Replace RE2 import with a dependency

third_party/re2/util/sparse_set.h

-// Copyright 2006 The RE2 Authors.  All Rights Reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// DESCRIPTION
-// 
-// SparseSet<T>(m) is a set of integers in [0, m).
-// It requires sizeof(int)*m memory, but it provides
-// fast iteration through the elements in the set and fast clearing
-// of the set.
-// 
-// Insertion and deletion are constant time operations.
-// 
-// Allocating the set is a constant time operation 
-// when memory allocation is a constant time operation.
-// 
-// Clearing the set is a constant time operation (unusual!).
-// 
-// Iterating through the set is an O(n) operation, where n
-// is the number of items in the set (not O(m)).
-//
-// The set iterator visits entries in the order they were first 
-// inserted into the array.  It is safe to add items to the set while
-// using an iterator: the iterator will visit indices added to the set
-// during the iteration, but will not re-visit indices whose values
-// change after visiting.  Thus SparseSet can be a convenient
-// implementation of a work queue.
-// 
-// The SparseSet implementation is NOT thread-safe.  It is up to the
-// caller to make sure only one thread is accessing the set.  (Typically
-// these sets are temporary values and used in situations where speed is
-// important.)
-// 
-// The SparseSet interface does not present all the usual STL bells and
-// whistles.
-// 
-// Implemented with reference to Briggs & Torczon, An Efficient
-// Representation for Sparse Sets, ACM Letters on Programming Languages
-// and Systems, Volume 2, Issue 1-4 (March-Dec.  1993), pp.  59-69.
-// 
-// For a generalization to sparse array, see sparse_array.h.
-
-// IMPLEMENTATION
-//
-// See sparse_array.h for implementation details
-
-#ifndef RE2_UTIL_SPARSE_SET_H__
-#define RE2_UTIL_SPARSE_SET_H__
-
-#include "util/util.h"
-
-namespace re2 {
-
-class SparseSet {
- public:
-  SparseSet()
-    : size_(0), max_size_(0), sparse_to_dense_(NULL), dense_(NULL) {}
-
-  SparseSet(int max_size) {
-    max_size_ = max_size;
-    sparse_to_dense_ = new int[max_size];
-    dense_ = new int[max_size];
-    // Don't need to zero the memory, but do so anyway
-    // to appease Valgrind.
-    if (InitMemory()) {
-      for (int i = 0; i < max_size; i++) {
-        dense_[i] = 0xababababU;
-        sparse_to_dense_[i] = 0xababababU;
-      }
-    }
-    size_ = 0;
-  }
-
-  ~SparseSet() {
-    delete[] sparse_to_dense_;
-    delete[] dense_;
-  }
-
-  typedef int* iterator;
-  typedef const int* const_iterator;
-
-  int size() const { return size_; }
-  iterator begin() { return dense_; }
-  iterator end() { return dense_ + size_; }
-  const_iterator begin() const { return dense_; }
-  const_iterator end() const { return dense_ + size_; }
-
-  // Change the maximum size of the array.
-  // Invalidates all iterators.
-  void resize(int new_max_size) {
-    if (size_ > new_max_size)
-      size_ = new_max_size;
-    if (new_max_size > max_size_) {
-      int* a = new int[new_max_size];
-      if (sparse_to_dense_) {
-        memmove(a, sparse_to_dense_, max_size_*sizeof a[0]);
-        if (InitMemory()) {
-          for (int i = max_size_; i < new_max_size; i++)
-            a[i] = 0xababababU;
-        }
-        delete[] sparse_to_dense_;
-      }
-      sparse_to_dense_ = a;
-
-      a = new int[new_max_size];
-      if (dense_) {
-        memmove(a, dense_, size_*sizeof a[0]);
-        if (InitMemory()) {
-          for (int i = size_; i < new_max_size; i++)
-            a[i] = 0xababababU;
-        }
-        delete[] dense_;
-      }
-      dense_ = a;
-    }
-    max_size_ = new_max_size;
-  }
-
-  // Return the maximum size of the array.
-  // Indices can be in the range [0, max_size).
-  int max_size() const { return max_size_; }
-
-  // Clear the array.
-  void clear() { size_ = 0; }
-
-  // Check whether i is in the array.
-  bool contains(int i) const {
-    DCHECK_GE(i, 0);
-    DCHECK_LT(i, max_size_);
-    if (static_cast<uint>(i) >= static_cast<uint>(max_size_)) {
-      return false;
-    }
-    // Unsigned comparison avoids checking sparse_to_dense_[i] < 0.
-    return (uint)sparse_to_dense_[i] < (uint)size_ && 
-      dense_[sparse_to_dense_[i]] == i;
-  }
-
-  // Adds i to the set.
-  void insert(int i) {
-    if (!contains(i))
-      insert_new(i);
-  }
-
-  // Set the value at the new index i to v.
-  // Fast but unsafe: only use if contains(i) is false.
-  void insert_new(int i) {
-    if (static_cast<uint>(i) >= static_cast<uint>(max_size_)) {
-      // Semantically, end() would be better here, but we already know
-      // the user did something stupid, so begin() insulates them from
-      // dereferencing an invalid pointer.
-      return;
-    }
-    DCHECK(!contains(i));
-    DCHECK_LT(size_, max_size_);
-    sparse_to_dense_[i] = size_;
-    dense_[size_] = i;
-    size_++;
-  }
-
-  // Comparison function for sorting.
-  // Can sort the sparse array so that future iterations
-  // will visit indices in increasing order using
-  // sort(arr.begin(), arr.end(), arr.less);
-  static bool less(int a, int b) { return a < b; }
-
- private:
-  static bool InitMemory() {
-#ifdef MEMORY_SANITIZER
-    return true;
-#else
-    return RunningOnValgrind();
-#endif
-  }
-
-  int size_;
-  int max_size_;
-  int* sparse_to_dense_;
-  int* dense_;
-
-  DISALLOW_COPY_AND_ASSIGN(SparseSet);
-};
-
-}  // namespace re2
-
-#endif  // RE2_UTIL_SPARSE_SET_H__