1 /* Copyright 2018 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 #ifndef TENSORFLOW_COMPILER_TF2TENSORRT_SEGMENT_UNION_FIND_H_ 17 #define TENSORFLOW_COMPILER_TF2TENSORRT_SEGMENT_UNION_FIND_H_ 18 19 namespace tensorflow { 20 namespace tensorrt { 21 namespace segment { 22 23 // Union-Find data structure. 24 // Each cluster has an associated value; when merging clusters we can control 25 // which value becomes the representative of the merged clusters. Values must be 26 // copyable. 27 template <typename T> 28 class UnionFind { 29 public: UnionFind()30 UnionFind() : size_(1), parent_(nullptr) {} UnionFind(const T & v)31 explicit UnionFind(const T& v) : size_(1), parent_(nullptr), value_(v) {} 32 33 // Returns the number of elements in a cluster. Size()34 int Size() { return FindRoot()->size_; } 35 36 // Merges this cluster with 'other'. This cluster's value becomes 37 // the value of the merged cluster; the value of 'other' is ignored. 38 void Merge(UnionFind* other); 39 40 // Each cluster has an associated value. Retrieves the value associated 41 // with this cluster. ParentValue()42 T& ParentValue() { return FindRoot()->value_; } 43 44 // Get the original value of this node. Value()45 T& Value() { return value_; } 46 47 private: 48 // Finds the root element of the cluster. Performs path compression. 49 UnionFind* FindRoot(); 50 51 int size_; 52 UnionFind* parent_; 53 T value_; 54 }; 55 56 template <typename T> Merge(UnionFind * other)57void UnionFind<T>::Merge(UnionFind* other) { 58 UnionFind<T>* a = FindRoot(); 59 UnionFind<T>* b = other->FindRoot(); 60 if (a == b) return; 61 62 b->parent_ = a; 63 a->size_ += b->size_; 64 } 65 66 template <typename T> FindRoot()67UnionFind<T>* UnionFind<T>::FindRoot() { 68 if (!parent_) return this; 69 // Path compression: update intermediate nodes to point to the root of the 70 // equivalence class. 71 parent_ = parent_->FindRoot(); 72 return parent_; 73 } 74 75 } // namespace segment 76 } // namespace tensorrt 77 } // namespace tensorflow 78 79 #endif // TENSORFLOW_COMPILER_TF2TENSORRT_SEGMENT_UNION_FIND_H_ 80