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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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
/* Public declarations for xptcall. */
#ifndef xptcall_h___
#define xptcall_h___
#include "nscore.h"
#include "nsISupports.h"
#include "xptinfo.h"
#include "js/Value.h"
#include "mozilla/MemoryReporting.h"
struct nsXPTCMiniVariant {
// No ctors or dtors so that we can use arrays of these on the stack
// with no penalty.
union Union {
int8_t i8;
int16_t i16;
int32_t i32;
int64_t i64;
uint8_t u8;
uint16_t u16;
uint32_t u32;
uint64_t u64;
float f;
double d;
bool b;
char c;
char16_t wc;
void* p;
};
Union val;
};
static_assert(offsetof(nsXPTCMiniVariant, val) == 0,
"nsXPTCMiniVariant must be a thin wrapper");
struct nsXPTCVariant {
union ExtendedVal {
// ExtendedVal is an extension on nsXPTCMiniVariant. It contains types
// unknown to the assembly implementations which must be passed by indirect
// semantics.
//
// nsXPTCVariant contains enough space to store ExtendedVal inline, which
// can be used to store these types when IsIndirect() is true.
nsXPTCMiniVariant mini;
nsID nsid;
nsCString nscstr;
nsString nsstr;
JS::Value jsval;
xpt::detail::UntypedTArray array;
// This type contains non-standard-layout types, so needs an explicit
// Ctor/Dtor - we'll just delete them.
ExtendedVal() = delete;
~ExtendedVal() = delete;
};
union {
// The `val` field from nsXPTCMiniVariant.
nsXPTCMiniVariant::Union val;
// Storage for any extended variants.
ExtendedVal ext;
};
nsXPTType type;
uint8_t flags;
// Clear to a valid, null state.
nsXPTCVariant() {
memset(this, 0, sizeof(nsXPTCVariant));
type = nsXPTType::T_VOID;
}
enum {
//
// Bitflag definitions
//
// Indicates that we &val.p should be passed n the stack, i.e. that
// val should be passed by reference.
IS_INDIRECT = 0x1,
};
void ClearFlags() { flags = 0; }
void SetIndirect() { flags |= IS_INDIRECT; }
bool IsIndirect() const { return 0 != (flags & IS_INDIRECT); }
// Implicitly convert to nsXPTCMiniVariant.
operator nsXPTCMiniVariant&() { return *(nsXPTCMiniVariant*)&val; }
operator const nsXPTCMiniVariant&() const {
return *(const nsXPTCMiniVariant*)&val;
}
// As this type contains an anonymous union, we need to provide an explicit
// destructor.
~nsXPTCVariant() {}
};
static_assert(offsetof(nsXPTCVariant, val) == offsetof(nsXPTCVariant, ext),
"nsXPTCVariant::{ext,val} must have matching offsets");
// static_assert that nsXPTCVariant::ExtendedVal is large enough and
// well-aligned enough for every XPT-supported type.
#define XPT_CHECK_SIZEOF(xpt, type) \
static_assert(sizeof(nsXPTCVariant::ExtendedVal) >= sizeof(type), \
"nsXPTCVariant::ext not big enough for " #xpt " (" #type ")"); \
static_assert(MOZ_ALIGNOF(nsXPTCVariant::ExtendedVal) >= MOZ_ALIGNOF(type), \
"nsXPTCVariant::ext not aligned enough for " #xpt " (" #type \
")");
XPT_FOR_EACH_TYPE(XPT_CHECK_SIZEOF)
#undef XPT_CHECK_SIZEOF
class nsIXPTCProxy : public nsISupports {
public:
NS_IMETHOD CallMethod(uint16_t aMethodIndex, const nsXPTMethodInfo* aInfo,
nsXPTCMiniVariant* aParams) = 0;
};
/**
* This is a typedef to avoid confusion between the canonical
* nsISupports* that provides object identity and an interface pointer
* for inheriting interfaces that aren't known at compile-time.
*/
typedef nsISupports nsISomeInterface;
/**
* Get a proxy object to implement the specified interface.
*
* @param aIID The IID of the interface to implement.
* @param aOuter An object to receive method calls from the proxy object.
* The stub forwards QueryInterface/AddRef/Release to the
* outer object. The proxy object does not hold a reference to
* the outer object; it is the caller's responsibility to
* ensure that this pointer remains valid until the stub has
* been destroyed.
* @param aStub Out parameter for the new proxy object. The object is
* not addrefed. The object never destroys itself. It must be
* explicitly destroyed by calling
* NS_DestroyXPTCallStub when it is no longer needed.
*/
XPCOM_API(nsresult)
NS_GetXPTCallStub(REFNSIID aIID, nsIXPTCProxy* aOuter,
nsISomeInterface** aStub);
/**
* Destroys an XPTCall stub previously created with NS_GetXPTCallStub.
*/
XPCOM_API(void)
NS_DestroyXPTCallStub(nsISomeInterface* aStub);
/**
* Measures the size of an XPTCall stub previously created with
* NS_GetXPTCallStub.
*/
XPCOM_API(size_t)
NS_SizeOfIncludingThisXPTCallStub(const nsISomeInterface* aStub,
mozilla::MallocSizeOf aMallocSizeOf);
// this is extern "C" because on some platforms it is implemented in assembly
extern "C" nsresult NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
uint32_t paramCount,
nsXPTCVariant* params);
#endif /* xptcall_h___ */