1 files changed, 102 insertions, 0 deletions
diff --git a/js/src/vm/BindingKind.h b/js/src/vm/BindingKind.h
new file mode 100644
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--- /dev/null
+++ b/js/src/vm/BindingKind.h
@@ -0,0 +1,102 @@
+/* -*- 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 vm_BindingKind_h
+#define vm_BindingKind_h
+
+#include "mozilla/Assertions.h"  // MOZ_ASSERT, MOZ_ASSERT_IF
+#include "mozilla/Casting.h"     // mozilla::AssertedCast
+
+#include <stdint.h>  // uint16_t, uint32_t
+
+#include "vm/BytecodeUtil.h"  // LOCALNO_LIMIT, ENVCOORD_SLOT_LIMIT
+
+namespace js {
+
+enum class BindingKind : uint8_t {
+  Import,
+  FormalParameter,
+  Var,
+  Let,
+  Const,
+
+  // So you think named lambda callee names are consts? Nope! They don't
+  // throw when being assigned to in sloppy mode.
+  NamedLambdaCallee
+};
+
+static inline bool BindingKindIsLexical(BindingKind kind) {
+  return kind == BindingKind::Let || kind == BindingKind::Const;
+}
+
+class BindingLocation {
+ public:
+  enum class Kind {
+    Global,
+    Argument,
+    Frame,
+    Environment,
+    Import,
+    NamedLambdaCallee
+  };
+
+ private:
+  Kind kind_;
+  uint32_t slot_;
+
+  BindingLocation(Kind kind, uint32_t slot) : kind_(kind), slot_(slot) {}
+
+ public:
+  static BindingLocation Global() {
+    return BindingLocation(Kind::Global, UINT32_MAX);
+  }
+
+  static BindingLocation Argument(uint16_t slot) {
+    return BindingLocation(Kind::Argument, slot);
+  }
+
+  static BindingLocation Frame(uint32_t slot) {
+    MOZ_ASSERT(slot < LOCALNO_LIMIT);
+    return BindingLocation(Kind::Frame, slot);
+  }
+
+  static BindingLocation Environment(uint32_t slot) {
+    MOZ_ASSERT(slot < ENVCOORD_SLOT_LIMIT);
+    return BindingLocation(Kind::Environment, slot);
+  }
+
+  static BindingLocation Import() {
+    return BindingLocation(Kind::Import, UINT32_MAX);
+  }
+
+  static BindingLocation NamedLambdaCallee() {
+    return BindingLocation(Kind::NamedLambdaCallee, UINT32_MAX);
+  }
+
+  bool operator==(const BindingLocation& other) const {
+    return kind_ == other.kind_ && slot_ == other.slot_;
+  }
+
+  bool operator!=(const BindingLocation& other) const {
+    return !operator==(other);
+  }
+
+  Kind kind() const { return kind_; }
+
+  uint32_t slot() const {
+    MOZ_ASSERT(kind_ == Kind::Frame || kind_ == Kind::Environment);
+    return slot_;
+  }
+
+  uint16_t argumentSlot() const {
+    MOZ_ASSERT(kind_ == Kind::Argument);
+    return mozilla::AssertedCast<uint16_t>(slot_);
+  }
+};
+
+}  // namespace js
+
+#endif  // vm_BindingKind_h