summaryrefslogtreecommitdiffstats
path: root/js/src/frontend/DefaultEmitter.h
diff options
context:
space:
mode:
Diffstat (limited to 'js/src/frontend/DefaultEmitter.h')
-rw-r--r--js/src/frontend/DefaultEmitter.h65
1 files changed, 65 insertions, 0 deletions
diff --git a/js/src/frontend/DefaultEmitter.h b/js/src/frontend/DefaultEmitter.h
new file mode 100644
index 0000000000..3dc9aba21b
--- /dev/null
+++ b/js/src/frontend/DefaultEmitter.h
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef frontend_DefaultEmitter_h
+#define frontend_DefaultEmitter_h
+
+#include "mozilla/Attributes.h" // MOZ_STACK_CLASS
+#include "mozilla/Maybe.h" // Maybe
+
+#include "frontend/IfEmitter.h" // IfEmitter
+
+namespace js {
+namespace frontend {
+
+struct BytecodeEmitter;
+
+// Class for emitting default parameter or default value.
+//
+// Usage: (check for the return value is omitted for simplicity)
+//
+// `x = 10` in `function (x = 10) {}`
+// // the value of arguments[0] is on the stack
+// DefaultEmitter de(this);
+// de.prepareForDefault();
+// emit(10);
+// de.emitEnd();
+//
+class MOZ_STACK_CLASS DefaultEmitter {
+ BytecodeEmitter* bce_;
+
+ mozilla::Maybe<IfEmitter> ifUndefined_;
+
+#ifdef DEBUG
+ // The state of this emitter.
+ //
+ // +-------+ prepareForDefault +---------+ emitEnd +-----+
+ // | Start |------------------>| Default |-------->| End |
+ // +-------+ +---------+ +-----+
+ enum class State {
+ // The initial state.
+ Start,
+
+ // After calling prepareForDefault.
+ Default,
+
+ // After calling emitEnd.
+ End
+ };
+ State state_ = State::Start;
+#endif
+
+ public:
+ explicit DefaultEmitter(BytecodeEmitter* bce);
+
+ [[nodiscard]] bool prepareForDefault();
+ [[nodiscard]] bool emitEnd();
+};
+
+} /* namespace frontend */
+} /* namespace js */
+
+#endif /* frontend_LabelEmitter_h */