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_ADT_DELTATREE_H 14 #define LLVM_ADT_DELTATREE_H 15 16 #include "llvm/Support/Compiler.h" 17 18 namespace llvm { 19 20 /// DeltaTree - a multiway search tree (BTree) structure with some fancy 21 /// features. B-Trees are generally more memory and cache efficient than 22 /// binary trees, because they store multiple keys/values in each node. This 23 /// implements a key/value mapping from index to delta, and allows fast lookup 24 /// on index. However, an added (important) bonus is that it can also 25 /// efficiently tell us the full accumulated delta for a specific file offset 26 /// as well, without traversing the whole tree. 27 class DeltaTree { 28 void *Root; // "DeltaTreeNode *" 29 30 public: 31 LLVM_ABI DeltaTree(); 32 33 // Note: Currently we only support copying when the RHS is empty. 34 LLVM_ABI DeltaTree(const DeltaTree &RHS); 35 36 DeltaTree &operator=(const DeltaTree &) = delete; 37 LLVM_ABI ~DeltaTree(); 38 39 /// getDeltaAt - Return the accumulated delta at the specified file offset. 40 /// This includes all insertions or delections that occurred *before* the 41 /// specified file index. 42 LLVM_ABI int getDeltaAt(unsigned FileIndex) const; 43 44 /// AddDelta - When a change is made that shifts around the text buffer, 45 /// this method is used to record that info. It inserts a delta of 'Delta' 46 /// into the current DeltaTree at offset FileIndex. 47 LLVM_ABI void AddDelta(unsigned FileIndex, int Delta); 48 }; 49 50 } // namespace llvm 51 52 #endif // LLVM_ADT_DELTATREE_H 53