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