| 1 | /*
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| 2 | * Souffle - A Datalog Compiler
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| 3 | * Copyright (c) 2022, The Souffle Developers. All rights reserved
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| 4 | * Licensed under the Universal Permissive License v 1.0 as shown at:
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| 5 | * - https://opensource.org/licenses/UPL
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| 6 | * - <souffle root>/licenses/SOUFFLE-UPL.txt
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| 7 | */
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| 8 |
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| 9 | /************************************************************************
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| 10 | *
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| 11 | * @file Nullaries.h
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| 12 | *
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| 13 | * Datastructure for Nullary relations
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| 14 | *
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| 15 | ***********************************************************************/
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| 16 |
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| 17 | #pragma once
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| 18 |
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| 19 | #include "souffle/RamTypes.h"
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| 20 | #include "souffle/SouffleInterface.h"
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| 21 | #include <atomic>
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| 22 |
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| 23 | namespace souffle {
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| 24 |
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| 25 | /** Nullary relations */
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| 26 | class t_nullaries {
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| 27 | private:
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| 28 | std::atomic<bool> data{false};
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| 29 |
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| 30 | public:
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| 31 | static constexpr Relation::arity_type Arity = 0;
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| 32 |
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| 33 | t_nullaries() = default;
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| 34 | using t_tuple = Tuple<RamDomain, 0>;
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| 35 | struct context {};
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| 36 | context createContext() {
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| 37 | return context();
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| 38 | }
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| 39 | class iterator {
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| 40 | bool value;
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| 41 |
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| 42 | public:
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| 43 | using iterator_category = std::forward_iterator_tag;
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| 44 | using value_type = RamDomain*;
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| 45 | using difference_type = ptrdiff_t;
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| 46 | using pointer = value_type*;
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| 47 | using reference = value_type&;
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| 48 |
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| 49 | iterator(bool v = false) : value(v) {}
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| 50 |
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| 51 | const RamDomain* operator*() {
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| 52 | return nullptr;
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| 53 | }
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| 54 |
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| 55 | bool operator==(const iterator& other) const {
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| 56 | return other.value == value;
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| 57 | }
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| 58 |
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| 59 | bool operator!=(const iterator& other) const {
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| 60 | return other.value != value;
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| 61 | }
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| 62 |
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| 63 | iterator& operator++() {
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| 64 | if (value) {
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| 65 | value = false;
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| 66 | }
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| 67 | return *this;
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| 68 | }
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| 69 | };
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| 70 | iterator begin() const {
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| 71 | return iterator(data);
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| 72 | }
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| 73 | iterator end() const {
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| 74 | return iterator();
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| 75 | }
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| 76 | void insert(const t_tuple& /* t */) {
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| 77 | data = true;
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| 78 | }
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| 79 | void insert(const t_tuple& /* t */, context& /* ctxt */) {
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| 80 | data = true;
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| 81 | }
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| 82 | void insert(const RamDomain* /* ramDomain */) {
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| 83 | data = true;
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| 84 | }
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| 85 | bool insert() {
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| 86 | bool result = data;
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| 87 | data = true;
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| 88 | return !result;
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| 89 | }
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| 90 | bool contains(const t_tuple& /* t */) const {
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| 91 | return data;
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| 92 | }
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| 93 | bool contains(const t_tuple& /* t */, context& /* ctxt */) const {
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| 94 | return data;
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| 95 | }
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| 96 | std::size_t size() const {
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| 97 | return data ? 1 : 0;
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| 98 | }
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| 99 | bool empty() const {
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| 100 | return !data;
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| 101 | }
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| 102 | void purge() {
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| 103 | data = false;
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| 104 | }
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| 105 | void printStatistics(std::ostream& /* o */) const {}
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| 106 | };
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| 107 |
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| 108 | } // namespace souffle
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