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91 lines
2.6 KiB
C++
91 lines
2.6 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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#include "Luau/TypeUtils.h"
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#include "Luau/Scope.h"
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#include "Luau/ToString.h"
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#include "Luau/TypeInfer.h"
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LUAU_FASTFLAGVARIABLE(LuauTerminateCyclicMetatableIndexLookup, false)
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namespace Luau
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{
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std::optional<TypeId> findMetatableEntry(ErrorVec& errors, const ScopePtr& globalScope, TypeId type, std::string entry, Location location)
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{
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type = follow(type);
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std::optional<TypeId> metatable = getMetatable(type);
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if (!metatable)
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return std::nullopt;
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TypeId unwrapped = follow(*metatable);
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if (get<AnyTypeVar>(unwrapped))
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return getSingletonTypes().anyType;
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const TableTypeVar* mtt = getTableType(unwrapped);
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if (!mtt)
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{
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errors.push_back(TypeError{location, GenericError{"Metatable was not a table."}});
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return std::nullopt;
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}
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auto it = mtt->props.find(entry);
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if (it != mtt->props.end())
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return it->second.type;
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else
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return std::nullopt;
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}
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std::optional<TypeId> findTablePropertyRespectingMeta(ErrorVec& errors, const ScopePtr& globalScope, TypeId ty, Name name, Location location)
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{
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if (get<AnyTypeVar>(ty))
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return ty;
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if (const TableTypeVar* tableType = getTableType(ty))
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{
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const auto& it = tableType->props.find(name);
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if (it != tableType->props.end())
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return it->second.type;
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}
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std::optional<TypeId> mtIndex = findMetatableEntry(errors, globalScope, ty, "__index", location);
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int count = 0;
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while (mtIndex)
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{
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TypeId index = follow(*mtIndex);
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if (FFlag::LuauTerminateCyclicMetatableIndexLookup)
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{
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if (count >= 100)
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return std::nullopt;
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++count;
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}
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if (const auto& itt = getTableType(index))
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{
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const auto& fit = itt->props.find(name);
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if (fit != itt->props.end())
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return fit->second.type;
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}
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else if (const auto& itf = get<FunctionTypeVar>(index))
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{
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std::optional<TypeId> r = first(follow(itf->retType));
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if (!r)
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return getSingletonTypes().nilType;
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else
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return *r;
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}
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else if (get<AnyTypeVar>(index))
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return getSingletonTypes().anyType;
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else
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errors.push_back(TypeError{location, GenericError{"__index should either be a function or table. Got " + toString(index)}});
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mtIndex = findMetatableEntry(errors, globalScope, *mtIndex, "__index", location);
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}
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return std::nullopt;
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}
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} // namespace Luau
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