1 files changed, 76 insertions, 0 deletions
diff --git a/js/src/frontend/DefaultEmitter.cpp b/js/src/frontend/DefaultEmitter.cpp
new file mode 100644
index 0000000000..a9e8512369
--- /dev/null
+++ b/js/src/frontend/DefaultEmitter.cpp
@@ -0,0 +1,76 @@
+/* -*- 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/. */
+
+#include "frontend/DefaultEmitter.h"
+
+#include "mozilla/Assertions.h"  // MOZ_ASSERT
+
+#include "frontend/BytecodeEmitter.h"  // BytecodeEmitter
+#include "vm/Opcodes.h"                // JSOp
+
+using namespace js;
+using namespace js::frontend;
+
+using mozilla::Maybe;
+using mozilla::Nothing;
+
+DefaultEmitter::DefaultEmitter(BytecodeEmitter* bce) : bce_(bce) {}
+
+bool DefaultEmitter::prepareForDefault() {
+  MOZ_ASSERT(state_ == State::Start);
+
+  //                [stack] VALUE
+
+  ifUndefined_.emplace(bce_);
+  if (!ifUndefined_->emitIf(Nothing())) {
+    return false;
+  }
+
+  if (!bce_->emit1(JSOp::Dup)) {
+    //              [stack] VALUE VALUE
+    return false;
+  }
+  if (!bce_->emit1(JSOp::Undefined)) {
+    //              [stack] VALUE VALUE UNDEFINED
+    return false;
+  }
+  if (!bce_->emit1(JSOp::StrictEq)) {
+    //              [stack] VALUE EQ?
+    return false;
+  }
+
+  if (!ifUndefined_->emitThen()) {
+    //              [stack] VALUE
+    return false;
+  }
+
+  if (!bce_->emit1(JSOp::Pop)) {
+    //              [stack]
+    return false;
+  }
+
+#ifdef DEBUG
+  state_ = State::Default;
+#endif
+  return true;
+}
+
+bool DefaultEmitter::emitEnd() {
+  MOZ_ASSERT(state_ == State::Default);
+
+  //                [stack] DEFAULTVALUE
+
+  if (!ifUndefined_->emitEnd()) {
+    //              [stack] VALUE/DEFAULTVALUE
+    return false;
+  }
+  ifUndefined_.reset();
+
+#ifdef DEBUG
+  state_ = State::End;
+#endif
+  return true;
+}