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carbon-lang/executable_semantics/interpreter/address.h
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#ifndef EXECUTABLE_SEMANTICS_INTERPRETER_ADDRESS_H_
#define EXECUTABLE_SEMANTICS_INTERPRETER_ADDRESS_H_
#include <cstdint>
#include <string>
#include <vector>
#include "common/ostream.h"
#include "executable_semantics/interpreter/field_path.h"
#include "llvm/Support/Compiler.h"
namespace Carbon {
// An AllocationId identifies an _allocation_ produced by a Heap. An allocation
// is analogous to the C++ notion of a complete object: the the `Value` in an
// allocation is not a sub-part of any other `Value`.
class AllocationId {
public:
AllocationId(const AllocationId&) = default;
auto operator=(const AllocationId&) -> AllocationId& = default;
// Prints a human-readable representation of *this to `out`.
//
// Currently that representation consists of an integer index.
void Print(llvm::raw_ostream& out) const {
out << "Allocation(" << index_ << ")";
}
private:
// The representation of AllocationId describes how to locate an object within
// a Heap, so its implementation details are tied to the implementation
// details of Heap.
friend class Heap;
explicit AllocationId(size_t index) : index_(index) {}
size_t index_;
};
// An Address represents a memory address in the Carbon virtual machine.
// Addresses are used to access values stored in a Heap. Unlike an
// AllocationId, an Address can refer to a sub-Value of some larger Value.
class Address {
public:
// Constructs an `Address` that refers to the value stored in `allocation`.
explicit Address(AllocationId allocation) : allocation_(allocation) {}
Address(const Address&) = default;
Address(Address&&) = default;
auto operator=(const Address&) -> Address& = default;
auto operator=(Address&&) -> Address& = default;
// Prints a human-readable representation of `a` to `out`.
//
// Currently, that representation consists of an AllocationId followed by an
// optional FieldPath specifying a particular field within that allocation.
void Print(llvm::raw_ostream& out) const {
out << allocation_ << field_path_;
}
LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
// If *this represents the address of an object with a field named
// `field_name`, this method returns the address of that field.
auto SubobjectAddress(std::string field_name) const -> Address {
Address result = *this;
result.field_path_.Append(std::move(field_name));
return result;
}
private:
// The representation of Address describes how to locate an object within
// the Heap, so its implementation details are tied to the implementation
// details of the Heap.
friend class Heap;
AllocationId allocation_;
FieldPath field_path_;
};
} // namespace Carbon
#endif // EXECUTABLE_SEMANTICS_INTERPRETER_ADDRESS_H_