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.. _embedding_debug_interface:
===============
Debug Interface
===============
The squirrel VM exposes a very simple debug interface that allows to easily built a full
featured debugger.
Through the functions sq_setdebughook and sq_setnativedebughook is possible in fact to set a callback function that
will be called every time the VM executes an new line of a script or if a function get
called/returns. The callback will pass as argument the current line the current source and the
current function name (if any).::
SQUIRREL_API void sq_setdebughook(HSQUIRRELVM v);
or ::
SQUIRREL_API void sq_setnativedebughook(HSQUIRRELVM v,SQDEBUGHOOK hook);
The following code shows how a debug hook could look like(obviously is possible to
implement this function in C as well). ::
function debughook(event_type,sourcefile,line,funcname)
{
local fname=funcname?funcname:"unknown";
local srcfile=sourcefile?sourcefile:"unknown"
switch (event_type) {
case 'l': //called every line(that contains some code)
::print("LINE line [" + line + "] func [" + fname + "]");
::print("file [" + srcfile + "]\n");
break;
case 'c': //called when a function has been called
::print("LINE line [" + line + "] func [" + fname + "]");
::print("file [" + srcfile + "]\n");
break;
case 'r': //called when a function returns
::print("LINE line [" + line + "] func [" + fname + "]");
::print("file [" + srcfile + "]\n");
break;
}
}
The parameter *event_type* can be 'l' ,'c' or 'r' ; a hook with a 'l' event is called for each line that
gets executed, 'c' every time a function gets called and 'r' every time a function returns.
A full-featured debugger always allows displaying local variables and calls stack.
The call stack information are retrieved through sq_getstackinfos()::
SQInteger sq_stackinfos(HSQUIRRELVM v,SQInteger level,SQStackInfos *si);
While the local variables info through sq_getlocal()::
SQInteger sq_getlocal(HSQUIRRELVM v,SQUnsignedInteger level,SQUnsignedInteger nseq);
In order to receive line callbacks the scripts have to be compiled with debug infos enabled
this is done through sq_enabledebuginfo(); ::
void sq_enabledebuginfo(HSQUIRRELVM v, SQInteger debuginfo);
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