigned FileIndex, int Delta); |
| 46 | }; |
| 47 | |
| 48 | } // namespace clang |
| 49 | |
| 50 | #endif // LLVM_CLANG_REWRITE_CORE_DELTATREE_H |
| 51 |