Files
carbon-lang/executable_semantics/interpreter/impl_scope.h
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7cce1bd124 interfaces, impls, and constrained generics (basics) (#1073)
* interfaces, impls, and constrained generics (basics)

* separate type checking into declare vs. type check, removing redundancy

* external impls

* added impl scopes to handle generics calling generics

* cleanup

* more cleanup

* Update executable_semantics/testdata/interface/external_impl_point_vector.carbon

Co-authored-by: josh11b <josh11b@users.noreply.github.com>

* Update executable_semantics/testdata/interface/generic_call_generic.carbon

Co-authored-by: josh11b <josh11b@users.noreply.github.com>

* Update executable_semantics/testdata/interface/tuple_vector_add_scale.carbon

Co-authored-by: josh11b <josh11b@users.noreply.github.com>

* Update executable_semantics/testdata/interface/vector_point_add_scale.carbon

Co-authored-by: josh11b <josh11b@users.noreply.github.com>

* change ImplementationDeclaration to ImplDeclaration

* remove impl_type_value

* split NamedEntity into two

* changed GetName to be a free function

* adding comments

* more edits to respond to review

* introduce ImplBinding, remove punning on GenericBinding

* new test case and some minor edits

* refactor GetMember and GetField to move impl logic to interpreter

* remove commennt

* change EntityView to ImplBinding in FieldAccess...

* move ImplBinding

* review response

* added example to impl_scope.h

* minor edits

* Update executable_semantics/interpreter/field_path.h

Co-authored-by: Geoff Romer <gromer@google.com>

* Update executable_semantics/interpreter/value.cpp

Co-authored-by: Geoff Romer <gromer@google.com>

* Update executable_semantics/interpreter/interpreter.cpp

Co-authored-by: Geoff Romer <gromer@google.com>

* Update executable_semantics/ast/expression.h

Co-authored-by: Geoff Romer <gromer@google.com>

* Update executable_semantics/ast/expression.h

Co-authored-by: Geoff Romer <gromer@google.com>

* Update executable_semantics/ast/generic_binding.h

Co-authored-by: Geoff Romer <gromer@google.com>

* more edits from review

* review response

* Update executable_semantics/ast/static_scope.h

Co-authored-by: Geoff Romer <gromer@google.com>

* remove ImplType, renamed node_view to value_node

Co-authored-by: josh11b <josh11b@users.noreply.github.com>
Co-authored-by: Geoff Romer <gromer@google.com>
2022-03-02 15:58:45 -05:00

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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_AST_IMPL_SCOPE_H_
#define EXECUTABLE_SEMANTICS_AST_IMPL_SCOPE_H_
#include "executable_semantics/ast/declaration.h"
namespace Carbon {
class Value;
// The `ImplScope` class is responsible for mapping a type and
// interface to the location of the witness table for the `impl` for
// that type and interface. A scope may have parent scopes, whose
// impls will also be visible in the child scope.
//
// There is typically one instance of `ImplScope` class per scope
// because the impls that are visible for a given type and interface
// can vary from scope to scope. For example, consider the `bar` and
// `baz` methods in the following class C and nested class D.
//
// class C(U:! Type, T:! Type) {
// class D(V:! Type where U is Fooable(T)) {
// fn bar[me: Self](x: U, y : T) -> T{
// return x.foo(y)
// }
// }
// fn baz[me: Self](x: U, y : T) -> T {
// return x.foo(y);
// }
// }
//
// The call to `x.foo` in `bar` is valid because the `U is Fooable(T)`
// impl is visible in the body of `bar`. In contrast, the call to
// `x.foo` in `baz` is not valid because there is no visible impl for
// `U` and `Fooable` in that scope.
class ImplScope {
public:
// Associates `iface` and `type` with the `impl` in this scope.
void Add(Nonnull<const Value*> iface, Nonnull<const Value*> type,
ValueNodeView impl);
// Make `parent` a parent of this scope.
// REQUIRES: `parent` is not already a parent of this scope.
void AddParent(Nonnull<const ImplScope*> parent);
// Returns the associated impl for the given `iface` and `type` in
// the ancestor graph of this scope, or reports a compilation error
// at `source_loc` there isn't exactly one matching impl.
auto Resolve(Nonnull<const Value*> iface, Nonnull<const Value*> type,
SourceLocation source_loc) const -> ValueNodeView;
private:
auto TryResolve(Nonnull<const Value*> iface_type, Nonnull<const Value*> type,
SourceLocation source_loc) const
-> std::optional<ValueNodeView>;
auto ResolveHere(Nonnull<const Value*> iface_type,
Nonnull<const Value*> impl_type,
SourceLocation source_loc) const
-> std::optional<ValueNodeView>;
// The `Impl` struct is a key-value pair where the key is the
// combination of a type and an interface, e.g., `List` and `Container`,
// and the value is the result of statically resolving to the `impl`
// for `List` as `Container`, which is an `ValueNodeView`. The generality
// of `ValueNodeView` is needed (not just `ImplDeclaration`) because
// inside a generic, we need to map, e.g., from `T` and `Container` to the
// witness table that is passed into the generic.
struct Impl {
Nonnull<const Value*> interface;
Nonnull<const Value*> type;
ValueNodeView impl;
};
std::vector<Impl> impls_;
std::vector<Nonnull<const ImplScope*>> parent_scopes_;
};
} // namespace Carbon
#endif // EXECUTABLE_SEMANTICS_AST_IMPL_SCOPE_H_