3 * =============================================================================
5 * Copyright (C) 2004-2008 AlliedModders LLC. All rights reserved.
6 * =============================================================================
8 * This program is free software; you can redistribute it and/or modify it under
9 * the terms of the GNU General Public License, version 3.0, as published by the
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14 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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18 * this program. If not, see <http://www.gnu.org/licenses/>.
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21 * code of this program (as well as its derivative works) to "Half-Life 2," the
22 * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software
23 * by the Valve Corporation. You must obey the GNU General Public License in
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25 * this exception to all derivative works. AlliedModders LLC defines further
26 * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
27 * or <http://www.sourcemod.net/license.php>.
32 #ifndef _INCLUDE_SOURCEMOD_FORWARDINTERFACE_H_
33 #define _INCLUDE_SOURCEMOD_FORWARDINTERFACE_H_
37 * @brief Defines the interface for managing collections ("forwards") of plugin calls.
39 * The Forward System is responsible for managing automated collections of IPluginFunctions.
40 * It thus provides wrappers to calling many functions at once. There are two types of such
41 * wrappers: Managed and Unmanaged. Confusingly, these terms refer to whether the user manages
42 * the forwards, not Core. Managed forwards are completely managed by the user, and are custom
43 * editable collections. Unmanaged forwards are the opposite, and will only work on a single global
44 * function name in all plugins.
47 #include <IPluginSys.h>
48 #include <sp_vm_api.h>
50 using namespace SourcePawn;
52 #define SMINTERFACE_FORWARDMANAGER_NAME "IForwardManager"
53 #define SMINTERFACE_FORWARDMANAGER_VERSION 3
56 * There is some very important documentation at the bottom of this file.
57 * Readers interested in knowing more about the forward system, scrolling down is a must!
63 * @brief Defines the event hook result types plugins can return.
67 Pl_Continue = 0, /**< No result */
68 Pl_Changed = 1, /**< Inputs or outputs have been overridden with new values */
69 Pl_Handled = 3, /**< Result was handled, stop at the end */
70 Pl_Stop = 4, /**< Result was handled, stop now */
74 * @brief Defines how a forward iterates through plugin functions.
78 ET_Ignore = 0, /**< Ignore all return values, return 0 */
79 ET_Single = 1, /**< Only return the last exec, ignore all others */
80 ET_Event = 2, /**< Acts as an event with the ResultTypes above, no mid-Stops allowed, returns highest */
81 ET_Hook = 3, /**< Acts as a hook with the ResultTypes above, mid-Stops allowed, returns highest */
82 ET_LowEvent = 4, /**< Same as ET_Event except that it returns the lowest value */
89 * @brief Unmanaged Forward, abstracts calling multiple functions as "forwards," or collections of functions.
91 * Parameters should be pushed in forward order, unlike the virtual machine/IPluginContext order.
92 * Some functions are repeated in here because their documentation differs from their IPluginFunction equivalents.
93 * Missing are the Push functions, whose only doc change is that they throw SP_ERROR_PARAM on type mismatches.
95 class IForward : public ICallable
98 /** Virtual Destructor */
104 * @brief Returns the name of the forward.
106 * @return Forward name.
108 virtual const char *GetForwardName() =0;
111 * @brief Returns the number of functions in this forward.
113 * @return Number of functions in forward.
115 virtual unsigned int GetFunctionCount() =0;
118 * @brief Returns the method of multi-calling this forward has.
120 * @return ExecType of the forward.
122 virtual ExecType GetExecType() =0;
125 * @brief Executes the forward.
127 * @param result Optional pointer to store result in.
128 * @param filter Do not use.
129 * @return Error code, if any.
131 virtual int Execute(cell_t *result, IForwardFilter *filter=NULL) =0;
134 * @brief Pushes an array of cells onto the current call. Different rules than ICallable.
135 * NOTE: On Execute, the pointer passed will be modified according to the copyback rule.
137 * @param inarray Array to copy. Cannot be NULL, unlike ICallable's version.
138 * @param cells Number of cells to allocate and optionally read from the input array.
139 * @param flags Whether or not changes should be copied back to the input array.
140 * @return Error code, if any.
142 virtual int PushArray(cell_t *inarray, unsigned int cells, int flags=0) =0;
146 * @brief Managed Forward, same as IForward, except the collection can be modified.
148 class IChangeableForward : public IForward
152 * @brief Removes a function from the call list.
153 * NOTE: Only removes one instance.
155 * @param func Function to remove.
156 * @return Whether or not the function was removed.
158 virtual bool RemoveFunction(IPluginFunction *func) =0;
161 * @brief Removes all instances of a plugin from the call list.
163 * @param plugin Plugin to remove instances of.
164 * @return Number of functions removed therein.
166 virtual unsigned int RemoveFunctionsOfPlugin(IPlugin *plugin) =0;
169 * @brief Adds a function to the call list.
170 * NOTE: Cannot be used during an incomplete call.
171 * NOTE: If used during a call, function is temporarily queued until calls are over.
172 * NOTE: Adding multiple copies of the same function is illegal.
174 * @param func Function to add.
175 * @return True on success, otherwise false.
177 virtual bool AddFunction(IPluginFunction *func) =0;
180 * @brief Adds a function to the call list.
181 * NOTE: Cannot be used during an incomplete call.
182 * NOTE: If used during a call, function is temporarily queued until calls are over.
184 * @param ctx Context to use as a look-up.
185 * @param index Function id to add.
186 * @return True on success, otherwise false.
188 virtual bool AddFunction(IPluginContext *ctx, funcid_t index) =0;
191 * @brief Removes a function from the call list.
192 * NOTE: Only removes one instance.
194 * @param ctx Context to use as a look-up.
195 * @param index Function id to add.
196 * @return Whether or not the function was removed.
198 virtual bool RemoveFunction(IPluginContext *ctx, funcid_t index) =0;
201 #define SP_PARAMTYPE_ANY 0
202 #define SP_PARAMFLAG_BYREF (1<<0)
203 #define SP_PARAMTYPE_CELL (1<<1)
204 #define SP_PARAMTYPE_FLOAT (2<<1)
205 #define SP_PARAMTYPE_STRING (3<<1)|SP_PARAMFLAG_BYREF
206 #define SP_PARAMTYPE_ARRAY (4<<1)|SP_PARAMFLAG_BYREF
207 #define SP_PARAMTYPE_VARARG (5<<1)
210 * @brief Describes the various ways to pass parameters to plugins.
214 Param_Any = SP_PARAMTYPE_ANY, /**< Any data type can be pushed */
215 Param_Cell = SP_PARAMTYPE_CELL, /**< Only basic cells can be pushed */
216 Param_Float = SP_PARAMTYPE_FLOAT, /**< Only floats can be pushed */
217 Param_String = SP_PARAMTYPE_STRING, /**< Only strings can be pushed */
218 Param_Array = SP_PARAMTYPE_ARRAY, /**< Only arrays can be pushed */
219 Param_VarArgs = SP_PARAMTYPE_VARARG, /**< Same as "..." in plugins, anything can be pushed, but it will always be byref */
220 Param_CellByRef = SP_PARAMTYPE_CELL|SP_PARAMFLAG_BYREF, /**< Only a cell by reference can be pushed */
221 Param_FloatByRef = SP_PARAMTYPE_FLOAT|SP_PARAMFLAG_BYREF, /**< Only a float by reference can be pushed */
225 * @brief Provides functions for creating/destroying managed and unmanaged forwards.
227 class IForwardManager : public SMInterface
230 virtual const char *GetInterfaceName()
232 return SMINTERFACE_FORWARDMANAGER_NAME;
234 virtual unsigned int GetInterfaceVersion()
236 return SMINTERFACE_FORWARDMANAGER_VERSION;
238 virtual bool IsVersionCompatible(unsigned int version)
240 if (version < 2 || version > GetInterfaceVersion())
248 * @brief Creates a managed forward. This forward exists globally.
249 * The name used to create the forward is used as its public function in all target plugins.
250 * As new non-private plugins become loaded or unloaded, they will be automatically added
251 * or removed. This is ideal for global, static forwards that are never changed.
253 * @param name Name of public function to use in forward.
254 * @param et Execution type to be used.
255 * @param num_params Number of parameter this function will have.
256 * NOTE: For varargs, this should include the vararg parameter.
257 * @param types Array of type information about each parameter. If NULL, types
258 * are read off the vararg stream.
259 * @param ... If types is NULL, num_params ParamTypes should be pushed.
260 * @return A new IForward on success, NULL if type combination is impossible.
262 virtual IForward *CreateForward(const char *name,
264 unsigned int num_params,
265 const ParamType *types,
269 * @brief Creates an unmanaged forward. This forward exists privately.
270 * Unlike managed forwards, no functions are ever added by the Manager.
271 * However, functions will be removed automatically if their parent plugin is unloaded.
273 * @param name Name of forward (unused except for lookup, can be NULL for anonymous).
274 * @param et Execution type to be used.
275 * @param num_params Number of parameter this function will have.
276 * NOTE: For varargs, this should include the vararg parameter.
277 * @param types Array of type information about each parameter. If NULL, types
278 * are read off the vararg stream.
279 * @param ... If types is NULL, num_params ParamTypes should be pushed.
280 * @return A new IChangeableForward on success, NULL if type combination is impossible.
282 virtual IChangeableForward *CreateForwardEx(const char *name,
285 const ParamType *types,
289 * @brief Finds a forward by name. Does not return anonymous forwards (named NULL or "").
291 * @param name Name of forward.
292 * @param ifchng Optionally store either NULL or an IChangeableForward pointer
293 * depending on type of forward.
294 * @return IForward pointer, or NULL if none found matching the name.
296 virtual IForward *FindForward(const char *name, IChangeableForward **ifchng) =0;
299 * @brief Frees and destroys a forward object.
301 * @param forward An IForward created by CreateForward() or CreateForwardEx().
303 virtual void ReleaseForward(IForward *forward) =0;
308 * In the AMX Mod X model of forwarding, each forward contained a list of pairs, each pair containing
309 * a function ID and an AMX structure. The forward structure itself did very little but hold parameter types.
310 * An execution call worked like this:
311 * - executeForward() took in a function id and a list of parameters
312 * - for each contained plugin:
313 * - the list of parameters was preprocessed and pushed
314 * - the call was made
315 * - the list was freed and copybacks were made
318 * The advantages to this is that the system is very easy to implement, and it's fast. The disadvantage is
319 * varargs tend to be very unforgiving and inflexible, and thus weird problems arose with casting. You also
320 * lose flexibility, type checking, and the ability to reasonably use variable arguments lists in the VM.
322 * SourceMod replaces this forward system with a far more advanced, but a bit bulkier one. The idea is that
323 * each plugin has a table of functions, and each function is an ICallable object. As well as being an ICallable,
324 * each function is an IPluginFunction. An ICallable simply describes the process of adding parameters to a
325 * function call. An IPluginFunction describes the process of actually calling a function and performing allocation,
326 * copybacks, and deallocations.
328 * A very powerful forward system emerges: a Forward is just a collection of IPluginFunctions. Thus, the same
329 * API can be easily wrapped around a simple list, and it will look transparent to the user.
331 * 1) "SP Forwards" from AMX Mod X are simply IPluginFunctions without a collection.
332 * 2) Forwards are function based, rather than plugin based, and are thus far more flexible at runtime..
333 * 3) [2] Individual functions can be paused and more than one function from the same plugin can be hooked.
334 * 4) [2] One hook type that used to map to many SP Forwards can now be centralized as one Forward.
335 * This helps alleviate messes like Fakemeta.
336 * 5) Parameter pushing is type-checked and allows for variable arguments.
338 * Note that while #2,3,4 could be added to AMX Mod X, the real binding property is #1, which makes the system
339 * object oriented, rather than AMX Mod X, which hides the objects behind static functions. It is entirely a design
340 * issue, rather than a usability one. The interesting part is when it gets to implementation, which has to cache
341 * parameter pushing until execution. Without this, multiple function calls can be started across one plugin, which
342 * will result in heap corruption given SourcePawn's implementation.
344 * Observe the new calling process:
345 * - Each parameter is pushed into a local cache using the ICallable interface.
346 * - For each function in the collection:
347 * - Each parameter is decoded and -pushed into the function.
348 * - The call is made.
351 * Astute readers will note the (minor) problems:
352 * 1) More memory is used. Specifically, rather than N params of memory, you now have N params * M plugins.
353 * This is because, again, parameters are cached both per-function and per-forward.
354 * 2) There are slightly more calls going around: one extra call for each parameter, since each push is manual.
357 * There used to be a # about copy backs.
358 * Note that originally, the Forward implementation was a thin wrapper around IForwards. It did not cache pushes,
359 * and instead immediately fired them to each internal plugin. This was to allow users to know that pointers would
360 * be immediately resolved. Unfortunately, this became extremely burdensome on the API and exposed many problems,
361 * the major (and breaking) one was that two separate Function objects cannot be in a calling process on the same
362 * plugin at once. (:TODO: perhaps prevent that in the IPlugin object?) This is because heap functions lose their order
363 * and become impossible to re-arrange without some global heap tracking mechanism. It also made iterative copy backs
364 * for arrays/references overwhelmingly complex, since each plugin had to have its memory back-patched for each copy.
365 * Therefore, this was scrapped for cached parameters (current implementation), which is the implementation AMX Mod X
366 * uses. It is both faster and works better.
369 #endif //_INCLUDE_SOURCEMOD_FORWARDINTERFACE_H_
