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Diffstat (limited to 'xpcom/base/nsID.h')
| -rw-r--r-- | xpcom/base/nsID.h | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/xpcom/base/nsID.h b/xpcom/base/nsID.h new file mode 100644 index 0000000000..f0332d899b --- /dev/null +++ b/xpcom/base/nsID.h @@ -0,0 +1,170 @@ +/* -*- 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 + +/** + * 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 an allocated string in + * {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} format. Caller should free string. + * YOU SHOULD ONLY USE THIS IF YOU CANNOT USE ToProvidedString() BELOW. + */ + char* 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 |