/* 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 add a static constexpr kIID variable.
*/
#define NS_INLINE_DECL_STATIC_IID(the_iid) \
static constexpr nsIID 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 constexpr nsID cid = the_cid; \
return cid; \
}
#define NS_GET_IID(T) (T::kIID)
#endif
