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Code Issues Packages Projects Releases 10 Wiki Activity

Reorganize and document Action (#1024)

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This commit is contained in:
Geoff Romer
2022-01-18 13:29:44 -08:00
committed by GitHub
parent ad5072b7b8
commit b954542d06
2 changed files with 37 additions and 39 deletions
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executable_semantics/interpreter/action.cpp
-8
View File
@@ -72,12 +72,4 @@ void Action::Print(llvm::raw_ostream& out) const {
}
}
void Action::PrintList(const Stack<Nonnull<Action*>>& ls,
llvm::raw_ostream& out) {
llvm::ListSeparator sep(" :: ");
for (const auto& action : ls) {
out << sep << *action;
}
}
} // namespace Carbon
executable_semantics/interpreter/action.h
+37 -31
View File
@@ -58,6 +58,18 @@ class Scope {
Nonnull<HeapAllocationInterface*> heap_;
};
// An Action represents the current state of a self-contained computation,
// usually associated with some AST node, such as evaluation of an expression or
// execution of a statement. Execution of an action is divided into a series of
// steps, and the `pos` field typically counts the number of steps executed.
//
// They should be destroyed as soon as they are done executing, in order to
// clean up the associated Carbon scope, and consequently they should not be
// allocated on an Arena. Actions are typically owned by the ActionStack.
//
// The actual behavior of an Action step is defined by Interpreter::Step, not by
// Action or its subclasses.
// TODO: consider moving this logic to a virtual method `Step`.
class Action {
public:
enum class Kind {
@@ -72,14 +84,38 @@ class Action {
Action(const Value&) = delete;
auto operator=(const Value&) -> Action& = delete;
void AddResult(Nonnull<const Value*> result) { results_.push_back(result); }
virtual ~Action() = default;
void Print(llvm::raw_ostream& out) const;
LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
// Resets this Action to its initial state.
void Clear() {
CHECK(!scope_.has_value());
pos_ = 0;
results_.clear();
}
// Returns the enumerator corresponding to the most-derived type of this
// object.
auto kind() const -> Kind { return kind_; }
// The position or state of the action. Starts at 0 and is typically
// incremented after each step.
auto pos() const -> int { return pos_; }
void set_pos(int pos) { this->pos_ = pos; }
// The results of any Actions spawned by this Action.
auto results() const -> const std::vector<Nonnull<const Value*>>& {
return results_;
}
// Appends `result` to `results`.
void AddResult(Nonnull<const Value*> result) { results_.push_back(result); }
// Returns the scope associated with this Action, if any.
auto scope() -> std::optional<Scope>& { return scope_; }
// Associates this action with a new scope, with initial state `scope`.
// Values that are local to this scope will be deallocated when this
// Action is completed or unwound. Can only be called once on a given
@@ -89,36 +125,6 @@ class Action {
scope_ = std::move(scope);
}
// Returns the scope associated with this Action, if any.
auto scope() -> std::optional<Scope>& { return scope_; }
static void PrintList(const Stack<Nonnull<Action*>>& ls,
llvm::raw_ostream& out);
void Print(llvm::raw_ostream& out) const;
LLVM_DUMP_METHOD void Dump() const { Print(llvm::errs()); }
// Returns the enumerator corresponding to the most-derived type of this
// object.
auto kind() const -> Kind { return kind_; }
// The position or state of the action. Starts at 0 and goes up to the number
// of subexpressions.
//
// pos indicates how many of the entries in the following `results` vector
// will be filled in the next time this action is active.
// For each i < pos, results[i] contains a pointer to a Value.
auto pos() const -> int { return pos_; }
void set_pos(int pos) { this->pos_ = pos; }
// Results from a subexpression.
auto results() const -> const std::vector<Nonnull<const Value*>>& {
return results_;
}
virtual ~Action() = default;
protected:
// Constructs an Action. `kind` must be the enumerator corresponding to the
// most-derived type being constructed.