1 files changed, 173 insertions, 0 deletions
diff --git a/xpcom/base/nsID.h b/xpcom/base/nsID.h
new file mode 100644
index 0000000000..c7feddd1cc
--- /dev/null
+++ b/xpcom/base/nsID.h
@@ -0,0 +1,173 @@
+/* -*- 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 nsID_h__
+#define nsID_h__
+
+#include <string.h>
+
+#include "nscore.h"
+
+#define NSID_LENGTH 39
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+class nsIDToCString;
+#endif
+
+/**
+ * A "unique identifier". This is modeled after OSF DCE UUIDs.
+ */
+
+struct nsID {
+  uint32_t m0;
+  uint16_t m1;
+  uint16_t m2;
+  uint8_t m3[8];
+
+  /**
+   * Create a new random UUID.
+   * GenerateUUIDInPlace() is fallible, whereas GenerateUUID() will abort in
+   * the unlikely case that the OS RNG returns an error.
+   */
+  [[nodiscard]] static nsresult GenerateUUIDInPlace(nsID& aId);
+  static nsID GenerateUUID();
+
+  /**
+   * Ensures everything is zeroed out.
+   */
+  void Clear();
+
+  /**
+   * Equivalency method. Compares this nsID with another.
+   * @return true if they are the same, false if not.
+   */
+
+  inline bool Equals(const nsID& aOther) const {
+    // At the time of this writing, modern compilers (namely Clang) inline this
+    // memcmp call into a single SIMD operation on x86/x86-64 architectures (as
+    // long as we compare to zero rather than returning the full integer return
+    // value), which is measurably more efficient to any manual comparisons we
+    // can do directly.
+#if defined(__x86_64__) || defined(__i386__)
+    return !memcmp(this, &aOther, sizeof *this);
+#else
+    // However, on ARM architectures, compilers still tend to generate a direct
+    // memcmp call, which we'd like to avoid.
+    return (((uint32_t*)&m0)[0] == ((uint32_t*)&aOther.m0)[0]) &&
+           (((uint32_t*)&m0)[1] == ((uint32_t*)&aOther.m0)[1]) &&
+           (((uint32_t*)&m0)[2] == ((uint32_t*)&aOther.m0)[2]) &&
+           (((uint32_t*)&m0)[3] == ((uint32_t*)&aOther.m0)[3]);
+#endif
+  }
+
+  inline bool operator==(const nsID& aOther) const { return Equals(aOther); }
+
+  /**
+   * nsID Parsing method. Turns a {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
+   * string into an nsID
+   */
+  bool Parse(const char* aIDStr);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+  /**
+   * nsID string encoder. Returns a managed string in
+   * {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format.
+   */
+  nsIDToCString ToString() const;
+
+  /**
+   * nsID string encoder. Builds a string in
+   * {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format, into a char[NSID_LENGTH]
+   * buffer provided by the caller (for instance, on the stack).
+   */
+  void ToProvidedString(char (&aDest)[NSID_LENGTH]) const;
+
+#endif  // XPCOM_GLUE_AVOID_NSPR
+
+  // Infallibly duplicate an nsID. Must be freed with free().
+  nsID* Clone() const;
+};
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+/**
+ * A stack helper class to convert a nsID to a string.  Useful
+ * for printing nsIDs.  For example:
+ *   nsID aID = ...;
+ *   printf("%s", nsIDToCString(aID).get());
+ */
+class nsIDToCString {
+ public:
+  explicit nsIDToCString(const nsID& aID) {
+    aID.ToProvidedString(mStringBytes);
+  }
+
+  const char* get() const { return mStringBytes; }
+
+ protected:
+  char mStringBytes[NSID_LENGTH];
+};
+#endif
+
+/*
+ * Class IDs
+ */
+
+typedef nsID nsCID;
+
+// Define an CID
+#define NS_DEFINE_CID(_name, _cidspec) const nsCID _name = _cidspec
+
+#define NS_DEFINE_NAMED_CID(_name) static const nsCID k##_name = _name
+
+#define REFNSCID const nsCID&
+
+/**
+ * An "interface id" which can be used to uniquely identify a given
+ * interface.
+ */
+
+typedef nsID nsIID;
+
+/**
+ * A macro shorthand for <tt>const nsIID&<tt>
+ */
+
+#define REFNSIID const nsIID&
+
+/**
+ * A macro to build the static const IID accessor method. The Dummy
+ * template parameter only exists so that the kIID symbol will be linked
+ * properly (weak symbol on linux, gnu_linkonce on mac, multiple-definitions
+ * merged on windows). Dummy should always be instantiated as "void".
+ */
+
+#define NS_DECLARE_STATIC_IID_ACCESSOR(the_iid) \
+  template <typename T, typename U>             \
+  struct COMTypeInfo;
+
+#define NS_DEFINE_STATIC_IID_ACCESSOR(the_interface, the_iid)                \
+  template <typename T>                                                      \
+  struct the_interface::COMTypeInfo<the_interface, T> {                      \
+    static const nsIID kIID NS_HIDDEN;                                       \
+  };                                                                         \
+  template <typename T>                                                      \
+  const nsIID the_interface::COMTypeInfo<the_interface, T>::kIID NS_HIDDEN = \
+      the_iid;
+
+/**
+ * A macro to build the static const CID accessor method
+ */
+
+#define NS_DEFINE_STATIC_CID_ACCESSOR(the_cid) \
+  static const nsID& GetCID() {                \
+    static const nsID cid = the_cid;           \
+    return cid;                                \
+  }
+
+#define NS_GET_IID(T) (T::COMTypeInfo<T, void>::kIID)
+#define NS_GET_TEMPLATE_IID(T) (T::template COMTypeInfo<T, void>::kIID)
+
+#endif