15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Copyright 2006 The RE2 Authors. All Rights Reserved. 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Use of this source code is governed by a BSD-style 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// license that can be found in the LICENSE file. 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// DESCRIPTION 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// SparseSet<T>(m) is a set of integers in [0, m). 85821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// It requires sizeof(int)*m memory, but it provides 95821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// fast iteration through the elements in the set and fast clearing 105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// of the set. 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Insertion and deletion are constant time operations. 135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Allocating the set is a constant time operation 155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// when memory allocation is a constant time operation. 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Clearing the set is a constant time operation (unusual!). 185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Iterating through the set is an O(n) operation, where n 205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// is the number of items in the set (not O(m)). 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// The set iterator visits entries in the order they were first 235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// inserted into the array. It is safe to add items to the set while 245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// using an iterator: the iterator will visit indices added to the set 255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// during the iteration, but will not re-visit indices whose values 265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// change after visiting. Thus SparseSet can be a convenient 275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// implementation of a work queue. 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// The SparseSet implementation is NOT thread-safe. It is up to the 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// caller to make sure only one thread is accessing the set. (Typically 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// these sets are temporary values and used in situations where speed is 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// important.) 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// The SparseSet interface does not present all the usual STL bells and 355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// whistles. 365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Implemented with reference to Briggs & Torczon, An Efficient 385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// Representation for Sparse Sets, ACM Letters on Programming Languages 395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// and Systems, Volume 2, Issue 1-4 (March-Dec. 1993), pp. 59-69. 405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// For a generalization to sparse array, see sparse_array.h. 425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// IMPLEMENTATION 445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// 455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)// See sparse_array.h for implementation details 465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifndef RE2_UTIL_SPARSE_SET_H__ 485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define RE2_UTIL_SPARSE_SET_H__ 495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "util/util.h" 515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)namespace re2 { 535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)class SparseSet { 555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) public: 565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) SparseSet() 575d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) : size_(0), max_size_(0), sparse_to_dense_(NULL), dense_(NULL), 585d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) valgrind_(RunningOnValgrindOrMemorySanitizer()) {} 595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) SparseSet(int max_size) { 615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) max_size_ = max_size; 625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sparse_to_dense_ = new int[max_size]; 635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) dense_ = new int[max_size]; 645d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles) valgrind_ = RunningOnValgrindOrMemorySanitizer(); 655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Don't need to zero the memory, but do so anyway 665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // to appease Valgrind. 675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (valgrind_) { 685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for (int i = 0; i < max_size; i++) { 695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) dense_[i] = 0xababababU; 705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sparse_to_dense_[i] = 0xababababU; 715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) size_ = 0; 745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ~SparseSet() { 775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) delete[] sparse_to_dense_; 785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) delete[] dense_; 795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef int* iterator; 825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) typedef const int* const_iterator; 835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int size() const { return size_; } 855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) iterator begin() { return dense_; } 865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) iterator end() { return dense_ + size_; } 875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) const_iterator begin() const { return dense_; } 885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) const_iterator end() const { return dense_ + size_; } 895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Change the maximum size of the array. 915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Invalidates all iterators. 925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void resize(int new_max_size) { 935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (size_ > new_max_size) 945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) size_ = new_max_size; 955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (new_max_size > max_size_) { 965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int* a = new int[new_max_size]; 975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (sparse_to_dense_) { 985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) memmove(a, sparse_to_dense_, max_size_*sizeof a[0]); 995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (valgrind_) { 1005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for (int i = max_size_; i < new_max_size; i++) 1015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) a[i] = 0xababababU; 1025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) delete[] sparse_to_dense_; 1045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sparse_to_dense_ = a; 1065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) a = new int[new_max_size]; 1085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (dense_) { 1095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) memmove(a, dense_, size_*sizeof a[0]); 1105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (valgrind_) { 1115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for (int i = size_; i < new_max_size; i++) 1125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) a[i] = 0xababababU; 1135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) delete[] dense_; 1155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) dense_ = a; 1175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) max_size_ = new_max_size; 1195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Return the maximum size of the array. 1225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Indices can be in the range [0, max_size). 1235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int max_size() const { return max_size_; } 1245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Clear the array. 1265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void clear() { size_ = 0; } 1275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Check whether i is in the array. 1295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) bool contains(int i) const { 1305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) DCHECK_GE(i, 0); 1315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) DCHECK_LT(i, max_size_); 1325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (static_cast<uint>(i) >= max_size_) { 1335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return false; 1345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Unsigned comparison avoids checking sparse_to_dense_[i] < 0. 1365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return (uint)sparse_to_dense_[i] < (uint)size_ && 1375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) dense_[sparse_to_dense_[i]] == i; 1385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Adds i to the set. 1415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void insert(int i) { 1425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (!contains(i)) 1435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) insert_new(i); 1445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Set the value at the new index i to v. 1475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Fast but unsafe: only use if contains(i) is false. 1485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void insert_new(int i) { 1495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if (static_cast<uint>(i) >= max_size_) { 1505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Semantically, end() would be better here, but we already know 1515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // the user did something stupid, so begin() insulates them from 1525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // dereferencing an invalid pointer. 1535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return; 1545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) DCHECK(!contains(i)); 1565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) DCHECK_LT(size_, max_size_); 1575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sparse_to_dense_[i] = size_; 1585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) dense_[size_] = i; 1595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) size_++; 1605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Comparison function for sorting. 1635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // Can sort the sparse array so that future iterations 1645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // will visit indices in increasing order using 1655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) // sort(arr.begin(), arr.end(), arr.less); 1665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static bool less(int a, int b) { return a < b; } 1675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) private: 1695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int size_; 1705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int max_size_; 1715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int* sparse_to_dense_; 1725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int* dense_; 1735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) bool valgrind_; 1745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) DISALLOW_EVIL_CONSTRUCTORS(SparseSet); 1765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 1775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} // namespace re2 1795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif // RE2_UTIL_SPARSE_SET_H__ 181