utils/virtual.h

Provides low-level helpers for:

Retrieving virtual functions from objects
Calling virtual methods by index

This is unsafe low-level functionality. Incorrect usage may lead to crashes or undefined behavior.

Header source2mod/utils/virtual.h

Functions

`GetVMethod`

template <typename T = void*> inline T GetVMethod(uint32 uIndex, void* pClass);

Retrieves a virtual function pointer from an object's VTable.

No bounds checking is performed.

Parameter	Type	Description
`uIndex`	`uint32`	Index in virtual table
`pClass`	`void*`	Pointer to class instance

Returns T — Function pointer or nullptr if invalid

`CallVirtual`

template <typename T, typename... Args> inline T CallVirtual(uint32 uIndex, void* pClass, Args... args);

Calls a virtual function by index.

int result = vmt::CallVirtual<int>(10, entity, arg1);

Calling convention differs between platforms: - Windows: __thiscall - Linux: __cdecl

Index must match correct function signature.

Parameter	Type	Description
`uIndex`	`uint32`	Virtual table index
`pClass`	`void*`	Pointer to class instance
`args`	`Args...`	Arguments passed to function

Returns T — Function result or default value if failed

`CallVirtualOverrideVTable`

template <typename T = void, typename... Args> inline T CallVirtualOverrideVTable(uint32 uIndex, void** pVTable, void* pClass, Args... args);

Calls a virtual function through a caller-supplied vtable.

Same as CallVirtual, except the table is passed in rather than read out of the object. Needed when the instance does not carry the vtable you want to dispatch through -- e.g. a trace filter whose table was resolved from the server module by name.

Parameter	Type	Description
`uIndex`	`uint32`	Virtual table index
`pVTable`	`void**`	The vtable to dispatch through
`pClass`	`void*`	Pointer passed as the implicit this
`args`	`Args...`	Arguments passed to the function

Returns T — Function result, or a default-constructed T if the table or entry is null.

`CallVirtualChain`

template <typename T, typename... Args> inline T CallVirtualChain(uint32 uIndex, HookChain eChain, void* pClass, Args... args);

Calls a virtual function by index, running or bypassing the hooks on it as eChain says (see HookChain in ISource2ModTypes.h).

Parameter	Type
`uIndex`	`uint32`
`eChain`	`HookChain`
`pClass`	`void*`
`args`	`Args...`

Returns T — Function result, or a default-constructed T if the slot is null.

Macros

`CALL_VIRTUAL`

#define CALL_VIRTUAL(retType, idx, ...) vmt::CallVirtual<retType>(idx, __VA_ARGS__)

Convenience macro for calling virtual functions.

CALL_VIRTUAL(void, 5, entity, arg1, arg2);

`CALL_VIRTUAL_CHAIN`

#define CALL_VIRTUAL_CHAIN(retType, idx, eChain, ...) vmt::CallVirtualChain<retType>(idx, eChain, __VA_ARGS__)

CALL_VIRTUAL that runs or bypasses the hooks on the function.

CALL_VIRTUAL_CHAIN(void, offset, HookChain::Bypass, this, bExplode, bForce);

`CALL_VIRTUAL_OVERRIDE_VTBL`

#define CALL_VIRTUAL_OVERRIDE_VTBL(retType, idx, vtable, ...) vmt::CallVirtualOverrideVTable<retType>(idx, vtable, __VA_ARGS__)

Calls a virtual function through a vtable the caller supplies.

For objects whose vtable is not the one stored in the instance -- a filter whose table was looked up in the server module by name, say -- where CALL_VIRTUAL would dispatch through the wrong table.

CALL_VIRTUAL_OVERRIDE_VTBL(bool, offset, pVTable, this, pEntity);

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