mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-25 16:00:09 +01:00
Adrien Leravat
d0645c6a85
Rename value categories to expression categories based on [Discord discussion](https://discord.com/channels/655572317891461132/753021843459538996/1092924035517665332) regarding naming and behavior. >* let expression -> value expression >* var expression -> reference expression >* located expression -> initializing expression >So: >- "value expressions" produce values (with no associated location). "reference expressions" produce a location of an existing value. "initializing expressions" take a location and initialize it. >- A let binding is initialized by a value expression, because lets represent values (with category conversions performed as needed, but if a conversion is performed from a different category of expression, the value of the object is pinned for the lifetime of the let). >- A var binding is initialized by an initializing expression, without performing a copy (with category conversions performed as needed, calling a copy constructor if the initializer is a different expression category). >- The & operator requires a reference expression, and it's an error to give it other kinds. >- The left-hand side of . requires a value expression when calling a function with a non-addr receiver, and requires a reference expression when calling a function with an addr receiver (it's an error to give it a value expression, and for an initializing expression, a temporary is materialized). Changes * Rename "value category" to "expression category" * Rename Var and Let value categories to Value, Reference, and Initializing expression * Rename `lvalue` to `location` (most of the time)
106 lines
3.4 KiB
C++
106 lines
3.4 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_AST_IMPL_BINDING_H_
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#define CARBON_EXPLORER_AST_IMPL_BINDING_H_
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#include <map>
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#include "common/check.h"
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#include "common/ostream.h"
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#include "explorer/ast/ast_node.h"
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#include "explorer/ast/expression_category.h"
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namespace Carbon {
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class Value;
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class Expression;
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class GenericBinding;
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// `ImplBinding` plays the role of the parameter for passing witness
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// tables to a generic. However, unlike regular parameters
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// (`BindingPattern`) there is no explicit syntax that corresponds to
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// an `ImplBinding`, so they are not created during parsing. Instances
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// of `ImplBinding` are created during type checking, when processing
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// a type parameter (a `GenericBinding`), or an `impls` requirement in
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// a `where` clause.
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class ImplBinding : public AstNode {
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public:
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using ImplementsCarbonValueNode = void;
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ImplBinding(SourceLocation source_loc,
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Nonnull<const GenericBinding*> type_var,
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std::optional<Nonnull<const Value*>> iface)
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: AstNode(AstNodeKind::ImplBinding, source_loc),
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type_var_(type_var),
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iface_(iface) {}
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explicit ImplBinding(CloneContext& context, const ImplBinding& other);
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static auto classof(const AstNode* node) -> bool {
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return InheritsFromImplBinding(node->kind());
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}
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void Print(llvm::raw_ostream& out) const override;
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void PrintID(llvm::raw_ostream& out) const override;
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// The binding for the type variable.
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auto type_var() const -> Nonnull<const GenericBinding*> { return type_var_; }
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// The constraint being implemented.
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// TODO: Rename this to `constraint`.
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auto interface() const -> Nonnull<const Value*> {
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CARBON_CHECK(iface_) << "interface has not been set yet";
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return *iface_;
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}
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// Set the interface being implemented, if not set by the constructor. Should
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// only be called by typechecking.
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void set_interface(Nonnull<const Value*> iface) {
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CARBON_CHECK(!iface_) << "interface set twice";
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iface_ = iface;
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}
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// Required for the ValueNode interface
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auto constant_value() const -> std::optional<Nonnull<const Value*>> {
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return std::nullopt;
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}
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auto symbolic_identity() const -> std::optional<Nonnull<const Value*>> {
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return symbolic_identity_;
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}
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void set_symbolic_identity(Nonnull<const Value*> value) {
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CARBON_CHECK(!symbolic_identity_.has_value());
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symbolic_identity_ = value;
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}
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// These functions exist only so that an `ImplBinding` can be used as a
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// `ValueNodeView` as a key in a `StaticScope`.
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auto static_type() const -> const Value& {
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CARBON_FATAL() << "an ImplBinding has no type";
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}
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auto expression_category() const -> ExpressionCategory {
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return ExpressionCategory::Value;
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}
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// Return the original impl binding.
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auto original() const -> Nonnull<const ImplBinding*> {
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if (original_.has_value()) {
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return *original_;
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} else {
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return this;
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}
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}
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// Set the original impl binding.
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void set_original(Nonnull<const ImplBinding*> orig) { original_ = orig; }
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private:
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Nonnull<const GenericBinding*> type_var_;
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std::optional<Nonnull<const Value*>> iface_;
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std::optional<Nonnull<const Value*>> symbolic_identity_;
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std::optional<Nonnull<const ImplBinding*>> original_;
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};
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} // namespace Carbon
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#endif // CARBON_EXPLORER_AST_IMPL_BINDING_H_
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