/* 
 * tclProc.c --
 *
 *	This file contains routines that implement Tcl procedures,
 *	including the "proc" and "uplevel" commands.
 *
 * Copyright (c) 1987-1993 The Regents of the University of California.
 * Copyright (c) 1994-1998 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclProc.c,v 1.57 2004/10/01 12:45:20 dkf Exp $
 */

#include "tclInt.h"
#include "tclCompile.h"

/*
 * Prototypes for static functions in this file

Tcl_ObjType tclProcBodyType = {
    "procbody",			/* name for this type */
    ProcBodyFree,		/* FreeInternalRep procedure */
    ProcBodyDup,		/* DupInternalRep procedure */
    ProcBodyUpdateString,	/* UpdateString procedure */
    ProcBodySetFromAny		/* SetFromAny procedure */
};

/*
 * The [upvar]/[uplevel] level reference type.  Uses the twoPtrValue
 * field, encoding the type of level reference in ptr1 and the actual
 * parsed out offset in ptr2.
 *
 * Uses the default behaviour throughout, and never disposes of the
 * string rep; it's just a cache type.
 */

Tcl_ObjType tclLevelReferenceType = {
    "levelReference",
    NULL, NULL, NULL, NULL
};

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ProcObjCmd --
 *
 *	This object-based procedure is invoked to process the "proc" Tcl 

 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TclGetFrame(interp, name, framePtrPtr)
    Tcl_Interp *interp;		/* Interpreter in which to find frame. */
    CONST char *name;		/* String describing frame. */
    CallFrame **framePtrPtr;	/* Store pointer to frame here (or NULL
				 * if global frame indicated). */
{
    register Interp *iPtr = (Interp *) interp;
    int curLevel, level, result;
    CallFrame *framePtr;

    /*
     * Parse string to figure out which level number to go to.
     */

    result = 1;
    curLevel = (iPtr->varFramePtr == NULL) ? 0 : iPtr->varFramePtr->level;
    if (*name== '#') {
	if (Tcl_GetInt(interp, name+1, &level) != TCL_OK) {
	    return -1;
	}
	if (level < 0) {
	    levelError:
	    Tcl_AppendResult(interp, "bad level \"", name, "\"",
		    (char *) NULL);
	    return -1;
	}
    } else if (isdigit(UCHAR(*name))) { /* INTL: digit */
	if (Tcl_GetInt(interp, name, &level) != TCL_OK) {
	    return -1;
	}
	level = curLevel - level;
    } else {
	level = curLevel - 1;
	result = 0;
    }

    /* Figure out which frame to use, and return it to the caller */

    if (level == 0) {
	framePtr = NULL;
    } else {
	for (framePtr = iPtr->varFramePtr; framePtr != NULL;
		framePtr = framePtr->callerVarPtr) {
	    if (framePtr->level == level) {
		break;
	    }
	}
	if (framePtr == NULL) {
	    goto levelError;
	}
    }
    *framePtrPtr = framePtr;
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * TclObjGetFrame --
 *
 *	Given a description of a procedure frame, such as the first
 *	argument to an "uplevel" or "upvar" command, locate the
 *	call frame for the appropriate level of procedure.
 *
 * Results:
 *	The return value is -1 if an error occurred in finding the frame
 *	(in this case an error message is left in the interp's result).
 *	1 is returned if objPtr was either a number or a number preceded
 *	by "#" and it specified a valid frame.  0 is returned if objPtr
 *	isn't one of the two things above (in this case, the lookup
 *	acts as if objPtr were "1").  The variable pointed to by
 *	framePtrPtr is filled in with the address of the desired frame
 *	(unless an error occurs, in which case it isn't modified).
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TclObjGetFrame(interp, objPtr, framePtrPtr)
    Tcl_Interp *interp;		/* Interpreter in which to find frame. */
    Tcl_Obj *objPtr;		/* Object describing frame. */
    CallFrame **framePtrPtr;	/* Store pointer to frame here (or NULL
				 * if global frame indicated). */
{
    register Interp *iPtr = (Interp *) interp;
    int curLevel, level, result;
    CallFrame *framePtr;
    CONST char *name = TclGetString(objPtr);

    /*
     * Parse object to figure out which level number to go to.
     */

    result = 1;
    curLevel = (iPtr->varFramePtr == NULL) ? 0 : iPtr->varFramePtr->level;
    if (objPtr->typePtr == &tclLevelReferenceType) {
	if ((int) objPtr->internalRep.twoPtrValue.ptr1) {
	    level = curLevel - (int) objPtr->internalRep.twoPtrValue.ptr2;
	} else {
	    level = (int) objPtr->internalRep.twoPtrValue.ptr2;
	}
	if (level < 0) {
	    goto levelError;
	}
    } else if (objPtr->typePtr == &tclIntType ||
	    objPtr->typePtr == &tclWideIntType) {
	if (Tcl_GetIntFromObj(NULL, objPtr, &level) != TCL_OK || level < 0) {
	    goto levelError;
	}
	level = curLevel - level;
    } else {
	if (*name == '#') {
	    if (Tcl_GetInt(interp, name+1, &level) != TCL_OK) {
		return -1;
	    }
	    if (level < 0) {
		goto levelError;
	    }
	    /*
	     * Cache for future reference.
	     */
	    TclFreeIntRep(objPtr);
	    objPtr->typePtr = &tclLevelReferenceType;
	    objPtr->internalRep.twoPtrValue.ptr1 = (VOID *) 0;
	    objPtr->internalRep.twoPtrValue.ptr2 = (VOID *) level;
	} else if (isdigit(UCHAR(*name))) { /* INTL: digit */
	    if (Tcl_GetInt(interp, name, &level) != TCL_OK) {
		return -1;
	    }
	    /*
	     * Cache for future reference.
	     */
	    TclFreeIntRep(objPtr);
	    objPtr->typePtr = &tclLevelReferenceType;
	    objPtr->internalRep.twoPtrValue.ptr1 = (VOID *) 1;
	    objPtr->internalRep.twoPtrValue.ptr2 = (VOID *) level;
	    level = curLevel - level;
	} else {
	    /*
	     * Don't cache as the object *isn't* a level reference.
	     */
	    level = curLevel - 1;
	    result = 0;
	}
    }

    /* Figure out which frame to use, and return it to the caller */

    if (level == 0) {
	framePtr = NULL;
    } else {
	for (framePtr = iPtr->varFramePtr; framePtr != NULL;
		framePtr = framePtr->callerVarPtr) {
	    if (framePtr->level == level) {
		break;
	    }
	}
	if (framePtr == NULL) {
	    goto levelError;
	}
    }
    *framePtrPtr = framePtr;
    return result;

levelError:
    Tcl_AppendResult(interp, "bad level \"", name, "\"", (char *) NULL);
    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UplevelObjCmd --
 *

Tcl_UplevelObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    register Interp *iPtr = (Interp *) interp;

    int result;
    CallFrame *savedVarFramePtr, *framePtr;

    if (objc < 2) {
	uplevelSyntax:
	Tcl_WrongNumArgs(interp, 1, objv, "?level? command ?arg ...?");
	return TCL_ERROR;
    }

    /*
     * Find the level to use for executing the command.
     */


    result = TclObjGetFrame(interp, objv[1], &framePtr);
    if (result == -1) {
	return TCL_ERROR;
    }
    objc -= (result+1);
    if (objc == 0) {
	goto uplevelSyntax;
    }