path: root/generic/tclCmdMZ.c

/* 
 * tclCmdMZ.c --
 *
 *	This file contains the top-level command routines for most of
 *	the Tcl built-in commands whose names begin with the letters
 *	M to Z.  It contains only commands in the generic core (i.e.
 *	those that don't depend much upon UNIX facilities).
 *
 * Copyright (c) 1987-1993 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 * Copyright (c) 1998-2000 Scriptics Corporation.
 * Copyright (c) 2002 ActiveState Corporation.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclCmdMZ.c,v 1.75 2002/08/12 12:23:39 msofer Exp $
 */

#include "tclInt.h"
#include "tclPort.h"
#include "tclRegexp.h"

/*
 * Structure used to hold information about variable traces:
 */

typedef struct {
    int flags;			/* Operations for which Tcl command is
				 * to be invoked. */
    size_t length;		/* Number of non-NULL chars. in command. */
    char command[4];		/* Space for Tcl command to invoke.  Actual
				 * size will be as large as necessary to
				 * hold command.  This field must be the
				 * last in the structure, so that it can
				 * be larger than 4 bytes. */
} TraceVarInfo;

/*
 * Structure used to hold information about command traces:
 */

typedef struct {
    int flags;			/* Operations for which Tcl command is
				 * to be invoked. */
    size_t length;		/* Number of non-NULL chars. in command. */
    Tcl_Trace stepTrace;        /* Used for execution traces, when tracing
                                 * inside the given command */
    int startLevel;             /* Used for bookkeeping with execution traces */
    int curFlags;               /* Trace flags for the current command */
    int curCode;                /* Return code for the current command */
    char command[4];		/* Space for Tcl command to invoke.  Actual
				 * size will be as large as necessary to
				 * hold command.  This field must be the
				 * last in the structure, so that it can
				 * be larger than 4 bytes. */
} TraceCommandInfo;

/* 
 * Used by command execution traces.  Note that we assume in the code
 * that the first two defines are exactly 4 times the
 * 'TCL_TRACE_ENTER_EXEC' and 'TCL_TRACE_LEAVE_EXEC' constants.
 * 
 * TCL_TRACE_ENTER_DURING_EXEC  - Trace each command inside the command
 *                                currently being traced, before execution.
 * TCL_TRACE_LEAVE_DURING_EXEC  - Trace each command inside the command
 *                                currently being traced, after execution.
 * TCL_TRACE_ANY_EXEC           - OR'd combination of all EXEC flags.
 * TCL_TRACE_EXEC_IN_PROGRESS   - The callback procedure on this trace
 *                                is currently executing.  Therefore we
 *                                don't let further traces execute.
 * TCL_TRACE_EXEC_DIRECT        - This execution trace is triggered directly
 *                                by the command being traced, not because
 *                                of an internal trace.
 * The flags 'TCL_TRACE_DESTROYED' and 'TCL_INTERP_DESTROYED' may also
 * be used in command execution traces.
 */
#define TCL_TRACE_ENTER_DURING_EXEC	4
#define TCL_TRACE_LEAVE_DURING_EXEC	8
#define TCL_TRACE_ANY_EXEC              15
#define TCL_TRACE_EXEC_IN_PROGRESS      0x10
#define TCL_TRACE_EXEC_DIRECT           0x20

/*
 * Forward declarations for procedures defined in this file:
 */

typedef int (Tcl_TraceTypeObjCmd) _ANSI_ARGS_((Tcl_Interp *interp,
	int optionIndex, int objc, Tcl_Obj *CONST objv[]));

Tcl_TraceTypeObjCmd TclTraceVariableObjCmd;
Tcl_TraceTypeObjCmd TclTraceCommandObjCmd;
Tcl_TraceTypeObjCmd TclTraceExecutionObjCmd;

/* 
 * Each subcommand has a number of 'types' to which it can apply.
 * Currently 'execution', 'command' and 'variable' are the only
 * types supported.  These three arrays MUST be kept in sync!
 * In the future we may provide an API to add to the list of
 * supported trace types.
 */
static CONST char *traceTypeOptions[] = {
    "execution", "command", "variable", (char*) NULL
};
static Tcl_TraceTypeObjCmd* traceSubCmds[] = {
    TclTraceExecutionObjCmd,
    TclTraceCommandObjCmd,
    TclTraceVariableObjCmd,
};

/*
 * Declarations for local procedures to this file:
 */
static int              CallTraceProcedure _ANSI_ARGS_((Tcl_Interp *interp,
                            Trace *tracePtr, Command *cmdPtr,
                            CONST char *command, int numChars,
                            int objc, Tcl_Obj *CONST objv[]));
static char *		TraceVarProc _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp, CONST char *name1, 
                            CONST char *name2, int flags));
static void		TraceCommandProc _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp, CONST char *oldName,
                            CONST char *newName, int flags));
static Tcl_CmdObjTraceProc TraceExecutionProc;

/*
 *----------------------------------------------------------------------
 *
 * Tcl_PwdObjCmd --
 *
 *	This procedure is invoked to process the "pwd" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_PwdObjCmd(dummy, interp, objc, objv)
    ClientData dummy;			/* Not used. */
    Tcl_Interp *interp;			/* Current interpreter. */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];		/* Argument objects. */
{
    Tcl_Obj *retVal;

    if (objc != 1) {
	Tcl_WrongNumArgs(interp, 1, objv, NULL);
	return TCL_ERROR;
    }

    retVal = Tcl_FSGetCwd(interp);
    if (retVal == NULL) {
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, retVal);
    Tcl_DecrRefCount(retVal);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_RegexpObjCmd --
 *
 *	This procedure is invoked to process the "regexp" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_RegexpObjCmd(dummy, interp, objc, objv)
    ClientData dummy;			/* Not used. */
    Tcl_Interp *interp;			/* Current interpreter. */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];		/* Argument objects. */
{
    int i, indices, match, about, offset, all, doinline, numMatchesSaved;
    int cflags, eflags, stringLength;
    Tcl_RegExp regExpr;
    Tcl_Obj *objPtr, *resultPtr;
    Tcl_RegExpInfo info;
    static CONST char *options[] = {
	"-all",		"-about",	"-indices",	"-inline",
	"-expanded",	"-line",	"-linestop",	"-lineanchor",
	"-nocase",	"-start",	"--",		(char *) NULL
    };
    enum options {
	REGEXP_ALL,	REGEXP_ABOUT,	REGEXP_INDICES,	REGEXP_INLINE,
	REGEXP_EXPANDED,REGEXP_LINE,	REGEXP_LINESTOP,REGEXP_LINEANCHOR,
	REGEXP_NOCASE,	REGEXP_START,	REGEXP_LAST
    };

    indices	= 0;
    about	= 0;
    cflags	= TCL_REG_ADVANCED;
    eflags	= 0;
    offset	= 0;
    all		= 0;
    doinline	= 0;
    
    for (i = 1; i < objc; i++) {
	char *name;
	int index;

	name = Tcl_GetString(objv[i]);
	if (name[0] != '-') {
	    break;
	}
	if (Tcl_GetIndexFromObj(interp, objv[i], options, "switch", TCL_EXACT,
		&index) != TCL_OK) {
	    return TCL_ERROR;
	}
	switch ((enum options) index) {
	    case REGEXP_ALL: {
		all = 1;
		break;
	    }
	    case REGEXP_INDICES: {
		indices = 1;
		break;
	    }
	    case REGEXP_INLINE: {
		doinline = 1;
		break;
	    }
	    case REGEXP_NOCASE: {
		cflags |= TCL_REG_NOCASE;
		break;
	    }
	    case REGEXP_ABOUT: {
		about = 1;
		break;
	    }
	    case REGEXP_EXPANDED: {
		cflags |= TCL_REG_EXPANDED;
		break;
	    }
	    case REGEXP_LINE: {
		cflags |= TCL_REG_NEWLINE;
		break;
	    }
	    case REGEXP_LINESTOP: {
		cflags |= TCL_REG_NLSTOP;
		break;
	    }
	    case REGEXP_LINEANCHOR: {
		cflags |= TCL_REG_NLANCH;
		break;
	    }
	    case REGEXP_START: {
		if (++i >= objc) {
		    goto endOfForLoop;
		}
		if (Tcl_GetIntFromObj(interp, objv[i], &offset) != TCL_OK) {
		    return TCL_ERROR;
		}
		if (offset < 0) {
		    offset = 0;
		}
		break;
	    }
	    case REGEXP_LAST: {
		i++;
		goto endOfForLoop;
	    }
	}
    }

    endOfForLoop:
    if ((objc - i) < (2 - about)) {
	Tcl_WrongNumArgs(interp, 1, objv, "?switches? exp string ?matchVar? ?subMatchVar subMatchVar ...?");
	return TCL_ERROR;
    }
    objc -= i;
    objv += i;

    if (doinline && ((objc - 2) != 0)) {
	/*
	 * User requested -inline, but specified match variables - a no-no.
	 */
	Tcl_AppendResult(interp, "regexp match variables not allowed",
		" when using -inline", (char *) NULL);
	return TCL_ERROR;
    }

    /*
     * Handle the odd about case separately.
     */
    if (about) {
	regExpr = Tcl_GetRegExpFromObj(interp, objv[0], cflags);
	if ((regExpr == NULL) || (TclRegAbout(interp, regExpr) < 0)) {
	    return TCL_ERROR;
	}
	return TCL_OK;
    }

    /*
     * Get the length of the string that we are matching against so
     * we can do the termination test for -all matches.  Do this before
     * getting the regexp to avoid shimmering problems.
     */
    objPtr = objv[1];
    stringLength = Tcl_GetCharLength(objPtr);

    regExpr = Tcl_GetRegExpFromObj(interp, objv[0], cflags);
    if (regExpr == NULL) {
	return TCL_ERROR;
    }

    if (offset > 0) {
	/*
	 * Add flag if using offset (string is part of a larger string),
	 * so that "^" won't match.
	 */
	eflags |= TCL_REG_NOTBOL;
    }

    objc -= 2;
    objv += 2;
    resultPtr = Tcl_GetObjResult(interp);

    if (doinline) {
	/*
	 * Save all the subexpressions, as we will return them as a list
	 */
	numMatchesSaved = -1;
    } else {
	/*
	 * Save only enough subexpressions for matches we want to keep,
	 * expect in the case of -all, where we need to keep at least
	 * one to know where to move the offset.
	 */
	numMatchesSaved = (objc == 0) ? all : objc;
    }

    /*
     * The following loop is to handle multiple matches within the
     * same source string;  each iteration handles one match.  If "-all"
     * hasn't been specified then the loop body only gets executed once.
     * We terminate the loop when the starting offset is past the end of the
     * string.
     */

    while (1) {
	match = Tcl_RegExpExecObj(interp, regExpr, objPtr,
		offset /* offset */, numMatchesSaved, eflags);

	if (match < 0) {
	    return TCL_ERROR;
	}

	if (match == 0) {
	    /*
	     * We want to set the value of the intepreter result only when
	     * this is the first time through the loop.
	     */
	    if (all <= 1) {
		/*
		 * If inlining, set the interpreter's object result to an
		 * empty list, otherwise set it to an integer object w/
		 * value 0.
		 */
		if (doinline) {
		    Tcl_SetListObj(resultPtr, 0, NULL);
		} else {
		    Tcl_SetIntObj(resultPtr, 0);
		}
		return TCL_OK;
	    }
	    break;
	}

	/*
	 * If additional variable names have been specified, return
	 * index information in those variables.
	 */

	Tcl_RegExpGetInfo(regExpr, &info);
	if (doinline) {
	    /*
	     * It's the number of substitutions, plus one for the matchVar
	     * at index 0
	     */
	    objc = info.nsubs + 1;
	}
	for (i = 0; i < objc; i++) {
	    Tcl_Obj *newPtr;

	    if (indices) {
		int start, end;
		Tcl_Obj *objs[2];

		/*
		 * Only adjust the match area if there was a match for
		 * that area.  (Scriptics Bug 4391/SF Bug #219232)
		 */
		if (i <= info.nsubs && info.matches[i].start >= 0) {
		    start = offset + info.matches[i].start;
		    end   = offset + info.matches[i].end;

		    /*
		     * Adjust index so it refers to the last character in the
		     * match instead of the first character after the match.
		     */

		    if (end >= offset) {
			end--;
		    }
		} else {
		    start = -1;
		    end   = -1;
		}

		objs[0] = Tcl_NewLongObj(start);
		objs[1] = Tcl_NewLongObj(end);

		newPtr = Tcl_NewListObj(2, objs);
	    } else {
		if (i <= info.nsubs) {
		    newPtr = Tcl_GetRange(objPtr,
			    offset + info.matches[i].start,
			    offset + info.matches[i].end - 1);
		} else {
		    newPtr = Tcl_NewObj();
		}
	    }
	    if (doinline) {
		if (Tcl_ListObjAppendElement(interp, resultPtr, newPtr)
			!= TCL_OK) {
		    Tcl_DecrRefCount(newPtr);
		    return TCL_ERROR;
		}
	    } else {
		Tcl_Obj *valuePtr;
		valuePtr = Tcl_ObjSetVar2(interp, objv[i], NULL, newPtr, 0);
		if (valuePtr == NULL) {
		    Tcl_DecrRefCount(newPtr);
		    Tcl_AppendResult(interp, "couldn't set variable \"",
			    Tcl_GetString(objv[i]), "\"", (char *) NULL);
		    return TCL_ERROR;
		}
	    }
	}

	if (all == 0) {
	    break;
	}
	/*
	 * Adjust the offset to the character just after the last one
	 * in the matchVar and increment all to count how many times
	 * we are making a match.  We always increment the offset by at least
	 * one to prevent endless looping (as in the case:
	 * regexp -all {a*} a).  Otherwise, when we match the NULL string at
	 * the end of the input string, we will loop indefinately (because the
	 * length of the match is 0, so offset never changes).
	 */
	if (info.matches[0].end == 0) {
	    offset++;
	}
	offset += info.matches[0].end;
	all++;
	eflags |= TCL_REG_NOTBOL;
	if (offset >= stringLength) {
	    break;
	}
    }

    /*
     * Set the interpreter's object result to an integer object
     * with value 1 if -all wasn't specified, otherwise it's all-1
     * (the number of times through the while - 1).
     * Get the resultPtr again as the Tcl_ObjSetVar2 above may have
     * cause the result to change. [Patch #558324] (watson).
     */

    if (!doinline) {
	resultPtr = Tcl_GetObjResult(interp);
	Tcl_SetIntObj(resultPtr, (all ? all-1 : 1));
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_RegsubObjCmd --
 *
 *	This procedure is invoked to process the "regsub" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_RegsubObjCmd(dummy, interp, objc, objv)
    ClientData dummy;			/* Not used. */
    Tcl_Interp *interp;			/* Current interpreter. */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];		/* Argument objects. */
{
    int idx, result, cflags, all, wlen, wsublen, numMatches, offset;
    int start, end, subStart, subEnd, match;
    Tcl_RegExp regExpr;
    Tcl_RegExpInfo info;
    Tcl_Obj *resultPtr, *subPtr, *objPtr;
    Tcl_UniChar ch, *wsrc, *wfirstChar, *wstring, *wsubspec, *wend;

    static CONST char *options[] = {
	"-all",		"-nocase",	"-expanded",
	"-line",	"-linestop",	"-lineanchor",	"-start",
	"--",		NULL
    };
    enum options {
	REGSUB_ALL,	REGSUB_NOCASE,	REGSUB_EXPANDED,
	REGSUB_LINE,	REGSUB_LINESTOP, REGSUB_LINEANCHOR,	REGSUB_START,
	REGSUB_LAST
    };

    cflags = TCL_REG_ADVANCED;
    all = 0;
    offset = 0;
    resultPtr = NULL;

    for (idx = 1; idx < objc; idx++) {
	char *name;
	int index;
	
	name = Tcl_GetString(objv[idx]);
	if (name[0] != '-') {
	    break;
	}
	if (Tcl_GetIndexFromObj(interp, objv[idx], options, "switch",
		TCL_EXACT, &index) != TCL_OK) {
	    return TCL_ERROR;
	}
	switch ((enum options) index) {
	    case REGSUB_ALL: {
		all = 1;
		break;
	    }
	    case REGSUB_NOCASE: {
		cflags |= TCL_REG_NOCASE;
		break;
	    }
	    case REGSUB_EXPANDED: {
		cflags |= TCL_REG_EXPANDED;
		break;
	    }
	    case REGSUB_LINE: {
		cflags |= TCL_REG_NEWLINE;
		break;
	    }
	    case REGSUB_LINESTOP: {
		cflags |= TCL_REG_NLSTOP;
		break;
	    }
	    case REGSUB_LINEANCHOR: {
		cflags |= TCL_REG_NLANCH;
		break;
	    }
	    case REGSUB_START: {
		if (++idx >= objc) {
		    goto endOfForLoop;
		}
		if (Tcl_GetIntFromObj(interp, objv[idx], &offset) != TCL_OK) {
		    return TCL_ERROR;
		}
		if (offset < 0) {
		    offset = 0;
		}
		break;
	    }
	    case REGSUB_LAST: {
		idx++;
		goto endOfForLoop;
	    }
	}
    }
    endOfForLoop:
    if (objc-idx < 3 || objc-idx > 4) {
	Tcl_WrongNumArgs(interp, 1, objv,
		"?switches? exp string subSpec ?varName?");
	return TCL_ERROR;
    }

    objc -= idx;
    objv += idx;

    if (all && (offset == 0)
	    && (strpbrk(Tcl_GetString(objv[2]), "&\\") == NULL)
	    && (strpbrk(Tcl_GetString(objv[0]), "*+?{}()[].\\|^$") == NULL)) {
	/*
	 * This is a simple one pair string map situation.  We make use of
	 * a slightly modified version of the one pair STR_MAP code.
	 */
	int slen, nocase;
	int (*strCmpFn)_ANSI_ARGS_((CONST Tcl_UniChar *, CONST Tcl_UniChar *,
		unsigned long));
	Tcl_UniChar *p, wsrclc;

	numMatches = 0;
	nocase     = (cflags & TCL_REG_NOCASE);
	strCmpFn   = nocase ? Tcl_UniCharNcasecmp : Tcl_UniCharNcmp;

	wsrc     = Tcl_GetUnicodeFromObj(objv[0], &slen);
	wstring  = Tcl_GetUnicodeFromObj(objv[1], &wlen);
	wsubspec = Tcl_GetUnicodeFromObj(objv[2], &wsublen);
	wend     = wstring + wlen - (slen ? slen - 1 : 0);
	result   = TCL_OK;

	if (slen == 0) {
	    /*
	     * regsub behavior for "" matches between each character.
	     * 'string map' skips the "" case.
	     */
	    if (wstring < wend) {
		resultPtr = Tcl_NewUnicodeObj(wstring, 0);
		Tcl_IncrRefCount(resultPtr);
		for (; wstring < wend; wstring++) {
		    Tcl_AppendUnicodeToObj(resultPtr, wsubspec, wsublen);
		    Tcl_AppendUnicodeToObj(resultPtr, wstring, 1);
		    numMatches++;
		}
		wlen = 0;
	    }
	} else {
	    wsrclc = Tcl_UniCharToLower(*wsrc);
	    for (p = wfirstChar = wstring; wstring < wend; wstring++) {
		if (((*wstring == *wsrc) ||
			(nocase && (Tcl_UniCharToLower(*wstring) ==
				wsrclc))) &&
			((slen == 1) || (strCmpFn(wstring, wsrc,
				(unsigned long) slen) == 0))) {
		    if (numMatches == 0) {
			resultPtr = Tcl_NewUnicodeObj(wstring, 0);
			Tcl_IncrRefCount(resultPtr);
		    }
		    if (p != wstring) {
			Tcl_AppendUnicodeToObj(resultPtr, p, wstring - p);
			p = wstring + slen;
		    } else {
			p += slen;
		    }
		    wstring = p - 1;

		    Tcl_AppendUnicodeToObj(resultPtr, wsubspec, wsublen);
		    numMatches++;
		}
	    }
	    if (numMatches) {
		wlen    = wfirstChar + wlen - p;
		wstring = p;
	    }
	}
	objPtr = NULL;
	subPtr = NULL;
	goto regsubDone;
    }

    regExpr = Tcl_GetRegExpFromObj(interp, objv[0], cflags);
    if (regExpr == NULL) {
	return TCL_ERROR;
    }

    /*
     * Make sure to avoid problems where the objects are shared.  This
     * can cause RegExpObj <> UnicodeObj shimmering that causes data
     * corruption.  [Bug #461322]
     */

    if (objv[1] == objv[0]) {
	objPtr = Tcl_DuplicateObj(objv[1]);
    } else {
	objPtr = objv[1];
    }
    wstring = Tcl_GetUnicodeFromObj(objPtr, &wlen);
    if (objv[2] == objv[0]) {
	subPtr = Tcl_DuplicateObj(objv[2]);
    } else {
	subPtr = objv[2];
    }
    wsubspec = Tcl_GetUnicodeFromObj(subPtr, &wsublen);

    result = TCL_OK;

    /*
     * The following loop is to handle multiple matches within the
     * same source string;  each iteration handles one match and its
     * corresponding substitution.  If "-all" hasn't been specified
     * then the loop body only gets executed once.
     */

    numMatches = 0;
    for ( ; offset < wlen; ) {

	/*
	 * The flags argument is set if string is part of a larger string,
	 * so that "^" won't match.
	 */

	match = Tcl_RegExpExecObj(interp, regExpr, objPtr, offset,
		10 /* matches */, ((offset > 0) ? TCL_REG_NOTBOL : 0));

	if (match < 0) {
	    result = TCL_ERROR;
	    goto done;
	}
	if (match == 0) {
	    break;
	}
	if (numMatches == 0) {
	    resultPtr = Tcl_NewUnicodeObj(wstring, 0);
	    Tcl_IncrRefCount(resultPtr);
	    if (offset > 0) {
		/*
		 * Copy the initial portion of the string in if an offset
		 * was specified.
		 */
		Tcl_AppendUnicodeToObj(resultPtr, wstring, offset);
	    }
	}
	numMatches++;

	/*
	 * Copy the portion of the source string before the match to the
	 * result variable.
	 */

	Tcl_RegExpGetInfo(regExpr, &info);
	start = info.matches[0].start;
	end = info.matches[0].end;
	Tcl_AppendUnicodeToObj(resultPtr, wstring + offset, start);

	/*
	 * Append the subSpec argument to the variable, making appropriate
	 * substitutions.  This code is a bit hairy because of the backslash
	 * conventions and because the code saves up ranges of characters in
	 * subSpec to reduce the number of calls to Tcl_SetVar.
	 */

	wsrc = wfirstChar = wsubspec;
	wend = wsubspec + wsublen;
	for (ch = *wsrc; wsrc != wend; wsrc++, ch = *wsrc) {
	    if (ch == '&') {
		idx = 0;
	    } else if (ch == '\\') {
		ch = wsrc[1];
		if ((ch >= '0') && (ch <= '9')) {
		    idx = ch - '0';
		} else if ((ch == '\\') || (ch == '&')) {
		    *wsrc = ch;
		    Tcl_AppendUnicodeToObj(resultPtr, wfirstChar,
			    wsrc - wfirstChar + 1);
		    *wsrc = '\\';
		    wfirstChar = wsrc + 2;
		    wsrc++;
		    continue;
		} else {
		    continue;
		}
	    } else {
		continue;
	    }
	    if (wfirstChar != wsrc) {
		Tcl_AppendUnicodeToObj(resultPtr, wfirstChar,
			wsrc - wfirstChar);
	    }
	    if (idx <= info.nsubs) {
		subStart = info.matches[idx].start;
		subEnd = info.matches[idx].end;
		if ((subStart >= 0) && (subEnd >= 0)) {
		    Tcl_AppendUnicodeToObj(resultPtr,
			    wstring + offset + subStart, subEnd - subStart);
		}
	    }
	    if (*wsrc == '\\') {
		wsrc++;
	    }
	    wfirstChar = wsrc + 1;
	}
	if (wfirstChar != wsrc) {
	    Tcl_AppendUnicodeToObj(resultPtr, wfirstChar, wsrc - wfirstChar);
	}
	if (end == 0) {
	    /*
	     * Always consume at least one character of the input string
	     * in order to prevent infinite loops.
	     */

	    Tcl_AppendUnicodeToObj(resultPtr, wstring + offset, 1);
	    offset++;
	} else {
	    offset += end;
	}
	if (!all) {
	    break;
	}
    }

    /*
     * Copy the portion of the source string after the last match to the
     * result variable.
     */
    regsubDone:
    if (numMatches == 0) {
	/*
	 * On zero matches, just ignore the offset, since it shouldn't
	 * matter to us in this case, and the user may have skewed it.
	 */
	resultPtr = objv[1];
	Tcl_IncrRefCount(resultPtr);
    } else if (offset < wlen) {
	Tcl_AppendUnicodeToObj(resultPtr, wstring + offset, wlen - offset);
    }
    if (objc == 4) {
	if (Tcl_ObjSetVar2(interp, objv[3], NULL, resultPtr, 0) == NULL) {
	    Tcl_AppendResult(interp, "couldn't set variable \"",
		    Tcl_GetString(objv[3]), "\"", (char *) NULL);
	    result = TCL_ERROR;
	} else {
	    /*
	     * Set the interpreter's object result to an integer object
	     * holding the number of matches. 
	     */

	    Tcl_SetIntObj(Tcl_GetObjResult(interp), numMatches);
	}
    } else {
	/*
	 * No varname supplied, so just return the modified string.
	 */
	Tcl_SetObjResult(interp, resultPtr);
    }

    done:
    if (objPtr && (objv[1] == objv[0])) { Tcl_DecrRefCount(objPtr); }
    if (subPtr && (objv[2] == objv[0])) { Tcl_DecrRefCount(subPtr); }
    if (resultPtr) { Tcl_DecrRefCount(resultPtr); }
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_RenameObjCmd --
 *
 *	This procedure is invoked to process the "rename" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl object result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_RenameObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Arbitrary value passed to the command. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    char *oldName, *newName;
    
    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "oldName newName");
	return TCL_ERROR;
    }

    oldName = Tcl_GetString(objv[1]);
    newName = Tcl_GetString(objv[2]);
    return TclRenameCommand(interp, oldName, newName);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ReturnObjCmd --
 *
 *	This object-based procedure is invoked to process the "return" Tcl
 *	command. See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl object result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_ReturnObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    Interp *iPtr = (Interp *) interp;
    int optionLen, argLen, code, result;

    if (iPtr->errorInfo != NULL) {
	ckfree(iPtr->errorInfo);
	iPtr->errorInfo = NULL;
    }
    if (iPtr->errorCode != NULL) {
	ckfree(iPtr->errorCode);
	iPtr->errorCode = NULL;
    }
    code = TCL_OK;
    
    for (objv++, objc--;  objc > 1;  objv += 2, objc -= 2) {
	char *option = Tcl_GetStringFromObj(objv[0], &optionLen);
	char *arg = Tcl_GetStringFromObj(objv[1], &argLen);
    	
	if (strcmp(option, "-code") == 0) {
	    register int c = arg[0];
	    if ((c == 'o') && (strcmp(arg, "ok") == 0)) {
		code = TCL_OK;
	    } else if ((c == 'e') && (strcmp(arg, "error") == 0)) {
		code = TCL_ERROR;
	    } else if ((c == 'r') && (strcmp(arg, "return") == 0)) {
		code = TCL_RETURN;
	    } else if ((c == 'b') && (strcmp(arg, "break") == 0)) {
		code = TCL_BREAK;
	    } else if ((c == 'c') && (strcmp(arg, "continue") == 0)) {
		code = TCL_CONTINUE;
	    } else {
		result = Tcl_GetIntFromObj((Tcl_Interp *) NULL, objv[1],
		        &code);
		if (result != TCL_OK) {
		    Tcl_ResetResult(interp);
		    Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
			    "bad completion code \"",
			    Tcl_GetString(objv[1]),
			    "\": must be ok, error, return, break, ",
			    "continue, or an integer", (char *) NULL);
		    return result;
		}
	    }
	} else if (strcmp(option, "-errorinfo") == 0) {
	    iPtr->errorInfo =
		(char *) ckalloc((unsigned) (strlen(arg) + 1));
	    strcpy(iPtr->errorInfo, arg);
	} else if (strcmp(option, "-errorcode") == 0) {
	    iPtr->errorCode =
		(char *) ckalloc((unsigned) (strlen(arg) + 1));
	    strcpy(iPtr->errorCode, arg);
	} else {
	    Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
		    "bad option \"", option,
		    "\": must be -code, -errorcode, or -errorinfo",
		    (char *) NULL);
	    return TCL_ERROR;
	}
    }
    
    if (objc == 1) {
	/*
	 * Set the interpreter's object result. An inline version of
	 * Tcl_SetObjResult.
	 */

	Tcl_SetObjResult(interp, objv[0]);
    }
    iPtr->returnCode = code;
    return TCL_RETURN;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SourceObjCmd --
 *
 *	This procedure is invoked to process the "source" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl object result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_SourceObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    if (objc != 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "fileName");
	return TCL_ERROR;
    }

    return Tcl_FSEvalFile(interp, objv[1]);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SplitObjCmd --
 *
 *	This procedure is invoked to process the "split" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_SplitObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    Tcl_UniChar ch;
    int len;
    char *splitChars, *string, *end;
    int splitCharLen, stringLen;
    Tcl_Obj *listPtr, *objPtr;

    if (objc == 2) {
	splitChars = " \n\t\r";
	splitCharLen = 4;
    } else if (objc == 3) {
	splitChars = Tcl_GetStringFromObj(objv[2], &splitCharLen);
    } else {
	Tcl_WrongNumArgs(interp, 1, objv, "string ?splitChars?");
	return TCL_ERROR;
    }

    string = Tcl_GetStringFromObj(objv[1], &stringLen);
    end = string + stringLen;
    listPtr = Tcl_GetObjResult(interp);
    
    if (stringLen == 0) {
	/*
	 * Do nothing.
	 */
    } else if (splitCharLen == 0) {
	Tcl_HashTable charReuseTable;
	Tcl_HashEntry *hPtr;
	int isNew;

	/*
	 * Handle the special case of splitting on every character.
	 *
	 * Uses a hash table to ensure that each kind of character has
	 * only one Tcl_Obj instance (multiply-referenced) in the
	 * final list.  This is a *major* win when splitting on a long
	 * string (especially in the megabyte range!) - DKF
	 */

	Tcl_InitHashTable(&charReuseTable, TCL_ONE_WORD_KEYS);
	for ( ; string < end; string += len) {
	    len = Tcl_UtfToUniChar(string, &ch);
	    /* Assume Tcl_UniChar is an integral type... */
	    hPtr = Tcl_CreateHashEntry(&charReuseTable, (char*)0 + ch, &isNew);
	    if (isNew) {
		objPtr = Tcl_NewStringObj(string, len);
		/* Don't need to fiddle with refcount... */
		Tcl_SetHashValue(hPtr, (ClientData) objPtr);
	    } else {
		objPtr = (Tcl_Obj*) Tcl_GetHashValue(hPtr);
	    }
	    Tcl_ListObjAppendElement(NULL, listPtr, objPtr);
	}
	Tcl_DeleteHashTable(&charReuseTable);
    } else {
	char *element, *p, *splitEnd;
	int splitLen;
	Tcl_UniChar splitChar;
	
	/*
	 * Normal case: split on any of a given set of characters.
	 * Discard instances of the split characters.
	 */

	splitEnd = splitChars + splitCharLen;

	for (element = string; string < end; string += len) {
	    len = Tcl_UtfToUniChar(string, &ch);
	    for (p = splitChars; p < splitEnd; p += splitLen) {
		splitLen = Tcl_UtfToUniChar(p, &splitChar);
		if (ch == splitChar) {
		    objPtr = Tcl_NewStringObj(element, string - element);
		    Tcl_ListObjAppendElement(NULL, listPtr, objPtr);
		    element = string + len;
		    break;
		}
	    }
	}
	objPtr = Tcl_NewStringObj(element, string - element);
	Tcl_ListObjAppendElement(NULL, listPtr, objPtr);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_StringObjCmd --
 *
 *	This procedure is invoked to process the "string" Tcl command.
 *	See the user documentation for details on what it does.  Note
 *	that this command only functions correctly on properly formed
 *	Tcl UTF strings.
 *
 *	Note that the primary methods here (equal, compare, match, ...)
 *	have bytecode equivalents.  You will find the code for those in
 *	tclExecute.c.  The code here will only be used in the non-bc
 *	case (like in an 'eval').
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_StringObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    int index, left, right;
    Tcl_Obj *resultPtr;
    char *string1, *string2;
    int length1, length2;
    static CONST char *options[] = {
	"bytelength",	"compare",	"equal",	"first",
	"index",	"is",		"last",		"length",
	"map",		"match",	"range",	"repeat",
	"replace",	"tolower",	"toupper",	"totitle",
	"trim",		"trimleft",	"trimright",
	"wordend",	"wordstart",	(char *) NULL
    };
    enum options {
	STR_BYTELENGTH,	STR_COMPARE,	STR_EQUAL,	STR_FIRST,
	STR_INDEX,	STR_IS,		STR_LAST,	STR_LENGTH,
	STR_MAP,	STR_MATCH,	STR_RANGE,	STR_REPEAT,
	STR_REPLACE,	STR_TOLOWER,	STR_TOUPPER,	STR_TOTITLE,
	STR_TRIM,	STR_TRIMLEFT,	STR_TRIMRIGHT,
	STR_WORDEND,	STR_WORDSTART
    };	  

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "option arg ?arg ...?");
	return TCL_ERROR;
    }
    
    if (Tcl_GetIndexFromObj(interp, objv[1], options, "option", 0,
	    &index) != TCL_OK) {
	return TCL_ERROR;
    }

    resultPtr = Tcl_GetObjResult(interp);
    switch ((enum options) index) {
	case STR_EQUAL:
	case STR_COMPARE: {
	    /*
	     * Remember to keep code here in some sync with the
	     * byte-compiled versions in tclExecute.c (INST_STR_EQ,
	     * INST_STR_NEQ and INST_STR_CMP as well as the expr string
	     * comparison in INST_EQ/INST_NEQ/INST_LT/...).
	     */
	    int i, match, length, nocase = 0, reqlength = -1;
	    int (*strCmpFn)();

	    if (objc < 4 || objc > 7) {
	    str_cmp_args:
	        Tcl_WrongNumArgs(interp, 2, objv,
				 "?-nocase? ?-length int? string1 string2");
		return TCL_ERROR;
	    }

	    for (i = 2; i < objc-2; i++) {
		string2 = Tcl_GetStringFromObj(objv[i], &length2);
		if ((length2 > 1)
			&& strncmp(string2, "-nocase", (size_t)length2) == 0) {
		    nocase = 1;
		} else if ((length2 > 1)
			&& strncmp(string2, "-length", (size_t)length2) == 0) {
		    if (i+1 >= objc-2) {
			goto str_cmp_args;
		    }
		    if (Tcl_GetIntFromObj(interp, objv[++i],
			    &reqlength) != TCL_OK) {
			return TCL_ERROR;
		    }
		} else {
		    Tcl_AppendStringsToObj(resultPtr, "bad option \"",
			    string2, "\": must be -nocase or -length",
			    (char *) NULL);
		    return TCL_ERROR;
		}
	    }

	    /*
	     * From now on, we only access the two objects at the end
	     * of the argument array.
	     */
	    objv += objc-2;

	    if ((reqlength == 0) || (objv[0] == objv[1])) {
		/*
		 * Alway match at 0 chars of if it is the same obj.
		 */

		Tcl_SetBooleanObj(resultPtr,
			((enum options) index == STR_EQUAL));
		break;
	    } else if (!nocase && objv[0]->typePtr == &tclByteArrayType &&
		    objv[1]->typePtr == &tclByteArrayType) {
		/*
		 * Use binary versions of comparisons since that won't
		 * cause undue type conversions and it is much faster.
		 * Only do this if we're case-sensitive (which is all
		 * that really makes sense with byte arrays anyway, and
		 * we have no memcasecmp() for some reason... :^)
		 */
		string1 = (char*) Tcl_GetByteArrayFromObj(objv[0], &length1);
		string2 = (char*) Tcl_GetByteArrayFromObj(objv[1], &length2);
		strCmpFn = memcmp;
	    } else if ((objv[0]->typePtr == &tclStringType)
		    && (objv[1]->typePtr == &tclStringType)) {
		/*
		 * Do a unicode-specific comparison if both of the args
		 * are of String type.  In benchmark testing this proved
		 * the most efficient check between the unicode and
		 * string comparison operations.
		 */
		string1 = (char*) Tcl_GetUnicodeFromObj(objv[0], &length1);
		string2 = (char*) Tcl_GetUnicodeFromObj(objv[1], &length2);
		strCmpFn = nocase ? Tcl_UniCharNcasecmp : Tcl_UniCharNcmp;
	    } else {
		/*
		 * As a catch-all we will work with UTF-8.  We cannot use
		 * memcmp() as that is unsafe with any string containing
		 * NULL (\xC0\x80 in Tcl's utf rep).  We can use the more
		 * efficient TclpUtfNcmp2 if we are case-sensitive and no
		 * specific length was requested.
		 */
		string1 = (char*) Tcl_GetStringFromObj(objv[0], &length1);
		string2 = (char*) Tcl_GetStringFromObj(objv[1], &length2);
		if ((reqlength < 0) && !nocase) {
		    strCmpFn = TclpUtfNcmp2;
		} else {
		    length1 = Tcl_NumUtfChars(string1, length1);
		    length2 = Tcl_NumUtfChars(string2, length2);
		    strCmpFn = nocase ? Tcl_UtfNcasecmp : Tcl_UtfNcmp;
		}
	    }

	    if (((enum options) index == STR_EQUAL)
		    && (reqlength < 0) && (length1 != length2)) {
		match = 1; /* this will be reversed below */
	    } else {
		length = (length1 < length2) ? length1 : length2;
		if (reqlength > 0 && reqlength < length) {
		    length = reqlength;
		} else if (reqlength < 0) {
		    /*
		     * The requested length is negative, so we ignore it by
		     * setting it to length + 1 so we correct the match var.
		     */
		    reqlength = length + 1;
		}
		match = strCmpFn(string1, string2, (unsigned) length);
		if ((match == 0) && (reqlength > length)) {
		    match = length1 - length2;
		}
	    }

	    if ((enum options) index == STR_EQUAL) {
		Tcl_SetBooleanObj(resultPtr, (match) ? 0 : 1);
	    } else {
		Tcl_SetIntObj(resultPtr, ((match > 0) ? 1 :
					  (match < 0) ? -1 : 0));
	    }
	    break;
	}
	case STR_FIRST: {
	    Tcl_UniChar *ustring1, *ustring2;
	    int match, start;

	    if (objc < 4 || objc > 5) {
	        Tcl_WrongNumArgs(interp, 2, objv,
				 "subString string ?startIndex?");
		return TCL_ERROR;
	    }

	    /*
	     * We are searching string2 for the sequence string1.
	     */

	    match = -1;
	    start = 0;
	    length2 = -1;

	    ustring1 = Tcl_GetUnicodeFromObj(objv[2], &length1);
	    ustring2 = Tcl_GetUnicodeFromObj(objv[3], &length2);

	    if (objc == 5) {
		/*
		 * If a startIndex is specified, we will need to fast
		 * forward to that point in the string before we think
		 * about a match
		 */
		if (TclGetIntForIndex(interp, objv[4], length2 - 1,
			&start) != TCL_OK) {
		    return TCL_ERROR;
		}
		if (start >= length2) {
		    goto str_first_done;
		} else if (start > 0) {
		    ustring2 += start;
		    length2  -= start;
		} else if (start < 0) {
		    /*
		     * Invalid start index mapped to string start;
		     * Bug #423581
		     */
		    start = 0;
		}
	    }

	    if (length1 > 0) {
		register Tcl_UniChar *p, *end;

		end = ustring2 + length2 - length1 + 1;
		for (p = ustring2;  p < end;  p++) {
		    /*
		     * Scan forward to find the first character.
		     */
		    if ((*p == *ustring1) &&
			    (TclUniCharNcmp(ustring1, p,
				    (unsigned long) length1) == 0)) {
			match = p - ustring2;
			break;
		    }
		}
	    }
	    /*
	     * Compute the character index of the matching string by
	     * counting the number of characters before the match.
	     */
	    if ((match != -1) && (objc == 5)) {
		match += start;
	    }

	    str_first_done:
	    Tcl_SetIntObj(resultPtr, match);
	    break;
	}
	case STR_INDEX: {
	    if (objc != 4) {
	        Tcl_WrongNumArgs(interp, 2, objv, "string charIndex");
		return TCL_ERROR;
	    }

	    /*
	     * If we have a ByteArray object, avoid indexing in the
	     * Utf string since the byte array contains one byte per
	     * character.  Otherwise, use the Unicode string rep to
	     * get the index'th char.
	     */

	    if (objv[2]->typePtr == &tclByteArrayType) {
		string1 = (char *) Tcl_GetByteArrayFromObj(objv[2], &length1);

		if (TclGetIntForIndex(interp, objv[3], length1 - 1,
			&index) != TCL_OK) {
		    return TCL_ERROR;
		}
		if ((index >= 0) && (index < length1)) {
		    Tcl_SetByteArrayObj(resultPtr,
			    (unsigned char *)(&string1[index]), 1);
		}
	    } else {
		/*
		 * Get Unicode char length to calulate what 'end' means.
		 */
		length1 = Tcl_GetCharLength(objv[2]);

		if (TclGetIntForIndex(interp, objv[3], length1 - 1,
			&index) != TCL_OK) {
		    return TCL_ERROR;
		}
		if ((index >= 0) && (index < length1)) {
		    char buf[TCL_UTF_MAX];
		    Tcl_UniChar ch;

		    ch      = Tcl_GetUniChar(objv[2], index);
		    length1 = Tcl_UniCharToUtf(ch, buf);
		    Tcl_SetStringObj(resultPtr, buf, length1);
		}
	    }
	    break;
	}
	case STR_IS: {
	    char *end;
	    Tcl_UniChar ch;

            /*
	     * The UniChar comparison function
	     */

	    int (*chcomp)_ANSI_ARGS_((int)) = NULL; 
	    int i, failat = 0, result = 1, strict = 0;
	    Tcl_Obj *objPtr, *failVarObj = NULL;

	    static CONST char *isOptions[] = {
		"alnum",	"alpha",	"ascii",	"control",
		"boolean",	"digit",	"double",	"false",
		"graph",	"integer",	"lower",	"print",
		"punct",	"space",	"true",		"upper",
		"wordchar",	"xdigit",	(char *) NULL
	    };
	    enum isOptions {
		STR_IS_ALNUM,	STR_IS_ALPHA,	STR_IS_ASCII,	STR_IS_CONTROL,
		STR_IS_BOOL,	STR_IS_DIGIT,	STR_IS_DOUBLE,	STR_IS_FALSE,
		STR_IS_GRAPH,	STR_IS_INT,	STR_IS_LOWER,	STR_IS_PRINT,
		STR_IS_PUNCT,	STR_IS_SPACE,	STR_IS_TRUE,	STR_IS_UPPER,
		STR_IS_WORD,	STR_IS_XDIGIT
	    };

	    if (objc < 4 || objc > 7) {
		Tcl_WrongNumArgs(interp, 2, objv,
				 "class ?-strict? ?-failindex var? str");
		return TCL_ERROR;
	    }
	    if (Tcl_GetIndexFromObj(interp, objv[2], isOptions, "class", 0,
				    &index) != TCL_OK) {
		return TCL_ERROR;
	    }
	    if (objc != 4) {
		for (i = 3; i < objc-1; i++) {
		    string2 = Tcl_GetStringFromObj(objv[i], &length2);
		    if ((length2 > 1) &&
			strncmp(string2, "-strict", (size_t) length2) == 0) {
			strict = 1;
		    } else if ((length2 > 1) &&
			    strncmp(string2, "-failindex",
				    (size_t) length2) == 0) {
			if (i+1 >= objc-1) {
			    Tcl_WrongNumArgs(interp, 3, objv,
					     "?-strict? ?-failindex var? str");
			    return TCL_ERROR;
			}
			failVarObj = objv[++i];
		    } else {
			Tcl_AppendStringsToObj(resultPtr, "bad option \"",
				string2, "\": must be -strict or -failindex",
				(char *) NULL);
			return TCL_ERROR;
		    }
		}
	    }

	    /*
	     * We get the objPtr so that we can short-cut for some classes
	     * by checking the object type (int and double), but we need
	     * the string otherwise, because we don't want any conversion
	     * of type occuring (as, for example, Tcl_Get*FromObj would do
	     */
	    objPtr = objv[objc-1];
	    string1 = Tcl_GetStringFromObj(objPtr, &length1);
	    if (length1 == 0) {
		if (strict) {
		    result = 0;
		}
		goto str_is_done;
	    }
	    end = string1 + length1;

	    /*
	     * When entering here, result == 1 and failat == 0
	     */
	    switch ((enum isOptions) index) {
		case STR_IS_ALNUM:
		    chcomp = Tcl_UniCharIsAlnum;
		    break;
		case STR_IS_ALPHA:
		    chcomp = Tcl_UniCharIsAlpha;
		    break;
		case STR_IS_ASCII:
		    for (; string1 < end; string1++, failat++) {
			/*
			 * This is a valid check in unicode, because all
			 * bytes < 0xC0 are single byte chars (but isascii
			 * limits that def'n to 0x80).
			 */
			if (*((unsigned char *)string1) >= 0x80) {
			    result = 0;
			    break;
			}
		    }
		    break;
		case STR_IS_BOOL:
		case STR_IS_TRUE:
		case STR_IS_FALSE:
		    if (objPtr->typePtr == &tclBooleanType) {
			if ((((enum isOptions) index == STR_IS_TRUE) &&
			     objPtr->internalRep.longValue == 0) ||
			    (((enum isOptions) index == STR_IS_FALSE) &&
			     objPtr->internalRep.longValue != 0)) {
			    result = 0;
			}
		    } else if ((Tcl_GetBoolean(NULL, string1, &i)
				== TCL_ERROR) ||
			       (((enum isOptions) index == STR_IS_TRUE) &&
				i == 0) ||
			       (((enum isOptions) index == STR_IS_FALSE) &&
				i != 0)) {
			result = 0;
		    }
		    break;
		case STR_IS_CONTROL:
		    chcomp = Tcl_UniCharIsControl;
		    break;
		case STR_IS_DIGIT:
		    chcomp = Tcl_UniCharIsDigit;
		    break;
		case STR_IS_DOUBLE: {
		    char *stop;

		    if ((objPtr->typePtr == &tclDoubleType) ||
			(objPtr->typePtr == &tclIntType)) {
			break;
		    }
		    /*
		     * This is adapted from Tcl_GetDouble
		     *
		     * The danger in this function is that
		     * "12345678901234567890" is an acceptable 'double',
		     * but will later be interp'd as an int by something
		     * like [expr].  Therefore, we check to see if it looks
		     * like an int, and if so we do a range check on it.
		     * If strtoul gets to the end, we know we either
		     * received an acceptable int, or over/underflow
		     */
		    if (TclLooksLikeInt(string1, length1)) {
			errno = 0;
#ifdef TCL_WIDE_INT_IS_LONG
			strtoul(string1, &stop, 0); /* INTL: Tcl source. */
#else
			strtoull(string1, &stop, 0); /* INTL: Tcl source. */
#endif
			if (stop == end) {
			    if (errno == ERANGE) {
				result = 0;
				failat = -1;
			    }
			    break;
			}
		    }
		    errno = 0;
		    strtod(string1, &stop); /* INTL: Tcl source. */
		    if (errno == ERANGE) {
			/*
			 * if (errno == ERANGE), then it was an over/underflow
			 * problem, but in this method, we only want to know
			 * yes or no, so bad flow returns 0 (false) and sets
			 * the failVarObj to the string length.
			 */
			result = 0;
			failat = -1;
		    } else if (stop == string1) {
			/*
			 * In this case, nothing like a number was found
			 */
			result = 0;
			failat = 0;
		    } else {
			/*
			 * Assume we sucked up one char per byte
			 * and then we go onto SPACE, since we are
			 * allowed trailing whitespace
			 */
			failat = stop - string1;
			string1 = stop;
			chcomp = Tcl_UniCharIsSpace;
		    }
		    break;
		}
		case STR_IS_GRAPH:
		    chcomp = Tcl_UniCharIsGraph;
		    break;
		case STR_IS_INT: {
		    char *stop;

		    if ((objPtr->typePtr == &tclIntType) ||
			(Tcl_GetInt(NULL, string1, &i) == TCL_OK)) {
			break;
		    }
		    /*
		     * Like STR_IS_DOUBLE, but we use strtoul.
		     * Since Tcl_GetInt already failed, we set result to 0.
		     */
		    result = 0;
		    errno = 0;
#ifdef TCL_WIDE_INT_IS_LONG
		    strtoul(string1, &stop, 0); /* INTL: Tcl source. */
#else
		    strtoull(string1, &stop, 0); /* INTL: Tcl source. */
#endif
		    if (errno == ERANGE) {
			/*
			 * if (errno == ERANGE), then it was an over/underflow
			 * problem, but in this method, we only want to know
			 * yes or no, so bad flow returns 0 (false) and sets
			 * the failVarObj to the string length.
			 */
			failat = -1;
		    } else if (stop == string1) {
			/*
			 * In this case, nothing like a number was found
			 */
			failat = 0;
		    } else {
			/*
			 * Assume we sucked up one char per byte
			 * and then we go onto SPACE, since we are
			 * allowed trailing whitespace
			 */
			failat = stop - string1;
			string1 = stop;
			chcomp = Tcl_UniCharIsSpace;
		    }
		    break;
		}
		case STR_IS_LOWER:
		    chcomp = Tcl_UniCharIsLower;
		    break;
		case STR_IS_PRINT:
		    chcomp = Tcl_UniCharIsPrint;
		    break;
		case STR_IS_PUNCT:
		    chcomp = Tcl_UniCharIsPunct;
		    break;
		case STR_IS_SPACE:
		    chcomp = Tcl_UniCharIsSpace;
		    break;
		case STR_IS_UPPER:
		    chcomp = Tcl_UniCharIsUpper;
		    break;
		case STR_IS_WORD:
		    chcomp = Tcl_UniCharIsWordChar;
		    break;
		case STR_IS_XDIGIT: {
		    for (; string1 < end; string1++, failat++) {
			/* INTL: We assume unicode is bad for this class */
			if ((*((unsigned char *)string1) >= 0xC0) ||
			    !isxdigit(*(unsigned char *)string1)) {
			    result = 0;
			    break;
			}
		    }
		    break;
		}
	    }
	    if (chcomp != NULL) {
		for (; string1 < end; string1 += length2, failat++) {
		    length2 = Tcl_UtfToUniChar(string1, &ch);
		    if (!chcomp(ch)) {
			result = 0;
			break;
		    }
		}
	    }
	str_is_done:
	    /*
	     * Only set the failVarObj when we will return 0
	     * and we have indicated a valid fail index (>= 0)
	     */
	    if ((result == 0) && (failVarObj != NULL) &&
		Tcl_ObjSetVar2(interp, failVarObj, NULL, Tcl_NewIntObj(failat),
			       TCL_LEAVE_ERR_MSG) == NULL) {
		return TCL_ERROR;
	    }
	    Tcl_SetBooleanObj(resultPtr, result);
	    break;
	}
	case STR_LAST: {
	    Tcl_UniChar *ustring1, *ustring2, *p;
	    int match, start;

	    if (objc < 4 || objc > 5) {
	        Tcl_WrongNumArgs(interp, 2, objv,
				 "subString string ?startIndex?");
		return TCL_ERROR;
	    }

	    /*
	     * We are searching string2 for the sequence string1.
	     */

	    match = -1;
	    start = 0;
	    length2 = -1;

	    ustring1 = Tcl_GetUnicodeFromObj(objv[2], &length1);
	    ustring2 = Tcl_GetUnicodeFromObj(objv[3], &length2);

	    if (objc == 5) {
		/*
		 * If a startIndex is specified, we will need to restrict
		 * the string range to that char index in the string
		 */
		if (TclGetIntForIndex(interp, objv[4], length2 - 1,
			&start) != TCL_OK) {
		    return TCL_ERROR;
		}
		if (start < 0) {
		    goto str_last_done;
		} else if (start < length2) {
		    p = ustring2 + start + 1 - length1;
		} else {
		    p = ustring2 + length2 - length1;
		}
	    } else {
		p = ustring2 + length2 - length1;
	    }

	    if (length1 > 0) {
		for (; p >= ustring2;  p--) {
		    /*
		     * Scan backwards to find the first character.
		     */
		    if ((*p == *ustring1) &&
			    (memcmp((char *) ustring1, (char *) p, (size_t)
				    (length1 * sizeof(Tcl_UniChar))) == 0)) {
			match = p - ustring2;
			break;
		    }
		}
	    }

	    str_last_done:
	    Tcl_SetIntObj(resultPtr, match);
	    break;
	}
	case STR_BYTELENGTH:
	case STR_LENGTH: {
	    if (objc != 3) {
	        Tcl_WrongNumArgs(interp, 2, objv, "string");
		return TCL_ERROR;
	    }

	    if ((enum options) index == STR_BYTELENGTH) {
		(void) Tcl_GetStringFromObj(objv[2], &length1);
	    } else {
		/*
		 * If we have a ByteArray object, avoid recomputing the
		 * string since the byte array contains one byte per
		 * character.  Otherwise, use the Unicode string rep to
		 * calculate the length.
		 */

		if (objv[2]->typePtr == &tclByteArrayType) {
		    (void) Tcl_GetByteArrayFromObj(objv[2], &length1);
		} else {
		    length1 = Tcl_GetCharLength(objv[2]);
		}
	    }
	    Tcl_SetIntObj(resultPtr, length1);
	    break;
	}
	case STR_MAP: {
	    int mapElemc, nocase = 0;
	    Tcl_Obj **mapElemv;
	    Tcl_UniChar *ustring1, *ustring2, *p, *end;
	    int (*strCmpFn)_ANSI_ARGS_((CONST Tcl_UniChar*,
					CONST Tcl_UniChar*, unsigned long));

	    if (objc < 4 || objc > 5) {
	        Tcl_WrongNumArgs(interp, 2, objv, "?-nocase? charMap string");
		return TCL_ERROR;
	    }

	    if (objc == 5) {
		string2 = Tcl_GetStringFromObj(objv[2], &length2);
		if ((length2 > 1) &&
		    strncmp(string2, "-nocase", (size_t) length2) == 0) {
		    nocase = 1;
		} else {
		    Tcl_AppendStringsToObj(resultPtr, "bad option \"",
					   string2, "\": must be -nocase",
					   (char *) NULL);
		    return TCL_ERROR;
		}
	    }

	    if (Tcl_ListObjGetElements(interp, objv[objc-2], &mapElemc,
				       &mapElemv) != TCL_OK) {
		return TCL_ERROR;
	    }
	    if (mapElemc == 0) {
		/*
		 * empty charMap, just return whatever string was given
		 */
		Tcl_SetObjResult(interp, objv[objc-1]);
		return TCL_OK;
	    } else if (mapElemc & 1) {
		/*
		 * The charMap must be an even number of key/value items
		 */
		Tcl_SetStringObj(resultPtr, "char map list unbalanced", -1);
		return TCL_ERROR;
	    }
	    objc--;

	    ustring1 = Tcl_GetUnicodeFromObj(objv[objc], &length1);
	    if (length1 == 0) {
		/*
		 * Empty input string, just stop now
		 */
		break;
	    }
	    end = ustring1 + length1;

	    strCmpFn = nocase ? Tcl_UniCharNcasecmp : Tcl_UniCharNcmp;

	    /*
	     * Force result to be Unicode
	     */
	    Tcl_SetUnicodeObj(resultPtr, ustring1, 0);

	    if (mapElemc == 2) {
		/*
		 * Special case for one map pair which avoids the extra
		 * for loop and extra calls to get Unicode data.  The
		 * algorithm is otherwise identical to the multi-pair case.
		 * This will be >30% faster on larger strings.
		 */
		int mapLen;
		Tcl_UniChar *mapString, u2lc;

		ustring2 = Tcl_GetUnicodeFromObj(mapElemv[0], &length2);
		p = ustring1;
		if (length2 == 0) {
		    ustring1 = end;
		} else {
		    mapString = Tcl_GetUnicodeFromObj(mapElemv[1], &mapLen);
		    u2lc = (nocase ? Tcl_UniCharToLower(*ustring2) : 0);
		    for (; ustring1 < end; ustring1++) {
			if (((*ustring1 == *ustring2) ||
				(nocase && (Tcl_UniCharToLower(*ustring1) ==
					u2lc))) &&
				((length2 == 1) || strCmpFn(ustring1, ustring2,
					(unsigned long) length2) == 0)) {
			    if (p != ustring1) {
				Tcl_AppendUnicodeToObj(resultPtr, p,
					ustring1 - p);
				p = ustring1 + length2;
			    } else {
				p += length2;
			    }
			    ustring1 = p - 1;

			    Tcl_AppendUnicodeToObj(resultPtr, mapString,
				    mapLen);
			}
		    }
		}
	    } else {
		Tcl_UniChar **mapStrings, *u2lc = NULL;
		int *mapLens;
		/*
		 * Precompute pointers to the unicode string and length.
		 * This saves us repeated function calls later,
		 * significantly speeding up the algorithm.  We only need
		 * the lowercase first char in the nocase case.
		 */
		mapStrings = (Tcl_UniChar **) ckalloc((mapElemc * 2)
			* sizeof(Tcl_UniChar *));
		mapLens = (int *) ckalloc((mapElemc * 2) * sizeof(int));
		if (nocase) {
		    u2lc = (Tcl_UniChar *)
			ckalloc((mapElemc) * sizeof(Tcl_UniChar));
		}
		for (index = 0; index < mapElemc; index++) {
		    mapStrings[index] = Tcl_GetUnicodeFromObj(mapElemv[index],
			    &(mapLens[index]));
		    if (nocase && ((index % 2) == 0)) {
			u2lc[index/2] = Tcl_UniCharToLower(*mapStrings[index]);
		    }
		}
		for (p = ustring1; ustring1 < end; ustring1++) {
		    for (index = 0; index < mapElemc; index += 2) {
			/*
			 * Get the key string to match on.
			 */
			ustring2 = mapStrings[index];
			length2  = mapLens[index];
			if ((length2 > 0) && ((*ustring1 == *ustring2) ||
				(nocase && (Tcl_UniCharToLower(*ustring1) ==
					u2lc[index/2]))) &&
				((length2 == 1) || strCmpFn(ustring2, ustring1,
					(unsigned long) length2) == 0)) {
			    if (p != ustring1) {
				/*
				 * Put the skipped chars onto the result first
				 */
				Tcl_AppendUnicodeToObj(resultPtr, p,
					ustring1 - p);
				p = ustring1 + length2;
			    } else {
				p += length2;
			    }
			    /*
			     * Adjust len to be full length of matched string
			     */
			    ustring1 = p - 1;

			    /*
			     * Append the map value to the unicode string
			     */
			    Tcl_AppendUnicodeToObj(resultPtr,
				    mapStrings[index+1], mapLens[index+1]);
			    break;
			}
		    }
		}
		ckfree((char *) mapStrings);
		ckfree((char *) mapLens);
		if (nocase) {
		    ckfree((char *) u2lc);
		}
	    }
	    if (p != ustring1) {
		/*
		 * Put the rest of the unmapped chars onto result
		 */
		Tcl_AppendUnicodeToObj(resultPtr, p, ustring1 - p);
	    }
	    break;
	}
	case STR_MATCH: {
	    int nocase = 0;

	    if (objc < 4 || objc > 5) {
	        Tcl_WrongNumArgs(interp, 2, objv, "?-nocase? pattern string");
		return TCL_ERROR;
	    }

	    if (objc == 5) {
		string2 = Tcl_GetStringFromObj(objv[2], &length2);
		if ((length2 > 1) &&
		    strncmp(string2, "-nocase", (size_t) length2) == 0) {
		    nocase = 1;
		} else {
		    Tcl_AppendStringsToObj(resultPtr, "bad option \"",
					   string2, "\": must be -nocase",
					   (char *) NULL);
		    return TCL_ERROR;
		}
	    }

	    Tcl_SetBooleanObj(resultPtr,
		    Tcl_UniCharCaseMatch(Tcl_GetUnicode(objv[objc-1]),
			    Tcl_GetUnicode(objv[objc-2]), nocase));
	    break;
	}
	case STR_RANGE: {
	    int first, last;

	    if (objc != 5) {
	        Tcl_WrongNumArgs(interp, 2, objv, "string first last");
		return TCL_ERROR;
	    }

	    /*
	     * Get the length in actual characters.
	     */
	    length1 = Tcl_GetCharLength(objv[2]) - 1;

	    if ((TclGetIntForIndex(interp, objv[3], length1, &first) != TCL_OK)
		    || (TclGetIntForIndex(interp, objv[4], length1,
			    &last) != TCL_OK)) {
		return TCL_ERROR;
	    }

	    if (first < 0) {
		first = 0;
	    }
	    if (last >= length1) {
		last = length1;
	    }
	    if (last >= first) {
		Tcl_SetObjResult(interp, Tcl_GetRange(objv[2], first, last));
	    }
	    break;
	}
	case STR_REPEAT: {
	    int count;

	    if (objc != 4) {
		Tcl_WrongNumArgs(interp, 2, objv, "string count");
		return TCL_ERROR;
	    }

	    if (Tcl_GetIntFromObj(interp, objv[3], &count) != TCL_OK) {
		return TCL_ERROR;
	    }

	    if (count == 1) {
		Tcl_SetObjResult(interp, objv[2]);
	    } else if (count > 1) {
		string1 = Tcl_GetStringFromObj(objv[2], &length1);
		if (length1 > 0) {
		    /*
		     * Only build up a string that has data.  Instead of
		     * building it up with repeated appends, we just allocate
		     * the necessary space once and copy the string value in.
		     */
		    length2		= length1 * count;
		    /*
		     * Include space for the NULL
		     */
		    string2		= (char *) ckalloc((size_t) length2+1);
		    for (index = 0; index < count; index++) {
			memcpy(string2 + (length1 * index), string1,
				(size_t) length1);
		    }
		    string2[length2]	= '\0';
		    /*
		     * We have to directly assign this instead of using
		     * Tcl_SetStringObj (and indirectly TclInitStringRep)
		     * because that makes another copy of the data.
		     */
		    resultPtr		= Tcl_NewObj();
		    resultPtr->bytes	= string2;
		    resultPtr->length	= length2;
		    Tcl_SetObjResult(interp, resultPtr);
		}
	    }
	    break;
	}
	case STR_REPLACE: {
	    Tcl_UniChar *ustring1;
	    int first, last;

	    if (objc < 5 || objc > 6) {
	        Tcl_WrongNumArgs(interp, 2, objv,
				 "string first last ?string?");
		return TCL_ERROR;
	    }

	    ustring1 = Tcl_GetUnicodeFromObj(objv[2], &length1);
	    length1--;

	    if ((TclGetIntForIndex(interp, objv[3], length1, &first) != TCL_OK)
		    || (TclGetIntForIndex(interp, objv[4], length1,
			    &last) != TCL_OK)) {
		return TCL_ERROR;
	    }

	    if ((last < first) || (last < 0) || (first > length1)) {
		Tcl_SetObjResult(interp, objv[2]);
	    } else {
		if (first < 0) {
		    first = 0;
		}

		Tcl_SetUnicodeObj(resultPtr, ustring1, first);
		if (objc == 6) {
		    Tcl_AppendObjToObj(resultPtr, objv[5]);
		}
		if (last < length1) {
		    Tcl_AppendUnicodeToObj(resultPtr, ustring1 + last + 1,
			    length1 - last);
		}
	    }
	    break;
	}
	case STR_TOLOWER:
	case STR_TOUPPER:
	case STR_TOTITLE:
	    if (objc < 3 || objc > 5) {
	        Tcl_WrongNumArgs(interp, 2, objv, "string ?first? ?last?");
		return TCL_ERROR;
	    }

	    string1 = Tcl_GetStringFromObj(objv[2], &length1);

	    if (objc == 3) {
		/*
		 * Since the result object is not a shared object, it is
		 * safe to copy the string into the result and do the
		 * conversion in place.  The conversion may change the length
		 * of the string, so reset the length after conversion.
		 */

		Tcl_SetStringObj(resultPtr, string1, length1);
		if ((enum options) index == STR_TOLOWER) {
		    length1 = Tcl_UtfToLower(Tcl_GetString(resultPtr));
		} else if ((enum options) index == STR_TOUPPER) {
		    length1 = Tcl_UtfToUpper(Tcl_GetString(resultPtr));
		} else {
		    length1 = Tcl_UtfToTitle(Tcl_GetString(resultPtr));
		}
		Tcl_SetObjLength(resultPtr, length1);
	    } else {
		int first, last;
		CONST char *start, *end;

		length1 = Tcl_NumUtfChars(string1, length1) - 1;
		if (TclGetIntForIndex(interp, objv[3], length1,
				      &first) != TCL_OK) {
		    return TCL_ERROR;
		}
		if (first < 0) {
		    first = 0;
		}
		last = first;
		if ((objc == 5) && (TclGetIntForIndex(interp, objv[4], length1,
						      &last) != TCL_OK)) {
		    return TCL_ERROR;
		}
		if (last >= length1) {
		    last = length1;
		}
		if (last < first) {
		    Tcl_SetObjResult(interp, objv[2]);
		    break;
		}
		start = Tcl_UtfAtIndex(string1, first);
		end = Tcl_UtfAtIndex(start, last - first + 1);
		length2 = end-start;
		string2 = ckalloc((size_t) length2+1);
		memcpy(string2, start, (size_t) length2);
		string2[length2] = '\0';
		if ((enum options) index == STR_TOLOWER) {
		    length2 = Tcl_UtfToLower(string2);
		} else if ((enum options) index == STR_TOUPPER) {
		    length2 = Tcl_UtfToUpper(string2);
		} else {
		    length2 = Tcl_UtfToTitle(string2);
		}
		Tcl_SetStringObj(resultPtr, string1, start - string1);
		Tcl_AppendToObj(resultPtr, string2, length2);
		Tcl_AppendToObj(resultPtr, end, -1);
		ckfree(string2);
	    }
	    break;

	case STR_TRIM: {
	    Tcl_UniChar ch, trim;
	    register CONST char *p, *end;
	    char *check, *checkEnd;
	    int offset;

	    left = 1;
	    right = 1;

	    dotrim:
	    if (objc == 4) {
		string2 = Tcl_GetStringFromObj(objv[3], &length2);
	    } else if (objc == 3) {
		string2 = " \t\n\r";
		length2 = strlen(string2);
	    } else {
	        Tcl_WrongNumArgs(interp, 2, objv, "string ?chars?");
		return TCL_ERROR;
	    }
	    string1 = Tcl_GetStringFromObj(objv[2], &length1);
	    checkEnd = string2 + length2;

	    if (left) {
		end = string1 + length1;
		/*
		 * The outer loop iterates over the string.  The inner
		 * loop iterates over the trim characters.  The loops
		 * terminate as soon as a non-trim character is discovered
		 * and string1 is left pointing at the first non-trim
		 * character.
		 */

		for (p = string1; p < end; p += offset) {
		    offset = Tcl_UtfToUniChar(p, &ch);
		    
		    for (check = string2; ; ) {
			if (check >= checkEnd) {
			    p = end;
			    break;
			}
			check += Tcl_UtfToUniChar(check, &trim);
			if (ch == trim) {
			    length1 -= offset;
			    string1 += offset;
			    break;
			}
		    }
		}
	    }
	    if (right) {
	        end = string1;

		/*
		 * The outer loop iterates over the string.  The inner
		 * loop iterates over the trim characters.  The loops
		 * terminate as soon as a non-trim character is discovered
		 * and length1 marks the last non-trim character.
		 */

		for (p = string1 + length1; p > end; ) {
		    p = Tcl_UtfPrev(p, string1);
		    offset = Tcl_UtfToUniChar(p, &ch);
		    for (check = string2; ; ) {
		        if (check >= checkEnd) {
			    p = end;
			    break;
			}
			check += Tcl_UtfToUniChar(check, &trim);
			if (ch == trim) {
			    length1 -= offset;
			    break;
			}
		    }
		}
	    }
	    Tcl_SetStringObj(resultPtr, string1, length1);
	    break;
	}
	case STR_TRIMLEFT: {
	    left = 1;
	    right = 0;
	    goto dotrim;
	}
	case STR_TRIMRIGHT: {
	    left = 0;
	    right = 1;
	    goto dotrim;
	}
	case STR_WORDEND: {
	    int cur;
	    Tcl_UniChar ch;
	    CONST char *p, *end;
	    int numChars;
	    
	    if (objc != 4) {
	        Tcl_WrongNumArgs(interp, 2, objv, "string index");
		return TCL_ERROR;
	    }

	    string1 = Tcl_GetStringFromObj(objv[2], &length1);
	    numChars = Tcl_NumUtfChars(string1, length1);
	    if (TclGetIntForIndex(interp, objv[3], numChars-1,
				  &index) != TCL_OK) {
		return TCL_ERROR;
	    }
	    if (index < 0) {
		index = 0;
	    }
	    if (index < numChars) {
		p = Tcl_UtfAtIndex(string1, index);
		end = string1+length1;
		for (cur = index; p < end; cur++) {
		    p += Tcl_UtfToUniChar(p, &ch);
		    if (!Tcl_UniCharIsWordChar(ch)) {
			break;
		    }
		}
		if (cur == index) {
		    cur++;
		}
	    } else {
		cur = numChars;
	    }
	    Tcl_SetIntObj(resultPtr, cur);
	    break;
	}
	case STR_WORDSTART: {
	    int cur;
	    Tcl_UniChar ch;
	    CONST char *p;
	    int numChars;
	    
	    if (objc != 4) {
	        Tcl_WrongNumArgs(interp, 2, objv, "string index");
		return TCL_ERROR;
	    }

	    string1 = Tcl_GetStringFromObj(objv[2], &length1);
	    numChars = Tcl_NumUtfChars(string1, length1);
	    if (TclGetIntForIndex(interp, objv[3], numChars-1,
				  &index) != TCL_OK) {
		return TCL_ERROR;
	    }
	    if (index >= numChars) {
		index = numChars - 1;
	    }
	    cur = 0;
	    if (index > 0) {
		p = Tcl_UtfAtIndex(string1, index);
	        for (cur = index; cur >= 0; cur--) {
		    Tcl_UtfToUniChar(p, &ch);
		    if (!Tcl_UniCharIsWordChar(ch)) {
			break;
		    }
		    p = Tcl_UtfPrev(p, string1);
		}
		if (cur != index) {
		    cur += 1;
		}
	    }
	    Tcl_SetIntObj(resultPtr, cur);
	    break;
	}
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SubstObjCmd --
 *
 *	This procedure is invoked to process the "subst" Tcl command.
 *	See the user documentation for details on what it does.  This
 *	command relies on Tcl_SubstObj() for its implementation.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_SubstObjCmd(dummy, interp, objc, objv)
    ClientData dummy;			/* Not used. */
    Tcl_Interp *interp;			/* Current interpreter. */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];       	/* Argument objects. */
{
    static CONST char *substOptions[] = {
	"-nobackslashes", "-nocommands", "-novariables", (char *) NULL
    };
    enum substOptions {
	SUBST_NOBACKSLASHES,      SUBST_NOCOMMANDS,       SUBST_NOVARS
    };
    Tcl_Obj *resultPtr;
    int optionIndex, flags, i;

    /*
     * Parse command-line options.
     */

    flags = TCL_SUBST_ALL;
    for (i = 1; i < (objc-1); i++) {
	if (Tcl_GetIndexFromObj(interp, objv[i], substOptions,
		"switch", 0, &optionIndex) != TCL_OK) {

	    return TCL_ERROR;
	}
	switch (optionIndex) {
	    case SUBST_NOBACKSLASHES: {
		flags &= ~TCL_SUBST_BACKSLASHES;
		break;
	    }
	    case SUBST_NOCOMMANDS: {
		flags &= ~TCL_SUBST_COMMANDS;
		break;
	    }
	    case SUBST_NOVARS: {
		flags &= ~TCL_SUBST_VARIABLES;
		break;
	    }
	    default: {
		panic("Tcl_SubstObjCmd: bad option index to SubstOptions");
	    }
	}
    }
    if (i != (objc-1)) {
	Tcl_WrongNumArgs(interp, 1, objv,
		"?-nobackslashes? ?-nocommands? ?-novariables? string");
	return TCL_ERROR;
    }

    /*
     * Perform the substitution.
     */
    resultPtr = Tcl_SubstObj(interp, objv[i], flags);

    if (resultPtr == NULL) {
	return TCL_ERROR;
    }
    Tcl_SetObjResult(interp, resultPtr);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SubstObj --
 *
 *	This function performs the substitutions specified on the
 *	given string as described in the user documentation for the
 *	"subst" Tcl command.  This code is heavily based on an
 *	implementation by Andrew Payne.  Note that if a command
 *	substitution returns TCL_CONTINUE or TCL_RETURN from its
 *	evaluation and is not completely well-formed, the results are
 *	not defined (or at least hard to characterise.)  This fault
 *	will be fixed at some point, but the cost of the only sane
 *	fix (well-formedness check first) is such that you need to
 *	"precompile and cache" to stop everyone from being hit with
 *	the consequences every time through.  Note that the current
 *	behaviour is not a security hole; it just restarts parsing
 *	the string following the substitution in a mildly surprising
 *	place, and it is a very bad idea to count on this remaining
 *	the same in future...
 *
 * Results:
 *	A Tcl_Obj* containing the substituted string, or NULL to
 *	indicate that an error occurred.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
Tcl_SubstObj(interp, objPtr, flags)
    Tcl_Interp *interp;
    Tcl_Obj *objPtr;
    int flags;
{
    Tcl_Obj *resultObj;
    char *p, *old;

    old = p = Tcl_GetString(objPtr);
    resultObj = Tcl_NewStringObj("", 0);
    while (1) {
	switch (*p) {
	case 0:
	    if (p != old) {
		Tcl_AppendToObj(resultObj, old, p-old);
	    }
	    return resultObj;

	case '\\':
	    if (flags & TCL_SUBST_BACKSLASHES) {
		char buf[TCL_UTF_MAX];
		int count;

		if (p != old) {
		    Tcl_AppendToObj(resultObj, old, p-old);
		}
		Tcl_AppendToObj(resultObj, buf,
				Tcl_UtfBackslash(p, &count, buf));
		p += count;
		old = p;
	    } else {
		p++;
	    }
	    break;

	case '$':
	    if (flags & TCL_SUBST_VARIABLES) {
		Tcl_Parse parse;
		int code;

		/*
		 * Code is simpler overall if we (effectively) inline
		 * Tcl_ParseVar, particularly as that allows us to use
		 * a non-string interface when we come to appending
		 * the variable contents to the result object.  There
		 * are a few other optimisations that doing this
		 * enables (like being able to continue the run of
		 * unsubstituted characters straight through if a '$'
		 * does not precede a variable name.)
		 */
		if (Tcl_ParseVarName(interp, p, -1, &parse, 0) != TCL_OK) {
		    goto errorResult;
		}
		if (parse.numTokens == 1) {
		    /*
		     * There isn't a variable name after all: the $ is
		     * just a $.
		     */
		    p++;
		    break;
		}
		if (p != old) {
		    Tcl_AppendToObj(resultObj, old, p-old);
		}
		p += parse.tokenPtr->size;
		code = Tcl_EvalTokensStandard(interp, parse.tokenPtr,
		        parse.numTokens);
		if (code == TCL_ERROR) {
		    goto errorResult;
		}
		if (code == TCL_BREAK) {
		    Tcl_ResetResult(interp);
		    return resultObj;
		}
		if (code != TCL_CONTINUE) {
		    Tcl_AppendObjToObj(resultObj, Tcl_GetObjResult(interp));
		}
		Tcl_ResetResult(interp);
		old = p;
	    } else {
		p++;
	    }
	    break;

	case '[':
	    if (flags & TCL_SUBST_COMMANDS) {
		Interp *iPtr = (Interp *) interp;
		int code;

		if (p != old) {
		    Tcl_AppendToObj(resultObj, old, p-old);
		}
		iPtr->evalFlags = TCL_BRACKET_TERM;
		code = Tcl_EvalEx(interp, p+1, -1, 0);
		switch (code) {
		case TCL_ERROR:
		    goto errorResult;
		case TCL_BREAK:
		    Tcl_ResetResult(interp);
		    return resultObj;
		default:
		    Tcl_AppendObjToObj(resultObj, Tcl_GetObjResult(interp));
		case TCL_CONTINUE:
		    Tcl_ResetResult(interp);
		    old = p = (p+1 + iPtr->termOffset + 1);
		}
	    } else {
		p++;
	    }
	    break;
	default:
	    p++;
	    break;
	}
    }

 errorResult:
    Tcl_DecrRefCount(resultObj);
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_SwitchObjCmd --
 *
 *	This object-based procedure is invoked to process the "switch" Tcl
 *	command. See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl object result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_SwitchObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    int i, j, index, mode, matched, result, splitObjs;
    char *string, *pattern;
    Tcl_Obj *stringObj;
    Tcl_Obj *CONST *savedObjv = objv;
    static CONST char *options[] = {
	"-exact",	"-glob",	"-regexp",	"--", 
	NULL
    };
    enum options {
	OPT_EXACT,	OPT_GLOB,	OPT_REGEXP,	OPT_LAST
    };

    mode = OPT_EXACT;
    for (i = 1; i < objc; i++) {
	string = Tcl_GetString(objv[i]);
	if (string[0] != '-') {
	    break;
	}
	if (Tcl_GetIndexFromObj(interp, objv[i], options, "option", 0, 
		&index) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (index == OPT_LAST) {
	    i++;
	    break;
	}
	mode = index;
    }

    if (objc - i < 2) {
	Tcl_WrongNumArgs(interp, 1, objv,
		"?switches? string pattern body ... ?default body?");
	return TCL_ERROR;
    }

    stringObj = objv[i];
    objc -= i + 1;
    objv += i + 1;

    /*
     * If all of the pattern/command pairs are lumped into a single
     * argument, split them out again.
     */

    splitObjs = 0;
    if (objc == 1) {
	Tcl_Obj **listv;

	if (Tcl_ListObjGetElements(interp, objv[0], &objc, &listv) != TCL_OK) {
	    return TCL_ERROR;
	}

	/*
	 * Ensure that the list is non-empty.
	 */

	if (objc < 1) {
	    Tcl_WrongNumArgs(interp, 1, savedObjv,
		    "?switches? string {pattern body ... ?default body?}");
	    return TCL_ERROR;
	}
	objv = listv;
	splitObjs = 1;
    }

    /*
     * Complain if there is an odd number of words in the list of
     * patterns and bodies.
     */

    if (objc % 2) {
	Tcl_ResetResult(interp);
	Tcl_AppendResult(interp, "extra switch pattern with no body", NULL);

	/*
	 * Check if this can be due to a badly placed comment
	 * in the switch block.
	 *
	 * The following is an heuristic to detect the infamous
	 * "comment in switch" error: just check if a pattern
	 * begins with '#'.
	 */

	if (splitObjs) {
	    for (i=0 ; i<objc ; i+=2) {
		if (Tcl_GetString(objv[i])[0] == '#') {
		    Tcl_AppendResult(interp, ", this may be due to a ",
			    "comment incorrectly placed outside of a ",
			    "switch body - see the \"switch\" ",
			    "documentation", NULL);
		    break;
		}
	    }
	}

	return TCL_ERROR;
    }

    /*
     * Complain if the last body is a continuation.  Note that this
     * check assumes that the list is non-empty!
     */

    if (strcmp(Tcl_GetString(objv[objc-1]), "-") == 0) {
	Tcl_ResetResult(interp);
	Tcl_AppendResult(interp, "no body specified for pattern \"",
		Tcl_GetString(objv[objc-2]), "\"", NULL);
	return TCL_ERROR;
    }

    for (i = 0; i < objc; i += 2) {
	/*
	 * See if the pattern matches the string.
	 */

	pattern = Tcl_GetString(objv[i]);

	matched = 0;
	if ((i == objc - 2) 
		&& (*pattern == 'd') 
		&& (strcmp(pattern, "default") == 0)) {
	    matched = 1;
	} else {
	    switch (mode) {
		case OPT_EXACT:
		    matched = (strcmp(Tcl_GetString(stringObj), pattern) == 0);
		    break;
		case OPT_GLOB:
		    matched = Tcl_StringMatch(Tcl_GetString(stringObj),
			    pattern);
		    break;
		case OPT_REGEXP:
		    matched = Tcl_RegExpMatchObj(interp, stringObj, objv[i]);
		    if (matched < 0) {
			return TCL_ERROR;
		    }
		    break;
	    }
	}
	if (matched == 0) {
	    continue;
	}

	/*
	 * We've got a match. Find a body to execute, skipping bodies
	 * that are "-".
	 */

	for (j = i + 1; ; j += 2) {
	    if (j >= objc) {
		/*
		 * This shouldn't happen since we've checked that the
		 * last body is not a continuation...
		 */
		panic("fall-out when searching for body to match pattern");
	    }
	    if (strcmp(Tcl_GetString(objv[j]), "-") != 0) {
		break;
	    }
	}
	result = Tcl_EvalObjEx(interp, objv[j], 0);
	if (result == TCL_ERROR) {
	    char msg[100 + TCL_INTEGER_SPACE];

	    sprintf(msg, "\n    (\"%.50s\" arm line %d)", pattern,
		    interp->errorLine);
	    Tcl_AddObjErrorInfo(interp, msg, -1);
	}
	return result;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_TimeObjCmd --
 *
 *	This object-based procedure is invoked to process the "time" Tcl
 *	command.  See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl object result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_TimeObjCmd(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 Tcl_Obj *objPtr;
    register int i, result;
    int count;
    double totalMicroSec;
    Tcl_Time start, stop;
    char buf[100];

    if (objc == 2) {
	count = 1;
    } else if (objc == 3) {
	result = Tcl_GetIntFromObj(interp, objv[2], &count);
	if (result != TCL_OK) {
	    return result;
	}
    } else {
	Tcl_WrongNumArgs(interp, 1, objv, "command ?count?");
	return TCL_ERROR;
    }
    
    objPtr = objv[1];
    i = count;
    Tcl_GetTime(&start);
    while (i-- > 0) {
	result = Tcl_EvalObjEx(interp, objPtr, 0);
	if (result != TCL_OK) {
	    return result;
	}
    }
    Tcl_GetTime(&stop);
    
    totalMicroSec = ( ( (double) ( stop.sec - start.sec ) ) * 1.0e6
		      + ( stop.usec - start.usec ) );
    sprintf(buf, "%.0f microseconds per iteration",
	((count <= 0) ? 0 : totalMicroSec/count));
    Tcl_ResetResult(interp);
    Tcl_AppendToObj(Tcl_GetObjResult(interp), buf, -1);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_TraceObjCmd --
 *
 *	This procedure is invoked to process the "trace" Tcl command.
 *	See the user documentation for details on what it does.
 *	
 *	Standard syntax as of Tcl 8.4 is
 *	
 *	 trace {add|info|remove} {command|variable} name ops cmd
 *
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_TraceObjCmd(dummy, interp, objc, objv)
    ClientData dummy;			/* Not used. */
    Tcl_Interp *interp;			/* Current interpreter. */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];		/* Argument objects. */
{
    int optionIndex, commandLength;
    char *name, *flagOps, *command, *p;
    size_t length;
    /* Main sub commands to 'trace' */
    static CONST char *traceOptions[] = {
	"add", "info", "remove", 
#ifndef TCL_REMOVE_OBSOLETE_TRACES
	"variable", "vdelete", "vinfo", 
#endif
	(char *) NULL
    };
    /* 'OLD' options are pre-Tcl-8.4 style */
    enum traceOptions {
	TRACE_ADD, TRACE_INFO, TRACE_REMOVE, 
#ifndef TCL_REMOVE_OBSOLETE_TRACES
	TRACE_OLD_VARIABLE, TRACE_OLD_VDELETE, TRACE_OLD_VINFO
#endif
    };

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

    if (Tcl_GetIndexFromObj(interp, objv[1], traceOptions,
		"option", 0, &optionIndex) != TCL_OK) {
	return TCL_ERROR;
    }
    switch ((enum traceOptions) optionIndex) {
	case TRACE_ADD: 
	case TRACE_REMOVE:
	case TRACE_INFO: {
	    /* 
	     * All sub commands of trace add/remove must take at least
	     * one more argument.  Beyond that we let the subcommand itself
	     * control the argument structure.
	     */
	    int typeIndex;
	    if (objc < 3) {
		Tcl_WrongNumArgs(interp, 2, objv, "type ?arg arg ...?");
		return TCL_ERROR;
	    }
	    if (Tcl_GetIndexFromObj(interp, objv[2], traceTypeOptions,
			"option", 0, &typeIndex) != TCL_OK) {
		return TCL_ERROR;
	    }
	    return (traceSubCmds[typeIndex])(interp, optionIndex, objc, objv);
	    break;
	}
#ifndef TCL_REMOVE_OBSOLETE_TRACES
        case TRACE_OLD_VARIABLE: {
	    int flags;
	    TraceVarInfo *tvarPtr;
	    if (objc != 5) {
		Tcl_WrongNumArgs(interp, 2, objv, "name ops command");
		return TCL_ERROR;
	    }

	    flags = 0;
	    flagOps = Tcl_GetString(objv[3]);
	    for (p = flagOps; *p != 0; p++) {
		if (*p == 'r') {
		    flags |= TCL_TRACE_READS;
		} else if (*p == 'w') {
		    flags |= TCL_TRACE_WRITES;
		} else if (*p == 'u') {
		    flags |= TCL_TRACE_UNSETS;
		} else if (*p == 'a') {
		    flags |= TCL_TRACE_ARRAY;
		} else {
		    goto badVarOps;
		}
	    }
	    if (flags == 0) {
		goto badVarOps;
	    }
	    flags |= TCL_TRACE_OLD_STYLE;
	    
	    command = Tcl_GetStringFromObj(objv[4], &commandLength);
	    length = (size_t) commandLength;
	    tvarPtr = (TraceVarInfo *) ckalloc((unsigned)
		    (sizeof(TraceVarInfo) - sizeof(tvarPtr->command)
			    + length + 1));
	    tvarPtr->flags = flags;
	    tvarPtr->length = length;
	    flags |= TCL_TRACE_UNSETS | TCL_TRACE_RESULT_OBJECT;
	    strcpy(tvarPtr->command, command);
	    name = Tcl_GetString(objv[2]);
	    if (Tcl_TraceVar(interp, name, flags, TraceVarProc,
		    (ClientData) tvarPtr) != TCL_OK) {
		ckfree((char *) tvarPtr);
		return TCL_ERROR;
	    }
	    break;
	}
	case TRACE_OLD_VDELETE: {
	    int flags;
	    TraceVarInfo *tvarPtr;
	    ClientData clientData;

	    if (objc != 5) {
		Tcl_WrongNumArgs(interp, 2, objv, "name ops command");
		return TCL_ERROR;
	    }

	    flags = 0;
	    flagOps = Tcl_GetString(objv[3]);
	    for (p = flagOps; *p != 0; p++) {
		if (*p == 'r') {
		    flags |= TCL_TRACE_READS;
		} else if (*p == 'w') {
		    flags |= TCL_TRACE_WRITES;
		} else if (*p == 'u') {
		    flags |= TCL_TRACE_UNSETS;
		} else if (*p == 'a') {
		    flags |= TCL_TRACE_ARRAY;
		} else {
		    goto badVarOps;
		}
	    }
	    if (flags == 0) {
		goto badVarOps;
	    }
	    flags |= TCL_TRACE_OLD_STYLE;

	    /*
	     * Search through all of our traces on this variable to
	     * see if there's one with the given command.  If so, then
	     * delete the first one that matches.
	     */

	    command = Tcl_GetStringFromObj(objv[4], &commandLength);
	    length = (size_t) commandLength;
	    clientData = 0;
	    name = Tcl_GetString(objv[2]);
	    while ((clientData = Tcl_VarTraceInfo(interp, name, 0,
		    TraceVarProc, clientData)) != 0) {
		tvarPtr = (TraceVarInfo *) clientData;
		if ((tvarPtr->length == length) && (tvarPtr->flags == flags)
			&& (strncmp(command, tvarPtr->command,
				(size_t) length) == 0)) {
		    Tcl_UntraceVar2(interp, name, NULL,
			    flags | TCL_TRACE_UNSETS | TCL_TRACE_RESULT_OBJECT,
			    TraceVarProc, clientData);
		    Tcl_EventuallyFree((ClientData) tvarPtr, TCL_DYNAMIC);
		    break;
		}
	    }
	    break;
	}
	case TRACE_OLD_VINFO: {
	    ClientData clientData;
	    char ops[5];
	    Tcl_Obj *resultListPtr, *pairObjPtr, *elemObjPtr;

	    if (objc != 3) {
		Tcl_WrongNumArgs(interp, 2, objv, "name");
		return TCL_ERROR;
	    }
	    resultListPtr = Tcl_GetObjResult(interp);
	    clientData = 0;
	    name = Tcl_GetString(objv[2]);
	    while ((clientData = Tcl_VarTraceInfo(interp, name, 0,
		    TraceVarProc, clientData)) != 0) {

		TraceVarInfo *tvarPtr = (TraceVarInfo *) clientData;

		pairObjPtr = Tcl_NewListObj(0, (Tcl_Obj **) NULL);
		p = ops;
		if (tvarPtr->flags & TCL_TRACE_READS) {
		    *p = 'r';
		    p++;
		}
		if (tvarPtr->flags & TCL_TRACE_WRITES) {
		    *p = 'w';
		    p++;
		}
		if (tvarPtr->flags & TCL_TRACE_UNSETS) {
		    *p = 'u';
		    p++;
		}
		if (tvarPtr->flags & TCL_TRACE_ARRAY) {
		    *p = 'a';
		    p++;
		}
		*p = '\0';

		/*
		 * Build a pair (2-item list) with the ops string as
		 * the first obj element and the tvarPtr->command string
		 * as the second obj element.  Append the pair (as an
		 * element) to the end of the result object list.
		 */

		elemObjPtr = Tcl_NewStringObj(ops, -1);
		Tcl_ListObjAppendElement(NULL, pairObjPtr, elemObjPtr);
		elemObjPtr = Tcl_NewStringObj(tvarPtr->command, -1);
		Tcl_ListObjAppendElement(NULL, pairObjPtr, elemObjPtr);
		Tcl_ListObjAppendElement(interp, resultListPtr, pairObjPtr);
	    }
	    Tcl_SetObjResult(interp, resultListPtr);
	    break;
	}
#endif /* TCL_REMOVE_OBSOLETE_TRACES */
    }
    return TCL_OK;

    badVarOps:
    Tcl_AppendResult(interp, "bad operations \"", flagOps,
	    "\": should be one or more of rwua", (char *) NULL);
    return TCL_ERROR;
}


/*
 *----------------------------------------------------------------------
 *
 * TclTraceExecutionObjCmd --
 *
 *	Helper function for Tcl_TraceObjCmd; implements the
 *	[trace {add|remove|info} execution ...] subcommands.
 *	See the user documentation for details on what these do.
 *
 * Results:
 *	Standard Tcl result.
 *
 * Side effects:
 *	Depends on the operation (add, remove, or info) being performed;
 *	may add or remove command traces on a command.
 *
 *----------------------------------------------------------------------
 */

int
TclTraceExecutionObjCmd(interp, optionIndex, objc, objv)
    Tcl_Interp *interp;			/* Current interpreter. */
    int optionIndex;			/* Add, info or remove */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];		/* Argument objects. */
{
    int commandLength, index;
    char *name, *command;
    size_t length;
    enum traceOptions { TRACE_ADD, TRACE_INFO, TRACE_REMOVE };
    static CONST char *opStrings[] = { "enter", "leave", 
                                 "enterstep", "leavestep", (char *) NULL };
    enum operations { TRACE_EXEC_ENTER, TRACE_EXEC_LEAVE,
                      TRACE_EXEC_ENTER_STEP, TRACE_EXEC_LEAVE_STEP };
    
    switch ((enum traceOptions) optionIndex) {
	case TRACE_ADD: 
	case TRACE_REMOVE: {
	    int flags = 0;
	    int i, listLen, result;
	    Tcl_Obj **elemPtrs;
	    if (objc != 6) {
		Tcl_WrongNumArgs(interp, 3, objv, "name opList execution");
		return TCL_ERROR;
	    }
	    /*
	     * Make sure the ops argument is a list object; get its length and
	     * a pointer to its array of element pointers.
	     */

	    result = Tcl_ListObjGetElements(interp, objv[4], &listLen,
		    &elemPtrs);
	    if (result != TCL_OK) {
		return result;
	    }
	    if (listLen == 0) {
		Tcl_SetResult(interp, "bad operation list \"\": must be "
			"one or more of enter, leave, enterstep, or leavestep", TCL_STATIC);
		return TCL_ERROR;
	    }
	    for (i = 0; i < listLen; i++) {
		if (Tcl_GetIndexFromObj(interp, elemPtrs[i], opStrings,
			"operation", TCL_EXACT, &index) != TCL_OK) {
		    return TCL_ERROR;
		}
		switch ((enum operations) index) {
		    case TRACE_EXEC_ENTER:
			flags |= TCL_TRACE_ENTER_EXEC;
			break;
		    case TRACE_EXEC_LEAVE:
			flags |= TCL_TRACE_LEAVE_EXEC;
			break;
		    case TRACE_EXEC_ENTER_STEP:
			flags |= TCL_TRACE_ENTER_DURING_EXEC;
			break;
		    case TRACE_EXEC_LEAVE_STEP:
			flags |= TCL_TRACE_LEAVE_DURING_EXEC;
			break;
		}
	    }
	    command = Tcl_GetStringFromObj(objv[5], &commandLength);
	    length = (size_t) commandLength;
	    if ((enum traceOptions) optionIndex == TRACE_ADD) {
		TraceCommandInfo *tcmdPtr;
		tcmdPtr = (TraceCommandInfo *) ckalloc((unsigned)
			(sizeof(TraceCommandInfo) - sizeof(tcmdPtr->command)
				+ length + 1));
		tcmdPtr->flags = flags;
		tcmdPtr->stepTrace = NULL;
		tcmdPtr->startLevel = 0;
		tcmdPtr->length = length;
		flags |= TCL_TRACE_DELETE;
		if (flags & (TRACE_EXEC_ENTER_STEP | TRACE_EXEC_LEAVE_STEP)) {
		    flags |= (TCL_TRACE_ENTER_EXEC | TCL_TRACE_LEAVE_EXEC);
		}
		strcpy(tcmdPtr->command, command);
		name = Tcl_GetString(objv[3]);
		if (Tcl_TraceCommand(interp, name, flags, TraceCommandProc,
			(ClientData) tcmdPtr) != TCL_OK) {
		    ckfree((char *) tcmdPtr);
		    return TCL_ERROR;
		}
	    } else {
		/*
		 * Search through all of our traces on this command to
		 * see if there's one with the given command.  If so, then
		 * delete the first one that matches.
		 */
		
		TraceCommandInfo *tcmdPtr;
		ClientData clientData;
		clientData = 0;
		name = Tcl_GetString(objv[3]);
		while ((clientData = Tcl_CommandTraceInfo(interp, name, 0,
			TraceCommandProc, clientData)) != 0) {
		    tcmdPtr = (TraceCommandInfo *) clientData;
		    /* 
		     * In checking the 'flags' field we must remove any extraneous
		     * flags which may have been temporarily added by various pieces
		     * of the trace mechanism.
		     */
		    if ((tcmdPtr->length == length)
			    && ((tcmdPtr->flags & (TCL_TRACE_ANY_EXEC | TCL_TRACE_RENAME | 
						   TCL_TRACE_DELETE)) == flags)
			    && (strncmp(command, tcmdPtr->command,
				    (size_t) length) == 0)) {
			flags |= TCL_TRACE_DELETE;
			if (flags & (TRACE_EXEC_ENTER_STEP | TRACE_EXEC_LEAVE_STEP)) {
			    flags |= (TCL_TRACE_ENTER_EXEC | TCL_TRACE_LEAVE_EXEC);
			}
			Tcl_UntraceCommand(interp, name,
				flags, TraceCommandProc, clientData);
			if (tcmdPtr->stepTrace != NULL) {
			    /* 
			     * We need to remove the interpreter-wide trace 
			     * which we created to allow 'step' traces.
			     */
			    Tcl_DeleteTrace(interp, tcmdPtr->stepTrace);
			    tcmdPtr->stepTrace = NULL;
			}
			/* Postpone deletion */
			if (tcmdPtr->flags & TCL_TRACE_EXEC_IN_PROGRESS) {
			    tcmdPtr->flags = 0;
			} else {
			    Tcl_EventuallyFree((ClientData) tcmdPtr, TCL_DYNAMIC);
			}
			break;
		    }
		}
	    }
	    break;
	}
	case TRACE_INFO: {
	    ClientData clientData;
	    Tcl_Obj *resultListPtr, *eachTraceObjPtr, *elemObjPtr;
	    if (objc != 4) {
		Tcl_WrongNumArgs(interp, 3, objv, "name");
		return TCL_ERROR;
	    }

	    resultListPtr = Tcl_GetObjResult(interp);
	    clientData = 0;
	    name = Tcl_GetString(objv[3]);
	    while ((clientData = Tcl_CommandTraceInfo(interp, name, 0,
		    TraceCommandProc, clientData)) != 0) {

		TraceCommandInfo *tcmdPtr = (TraceCommandInfo *) clientData;

		eachTraceObjPtr = Tcl_NewListObj(0, (Tcl_Obj **) NULL);

		/*
		 * Build a list with the ops list as the first obj
		 * element and the tcmdPtr->command string as the
		 * second obj element.  Append this list (as an
		 * element) to the end of the result object list.
		 */

		elemObjPtr = Tcl_NewListObj(0, (Tcl_Obj **) NULL);
		if (tcmdPtr->flags & TCL_TRACE_ENTER_EXEC) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("enter",6));
		}
		if (tcmdPtr->flags & TCL_TRACE_LEAVE_EXEC) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("leave",5));
		}
		if (tcmdPtr->flags & TCL_TRACE_ENTER_DURING_EXEC) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("enterstep",9));
		}
		if (tcmdPtr->flags & TCL_TRACE_LEAVE_DURING_EXEC) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("leavestep",10));
		}
		Tcl_ListObjAppendElement(NULL, eachTraceObjPtr, elemObjPtr);

		elemObjPtr = Tcl_NewStringObj(tcmdPtr->command, -1);
		Tcl_ListObjAppendElement(NULL, eachTraceObjPtr, elemObjPtr);
		Tcl_ListObjAppendElement(interp, resultListPtr,
			eachTraceObjPtr);
	    }
	    Tcl_SetObjResult(interp, resultListPtr);
	    break;
	}
    }
    return TCL_OK;
}


/*
 *----------------------------------------------------------------------
 *
 * TclTraceCommandObjCmd --
 *
 *	Helper function for Tcl_TraceObjCmd; implements the
 *	[trace {add|info|remove} command ...] subcommands.
 *	See the user documentation for details on what these do.
 *
 * Results:
 *	Standard Tcl result.
 *
 * Side effects:
 *	Depends on the operation (add, remove, or info) being performed;
 *	may add or remove command traces on a command.
 *
 *----------------------------------------------------------------------
 */

int
TclTraceCommandObjCmd(interp, optionIndex, objc, objv)
    Tcl_Interp *interp;			/* Current interpreter. */
    int optionIndex;			/* Add, info or remove */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];		/* Argument objects. */
{
    int commandLength, index;
    char *name, *command;
    size_t length;
    enum traceOptions { TRACE_ADD, TRACE_INFO, TRACE_REMOVE };
    static CONST char *opStrings[] = { "delete", "rename", (char *) NULL };
    enum operations { TRACE_CMD_DELETE, TRACE_CMD_RENAME };
    
    switch ((enum traceOptions) optionIndex) {
	case TRACE_ADD: 
	case TRACE_REMOVE: {
	    int flags = 0;
	    int i, listLen, result;
	    Tcl_Obj **elemPtrs;
	    if (objc != 6) {
		Tcl_WrongNumArgs(interp, 3, objv, "name opList command");
		return TCL_ERROR;
	    }
	    /*
	     * Make sure the ops argument is a list object; get its length and
	     * a pointer to its array of element pointers.
	     */

	    result = Tcl_ListObjGetElements(interp, objv[4], &listLen,
		    &elemPtrs);
	    if (result != TCL_OK) {
		return result;
	    }
	    if (listLen == 0) {
		Tcl_SetResult(interp, "bad operation list \"\": must be "
			"one or more of delete or rename", TCL_STATIC);
		return TCL_ERROR;
	    }
	    for (i = 0; i < listLen; i++) {
		if (Tcl_GetIndexFromObj(interp, elemPtrs[i], opStrings,
			"operation", TCL_EXACT, &index) != TCL_OK) {
		    return TCL_ERROR;
		}
		switch ((enum operations) index) {
		    case TRACE_CMD_RENAME:
			flags |= TCL_TRACE_RENAME;
			break;
		    case TRACE_CMD_DELETE:
			flags |= TCL_TRACE_DELETE;
			break;
		}
	    }
	    command = Tcl_GetStringFromObj(objv[5], &commandLength);
	    length = (size_t) commandLength;
	    if ((enum traceOptions) optionIndex == TRACE_ADD) {
		TraceCommandInfo *tcmdPtr;
		tcmdPtr = (TraceCommandInfo *) ckalloc((unsigned)
			(sizeof(TraceCommandInfo) - sizeof(tcmdPtr->command)
				+ length + 1));
		tcmdPtr->flags = flags;
		tcmdPtr->stepTrace = NULL;
		tcmdPtr->startLevel = 0;
		tcmdPtr->length = length;
		flags |= TCL_TRACE_DELETE;
		strcpy(tcmdPtr->command, command);
		name = Tcl_GetString(objv[3]);
		if (Tcl_TraceCommand(interp, name, flags, TraceCommandProc,
			(ClientData) tcmdPtr) != TCL_OK) {
		    ckfree((char *) tcmdPtr);
		    return TCL_ERROR;
		}
	    } else {
		/*
		 * Search through all of our traces on this command to
		 * see if there's one with the given command.  If so, then
		 * delete the first one that matches.
		 */
		
		TraceCommandInfo *tcmdPtr;
		ClientData clientData;
		clientData = 0;
		name = Tcl_GetString(objv[3]);
		while ((clientData = Tcl_CommandTraceInfo(interp, name, 0,
			TraceCommandProc, clientData)) != 0) {
		    tcmdPtr = (TraceCommandInfo *) clientData;
		    if ((tcmdPtr->length == length)
			    && (tcmdPtr->flags == flags)
			    && (strncmp(command, tcmdPtr->command,
				    (size_t) length) == 0)) {
			Tcl_UntraceCommand(interp, name,
				flags | TCL_TRACE_DELETE,
				TraceCommandProc, clientData);
			ckfree((char *) tcmdPtr);
			break;
		    }
		}
	    }
	    break;
	}
	case TRACE_INFO: {
	    ClientData clientData;
	    Tcl_Obj *resultListPtr, *eachTraceObjPtr, *elemObjPtr;
	    if (objc != 4) {
		Tcl_WrongNumArgs(interp, 3, objv, "name");
		return TCL_ERROR;
	    }

	    resultListPtr = Tcl_GetObjResult(interp);
	    clientData = 0;
	    name = Tcl_GetString(objv[3]);
	    while ((clientData = Tcl_CommandTraceInfo(interp, name, 0,
		    TraceCommandProc, clientData)) != 0) {

		TraceCommandInfo *tcmdPtr = (TraceCommandInfo *) clientData;

		eachTraceObjPtr = Tcl_NewListObj(0, (Tcl_Obj **) NULL);

		/*
		 * Build a list with the ops list as
		 * the first obj element and the tcmdPtr->command string
		 * as the second obj element.  Append this list (as an
		 * element) to the end of the result object list.
		 */

		elemObjPtr = Tcl_NewListObj(0, (Tcl_Obj **) NULL);
		if (tcmdPtr->flags & TCL_TRACE_RENAME) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("rename",6));
		}
		if (tcmdPtr->flags & TCL_TRACE_DELETE) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("delete",6));
		}
		Tcl_ListObjAppendElement(NULL, eachTraceObjPtr, elemObjPtr);

		elemObjPtr = Tcl_NewStringObj(tcmdPtr->command, -1);
		Tcl_ListObjAppendElement(NULL, eachTraceObjPtr, elemObjPtr);
		Tcl_ListObjAppendElement(interp, resultListPtr,
			eachTraceObjPtr);
	    }
	    Tcl_SetObjResult(interp, resultListPtr);
	    break;
	}
    }
    return TCL_OK;
}


/*
 *----------------------------------------------------------------------
 *
 * TclTraceVariableObjCmd --
 *
 *	Helper function for Tcl_TraceObjCmd; implements the
 *	[trace {add|info|remove} variable ...] subcommands.
 *	See the user documentation for details on what these do.
 *
 * Results:
 *	Standard Tcl result.
 *
 * Side effects:
 *	Depends on the operation (add, remove, or info) being performed;
 *	may add or remove variable traces on a variable.
 *
 *----------------------------------------------------------------------
 */

int
TclTraceVariableObjCmd(interp, optionIndex, objc, objv)
    Tcl_Interp *interp;			/* Current interpreter. */
    int optionIndex;			/* Add, info or remove */
    int objc;				/* Number of arguments. */
    Tcl_Obj *CONST objv[];		/* Argument objects. */
{
    int commandLength, index;
    char *name, *command;
    size_t length;
    enum traceOptions { TRACE_ADD, TRACE_INFO, TRACE_REMOVE };
    static CONST char *opStrings[] = { "array", "read", "unset", "write",
				     (char *) NULL };
    enum operations { TRACE_VAR_ARRAY, TRACE_VAR_READ, TRACE_VAR_UNSET,
			  TRACE_VAR_WRITE };
        
    switch ((enum traceOptions) optionIndex) {
	case TRACE_ADD: 
	case TRACE_REMOVE: {
	    int flags = 0;
	    int i, listLen, result;
	    Tcl_Obj **elemPtrs;
	    if (objc != 6) {
		Tcl_WrongNumArgs(interp, 3, objv, "name opList command");
		return TCL_ERROR;
	    }
	    /*
	     * Make sure the ops argument is a list object; get its length and
	     * a pointer to its array of element pointers.
	     */

	    result = Tcl_ListObjGetElements(interp, objv[4], &listLen,
		    &elemPtrs);
	    if (result != TCL_OK) {
		return result;
	    }
	    if (listLen == 0) {
		Tcl_SetResult(interp, "bad operation list \"\": must be "
			"one or more of array, read, unset, or write",
			TCL_STATIC);
		return TCL_ERROR;
	    }
	    for (i = 0; i < listLen ; i++) {
		if (Tcl_GetIndexFromObj(interp, elemPtrs[i], opStrings,
			"operation", TCL_EXACT, &index) != TCL_OK) {
		    return TCL_ERROR;
		}
		switch ((enum operations) index) {
		    case TRACE_VAR_ARRAY:
			flags |= TCL_TRACE_ARRAY;
			break;
		    case TRACE_VAR_READ:
			flags |= TCL_TRACE_READS;
			break;
		    case TRACE_VAR_UNSET:
			flags |= TCL_TRACE_UNSETS;
			break;
		    case TRACE_VAR_WRITE:
			flags |= TCL_TRACE_WRITES;
			break;
		}
	    }
	    command = Tcl_GetStringFromObj(objv[5], &commandLength);
	    length = (size_t) commandLength;
	    if ((enum traceOptions) optionIndex == TRACE_ADD) {
		TraceVarInfo *tvarPtr;
		tvarPtr = (TraceVarInfo *) ckalloc((unsigned)
			(sizeof(TraceVarInfo) - sizeof(tvarPtr->command)
				+ length + 1));
		tvarPtr->flags = flags;
		tvarPtr->length = length;
		flags |= TCL_TRACE_UNSETS | TCL_TRACE_RESULT_OBJECT;
		strcpy(tvarPtr->command, command);
		name = Tcl_GetString(objv[3]);
		if (Tcl_TraceVar(interp, name, flags, TraceVarProc,
			(ClientData) tvarPtr) != TCL_OK) {
		    ckfree((char *) tvarPtr);
		    return TCL_ERROR;
		}
	    } else {
		/*
		 * Search through all of our traces on this variable to
		 * see if there's one with the given command.  If so, then
		 * delete the first one that matches.
		 */
		
		TraceVarInfo *tvarPtr;
		ClientData clientData = 0;
		name = Tcl_GetString(objv[3]);
		while ((clientData = Tcl_VarTraceInfo(interp, name, 0,
			TraceVarProc, clientData)) != 0) {
		    tvarPtr = (TraceVarInfo *) clientData;
		    if ((tvarPtr->length == length)
			    && (tvarPtr->flags == flags)
			    && (strncmp(command, tvarPtr->command,
				    (size_t) length) == 0)) {
			Tcl_UntraceVar2(interp, name, NULL,
				flags | TCL_TRACE_UNSETS | TCL_TRACE_RESULT_OBJECT,
				TraceVarProc, clientData);
			Tcl_EventuallyFree((ClientData) tvarPtr, TCL_DYNAMIC);
			break;
		    }
		}
	    }
	    break;
	}
	case TRACE_INFO: {
	    ClientData clientData;
	    Tcl_Obj *resultListPtr, *eachTraceObjPtr, *elemObjPtr;
	    if (objc != 4) {
		Tcl_WrongNumArgs(interp, 3, objv, "name");
		return TCL_ERROR;
	    }

	    resultListPtr = Tcl_GetObjResult(interp);
	    clientData = 0;
	    name = Tcl_GetString(objv[3]);
	    while ((clientData = Tcl_VarTraceInfo(interp, name, 0,
		    TraceVarProc, clientData)) != 0) {

		TraceVarInfo *tvarPtr = (TraceVarInfo *) clientData;

		eachTraceObjPtr = Tcl_NewListObj(0, (Tcl_Obj **) NULL);
		/*
		 * Build a list with the ops list as
		 * the first obj element and the tcmdPtr->command string
		 * as the second obj element.  Append this list (as an
		 * element) to the end of the result object list.
		 */

		elemObjPtr = Tcl_NewListObj(0, (Tcl_Obj **) NULL);
		if (tvarPtr->flags & TCL_TRACE_ARRAY) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("array", 5));
		}
		if (tvarPtr->flags & TCL_TRACE_READS) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("read", 4));
		}
		if (tvarPtr->flags & TCL_TRACE_WRITES) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("write", 5));
		}
		if (tvarPtr->flags & TCL_TRACE_UNSETS) {
		    Tcl_ListObjAppendElement(NULL, elemObjPtr,
			    Tcl_NewStringObj("unset", 5));
		}
		Tcl_ListObjAppendElement(NULL, eachTraceObjPtr, elemObjPtr);

		elemObjPtr = Tcl_NewStringObj(tvarPtr->command, -1);
		Tcl_ListObjAppendElement(NULL, eachTraceObjPtr, elemObjPtr);
		Tcl_ListObjAppendElement(interp, resultListPtr,
			eachTraceObjPtr);
	    }
	    Tcl_SetObjResult(interp, resultListPtr);
	    break;
	}
    }
    return TCL_OK;
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_CommandTraceInfo --
 *
 *	Return the clientData value associated with a trace on a
 *	command.  This procedure can also be used to step through
 *	all of the traces on a particular command that have the
 *	same trace procedure.
 *
 * Results:
 *	The return value is the clientData value associated with
 *	a trace on the given command.  Information will only be
 *	returned for a trace with proc as trace procedure.  If
 *	the clientData argument is NULL then the first such trace is
 *	returned;  otherwise, the next relevant one after the one
 *	given by clientData will be returned.  If the command
 *	doesn't exist, or if there are no (more) traces for it,
 *	then NULL is returned.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

ClientData
Tcl_CommandTraceInfo(interp, cmdName, flags, proc, prevClientData)
    Tcl_Interp *interp;		/* Interpreter containing command. */
    CONST char *cmdName;	/* Name of command. */
    int flags;			/* OR-ed combo or TCL_GLOBAL_ONLY,
				 * TCL_NAMESPACE_ONLY (can be 0). */
    Tcl_CommandTraceProc *proc;	/* Procedure assocated with trace. */
    ClientData prevClientData;	/* If non-NULL, gives last value returned
				 * by this procedure, so this call will
				 * return the next trace after that one.
				 * If NULL, this call will return the
				 * first trace. */
{
    Command *cmdPtr;
    register CommandTrace *tracePtr;

    cmdPtr = (Command*)Tcl_FindCommand(interp, cmdName, 
		NULL, TCL_LEAVE_ERR_MSG);
    if (cmdPtr == NULL) {
	return NULL;
    }

    /*
     * Find the relevant trace, if any, and return its clientData.
     */

    tracePtr = cmdPtr->tracePtr;
    if (prevClientData != NULL) {
	for ( ;  tracePtr != NULL;  tracePtr = tracePtr->nextPtr) {
	    if ((tracePtr->clientData == prevClientData)
		    && (tracePtr->traceProc == proc)) {
		tracePtr = tracePtr->nextPtr;
		break;
	    }
	}
    }
    for ( ;  tracePtr != NULL;  tracePtr = tracePtr->nextPtr) {
	if (tracePtr->traceProc == proc) {
	    return tracePtr->clientData;
	}
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_TraceCommand --
 *
 *	Arrange for rename/deletes to a command to cause a
 *	procedure to be invoked, which can monitor the operations.
 *	
 *	Also optionally arrange for execution of that command
 *	to cause a procedure to be invoked.
 *
 * Results:
 *	A standard Tcl return value.
 *
 * Side effects:
 *	A trace is set up on the command given by cmdName, such that
 *	future changes to the command will be intermediated by
 *	proc.  See the manual entry for complete details on the calling
 *	sequence for proc.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_TraceCommand(interp, cmdName, flags, proc, clientData)
    Tcl_Interp *interp;		/* Interpreter in which command is
				 * to be traced. */
    CONST char *cmdName;	/* Name of command. */
    int flags;			/* OR-ed collection of bits, including any
				 * of TCL_TRACE_RENAME, TCL_TRACE_DELETE,
				 * and any of the TRACE_*_EXEC flags */
    Tcl_CommandTraceProc *proc;	/* Procedure to call when specified ops are
				 * invoked upon varName. */
    ClientData clientData;	/* Arbitrary argument to pass to proc. */
{
    Command *cmdPtr;
    register CommandTrace *tracePtr;

    cmdPtr = (Command*)Tcl_FindCommand(interp, cmdName,
	    NULL, TCL_LEAVE_ERR_MSG);
    if (cmdPtr == NULL) {
	return TCL_ERROR;
    }

    /*
     * Set up trace information.
     */

    tracePtr = (CommandTrace *) ckalloc(sizeof(CommandTrace));
    tracePtr->traceProc = proc;
    tracePtr->clientData = clientData;
    tracePtr->flags = flags & (TCL_TRACE_RENAME | TCL_TRACE_DELETE
			       | TCL_TRACE_ANY_EXEC);
    tracePtr->nextPtr = cmdPtr->tracePtr;
    cmdPtr->tracePtr = tracePtr;
    if (tracePtr->flags & TCL_TRACE_ANY_EXEC) {
        cmdPtr->flags |= CMD_HAS_EXEC_TRACES;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_UntraceCommand --
 *
 *	Remove a previously-created trace for a command.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	If there exists a trace for the command given by cmdName
 *	with the given flags, proc, and clientData, then that trace
 *	is removed.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_UntraceCommand(interp, cmdName, flags, proc, clientData)
    Tcl_Interp *interp;		/* Interpreter containing command. */
    CONST char *cmdName;	/* Name of command. */
    int flags;			/* OR-ed collection of bits, including any
				 * of TCL_TRACE_RENAME, TCL_TRACE_DELETE,
				 * and any of the TRACE_*_EXEC flags */
    Tcl_CommandTraceProc *proc;	/* Procedure assocated with trace. */
    ClientData clientData;	/* Arbitrary argument to pass to proc. */
{
    register CommandTrace *tracePtr;
    CommandTrace *prevPtr;
    Command *cmdPtr;
    Interp *iPtr = (Interp *) interp;
    ActiveCommandTrace *activePtr;
    int hasExecTraces = 0;
    
    cmdPtr = (Command*)Tcl_FindCommand(interp, cmdName, 
		NULL, TCL_LEAVE_ERR_MSG);
    if (cmdPtr == NULL) {
	return;
    }

    flags &= (TCL_TRACE_RENAME | TCL_TRACE_DELETE | TCL_TRACE_ANY_EXEC);

    for (tracePtr = cmdPtr->tracePtr, prevPtr = NULL;  ;
	 prevPtr = tracePtr, tracePtr = tracePtr->nextPtr) {
	if (tracePtr == NULL) {
	    return;
	}
	if ((tracePtr->traceProc == proc) && ((tracePtr->flags & (TCL_TRACE_RENAME | TCL_TRACE_DELETE | TCL_TRACE_ANY_EXEC)) == flags)
		&& (tracePtr->clientData == clientData)) {
	    if (tracePtr->flags & TCL_TRACE_ANY_EXEC) {
		hasExecTraces = 1;
	    }
	    break;
	}
    }
    
    /*
     * The code below makes it possible to delete traces while traces
     * are active: it makes sure that the deleted trace won't be
     * processed by CallCommandTraces.
     */

    for (activePtr = iPtr->activeCmdTracePtr;  activePtr != NULL;
	 activePtr = activePtr->nextPtr) {
	if (activePtr->nextTracePtr == tracePtr) {
	    activePtr->nextTracePtr = tracePtr->nextPtr;
	}
    }
    if (prevPtr == NULL) {
	cmdPtr->tracePtr = tracePtr->nextPtr;
    } else {
	prevPtr->nextPtr = tracePtr->nextPtr;
    }
    tracePtr->flags = 0;
    Tcl_EventuallyFree((int*)tracePtr, TCL_DYNAMIC);
    
    if (hasExecTraces) {
	for (tracePtr = cmdPtr->tracePtr, prevPtr = NULL; tracePtr != NULL ;
	     prevPtr = tracePtr, tracePtr = tracePtr->nextPtr) {
	    if (tracePtr->flags & TCL_TRACE_ANY_EXEC) {
	        return;
	    }
	}
	/* 
	 * None of the remaining traces on this command are execution
	 * traces.  We therefore remove this flag:
	 */
	cmdPtr->flags &= ~CMD_HAS_EXEC_TRACES;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TraceCommandProc --
 *
 *	This procedure is called to handle command changes that have
 *	been traced using the "trace" command, when using the 
 *	'rename' or 'delete' options.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Depends on the command associated with the trace.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
static void
TraceCommandProc(clientData, interp, oldName, newName, flags)
    ClientData clientData;	/* Information about the command trace. */
    Tcl_Interp *interp;		/* Interpreter containing command. */
    CONST char *oldName;	/* Name of command being changed. */
    CONST char *newName;	/* New name of command.  Empty string
                  		 * or NULL means command is being deleted
                  		 * (renamed to ""). */
    int flags;			/* OR-ed bits giving operation and other
				 * information. */
{
    Tcl_SavedResult state;
    TraceCommandInfo *tcmdPtr = (TraceCommandInfo *) clientData;
    int code;
    Tcl_DString cmd;
    
    Tcl_Preserve((ClientData) tcmdPtr);
    
    if ((tcmdPtr->flags & flags) && !(flags & TCL_INTERP_DESTROYED)) {
	/*
	 * Generate a command to execute by appending list elements
	 * for the old and new command name and the operation.
	 */

	Tcl_DStringInit(&cmd);
	Tcl_DStringAppend(&cmd, tcmdPtr->command, (int) tcmdPtr->length);
	Tcl_DStringAppendElement(&cmd, oldName);
	Tcl_DStringAppendElement(&cmd, (newName ? newName : ""));
	if (flags & TCL_TRACE_RENAME) {
	    Tcl_DStringAppend(&cmd, " rename", 7);
	} else if (flags & TCL_TRACE_DELETE) {
	    Tcl_DStringAppend(&cmd, " delete", 7);
	}

	/*
	 * Execute the command.  Save the interp's result used for
	 * the command. We discard any object result the command returns.
	 *
	 * Add the TCL_TRACE_DESTROYED flag to tcmdPtr to indicate to
	 * other areas that this will be destroyed by us, otherwise a
	 * double-free might occur depending on what the eval does.
	 */

	Tcl_SaveResult(interp, &state);
	if (flags & TCL_TRACE_DESTROYED) {
	    tcmdPtr->flags |= TCL_TRACE_DESTROYED;
	}

	code = Tcl_EvalEx(interp, Tcl_DStringValue(&cmd),
		Tcl_DStringLength(&cmd), 0);
	if (code != TCL_OK) {	     
	    /* We ignore errors in these traced commands */
	}

	Tcl_RestoreResult(interp, &state);

	Tcl_DStringFree(&cmd);
    }
    /*
     * We delete when the trace was destroyed or if this is a delete trace,
     * because command deletes are unconditional, so the trace must go away.
     */
    if (flags & (TCL_TRACE_DESTROYED | TCL_TRACE_DELETE)) {
	if (tcmdPtr->stepTrace != NULL) {
	    Tcl_DeleteTrace(interp, tcmdPtr->stepTrace);
	    tcmdPtr->stepTrace = NULL;
	}
	/* Postpone deletion, until exec trace returns */
	if (tcmdPtr->flags & TCL_TRACE_EXEC_IN_PROGRESS) {
	    tcmdPtr->flags = 0;
	} else {
	    Tcl_EventuallyFree((ClientData) tcmdPtr, TCL_DYNAMIC);
	}
    }
    Tcl_Release((ClientData) tcmdPtr);
    return;
}

/*
 *----------------------------------------------------------------------
 *
 * TclCheckExecutionTraces --
 *
 *	Checks on all current command execution traces, and invokes
 *	procedures which have been registered.  This procedure can be
 *	used by other code which performs execution to unify the
 *	tracing system, so that execution traces will function for that
 *	other code.
 *	
 *	For instance extensions like [incr Tcl] which use their
 *	own execution technique can make use of Tcl's tracing.
 *	
 *	This procedure is called by 'TclEvalObjvInternal'
 *
 * Results:
 *      The return value is a standard Tcl completion code such as
 *      TCL_OK or TCL_ERROR, etc.
 *
 * Side effects:
 *	Those side effects made by any trace procedures called.
 *
 *----------------------------------------------------------------------
 */
int 
TclCheckExecutionTraces(interp, command, numChars, cmdPtr, code, traceFlags, objc, objv)
    Tcl_Interp *interp;		/* The current interpreter. */
    CONST char *command;        /* Pointer to beginning of the current 
				 * command string. */
    int numChars;               /* The number of characters in 'command' 
				 * which are part of the command string. */
    Command *cmdPtr;		/* Points to command's Command struct. */
    int code;                   /* The current result code. */
    int traceFlags;             /* Current tracing situation. */
    int objc;			/* Number of arguments for the command. */
    Tcl_Obj *CONST objv[];	/* Pointers to Tcl_Obj of each argument. */
{
    Interp *iPtr = (Interp *) interp;
    CommandTrace *tracePtr, *lastTracePtr;
    ActiveCommandTrace active;
    int curLevel;
    int traceCode = TCL_OK;
    TraceCommandInfo* tcmdPtr;
    
    if (command == NULL || cmdPtr->tracePtr == NULL) {
	return(traceCode);
    }
    
    curLevel = ((iPtr->varFramePtr == NULL) ? 0 : iPtr->varFramePtr->level);
    
    active.nextPtr = iPtr->activeCmdTracePtr;
    iPtr->activeCmdTracePtr = &active;

    active.cmdPtr = cmdPtr;
    lastTracePtr = NULL;
    for ( tracePtr = cmdPtr->tracePtr;
          (traceCode == TCL_OK) && (tracePtr != NULL);
	  tracePtr = active.nextTracePtr) {
        if (traceFlags & TCL_TRACE_LEAVE_EXEC) {
            /* execute the trace command in order of creation for "leave" */
	    active.nextTracePtr = NULL;
            tracePtr = cmdPtr->tracePtr;
            while (tracePtr->nextPtr != lastTracePtr) {
	        active.nextTracePtr = tracePtr;
	        tracePtr = tracePtr->nextPtr;
            }
        } else {
	    active.nextTracePtr = tracePtr->nextPtr;
        }
	tcmdPtr = (TraceCommandInfo*)tracePtr->clientData;
	if (tcmdPtr->flags != 0) {
            tcmdPtr->curFlags = traceFlags | TCL_TRACE_EXEC_DIRECT;
            tcmdPtr->curCode  = code;
	    traceCode = TraceExecutionProc((ClientData)tcmdPtr, interp, 
	          curLevel, command, (Tcl_Command)cmdPtr, objc, objv);
	}
        lastTracePtr = tracePtr;
    }
    iPtr->activeCmdTracePtr = active.nextPtr;
    return(traceCode);
}

/*
 *----------------------------------------------------------------------
 *
 * TclCheckInterpTraces --
 *
 *	Checks on all current traces, and invokes procedures which
 *	have been registered.  This procedure can be used by other
 *	code which performs execution to unify the tracing system.
 *	For instance extensions like [incr Tcl] which use their
 *	own execution technique can make use of Tcl's tracing.
 *	
 *	This procedure is called by 'TclEvalObjvInternal'
 *
 * Results:
 *      The return value is a standard Tcl completion code such as
 *      TCL_OK or TCL_ERROR, etc.
 *
 * Side effects:
 *	Those side effects made by any trace procedures called.
 *
 *----------------------------------------------------------------------
 */
int 
TclCheckInterpTraces(interp, command, numChars, cmdPtr, code, traceFlags, objc, objv)
    Tcl_Interp *interp;		/* The current interpreter. */
    CONST char *command;        /* Pointer to beginning of the current 
				 * command string. */
    int numChars;               /* The number of characters in 'command' 
				 * which are part of the command string. */
    Command *cmdPtr;		/* Points to command's Command struct. */
    int code;                   /* The current result code. */
    int traceFlags;             /* Current tracing situation. */
    int objc;			/* Number of arguments for the command. */
    Tcl_Obj *CONST objv[];	/* Pointers to Tcl_Obj of each argument. */
{
    Interp *iPtr = (Interp *) interp;
    Trace *tracePtr, *lastTracePtr;
    ActiveInterpTrace active;
    int curLevel;
    int traceCode = TCL_OK;
    TraceCommandInfo* tcmdPtr;
    
    if (command == NULL || iPtr->tracePtr == NULL ||
           (iPtr->flags & INTERP_TRACE_IN_PROGRESS)) {
	return(traceCode);
    }
    
    curLevel = ((iPtr->varFramePtr == NULL) ? 0 : iPtr->varFramePtr->level);
    
    active.nextPtr = iPtr->activeInterpTracePtr;
    iPtr->activeInterpTracePtr = &active;

    lastTracePtr = NULL;
    for ( tracePtr = iPtr->tracePtr;
          (traceCode == TCL_OK) && (tracePtr != NULL);
	  tracePtr = active.nextTracePtr) {
        if (traceFlags & TCL_TRACE_ENTER_EXEC) {
            /* execute the trace command in reverse order of creation
             * for "enterstep" operation. The order is changed for
             * ""enterstep" instead of for "leavestep as was done in 
             * TclCheckExecutionTraces because for step traces,
             * Tcl_CreateObjTrace creates one more linked list of traces
             * which results in one more reversal of trace invocation.
             */
	    active.nextTracePtr = NULL;
            tracePtr = iPtr->tracePtr;
            while (tracePtr->nextPtr != lastTracePtr) {
	        active.nextTracePtr = tracePtr;
	        tracePtr = tracePtr->nextPtr;
            }
        } else {
	    active.nextTracePtr = tracePtr->nextPtr;
        }
	if (tracePtr->level > 0 && curLevel > tracePtr->level) {
	    continue;
	}
	if (!(tracePtr->flags & TCL_TRACE_EXEC_IN_PROGRESS)) {
	    tracePtr->flags |= TCL_TRACE_EXEC_IN_PROGRESS;
	    if ((tracePtr->flags != TCL_TRACE_EXEC_IN_PROGRESS) &&
		((tracePtr->flags & traceFlags) != 0)) {
	            tcmdPtr = (TraceCommandInfo*)tracePtr->clientData;
                    tcmdPtr->curFlags = traceFlags;
                    tcmdPtr->curCode  = code;
		    traceCode = (tracePtr->proc)((ClientData)tcmdPtr, 
                                                (Tcl_Interp*)interp,
                                                curLevel, command,
					        (Tcl_Command)cmdPtr,
                                                objc, objv);
	    } else {
		if (traceFlags & TCL_TRACE_ENTER_EXEC) {
		    /* 
		     * Old-style interpreter-wide traces only trigger
		     * before the command is executed.
		     */
		    traceCode = CallTraceProcedure(interp, tracePtr, cmdPtr,
				       command, numChars, objc, objv);
		}
	    }
	    tracePtr->flags &= ~TCL_TRACE_EXEC_IN_PROGRESS;
	}
        lastTracePtr = tracePtr;
    }
    iPtr->activeInterpTracePtr = active.nextPtr;
    return(traceCode);
}

/*
 *----------------------------------------------------------------------
 *
 * CallTraceProcedure --
 *
 *	Invokes a trace procedure registered with an interpreter. These
 *	procedures trace command execution. Currently this trace procedure
 *	is called with the address of the string-based Tcl_CmdProc for the
 *	command, not the Tcl_ObjCmdProc.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Those side effects made by the trace procedure.
 *
 *----------------------------------------------------------------------
 */

static int
CallTraceProcedure(interp, tracePtr, cmdPtr, command, numChars, objc, objv)
    Tcl_Interp *interp;		/* The current interpreter. */
    register Trace *tracePtr;	/* Describes the trace procedure to call. */
    Command *cmdPtr;		/* Points to command's Command struct. */
    CONST char *command;	/* Points to the first character of the
				 * command's source before substitutions. */
    int numChars;		/* The number of characters in the
				 * command's source. */
    register int objc;		/* Number of arguments for the command. */
    Tcl_Obj *CONST objv[];	/* Pointers to Tcl_Obj of each argument. */
{
    Interp *iPtr = (Interp *) interp;
    char *commandCopy;
    int traceCode;

   /*
     * Copy the command characters into a new string.
     */

    commandCopy = (char *) ckalloc((unsigned) (numChars + 1));
    memcpy((VOID *) commandCopy, (VOID *) command, (size_t) numChars);
    commandCopy[numChars] = '\0';
    
    /*
     * Call the trace procedure then free allocated storage.
     */
    
    traceCode = (tracePtr->proc)( tracePtr->clientData, (Tcl_Interp*) iPtr,
                              iPtr->numLevels, commandCopy,
                              (Tcl_Command) cmdPtr, objc, objv );

    ckfree((char *) commandCopy);
    return(traceCode);
}

/*
 *----------------------------------------------------------------------
 *
 * TraceExecutionProc --
 *
 *	This procedure is invoked whenever code relevant to a
 *	'trace execution' command is executed.  It is called in one
 *	of two ways in Tcl's core:
 *	
 *	(i) by the TclCheckExecutionTraces, when an execution trace has been
 *	triggered.
 *	(ii) by TclCheckInterpTraces, when a prior execution trace has
 *	created a trace of the internals of a procedure, passing in
 *	this procedure as the one to be called.
 *
 * Results:
 *      The return value is a standard Tcl completion code such as
 *      TCL_OK or TCL_ERROR, etc.
 *
 * Side effects:
 *	May invoke an arbitrary Tcl procedure, and may create or
 *	delete an interpreter-wide trace.
 *
 *----------------------------------------------------------------------
 */
int 
TraceExecutionProc(ClientData clientData, Tcl_Interp *interp, 
	      int level, CONST char* command, Tcl_Command cmdInfo,
	      int objc, struct Tcl_Obj *CONST objv[]) {
    int call = 0;
    Interp *iPtr = (Interp *) interp;
    TraceCommandInfo* tcmdPtr = (TraceCommandInfo*)clientData;
    int flags = tcmdPtr->curFlags;
    int code  = tcmdPtr->curCode;
    int traceCode  = TCL_OK;
    
    if (tcmdPtr->flags & TCL_TRACE_EXEC_IN_PROGRESS) {
	/* 
	 * Inside any kind of execution trace callback, we do
	 * not allow any further execution trace callbacks to
	 * be called for the same trace.
	 */
	return(traceCode);
    }
    
    if (!(flags & TCL_INTERP_DESTROYED)) {
	/*
	 * Check whether the current call is going to eval arbitrary
	 * Tcl code with a generated trace, or whether we are only
	 * going to setup interpreter-wide traces to implement the
	 * 'step' traces.  This latter situation can happen if
	 * we create a command trace without either before or after
	 * operations, but with either of the step operations.
	 */
	if (flags & TCL_TRACE_EXEC_DIRECT) {
	    call = flags & tcmdPtr->flags & (TCL_TRACE_ENTER_EXEC | TCL_TRACE_LEAVE_EXEC);
	} else {
	    call = 1;
	}
	/*
	 * First, if we have returned back to the level at which we
	 * created an interpreter trace, we remove it
	 */
	if (flags & TCL_TRACE_LEAVE_EXEC) {
	    if ((tcmdPtr->stepTrace != NULL) && (level == tcmdPtr->startLevel)) {
		Tcl_DeleteTrace(interp, tcmdPtr->stepTrace);
		tcmdPtr->stepTrace = NULL;
	    }
	    
	}
	
	/*
	 * Second, create the tcl callback, if required.
	 */
	if (call) {
	    Tcl_SavedResult state;
	    Tcl_DString cmd;
	    Tcl_DString sub;
	    int i;

	    Tcl_DStringInit(&cmd);
	    Tcl_DStringAppend(&cmd, tcmdPtr->command, (int)tcmdPtr->length);
	    /* Append command with arguments */
	    Tcl_DStringInit(&sub);
	    for (i = 0; i < objc; i++) {
	        char* str;
	        int len;
	        str = Tcl_GetStringFromObj(objv[i],&len);
	        Tcl_DStringAppendElement(&sub, str);
	    }
	    Tcl_DStringAppendElement(&cmd, Tcl_DStringValue(&sub));
	    Tcl_DStringFree(&sub);

	    if (flags & TCL_TRACE_ENTER_EXEC) {
		/* Append trace operation */
		if (flags & TCL_TRACE_EXEC_DIRECT) {
		    Tcl_DStringAppendElement(&cmd, "enter");
		} else {
		    Tcl_DStringAppendElement(&cmd, "enterstep");
		}
	    } else if (flags & TCL_TRACE_LEAVE_EXEC) {
		Tcl_Obj* resultCode;
		char* resultCodeStr;

		/* Append result code */
		resultCode = Tcl_NewIntObj(code);
		resultCodeStr = Tcl_GetString(resultCode);
		Tcl_DStringAppendElement(&cmd, resultCodeStr);
		Tcl_DecrRefCount(resultCode);
		
		/* Append result string */
		Tcl_DStringAppendElement(&cmd, Tcl_GetStringResult(interp));
		/* Append trace operation */
		if (flags & TCL_TRACE_EXEC_DIRECT) {
		    Tcl_DStringAppendElement(&cmd, "leave");
		} else {
		    Tcl_DStringAppendElement(&cmd, "leavestep");
		}
	    } else {
		panic("TraceExecutionProc: bad flag combination");
	    }
	    
	    /*
	     * Execute the command.  Save the interp's result used for
	     * the command. We discard any object result the command returns.
	     */

	    Tcl_SaveResult(interp, &state);

	    tcmdPtr->flags |= TCL_TRACE_EXEC_IN_PROGRESS;
	    iPtr->flags    |= INTERP_TRACE_IN_PROGRESS;
	    Tcl_Preserve((ClientData)tcmdPtr);
	    /* 
	     * This line can have quite arbitrary side-effects,
	     * including deleting the trace, the command being
	     * traced, or even the interpreter.
	     */
	    traceCode = Tcl_Eval(interp, Tcl_DStringValue(&cmd));
	    tcmdPtr->flags &= ~TCL_TRACE_EXEC_IN_PROGRESS;
	    iPtr->flags    &= ~INTERP_TRACE_IN_PROGRESS;
	    if (tcmdPtr->flags == 0) {
		flags |= TCL_TRACE_DESTROYED;
	    }
	    
            if (traceCode == TCL_OK) {
		/* Restore result if trace execution was successful */
		Tcl_RestoreResult(interp, &state);
            }

	    Tcl_DStringFree(&cmd);
	}
	
	/*
	 * Third, create an interpreter trace, if we need one for
	 * subsequent internal execution traces.
	 */
	if ((flags & TCL_TRACE_ENTER_EXEC) && (tcmdPtr->stepTrace == NULL)
	    && (tcmdPtr->flags & (TCL_TRACE_ENTER_DURING_EXEC | TCL_TRACE_LEAVE_DURING_EXEC))) {
		tcmdPtr->startLevel = level;
		tcmdPtr->stepTrace = Tcl_CreateObjTrace(interp, 0,
		   (tcmdPtr->flags & TCL_TRACE_ANY_EXEC) >> 2, 
		   TraceExecutionProc, (ClientData)tcmdPtr, NULL);
	}
    }
    if (flags & TCL_TRACE_DESTROYED) {
	if (tcmdPtr->stepTrace != NULL) {
	    Tcl_DeleteTrace(interp, tcmdPtr->stepTrace);
	    tcmdPtr->stepTrace = NULL;
	}
	Tcl_EventuallyFree((ClientData)tcmdPtr, TCL_DYNAMIC);
    }
    if (call) {
	Tcl_Release((ClientData)tcmdPtr);
    }
    return(traceCode);
}

/*
 *----------------------------------------------------------------------
 *
 * TraceVarProc --
 *
 *	This procedure is called to handle variable accesses that have
 *	been traced using the "trace" command.
 *
 * Results:
 *	Normally returns NULL.  If the trace command returns an error,
 *	then this procedure returns an error string.
 *
 * Side effects:
 *	Depends on the command associated with the trace.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
static char *
TraceVarProc(clientData, interp, name1, name2, flags)
    ClientData clientData;	/* Information about the variable trace. */
    Tcl_Interp *interp;		/* Interpreter containing variable. */
    CONST char *name1;		/* Name of variable or array. */
    CONST char *name2;		/* Name of element within array;  NULL means
				 * scalar variable is being referenced. */
    int flags;			/* OR-ed bits giving operation and other
				 * information. */
{
    Tcl_SavedResult state;
    TraceVarInfo *tvarPtr = (TraceVarInfo *) clientData;
    char *result;
    int code;
    Tcl_DString cmd;

    /* 
     * We might call Tcl_Eval() below, and that might evaluate
     * [trace vdelete] which might try to free tvarPtr.  We want
     * to use tvarPtr until the end of this function, so we use
     * Tcl_Preserve() and Tcl_Release() to be sure it is not 
     * freed while we still need it.
     */

    Tcl_Preserve((ClientData) tvarPtr);

    result = NULL;
    if ((tvarPtr->flags & flags) && !(flags & TCL_INTERP_DESTROYED)) {
	if (tvarPtr->length != (size_t) 0) {
	    /*
	     * Generate a command to execute by appending list elements
	     * for the two variable names and the operation. 
	     */

	    Tcl_DStringInit(&cmd);
	    Tcl_DStringAppend(&cmd, tvarPtr->command, (int) tvarPtr->length);
	    Tcl_DStringAppendElement(&cmd, name1);
	    Tcl_DStringAppendElement(&cmd, (name2 ? name2 : ""));
#ifndef TCL_REMOVE_OBSOLETE_TRACES
	    if (tvarPtr->flags & TCL_TRACE_OLD_STYLE) {
		if (flags & TCL_TRACE_ARRAY) {
		    Tcl_DStringAppend(&cmd, " a", 2);
		} else if (flags & TCL_TRACE_READS) {
		    Tcl_DStringAppend(&cmd, " r", 2);
		} else if (flags & TCL_TRACE_WRITES) {
		    Tcl_DStringAppend(&cmd, " w", 2);
		} else if (flags & TCL_TRACE_UNSETS) {
		    Tcl_DStringAppend(&cmd, " u", 2);
		}
	    } else {
#endif
		if (flags & TCL_TRACE_ARRAY) {
		    Tcl_DStringAppend(&cmd, " array", 6);
		} else if (flags & TCL_TRACE_READS) {
		    Tcl_DStringAppend(&cmd, " read", 5);
		} else if (flags & TCL_TRACE_WRITES) {
		    Tcl_DStringAppend(&cmd, " write", 6);
		} else if (flags & TCL_TRACE_UNSETS) {
		    Tcl_DStringAppend(&cmd, " unset", 6);
		}
#ifndef TCL_REMOVE_OBSOLETE_TRACES
	    }
#endif
	    
	    /*
	     * Execute the command.  Save the interp's result used for
	     * the command. We discard any object result the command returns.
	     *
	     * Add the TCL_TRACE_DESTROYED flag to tvarPtr to indicate to
	     * other areas that this will be destroyed by us, otherwise a
	     * double-free might occur depending on what the eval does.
	     */

	    Tcl_SaveResult(interp, &state);
	    if (flags & TCL_TRACE_DESTROYED) {
		tvarPtr->flags |= TCL_TRACE_DESTROYED;
	    }

	    code = Tcl_EvalEx(interp, Tcl_DStringValue(&cmd),
		    Tcl_DStringLength(&cmd), 0);
	    if (code != TCL_OK) {	     /* copy error msg to result */
		register Tcl_Obj *errMsgObj = Tcl_GetObjResult(interp);
		Tcl_IncrRefCount(errMsgObj);
		result = (char *) errMsgObj;
	    }

	    Tcl_RestoreResult(interp, &state);

	    Tcl_DStringFree(&cmd);
	}
    }
    if (flags & TCL_TRACE_DESTROYED) {
	if (result != NULL) {
	    register Tcl_Obj *errMsgObj = (Tcl_Obj *) result;

	    Tcl_DecrRefCount(errMsgObj);
	    result = NULL;
	}
	Tcl_EventuallyFree((ClientData) tvarPtr, TCL_DYNAMIC);
    }
    Tcl_Release((ClientData) tvarPtr);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_WhileObjCmd --
 *
 *      This procedure is invoked to process the "while" Tcl command.
 *      See the user documentation for details on what it does.
 *
 *	With the bytecode compiler, this procedure is only called when
 *	a command name is computed at runtime, and is "while" or the name
 *	to which "while" was renamed: e.g., "set z while; $z {$i<100} {}"
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
int
Tcl_WhileObjCmd(dummy, interp, objc, objv)
    ClientData dummy;                   /* Not used. */
    Tcl_Interp *interp;                 /* Current interpreter. */
    int objc;                           /* Number of arguments. */
    Tcl_Obj *CONST objv[];       	/* Argument objects. */
{
    int result, value;

    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "test command");
        return TCL_ERROR;
    }

    while (1) {
        result = Tcl_ExprBooleanObj(interp, objv[1], &value);
        if (result != TCL_OK) {
            return result;
        }
        if (!value) {
            break;
        }
        result = Tcl_EvalObjEx(interp, objv[2], 0);
        if ((result != TCL_OK) && (result != TCL_CONTINUE)) {
            if (result == TCL_ERROR) {
                char msg[32 + TCL_INTEGER_SPACE];

                sprintf(msg, "\n    (\"while\" body line %d)",
                        interp->errorLine);
                Tcl_AddErrorInfo(interp, msg);
            }
            break;
        }
    }
    if (result == TCL_BREAK) {
        result = TCL_OK;
    }
    if (result == TCL_OK) {
        Tcl_ResetResult(interp);
    }
    return result;
}