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Consistently use a Witness rather than an expression to represent a possibly-symbolic witness. (#2245)

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Previously we used an expression in some places and a `Witness` values in others. The eventual goal is to make `Witness` values behave like other symbolic values such as `NominalClassType`, but the first step is to consistently treat them like values rather than expressions.

No functionality change intended.
This commit is contained in:
Richard Smith
2022-10-03 14:00:41 -07:00
committed by GitHub
parent c198dafbe8
commit 04d49cebd8
11 changed files with 222 additions and 152 deletions
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explorer/interpreter/action_stack.cpp
+44 -24
View File
@@ -126,23 +126,47 @@ void ActionStack::InitializeFragment(ContinuationValue::StackFragment& fragment,
fragment.StoreReversed(std::move(reversed_todo));
}
namespace {
// The way in which FinishAction should be called for a particular kind of
// action.
enum class FinishActionKind {
// FinishAction should not be passed a value.
NoValue,
// FinishAction should be passed a value.
Value,
// FinishAction should not be called. The Action needs custom handling.
NeverCalled,
};
} // namespace
static auto FinishActionKindFor(Action::Kind kind) -> FinishActionKind {
switch (kind) {
case Action::Kind::ExpressionAction:
case Action::Kind::WitnessAction:
case Action::Kind::LValAction:
case Action::Kind::PatternAction:
return FinishActionKind::Value;
case Action::Kind::StatementAction:
case Action::Kind::DeclarationAction:
case Action::Kind::RecursiveAction:
return FinishActionKind::NoValue;
case Action::Kind::ScopeAction:
case Action::Kind::CleanUpAction:
return FinishActionKind::NeverCalled;
}
}
auto ActionStack::FinishAction() -> ErrorOr<Success> {
std::stack<std::unique_ptr<Action>> scopes_to_destroy;
std::unique_ptr<Action> act = todo_.Pop();
switch (act->kind()) {
case Action::Kind::CleanUpAction:
case Action::Kind::ExpressionAction:
case Action::Kind::LValAction:
case Action::Kind::PatternAction:
switch (FinishActionKindFor(act->kind())) {
case FinishActionKind::Value:
CARBON_FATAL() << "This kind of action must produce a result: " << *act;
case Action::Kind::ScopeAction:
CARBON_FATAL() << "ScopeAction at top of stack";
case Action::Kind::StatementAction:
case Action::Kind::DeclarationAction:
case Action::Kind::RecursiveAction: {
case FinishActionKind::NeverCalled:
CARBON_FATAL() << "Should not call FinishAction for: " << *act;
case FinishActionKind::NoValue:
PopScopes(scopes_to_destroy);
break;
}
}
PushCleanUpAction(std::move(act));
PushCleanUpActions(std::move(scopes_to_destroy));
@@ -153,17 +177,12 @@ auto ActionStack::FinishAction(Nonnull<const Value*> result)
-> ErrorOr<Success> {
std::stack<std::unique_ptr<Action>> scopes_to_destroy;
std::unique_ptr<Action> act = todo_.Pop();
switch (act->kind()) {
case Action::Kind::CleanUpAction:
case Action::Kind::StatementAction:
case Action::Kind::DeclarationAction:
case Action::Kind::RecursiveAction:
CARBON_FATAL() << "This kind of Action cannot produce results: " << *act;
case Action::Kind::ScopeAction:
CARBON_FATAL() << "ScopeAction at top of stack";
case Action::Kind::ExpressionAction:
case Action::Kind::LValAction:
case Action::Kind::PatternAction:
switch (FinishActionKindFor(act->kind())) {
case FinishActionKind::NoValue:
CARBON_FATAL() << "This kind of action cannot produce results: " << *act;
case FinishActionKind::NeverCalled:
CARBON_FATAL() << "Should not call FinishAction for: " << *act;
case FinishActionKind::Value:
PopScopes(scopes_to_destroy);
SetResult(result);
break;
@@ -192,8 +211,9 @@ auto ActionStack::Spawn(std::unique_ptr<Action> child, RuntimeScope scope)
auto ActionStack::ReplaceWith(std::unique_ptr<Action> replacement)
-> ErrorOr<Success> {
std::unique_ptr<Action> old = todo_.Pop();
CARBON_CHECK(replacement->kind() == old->kind())
<< "ReplaceWith can't change action kind";
CARBON_CHECK(FinishActionKindFor(old->kind()) ==
FinishActionKindFor(replacement->kind()))
<< "Can't replace action " << *old << " with " << *replacement;
todo_.Push(std::move(replacement));
return Success();
}