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ton/tolk/generics-helpers.h
tolk-vm f3e620f48c
[Tolk] Nullable types T? and null safety
This commit introduces nullable types `T?` that are
distinct from non-nullable `T`.
Example: `int?` (int or null) and `int` are different now.
Previously, `null` could be assigned to any primitive type.
Now, it can be assigned only to `T?`.

A non-null assertion operator `!` was also introduced,
similar to `!` in TypeScript and `!!` in Kotlin.

If `int?` still occupies 1 stack slot, `(int,int)?` and
other nullable tensors occupy N+1 slots, the last for
"null precedence". `v == null` actually compares that slot.
Assigning `(int,int)` to `(int,int)?` implicitly creates
a null presence slot. Assigning `null` to `(int,int)?` widens
this null value to 3 slots. This is called "type transitioning".

All stdlib functions prototypes have been updated to reflect
whether they return/accept a nullable or a strict value.

This commit also contains refactoring from `const FunctionData*`
to `FunctionPtr` and similar.
2025-02-28 16:41:41 +03:00

102 lines
3.6 KiB
C++

/*
This file is part of TON Blockchain Library.
TON Blockchain Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
TON Blockchain Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include "src-file.h"
#include "fwd-declarations.h"
#include "td/utils/Status.h"
#include <vector>
namespace tolk {
// when a function is declared `f<T>`, this "<T>" is represented as this class
// (not at AST, but at symbol storage level)
struct GenericsDeclaration {
struct GenericsItem {
std::string_view nameT;
explicit GenericsItem(std::string_view nameT)
: nameT(nameT) {}
};
explicit GenericsDeclaration(std::vector<GenericsItem>&& itemsT)
: itemsT(std::move(itemsT)) {}
const std::vector<GenericsItem> itemsT;
std::string as_human_readable() const;
size_t size() const { return itemsT.size(); }
bool has_nameT(std::string_view nameT) const { return find_nameT(nameT) != -1; }
int find_nameT(std::string_view nameT) const;
std::string get_nameT(int idx) const { return static_cast<std::string>(itemsT[idx].nameT); }
};
// when a function call is `f<int>()`, this "<int>" is represented as this class
struct GenericsInstantiation {
const std::vector<TypePtr> substitutions; // <SomeStruct, int> for genericTs <T1, T2>
const SrcLocation loc; // first instantiation location
explicit GenericsInstantiation(SrcLocation loc, std::vector<TypePtr>&& substitutions)
: substitutions(std::move(substitutions))
, loc(loc) {
}
};
// this class helps to deduce Ts on the fly
// purpose: having `f<T>(value: T)` and call `f(5)`, deduce T = int
// while analyzing a call, arguments are handled one by one, by `auto_deduce_from_argument()`
// this class also handles manually specified substitutions like `f<int>(5)`
class GenericSubstitutionsDeduceForCall {
FunctionPtr fun_ref;
std::vector<TypePtr> substitutionTs;
bool manually_specified = false;
void provide_deducedT(const std::string& nameT, TypePtr deduced);
void consider_next_condition(TypePtr param_type, TypePtr arg_type);
public:
explicit GenericSubstitutionsDeduceForCall(FunctionPtr fun_ref);
bool is_manually_specified() const {
return manually_specified;
}
void provide_manually_specified(std::vector<TypePtr>&& substitutionTs);
TypePtr replace_by_manually_specified(TypePtr param_type) const;
TypePtr auto_deduce_from_argument(SrcLocation loc, TypePtr param_type, TypePtr arg_type);
int get_first_not_deduced_idx() const;
std::vector<TypePtr>&& flush() {
return std::move(substitutionTs);
}
};
struct GenericDeduceError final : std::exception {
std::string message;
explicit GenericDeduceError(std::string message)
: message(std::move(message)) { }
const char* what() const noexcept override {
return message.c_str();
}
};
std::string generate_instantiated_name(const std::string& orig_name, const std::vector<TypePtr>& substitutions);
FunctionPtr instantiate_generic_function(SrcLocation loc, FunctionPtr fun_ref, const std::string& inst_name, std::vector<TypePtr>&& substitutionTs);
} // namespace tolk