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