mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 21:00:13 +01:00
Adrien Leravat
563768c6d3
Features: * Split `Member` class into 3 dedicated classes covering named, positional, and a new "base class" element Changes: * Rename `Member` to `Element` to better reflect the variants covered * Add `NamedElement`, `PositionalElement`, and `BaseElement` child classes for `Element` * Split `GetMember` into 3 function variants based on available attributes (index, name, nothing). * Add some unit tests to provide coverage of core features Motivation: This changeset splits Member into (currently 2) classes, as we see the need for more Member variants (base class access needed for #2378, possibly unnamed mixins, ...), which in addition to the current ones, also have significantly different attributes. This will allow supporting more Member types in the future cleanly. Alternatives considered: The alternative solution, "one class for positional, named & base class access", would expose unused or unavailable attributes depending on the Member actual type (`index()` only for positional, `name()` only for named, and neither for base class access).
110 lines
3.7 KiB
C++
110 lines
3.7 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#ifndef CARBON_EXPLORER_INTERPRETER_ELEMENT_PATH_H_
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#define CARBON_EXPLORER_INTERPRETER_ELEMENT_PATH_H_
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#include <optional>
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#include <string>
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#include <string_view>
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#include <vector>
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#include "common/ostream.h"
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#include "explorer/ast/element.h"
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#include "explorer/ast/static_scope.h"
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#include "llvm/Support/Compiler.h"
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namespace Carbon {
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class InterfaceType;
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class Witness;
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// Given some initial Value, a ElementPath identifies a sub-Value within it,
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// in much the same way that a file path identifies a file within some
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// directory. FieldPaths are relative rather than absolute: the initial
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// Value is specified by the context in which the ElementPath is used, not
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// by the ElementPath itself.
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//
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// A ElementPath consists of a series of steps, which specify how to
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// incrementally navigate from a Value to one of its fields. Currently
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// there is only one kind of step, a string specifying a child field by name,
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// but that may change as Carbon develops. Note that an empty ElementPath
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// refers to the initial Value itself.
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class ElementPath {
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public:
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// Constructs an empty ElementPath.
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ElementPath() = default;
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// A single component of the ElementPath, which is typically the name
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// of a field. However, inside a generic, when there is a field
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// access on something of a generic type, e.g., `T`, then we also
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// need `witness`, a pointer to the witness table containing that field.
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class Component {
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public:
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explicit Component(Nonnull<const Element*> element) : element_(element) {}
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Component(Nonnull<const Element*> element,
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std::optional<Nonnull<const InterfaceType*>> interface,
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std::optional<Nonnull<const Witness*>> witness)
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: element_(element), interface_(interface), witness_(witness) {}
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auto element() const -> Nonnull<const Element*> { return element_; }
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auto IsNamed(std::string_view name) const -> bool {
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return element_->IsNamed(name);
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}
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auto interface() const -> std::optional<Nonnull<const InterfaceType*>> {
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return interface_;
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}
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auto witness() const -> std::optional<Nonnull<const Witness*>> {
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return witness_;
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}
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void Print(llvm::raw_ostream& out) const { return element_->Print(out); }
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private:
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Nonnull<const Element*> element_;
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std::optional<Nonnull<const InterfaceType*>> interface_;
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std::optional<Nonnull<const Witness*>> witness_;
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};
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// Constructs a ElementPath consisting of a single step.
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explicit ElementPath(Nonnull<const Element*> element)
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: components_({Component(element)}) {}
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explicit ElementPath(const Component& f) : components_({f}) {}
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ElementPath(const ElementPath&) = default;
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ElementPath(ElementPath&&) = default;
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auto operator=(const ElementPath&) -> ElementPath& = default;
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auto operator=(ElementPath&&) -> ElementPath& = default;
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// Returns whether *this is empty.
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auto IsEmpty() const -> bool { return components_.empty(); }
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// Appends `element` to the end of *this.
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auto Append(Nonnull<const Element*> element) -> void {
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components_.push_back(Component(element));
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}
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void Print(llvm::raw_ostream& out) const {
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for (const Component& component : components_) {
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out << "." << component;
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}
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}
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LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
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private:
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// The representation of ElementPath describes how to locate a Value within
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// another Value, so its implementation details are tied to the implementation
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// details of Value.
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friend class Value;
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std::vector<Component> components_;
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};
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} // namespace Carbon
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#endif // CARBON_EXPLORER_INTERPRETER_ELEMENT_PATH_H_
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