| 1 | /*
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| 2 | * Souffle - A Datalog Compiler
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| 3 | * Copyright (c) 2021, 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 FunctionalUtil.h
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| 12 | *
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| 13 | * @brief Datalog project utilities
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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/utility/DynamicCasting.h"
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| 20 | #include "souffle/utility/Iteration.h"
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| 21 | #include "souffle/utility/MiscUtil.h"
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| 22 | #include <algorithm>
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| 23 | #include <cassert>
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| 24 | #include <functional>
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| 25 | #include <map>
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| 26 | #include <set>
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| 27 | #include <type_traits>
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| 28 | #include <utility>
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| 29 | #include <vector>
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| 30 |
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| 31 | namespace souffle {
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| 32 |
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| 33 | // -------------------------------------------------------------------------------
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| 34 | // Functional Utils
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| 35 | // -------------------------------------------------------------------------------
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| 36 |
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| 37 | /**
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| 38 | * A functor comparing the dereferenced value of a pointer type utilizing a
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| 39 | * given comparator. Its main use case are sets of non-null pointers which should
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| 40 | * be ordered according to the value addressed by the pointer.
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| 41 | */
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| 42 | template <typename T, typename C = std::less<T>>
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| 43 | struct deref_less {
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| 44 | bool operator()(const T* a, const T* b) const {
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| 45 | return C()(*a, *b);
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| 46 | }
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| 47 | };
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| 48 |
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| 49 | // -------------------------------------------------------------------------------
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| 50 | // Lambda Utils
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| 51 | // -------------------------------------------------------------------------------
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| 52 |
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| 53 | /**
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| 54 | * A type trait enabling the deduction of type properties of lambdas.
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| 55 | *
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| 56 | * source:
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| 57 | * https://stackoverflow.com/questions/7943525/is-it-possible-to-figure-out-the-parameter-type-and-return-type-of-a-lambda
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| 58 | */
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| 59 | template <typename A, typename = void>
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| 60 | struct lambda_traits;
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| 61 |
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| 62 | template <typename A>
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| 63 | struct lambda_traits<A, std::enable_if_t<std::is_class_v<std::decay_t<A>>>>
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| 64 | : lambda_traits<decltype(&std::decay_t<A>::operator())> {};
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| 65 |
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| 66 | #define LAMBDA_TYPE_INFO_REM_CTOR(...) __VA_ARGS__
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| 67 | #define LAMBDA_TYPE_INFO_SPEC(kind, cv, var, is_var) \
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| 68 | struct lambda_traits<R(kind)(Args... LAMBDA_TYPE_INFO_REM_CTOR var) cv, void> { \
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| 69 | using arity = std::integral_constant<std::size_t, sizeof...(Args)>; \
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| 70 | using is_variadic = std::integral_constant<bool, is_var>; \
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| 71 | using is_const = std::is_const<int cv>; \
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| 72 | \
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| 73 | using result_type = R; \
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| 74 | \
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| 75 | template <std::size_t i> \
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| 76 | using arg = typename std::tuple_element<i, std::tuple<Args..., void>>::type; \
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| 77 | };
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| 78 |
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| 79 | #define LAMBDA_TYPE_INFO_MEMBER(cv, var, is_var) \
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| 80 | template <typename C, typename R, typename... Args> \
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| 81 | LAMBDA_TYPE_INFO_SPEC(C::*, cv, var, is_var)
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| 82 |
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| 83 | #define LAMBDA_TYPE_INFO_FUNC(var, is_var) \
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| 84 | template <typename R, typename... Args> \
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| 85 | LAMBDA_TYPE_INFO_SPEC(*, , var, is_var) \
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| 86 | template <typename R, typename... Args> \
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| 87 | LAMBDA_TYPE_INFO_SPEC(&, , var, is_var)
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| 88 |
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| 89 | LAMBDA_TYPE_INFO_MEMBER(const, (, ...), 1)
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| 90 | LAMBDA_TYPE_INFO_MEMBER(const, (), 0)
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| 91 | LAMBDA_TYPE_INFO_MEMBER(, (, ...), 1)
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| 92 | LAMBDA_TYPE_INFO_MEMBER(, (), 0)
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| 93 | LAMBDA_TYPE_INFO_FUNC((, ...), 1)
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| 94 | LAMBDA_TYPE_INFO_FUNC((), 0)
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| 95 | #undef LAMBDA_TYPE_INFO_REM_CTOR
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| 96 | #undef LAMBDA_TYPE_INFO_SPEC
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| 97 | #undef LAMBDA_TYPE_INFO_MEMBER
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| 98 | #undef LAMBDA_TYPE_INFO_FUNC
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| 99 |
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| 100 | namespace detail {
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| 101 |
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| 102 | template <typename F>
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| 103 | struct LambdaFix {
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| 104 | F f;
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| 105 | template <typename... Args>
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| 106 | auto operator()(Args&&... args) -> decltype(f(*this, std::forward<Args>(args)...)) {
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| 107 | return f(*this, std::forward<Args>(args)...);
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| 108 | }
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| 109 | };
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| 110 |
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| 111 | } // namespace detail
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| 112 |
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| 113 | template <typename F /* f -> ... */>
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| 114 | detail::LambdaFix<F> fix(F f) {
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| 115 | return {std::move(f)};
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| 116 | }
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| 117 |
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| 118 | // -------------------------------------------------------------------------------
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| 119 | // General Algorithms
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| 120 | // -------------------------------------------------------------------------------
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| 121 |
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| 122 | namespace detail {
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| 123 | constexpr auto coerceToBool = [](auto&& x) { return (bool)x; };
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| 124 |
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| 125 | template <typename C, typename F /* : A -> B */>
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| 126 | auto mapVector(C& xs, F&& f) {
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| 127 | std::vector<decltype(f(xs[0]))> ys;
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| 128 | ys.reserve(xs.size());
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| 129 | for (auto&& x : xs) {
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| 130 | ys.push_back(f(x));
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| 131 | }
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| 132 | return ys;
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| 133 | }
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| 134 | } // namespace detail
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| 135 |
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| 136 | /**
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| 137 | * A generic test checking whether all elements within a container satisfy a
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| 138 | * certain predicate.
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| 139 | *
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| 140 | * @param c the container
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| 141 | * @param p the predicate
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| 142 | * @return true if for all elements x in c the predicate p(x) is true, false
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| 143 | * otherwise; for empty containers the result is always true
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| 144 | */
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| 145 | template <typename Container, typename UnaryPredicate>
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| 146 | bool all_of(const Container& c, UnaryPredicate p) {
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| 147 | return std::all_of(c.begin(), c.end(), p);
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| 148 | }
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| 149 |
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| 150 | /**
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| 151 | * A generic test checking whether any elements within a container satisfy a
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| 152 | * certain predicate.
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| 153 | *
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| 154 | * @param c the container
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| 155 | * @param p the predicate
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| 156 | * @return true if there is an element x in c such that predicate p(x) is true, false
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| 157 | * otherwise; for empty containers the result is always false
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| 158 | */
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| 159 | template <typename Container, typename UnaryPredicate>
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| 160 | bool any_of(const Container& c, UnaryPredicate p) {
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| 161 | return std::any_of(c.begin(), c.end(), p);
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| 162 | }
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| 163 |
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| 164 | /**
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| 165 | * A generic test checking whether all elements within a container satisfy a
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| 166 | * certain predicate.
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| 167 | *
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| 168 | * @param c the container
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| 169 | * @param p the predicate
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| 170 | * @return true if for all elements x in c the predicate p(x) is true, false
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| 171 | * otherwise; for empty containers the result is always true
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| 172 | */
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| 173 | template <typename Container, typename UnaryPredicate>
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| 174 | bool none_of(const Container& c, UnaryPredicate p) {
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| 175 | return std::none_of(c.begin(), c.end(), p);
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| 176 | }
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| 177 |
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| 178 | /**
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| 179 | * Filter a vector to exclude certain elements.
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| 180 | */
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| 181 | template <typename A, typename F>
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| 182 | std::vector<A> filterNot(std::vector<A> xs, F&& f) {
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| 183 | xs.erase(std::remove_if(xs.begin(), xs.end(), std::forward<F>(f)), xs.end());
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| 184 | return xs;
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| 185 | }
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| 186 |
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| 187 | /**
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| 188 | * Filter a vector to include certain elements.
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| 189 | */
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| 190 | template <typename A, typename F>
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| 191 | std::vector<A> filter(std::vector<A> xs, F&& f) {
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| 192 | return filterNot(std::move(xs), [&](auto&& x) { return !f(x); });
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| 193 | }
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| 194 |
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| 195 | template <typename B, typename CrossCast = void, typename C>
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| 196 | auto filterAs(C&& xs) {
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| 197 | return filterMap(std::forward<C>(xs), [](auto&& x) { return as<B, CrossCast>(x); });
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| 198 | }
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| 199 |
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| 200 | /**
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| 201 | * Fold left a sequence
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| 202 | */
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| 203 | template <typename A, typename B, typename F /* : B -> A -> B */>
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| 204 | B foldl(std::vector<A> xs, B zero, F&& f) {
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| 205 | B accum = std::move(zero);
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| 206 | for (auto&& x : xs)
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| 207 | accum = f(std::move(accum), std::move(x));
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| 208 | return accum;
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| 209 | }
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| 210 |
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| 211 | /**
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| 212 | * Fold left a non-empty sequence
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| 213 | */
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| 214 | template <typename A, typename F /* : A -> A -> A */>
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| 215 | auto foldl(std::vector<A> xs, F&& f) {
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| 216 | assert(!xs.empty() && "cannot foldl an empty sequence");
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| 217 | auto it = xs.begin();
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| 218 | A y = std::move(*it++);
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| 219 | for (; it != xs.end(); it++) {
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| 220 | y = f(std::move(y), std::move(*it));
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| 221 | }
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| 222 | return y;
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| 223 | }
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| 224 |
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| 225 | template <typename A, typename B, typename F /* : A -> B -> B */>
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| 226 | B foldr(std::vector<A> xs, B zero, F&& f) {
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| 227 | B accum = std::move(zero);
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| 228 | for (auto&& x : reverse(xs))
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| 229 | accum = f(std::move(x), std::move(accum));
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| 230 | return accum;
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| 231 | }
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| 232 |
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| 233 | template <typename A, typename F /* : A -> A -> A */>
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| 234 | auto foldr(std::vector<A> xs, F&& f) {
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| 235 | assert(!xs.empty() && "cannot foldr an empty sequence");
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| 236 | auto it = xs.rbegin();
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| 237 | A y = std::move(*it++);
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| 238 | for (; it != xs.rend(); it++) {
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| 239 | y = f(std::move(*it), std::move(y));
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| 240 | }
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| 241 | return y;
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| 242 | }
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| 243 |
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| 244 | /**
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| 245 | * Applies a function to each element of a vector and returns the results.
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| 246 | *
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| 247 | * Unlike `makeTransformRange`, this creates a transformed collection instead of a transformed view.
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| 248 | */
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| 249 | template <typename A, typename F /* : A -> B */>
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| 250 | auto map(std::vector<A>& xs, F&& f) {
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| 251 | return detail::mapVector(xs, std::forward<F>(f));
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| 252 | }
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| 253 |
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| 254 | template <typename A, typename F /* : A -> B */>
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| 255 | auto map(const std::vector<A>& xs, F&& f) {
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| 256 | return detail::mapVector(xs, std::forward<F>(f));
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| 257 | }
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| 258 |
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| 259 | template <typename A, typename F /* : A -> B */>
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| 260 | auto map(std::vector<A>&& xs, F&& f) {
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| 261 | return detail::mapVector(xs, std::forward<F>(f));
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| 262 | }
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| 263 |
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| 264 | template <typename A, typename F /* : A -> pointer_like<B> */>
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| 265 | auto filterMap(const std::vector<A>& xs, F&& f) {
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| 266 | using R = decltype(f(xs[0]));
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| 267 | // not a pointer -> assume it's `std::optional`
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| 268 | using B = std::conditional_t<std::is_pointer_v<R>, R, std::decay_t<decltype(*std::declval<R>())>>;
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| 269 | std::vector<B> ys;
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| 270 | ys.reserve(xs.size());
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| 271 | for (auto&& x : xs) {
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| 272 | auto y = f(std::move(x));
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| 273 | if (y) {
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| 274 | if constexpr (std::is_pointer_v<R>)
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| 275 | ys.push_back(std::move(y));
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| 276 | else // assume it's `std::optional`
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| 277 | ys.push_back(std::move(*y));
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| 278 | }
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| 279 | }
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| 280 | return ys;
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| 281 | }
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| 282 |
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| 283 | namespace detail {
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| 284 |
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| 285 | template <typename It>
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| 286 | constexpr bool IsLegacyIteratorOutput_v = std::is_reference_v<decltype(*std::declval<It>())>&&
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| 287 | std::is_move_assignable_v<std::remove_reference_t<decltype(*std::declval<It>())>>;
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| 288 |
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| 289 | // HACK: Workaround r-ref collapsing w/ template parameters.
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| 290 | template <typename C>
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| 291 | struct filter {
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| 292 | static_assert(!std::is_reference_v<C>);
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| 293 | static constexpr bool has_output_iter = IsLegacyIteratorOutput_v<typename C::iterator>;
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| 294 |
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| 295 | template <typename F>
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| 296 | C operator()(C&& xs, F&& f) {
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| 297 | // TODO: replace w/ C++20 `std::erase_if`
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| 298 | if constexpr (has_output_iter) {
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| 299 | xs.erase(std::remove_if(xs.begin(), xs.end(), [&](auto&& x) { return !f(x); }), xs.end());
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| 300 | } else {
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| 301 | auto end = xs.end();
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| 302 | for (auto it = xs.begin(); it != end;)
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| 303 | it = f(*it) ? ++it : xs.erase(it);
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| 304 | }
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| 305 | return std::move(xs);
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| 306 | }
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| 307 |
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| 308 | template <typename F, bool enable = std::is_copy_constructible_v<typename C::value_type>>
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| 309 | std::enable_if_t<enable, C> operator()(const C& xs, F&& f) {
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| 310 | C ys;
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| 311 | for (auto&& x : xs)
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| 312 | if (f(x)) {
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| 313 | if constexpr (has_output_iter)
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| 314 | ys.insert(ys.end(), x);
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| 315 | else
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| 316 | ys.insert(x);
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| 317 | }
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| 318 | return ys;
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| 319 | }
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| 320 | };
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| 321 | } // namespace detail
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| 322 |
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| 323 | template <typename C, typename F /* : C::element_type -> bool */>
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| 324 | auto filter(C&& xs, F&& f) {
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| 325 | return detail::filter<std::decay_t<C>>{}(std::forward<C>(xs), std::forward<F>(f));
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| 326 | }
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| 327 |
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| 328 | template <typename C, typename F /* : C::element_type -> bool */>
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| 329 | auto filterNot(C&& xs, F&& f) {
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| 330 | return filter(std::forward<C>(xs), [&](auto&& x) { return !f(x); });
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| 331 | }
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| 332 |
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| 333 | template <typename A, typename F /* : A -> B */>
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| 334 | auto groupBy(std::vector<A> xs, F&& key) {
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| 335 | std::map<decltype(key(xs.front())), std::vector<A>> m;
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| 336 | for (auto&& x : xs)
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| 337 | m[key(x)].push_back(std::move(x));
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| 338 | return m;
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| 339 | }
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| 340 |
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| 341 | template <typename A, typename B, typename F /* : const A& -> const B& -> () */>
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| 342 | void zipForEach(const std::vector<A>& xs, const std::vector<B>& ys, F&& f) {
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| 343 | for (size_t i = 0; i < std::min(xs.size(), ys.size()); i++)
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| 344 | f(xs[i], ys[i]);
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| 345 | }
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| 346 |
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| 347 | template <typename A, typename B, typename F /* : const A& -> const B& -> () */>
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| 348 | auto zipMap(const std::vector<A>& xs, const std::vector<B>& ys, F&& f) {
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| 349 | size_t n = std::min(xs.size(), ys.size());
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| 350 | std::vector<decltype(f(xs.front(), ys.front()))> zs;
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| 351 | zs.reserve(n);
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| 352 | for (size_t i = 0; i < n; i++)
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| 353 | zs.push_back(f(xs[i], ys[i]));
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| 354 | return zs;
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| 355 | }
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| 356 |
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| 357 | template <typename A, typename B>
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| 358 | std::vector<A> concat(std::vector<A> xs, std::vector<B> ys) {
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| 359 | for (auto&& y : ys)
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| 360 | xs.push_back(std::move(y));
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| 361 |
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| 362 | return xs;
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| 363 | }
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| 364 |
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| 365 | template <typename A, typename B>
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| 366 | std::vector<A> concat(std::vector<A> xs, const range<B>& ys) {
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| 367 | for (A y : ys)
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| 368 | xs.push_back(std::move(y));
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| 369 |
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| 370 | return xs;
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| 371 | }
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| 372 |
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| 373 | template <typename A, typename B>
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| 374 | std::vector<A> concat(std::vector<A> xs, B x) {
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| 375 | xs.push_back(std::move(x));
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| 376 | return xs;
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| 377 | }
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| 378 |
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| 379 | template <typename A, typename B>
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| 380 | void append(std::vector<A>& xs, B&& y) {
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| 381 | xs = concat(std::move(xs), std::forward<B>(y));
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| 382 | }
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| 383 |
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| 384 | // -------------------------------------------------------------------------------
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| 385 | // Set Utilities
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| 386 | // -------------------------------------------------------------------------------
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| 387 |
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| 388 | template <typename A>
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| 389 | std::set<A> operator&(const std::set<A, std::less<A>>& lhs, const std::set<A, std::less<A>>& rhs) {
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| 390 | std::set<A> result;
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| 391 | std::set_intersection(
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| 392 | lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), std::inserter(result, result.begin()));
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| 393 | return result;
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| 394 | }
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| 395 |
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| 396 | template <typename A>
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| 397 | std::set<A> operator|(const std::set<A, std::less<A>>& lhs, const std::set<A, std::less<A>>& rhs) {
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| 398 | std::set<A> result;
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| 399 | std::set_union(lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), std::inserter(result, result.begin()));
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| 400 | return result;
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| 401 | }
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| 402 |
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| 403 | template <typename A>
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| 404 | std::set<A> operator-(const std::set<A, std::less<A>>& lhs, const std::set<A, std::less<A>>& rhs) {
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| 405 | std::set<A> result;
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| 406 | std::set_difference(
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| 407 | lhs.begin(), lhs.end(), rhs.begin(), rhs.end(), std::inserter(result, result.begin()));
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| 408 | return result;
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| 409 | }
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| 410 |
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| 411 | } // namespace souffle
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