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/*
* ------------------------------------------------------------------------
* PACKAGE: [incr Tcl]
* DESCRIPTION: Object-Oriented Extensions to Tcl
*
* This file contains procedures that belong in the Tcl/Tk core.
* Hopefully, they'll migrate there soon.
*
* ========================================================================
* AUTHOR: Michael J. McLennan
* Bell Labs Innovations for Lucent Technologies
* mmclennan@lucent.com
* http://www.tcltk.com/itcl
*
* RCS: $Id$
* ========================================================================
* Copyright (c) 1993-1998 Lucent Technologies, Inc.
* ------------------------------------------------------------------------
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*/
#include "itclInt.h"
/*
*----------------------------------------------------------------------
*
* _Tcl_GetCallFrame --
*
* Checks the call stack and returns the call frame some number
* of levels up. It is often useful to know the invocation
* context for a command.
*
* Results:
* Returns a token for the call frame 0 or more levels up in
* the call stack.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
Tcl_CallFrame*
_Tcl_GetCallFrame(interp, level)
Tcl_Interp *interp; /* interpreter being queried */
int level; /* number of levels up in the call stack (>= 0) */
{
Interp *iPtr = (Interp*)interp;
CallFrame *framePtr;
if (level < 0) {
Tcl_Panic("itcl: _Tcl_GetCallFrame called with bad number of levels");
}
framePtr = iPtr->varFramePtr;
while (framePtr && level > 0) {
framePtr = framePtr->callerVarPtr;
level--;
}
return (Tcl_CallFrame*)framePtr;
}
/*
*----------------------------------------------------------------------
*
* _Tcl_ActivateCallFrame --
*
* Makes an existing call frame the current frame on the
* call stack. Usually called in conjunction with
* _Tcl_GetCallFrame to simulate the effect of an "uplevel"
* command.
*
* Note that this procedure is different from Tcl_PushCallFrame,
* which adds a new call frame to the call stack. This procedure
* assumes that the call frame is already initialized, and it
* merely activates it on the call stack.
*
* Results:
* Returns a token for the call frame that was in effect before
* activating the new context. That call frame can be restored
* by calling _Tcl_ActivateCallFrame again.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
Tcl_CallFrame*
_Tcl_ActivateCallFrame(interp, framePtr)
Tcl_Interp *interp; /* interpreter being queried */
Tcl_CallFrame *framePtr; /* call frame to be activated */
{
Interp *iPtr = (Interp*)interp;
CallFrame *oldFramePtr;
oldFramePtr = iPtr->varFramePtr;
iPtr->varFramePtr = (CallFrame *) framePtr;
return (Tcl_CallFrame *) oldFramePtr;
}
/*
*----------------------------------------------------------------------
*
* _TclNewVar --
*
* Create a new heap-allocated variable that will eventually be
* entered into a hashtable.
*
* Results:
* The return value is a pointer to the new variable structure. It is
* marked as a scalar variable (and not a link or array variable). Its
* value initially is NULL. The variable is not part of any hash table
* yet. Since it will be in a hashtable and not in a call frame, its
* name field is set NULL. It is initially marked as undefined.
*
* Side effects:
* Storage gets allocated.
*
*----------------------------------------------------------------------
*/
Var *
_TclNewVar()
{
register Var *varPtr;
varPtr = (Var *) ckalloc(sizeof(Var));
varPtr->value.objPtr = NULL;
varPtr->name = NULL;
varPtr->nsPtr = NULL;
varPtr->hPtr = NULL;
varPtr->refCount = 0;
varPtr->tracePtr = NULL;
varPtr->searchPtr = NULL;
varPtr->flags = (VAR_SCALAR | VAR_UNDEFINED | VAR_IN_HASHTABLE);
return varPtr;
}
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