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>
2026-09-24 22:02:23 +01:00 · 2022-03-02 15:58:45 -05:00
parent 8f6e42d866
commit 7cce1bd124
43 changed files with 1722 additions and 441 deletions
@@ -0,0 +1,78 @@
+// 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
+
+#include "executable_semantics/interpreter/impl_scope.h"
+
+#include "executable_semantics/common/error.h"
+#include "executable_semantics/interpreter/value.h"
+#include "llvm/Support/Casting.h"
+
+using llvm::cast;
+
+namespace Carbon {
+
+void ImplScope::Add(Nonnull<const Value*> iface, Nonnull<const Value*> type,
+                    ValueNodeView impl) {
+  impls_.push_back({.interface = iface, .type = type, .impl = impl});
+}
+
+void ImplScope::AddParent(Nonnull<const ImplScope*> parent) {
+  parent_scopes_.push_back(parent);
+}
+
+auto ImplScope::Resolve(Nonnull<const Value*> iface_type,
+                        Nonnull<const Value*> type,
+                        SourceLocation source_loc) const -> ValueNodeView {
+  std::optional<ValueNodeView> result =
+      TryResolve(iface_type, type, source_loc);
+  if (!result.has_value()) {
+    FATAL_COMPILATION_ERROR(source_loc) << "could not find implementation of "
+                                        << *iface_type << " for " << *type;
+  }
+  return *result;
+}
+
+auto ImplScope::TryResolve(Nonnull<const Value*> iface_type,
+                           Nonnull<const Value*> type,
+                           SourceLocation source_loc) const
+    -> std::optional<ValueNodeView> {
+  std::optional<ValueNodeView> result =
+      ResolveHere(iface_type, type, source_loc);
+  if (result.has_value()) {
+    return result;
+  }
+  for (Nonnull<const ImplScope*> parent : parent_scopes_) {
+    auto parent_result = parent->TryResolve(iface_type, type, source_loc);
+    if (parent_result.has_value() && result.has_value() &&
+        *parent_result != *result) {
+      FATAL_COMPILATION_ERROR(source_loc)
+          << "ambiguous implementations of " << *iface_type << " for " << *type;
+    }
+    result = parent_result;
+  }
+  return result;
+}
+
+auto ImplScope::ResolveHere(Nonnull<const Value*> iface_type,
+                            Nonnull<const Value*> impl_type,
+                            SourceLocation source_loc) const
+    -> std::optional<ValueNodeView> {
+  switch (iface_type->kind()) {
+    case Value::Kind::InterfaceType: {
+      const auto& iface = cast<InterfaceType>(*iface_type);
+      for (const Impl& impl : impls_) {
+        if (TypeEqual(&iface, impl.interface) &&
+            TypeEqual(impl_type, impl.type)) {
+          return impl.impl;
+        }
+      }
+      return std::nullopt;
+    }
+    default:
+      FATAL() << "expected an interface, not " << *iface_type;
+      break;
+  }
+}
+
+}  // namespace Carbon