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89 lines
2.8 KiB
C++
89 lines
2.8 KiB
C++
// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
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#pragma once
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#include "Luau/DenseHash.h"
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#include "Luau/NotNull.h"
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#include "Luau/TypePairHash.h"
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#include "Luau/TypeCheckLimits.h"
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#include "Luau/TypeFwd.h"
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#include <optional>
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#include <vector>
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#include <utility>
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namespace Luau
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{
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struct InternalErrorReporter;
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struct Scope;
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struct TypeArena;
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enum class OccursCheckResult
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{
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Pass,
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Fail
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};
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struct Unifier2
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{
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NotNull<TypeArena> arena;
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NotNull<BuiltinTypes> builtinTypes;
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NotNull<Scope> scope;
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NotNull<InternalErrorReporter> ice;
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TypeCheckLimits limits;
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DenseHashSet<std::pair<TypeId, TypeId>, TypePairHash> seenTypePairings{{nullptr, nullptr}};
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DenseHashSet<std::pair<TypePackId, TypePackId>, TypePairHash> seenTypePackPairings{{nullptr, nullptr}};
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DenseHashMap<TypeId, std::vector<TypeId>> expandedFreeTypes{nullptr};
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int recursionCount = 0;
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int recursionLimit = 0;
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Unifier2(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtinTypes, NotNull<Scope> scope, NotNull<InternalErrorReporter> ice);
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/** Attempt to commit the subtype relation subTy <: superTy to the type
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* graph.
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*
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* @returns true if successful.
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*
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* Note that incoherent types can and will successfully be unified. We stop
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* when we *cannot know* how to relate the provided types, not when doing so
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* would narrow something down to never or broaden it to unknown.
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*
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* Presently, the only way unification can fail is if we attempt to bind one
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* free TypePack to another and encounter an occurs check violation.
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*/
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bool unify(TypeId subTy, TypeId superTy);
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bool unify(TypeId subTy, const FunctionType* superFn);
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bool unify(const UnionType* subUnion, TypeId superTy);
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bool unify(TypeId subTy, const UnionType* superUnion);
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bool unify(const IntersectionType* subIntersection, TypeId superTy);
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bool unify(TypeId subTy, const IntersectionType* superIntersection);
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bool unify(const TableType* subTable, const TableType* superTable);
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bool unify(const MetatableType* subMetatable, const MetatableType* superMetatable);
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// TODO think about this one carefully. We don't do unions or intersections of type packs
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bool unify(TypePackId subTp, TypePackId superTp);
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std::optional<TypeId> generalize(TypeId ty);
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private:
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/**
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* @returns simplify(left | right)
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*/
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TypeId mkUnion(TypeId left, TypeId right);
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/**
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* @returns simplify(left & right)
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*/
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TypeId mkIntersection(TypeId left, TypeId right);
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// Returns true if needle occurs within haystack already. ie if we bound
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// needle to haystack, would a cyclic TypePack result?
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OccursCheckResult occursCheck(DenseHashSet<TypePackId>& seen, TypePackId needle, TypePackId haystack);
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};
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} // namespace Luau
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