135 lines
4.2 KiB
C++
135 lines
4.2 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#pragma once
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#include <unordered_set>
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#include <vector>
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#include <utility>
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#include <functional>
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#include "util/debug.h"
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#ifndef LEAN_SCOPED_SET_INITIAL_BUCKET_SIZE
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#define LEAN_SCOPED_SET_INITIAL_BUCKET_SIZE 8
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#endif
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namespace lean {
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/**
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\brief Scoped sets (aka backtrackable sets).
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*/
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template<typename Key, typename Hash = std::hash<Key>, typename KeyEqual = std::equal_to<Key>>
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class scoped_set {
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typedef std::unordered_set<Key, Hash, KeyEqual> set;
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typedef typename set::size_type size_type;
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enum class action_kind { Insert, Erase };
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set m_set;
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std::vector<std::pair<action_kind, Key>> m_actions;
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std::vector<unsigned> m_scopes;
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public:
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explicit scoped_set(size_type bucket_count = LEAN_SCOPED_SET_INITIAL_BUCKET_SIZE,
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const Hash& hash = Hash(),
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const KeyEqual& equal = KeyEqual()):
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m_set(bucket_count, hash, equal) {
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// the return type of Hash()(k) should be convertible to size_t
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static_assert(std::is_convertible<typename std::result_of<decltype(std::declval<Hash>())(Key const &)>::type,
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std::size_t>::value,
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"The return type of hash function is not convertible to std::size_t");
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// the return type of KeyEqual()(k1, k2) should be bool
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static_assert(std::is_same<typename std::result_of<decltype(std::declval<KeyEqual>())(Key const &, Key const &)>::type,
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bool>::value,
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"The return type of KeyEqual()(k1, k2) is not bool");
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}
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/** \brief Return the number of scopes. */
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unsigned num_scopes() const {
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return m_scopes.size();
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}
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/** \brief Return true iff there are no scopes. */
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bool at_base_lvl() const {
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return m_scopes.empty();
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}
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/** \brief Create a new scope (it allows us to restore the current state of the set). */
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void push() {
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m_scopes.push_back(m_actions.size());
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}
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/** \brief Remove \c num scopes, and restores the state of the set. */
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void pop(unsigned num = 1) {
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lean_assert(num <= num_scopes());
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unsigned old_sz = m_scopes[num_scopes() - num];
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lean_assert(old_sz <= m_actions.size());
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unsigned i = m_actions.size();
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while (i > old_sz) {
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--i;
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auto const & p = m_actions.back();
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if (p.first == action_kind::Insert) {
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m_set.erase(p.second);
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} else {
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m_set.insert(p.second);
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}
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m_actions.pop_back();
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}
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lean_assert(m_actions.size() == old_sz);
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m_scopes.resize(num_scopes() - num);
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}
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/** \brief Return true iff the set is empty */
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bool empty() const {
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return m_set.empty();
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}
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/** \brief Return the number of elements stored in the set. */
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unsigned size() const {
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return m_set.size();
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}
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/** \brief Insert an element in the set */
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void insert(Key const & k) {
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if (!at_base_lvl()) {
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if (m_set.find(k) == m_set.end())
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m_actions.emplace_back(action_kind::Insert, k);
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}
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m_set.insert(k);
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}
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/** \brief Remove an element from the set */
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void erase(Key const & k) {
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if (!at_base_lvl()) {
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if (m_set.find(k) != m_set.end())
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m_actions.emplace_back(action_kind::Erase, k);
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}
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m_set.erase(k);
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}
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/** \brief Remove all elements and scopes */
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void clear() {
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m_set.clear();
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m_actions.clear();
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m_scopes.clear();
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}
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typedef typename set::const_iterator const_iterator;
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const_iterator find(Key const & k) const {
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return m_set.find(k);
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}
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const_iterator begin() const {
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return m_set.begin();
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}
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const_iterator end() const {
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return m_set.end();
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}
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class mk_scope {
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scoped_set & m_set;
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public:
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mk_scope(scoped_set & s):m_set(s) { m_set.push(); }
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~mk_scope() { m_set.pop(); }
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};
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};
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}
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