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/*
* Copyright 2023 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef wasm_analysis_lattices_tuple_h
#define wasm_analysis_lattices_tuple_h
#include <tuple>
#include <utility>
#include "bool.h"
#include "support/utilities.h"
namespace wasm::analysis {
template<Lattice... Ls> struct Tuple {
using Element = std::tuple<typename Ls::Element...>;
std::tuple<Ls...> lattices;
Tuple(Ls&&... lattices) : lattices({std::move(lattices)...}) {}
private:
template<size_t... I>
Element getBottomImpl(std::index_sequence<I...>) const noexcept {
return {std::get<I>(lattices).getBottom()...};
}
template<size_t... I>
Element getTopImpl(std::index_sequence<I...>) const noexcept {
return {std::get<I>(lattices).getTop()...};
}
LatticeComparison compareImpl(const Element& a,
const Element& b,
LatticeComparison result,
std::index_sequence<>) const noexcept {
// Base case: there is nothing left to compare.
return result;
}
template<size_t I, size_t... Is>
LatticeComparison compareImpl(const Element& a,
const Element& b,
LatticeComparison result,
std::index_sequence<I, Is...>) const noexcept {
// Recursive case: compare the current elements, update `result`, and
// recurse to the next elements if necessary.
switch (std::get<I>(lattices).compare(std::get<I>(a), std::get<I>(b))) {
case EQUAL:
return compareImpl(a, b, result, std::index_sequence<Is...>{});
case LESS:
if (result == GREATER) {
// Cannot be both less and greater.
return NO_RELATION;
}
return compareImpl(a, b, LESS, std::index_sequence<Is...>{});
case GREATER:
if (result == LESS) {
// Cannot be both greater and less.
return NO_RELATION;
}
return compareImpl(a, b, GREATER, std::index_sequence<Is...>{});
case NO_RELATION:
return NO_RELATION;
}
WASM_UNREACHABLE("unexpected comparison");
}
int joinImpl(Element& joinee,
const Element& joiner,
std::index_sequence<>) const noexcept {
// Base case: there is nothing left to join.
return false;
}
template<size_t I, size_t... Is>
int joinImpl(Element& joinee,
const Element& joiner,
std::index_sequence<I, Is...>) const noexcept {
// Recursive case: join the current element and recurse to the next
// elements.
return std::get<I>(lattices).join(std::get<I>(joinee),
std::get<I>(joiner)) |
joinImpl(joinee, joiner, std::index_sequence<Is...>{});
}
int meetImpl(Element& meetee,
const Element& meeter,
std::index_sequence<>) const noexcept {
// Base case: there is nothing left to mee.
return false;
}
template<size_t I, size_t... Is>
int meetImpl(Element& meetee,
const Element& meeter,
std::index_sequence<I, Is...>) const noexcept {
// Recursive case: meet the current element and recurse to the next
// elements.
return (std::get<I>(lattices).meet(std::get<I>(meetee),
std::get<I>(meeter))) |
meetImpl(meetee, meeter, std::index_sequence<Is...>{});
}
public:
Element getBottom() const noexcept {
return getBottomImpl(std::index_sequence_for<Ls...>());
}
Element getTop() const noexcept {
return getTopImpl(std::index_sequence_for<Ls...>());
}
LatticeComparison compare(const Element& a, const Element& b) const noexcept {
return compareImpl(a, b, EQUAL, std::index_sequence_for<Ls...>());
}
bool join(Element& joinee, const Element& joiner) const noexcept {
return joinImpl(joinee, joiner, std::index_sequence_for<Ls...>());
}
bool meet(Element& meetee, const Element& meeter) const noexcept {
return meetImpl(meetee, meeter, std::index_sequence_for<Ls...>());
}
};
#if __cplusplus >= 202002L
static_assert(FullLattice<Tuple<>>);
static_assert(FullLattice<Tuple<Bool>>);
#endif
} // namespace wasm::analysis
#endif // wasm_analysis_lattices_tuple_h
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