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// A simple COM component, as per the book
#include <stdio.h>
#include <stddef.h>
#define interface class
typedef struct { unsigned char data[16]; } IID;
typedef int HRESULT;
typedef unsigned long ULONG;
#define IsEqualIID(a,b) (memcmp(a, b, sizeof(IID)) == 0)
#define InterlockedIncrement(p) (++(*(p)))
#define InterlockedDecrement(p) (--(*(p)))
#define S_OK 0
#define E_NOINTERFACE (-1)
IID IID_IUnknown = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x80 } };
IID IID_IX = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x81 } };
IID IID_IY = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x82 } };
interface IUnknown {
public:
virtual HRESULT QueryInterface(const IID& iid, void ** res) = 0;
virtual ULONG AddRef() = 0;
virtual ULONG Release() = 0;
};
interface IX : public IUnknown {
public:
virtual void F(int x) = 0;
};
interface IY : public IUnknown {
public:
virtual int G(int x) = 0;
virtual int H() = 0;
virtual int K(char ** str) = 0;
};
static int CA_ident = 0;
class CA : public IX, public IY {
private:
int refcount;
int ident;
public:
virtual HRESULT QueryInterface(const IID& iid, void ** res) {
if (IsEqualIID(&iid, &IID_IUnknown)) {
printf("%d: QueryInterface: return IUnknown pointer.\n", ident);
*res = (interface IX *) this;
} else if (IsEqualIID(&iid, &IID_IX)) {
printf("%d: QueryInterface: return IX pointer.\n", ident);
*res = (interface IX *) this;
} else if (IsEqualIID(&iid, &IID_IY)) {
printf("%d: QueryInterface: return IY pointer.\n", ident);
*res = (interface IY *) this;
} else {
printf("%d: QueryInterface: interface not supported.\n", ident);
*res = NULL;
return E_NOINTERFACE;
}
((IUnknown *)(*res))->AddRef();
return S_OK;
}
virtual ULONG AddRef() {
ULONG res = InterlockedIncrement(&refcount);
printf("%d: AddRef: new refcount is %lu\n", ident, res);
return res;
}
virtual ULONG Release() {
ULONG res = InterlockedDecrement(&refcount);
printf("%d: Release: new refcount is %lu\n", ident, res);
if (res == 0) {
printf("%d: destroying component.\n", ident);
delete this;
}
return res;
}
virtual void F(int x) {
printf("%d: F(%d) called.\n", ident, x);
}
virtual int G(int x) {
int res = 3 * x + 1;
printf("%d: G(%d) called, returning %d.\n", ident, x, res);
return res;
}
virtual int H() {
printf("%d: H() called, returning 0.\n", ident);
return 0;
}
virtual int K(char ** str) {
printf("%d: K() called, returning 0 and `foobar'.\n", ident);
*str = "foobar";
return 0;
}
// constructor:
CA() { refcount = 0; ident = ++CA_ident; }
// destructor:
~CA() {
printf("%d: destroy self.\n", ident);
}
};
extern "C"
interface IUnknown * create_instance()
{
interface IUnknown * res = (interface IX *) new CA();
res->AddRef();
return res;
}
extern "C"
void test_component(interface IUnknown * c)
{
interface IX * cix;
interface IY * ciy;
int res;
char * stringres;
// Test IX interface
if (c->QueryInterface(IID_IX, (void **) &cix) == S_OK) {
printf("test: got IX interface.\n");
printf("test: calling F(12) on it.\n");
cix->F(12);
printf("test: releasing the IX interface.\n");
res = cix->Release();
printf("test: return of Release() is %d.\n", res);
}
// Test IY interface
if (c->QueryInterface(IID_IY, (void **) &ciy) == S_OK) {
printf("test: got IY interface.\n");
printf("test: calling G(3) on it.\n");
res = ciy->G(3);
printf("test: return value is %d.\n", res);
printf("test: calling H() on it.\n");
res = ciy->H();
printf("test: return value is %d.\n", res);
printf("test: calling K() on it.\n");
res = ciy->K(&stringres);
printf("test: hresult is %d, return string is `%s'.\n", res, stringres);
printf("test: releasing the IY interface.\n");
res = ciy->Release();
printf("test: return of Release() is %d.\n", res);
}
}
extern "C"
void test_ix(interface IX * c)
{
test_component(c);
// printf("test: releasing the interface, return of Release() is %d.\n",
// c->Release());
}
extern "C"
void test_iy(interface IY * c)
{
test_component(c);
// printf("test: releasing the interface, return of Release() is %d.\n",
// c->Release());
}
#if 0
extern "C"
int main(int argc, char ** argv)
{
interface IUnknown * i = create_instance();
test_component(i);
i->Release();
return 0;
}
#endif
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