1 files changed, 120 insertions, 0 deletions
diff --git a/js/public/shadow/String.h b/js/public/shadow/String.h
new file mode 100644
index 0000000000..570c9f189b
--- /dev/null
+++ b/js/public/shadow/String.h
@@ -0,0 +1,120 @@
+/* -*- 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/. */
+
+/* Shadow definition of |JSString| innards.  Don't use this directly! */
+
+#ifndef js_shadow_String_h
+#define js_shadow_String_h
+
+#include <stdint.h>  // uint32_t, uintptr_t
+
+#include "jstypes.h"  // JS_PUBLIC_API, js::Bit, js::BitMask, JS_BITS_PER_WORD
+
+#include "js/TypeDecls.h"  // JS::Latin1Char
+
+class JS_PUBLIC_API JSAtom;
+struct JSExternalStringCallbacks;
+class JSLinearString;
+class JS_PUBLIC_API JSString;
+
+namespace js {
+namespace gc {
+struct Cell;
+}  // namespace gc
+}  // namespace js
+
+namespace JS {
+
+namespace shadow {
+
+struct String {
+  static constexpr uint32_t ATOM_BIT = js::Bit(3);
+  static constexpr uint32_t LINEAR_BIT = js::Bit(4);
+  static constexpr uint32_t INLINE_CHARS_BIT = js::Bit(6);
+  static constexpr uint32_t LATIN1_CHARS_BIT = js::Bit(9);
+  static constexpr uint32_t EXTERNAL_FLAGS = LINEAR_BIT | js::Bit(8);
+  static constexpr uint32_t TYPE_FLAGS_MASK = js::BitMask(9) - js::BitMask(3);
+  static constexpr uint32_t PERMANENT_ATOM_MASK = ATOM_BIT | js::Bit(8);
+
+  uintptr_t flags_;
+#if JS_BITS_PER_WORD == 32
+  uint32_t length_;
+#endif
+
+  union {
+    const JS::Latin1Char* nonInlineCharsLatin1;
+    const char16_t* nonInlineCharsTwoByte;
+    JS::Latin1Char inlineStorageLatin1[1];
+    char16_t inlineStorageTwoByte[1];
+  };
+  const JSExternalStringCallbacks* externalCallbacks;
+
+  uint32_t flags() const { return static_cast<uint32_t>(flags_); }
+  uint32_t length() const {
+#if JS_BITS_PER_WORD == 32
+    return length_;
+#else
+    return static_cast<uint32_t>(flags_ >> 32);
+#endif
+  }
+
+  static bool isPermanentAtom(const js::gc::Cell* cell) {
+    uint32_t flags = reinterpret_cast<const String*>(cell)->flags();
+    return (flags & PERMANENT_ATOM_MASK) == PERMANENT_ATOM_MASK;
+  }
+
+  bool isLinear() const { return flags() & LINEAR_BIT; }
+  bool hasLatin1Chars() const { return flags() & LATIN1_CHARS_BIT; }
+
+  // For hot code, prefer other type queries.
+  bool isExternal() const {
+    return (flags() & TYPE_FLAGS_MASK) == EXTERNAL_FLAGS;
+  }
+
+  const JS::Latin1Char* latin1LinearChars() const {
+    MOZ_ASSERT(isLinear());
+    MOZ_ASSERT(hasLatin1Chars());
+    return (flags() & String::INLINE_CHARS_BIT) ? inlineStorageLatin1
+                                                : nonInlineCharsLatin1;
+  }
+
+  const char16_t* twoByteLinearChars() const {
+    MOZ_ASSERT(isLinear());
+    MOZ_ASSERT(!hasLatin1Chars());
+    return (flags() & String::INLINE_CHARS_BIT) ? inlineStorageTwoByte
+                                                : nonInlineCharsTwoByte;
+  }
+};
+
+inline const String* AsShadowString(const JSString* str) {
+  return reinterpret_cast<const String*>(str);
+}
+
+inline String* AsShadowString(JSString* str) {
+  return reinterpret_cast<String*>(str);
+}
+
+inline const String* AsShadowString(const JSLinearString* str) {
+  return reinterpret_cast<const String*>(str);
+}
+
+inline String* AsShadowString(JSLinearString* str) {
+  return reinterpret_cast<String*>(str);
+}
+
+inline const String* AsShadowString(const JSAtom* str) {
+  return reinterpret_cast<const String*>(str);
+}
+
+inline String* AsShadowString(JSAtom* str) {
+  return reinterpret_cast<String*>(str);
+}
+
+}  // namespace shadow
+
+}  // namespace JS
+
+#endif  // js_shadow_String_h