tcldot.c   [plain text]

/*
 * Copyright (c) AT&T Corp. 1994, 1995.
 * Copyright (c) Lucent Technologies. 1996, 1997, 1998.
 *
 * This code is licensed by AT&T Corp.  For the
 * terms and conditions of the license, see
 * http://www.research.att.com/orgs/ssr/book/reuse
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

/* avoid compiler warnings with template changes in Tcl8.4 */
/*    specifically just the change to Tcl_CmdProc */
#define USE_NON_CONST

#include "tcldot.h"
#include "tclhandle.h"
#include "neatoprocs.h"
#include "circle.h"
#include "fdp.h"
#include "circular.h"
#include "gvrender.h"

#ifdef DMALLOC
#include "dmalloc.h"
#endif

char	*Info[] = {
	"tcldot",			/* Program */
	VERSION,			/* Version */
	BUILDDATE			/* Build Date */
};

/* ******* not ready yet
#if (TCL_MAJOR_VERSION > 7)
#define TCLOBJ
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION == 0)
char *
Tcl_GetString(Tcl_Obj *obj) {
    int len;
	return (Tcl_GetStringFromObj(obj, &len));
}
#else
#define UTF8
#endif
#endif
********* */

#if defined(_BLD_tcldot) && defined(_DLL)
    extern codegen_t TK_CodeGen;
#else
    extern codegen_t memGD_CodeGen, TK_CodeGen;
#if ENABLE_CODEGENS
    extern FILE               *Output_file;
    extern int                Output_lang;
#endif
#endif
extern void		*GDHandleTable;
extern int		Gdtclft_Init();

static void	    *graphTblPtr, *nodeTblPtr, *edgeTblPtr;
static tkgendata_t tkgendata;

static void
reset_layout(Agraph_t *sg)
{
	Agraph_t *g = sg->root;
	GVC_t *gvc;

	if (GD_drawing(g)) { /* only cleanup once between layouts */
		gvc = GD_gvc(g); /* save gvc link */
		switch (GD_drawing(g)->engine) {
		case DOT:
			dot_cleanup(g);
			break;
		case NEATO:
			neato_cleanup(g);
			break;
		case TWOPI:
			twopi_cleanup(g);
			break;
		case FDP:
			fdp_cleanup(g);
			break;
		case CIRCULAR:
			circular_cleanup(g);
			break;
		default:
			break;
		}
		GD_drawing(g) = NULL;
		GD_gvc(g) = gvc;   /* restore link to gvc */
	}
}

static void
deleteEdges(Tcl_Interp *interp, Agraph_t *g, Agnode_t *n)
{
	Agedge_t  **ep, *e, *e1;
	char		buf[16];

	e = agfstedge(g, n);
	while (e) {
		tclhandleString(edgeTblPtr, buf, e->handle);
		Tcl_DeleteCommand(interp, buf);
		ep = (Agedge_t **) tclhandleXlateIndex(edgeTblPtr, e->handle);
		if (!ep) fprintf(stderr, "Bad entry in edgeTbl\n");
		tclhandleFreeIndex(edgeTblPtr, e->handle);
		e1 = agnxtedge(g, e, n);
		agdelete(g->root, e);
		e = e1;
	}
}

static void
deleteNodes(Tcl_Interp *interp, Agraph_t *g)
{
	Agnode_t  **np, *n, *n1;
	char        buf[16];

	n = agfstnode(g);
	while (n) {
		tclhandleString(nodeTblPtr, buf, n->handle);
		Tcl_DeleteCommand(interp, buf);
		np = (Agnode_t **) tclhandleXlateIndex(nodeTblPtr, n->handle);
		if (!np) fprintf(stderr, "Bad entry in nodeTbl\n");
		tclhandleFreeIndex(nodeTblPtr, n->handle);
		deleteEdges(interp, g->root, n); 
		n1 = agnxtnode(g, n);
		agdelete(g->root, n);
		n = n1;
	}
}

static void
deleteGraph(Tcl_Interp *interp, Agraph_t *g)
{
	Agraph_t   **sgp;
	Agedge_t   *e;
	char        buf[16];

	if (g->meta_node) {
		for (e = agfstout(g->meta_node->graph, g->meta_node); e; e = agnxtout(g->meta_node->graph, e)) {
		    deleteGraph(interp, agusergraph(e->head));
		}
		tclhandleString(graphTblPtr, buf, g->handle);
		Tcl_DeleteCommand(interp, buf);
		sgp = (Agraph_t **) tclhandleXlateIndex(graphTblPtr, g->handle);
		if (!sgp) fprintf(stderr, "Bad entry in graphTbl\n");
		tclhandleFreeIndex(graphTblPtr, g->handle);
		if (g == g->root) {
			agclose (g);
		} else {
			agdelete(g->meta_node->graph, g->meta_node);
		}
	} else {
		fprintf (stderr, "Subgraph has no meta_node\n");
	}
}

static void
setgraphattributes(Agraph_t *g, char *argv[], int argc) {
	int	i;
	Agsym_t	*a;

	for (i = 0; i < argc; i++) {
		if (!(a = agfindattr(g->root, argv[i])))
			a = agraphattr(g->root, argv[i], "");
		agxset(g, a->index, argv[++i]);
	}
}

static void
setedgeattributes(Agraph_t* g, Agedge_t *e, char *argv[], int argc) {
	int	i;
	Agsym_t *a;

	for (i = 0; i < argc; i++) {
		/* silently ignore attempts to modify "key" */
		if (strcmp(argv[i],"key") == 0) {
			i++;
			continue;
		}
		if (!(a = agfindattr(g->proto->e, argv[i])))
			a = agedgeattr(g->root, argv[i], "");
		agxset(e, a->index, argv[++i]);
	}
}

static void
setnodeattributes (Agraph_t *g, Agnode_t *n, char *argv[], int argc) {
	int	i;
	Agsym_t	*a;

	for (i = 0; i < argc; i++) {
		if (!(a = agfindattr(g->proto->n, argv[i])))
			a = agnodeattr(g->root, argv[i], "");
		agxset(n, a->index, argv[++i]);
	}
}

static int
edgecmd(ClientData clientData, Tcl_Interp *interp,
#ifndef TCLOBJ
	int argc, char *argv[]
#else /* TCLOBJ */
	int argc, Tcl_Obj *CONST objv[]
#endif /* TCLOBJ */
)
{
	GVC_t          *gvc;
	char            c, buf[16], *s, **argv2;
	int             i, j, length, argc2;
	Agraph_t       *g;
	Agedge_t      **ep, *e;
	Agsym_t        *a;

	if (argc < 2) {
		Tcl_AppendResult(interp, "wrong # args: should be \"",
						 argv[0], "\" option ?arg arg ...?", (char *) NULL);
		return TCL_ERROR;
	}
	if (!(ep = (Agedge_t **) tclhandleXlate(edgeTblPtr, argv[0]))) {
		Tcl_AppendResult(interp, " \"", argv[0], "\"", (char *) NULL);
		return TCL_ERROR;
	}
	gvc = (GVC_t *)clientData;
	e = *ep;
	g = e->tail->graph;

	c = argv[1][0];
	length = strlen(argv[1]);

	if ((c == 'd') && (strncmp(argv[1], "delete", length) == 0)) {
		tclhandleFreeIndex(edgeTblPtr, e->handle);
		Tcl_DeleteCommand(interp, argv[0]);
		agdelete(g, e);
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listattributes", length) == 0)) {
		for (i = 0; i < dtsize(g->univ->edgeattr->dict); i++) {
			a = g->univ->edgeattr->list[i];
			Tcl_AppendElement(interp, a->name);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listnodes", length) == 0)) {
		tclhandleString(nodeTblPtr, buf, e->tail->handle);
		Tcl_AppendElement(interp, buf);
		tclhandleString(nodeTblPtr, buf, e->head->handle);
		Tcl_AppendElement(interp, buf);
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryattributes", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char ***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->e, argv2[j]))) {
					Tcl_AppendElement(interp, agxget(e, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryattributevalues", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->e, argv2[j]))) {
					Tcl_AppendElement(interp, argv2[j]);
					Tcl_AppendElement(interp, agxget(e, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "setattributes", length) == 0)) {
		if (argc == 3) {
			if (Tcl_SplitList(interp, argv[2], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			if ((argc2 == 0) || (argc2 % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"",
				 argv[0], "\" setattributes attributename attributevalue ?attributename attributevalue? ?...?",
							 (char *) NULL);
				Tcl_Free((char *)argv2);
				return TCL_ERROR;
			}
			setedgeattributes(g->root,e,argv2,argc2);
			Tcl_Free((char *)argv2);
		}
		else {
			if ((argc < 4) || (argc % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"",
				 argv[0], "\" setattributes attributename attributevalue ?attributename attributevalue? ?...?",
							 (char *) NULL);
				return TCL_ERROR;
			}
			setedgeattributes(g->root,e,&argv[2],argc-2);
		}
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "showname", length) == 0)) {
		if (g->kind && AGFLAG_DIRECTED) s = "->"; else s = "--";
		Tcl_AppendResult(interp,
				e->tail->name, s, e->head->name, (char *) NULL);
		return TCL_OK;

	} else {
		Tcl_AppendResult(interp, "bad option \"", argv[1],
				"\": must be one of:",
				"\n\tdelete, listattributes, listnodes,",
				"\n\tueryattributes, queryattributevalues,",
				"\n\tsetattributes, showname",
				(char *) NULL);
		return TCL_ERROR;
	}
}

static int
nodecmd(ClientData clientData, Tcl_Interp *interp,
#ifndef TCLOBJ
	int argc, char *argv[]
#else /* TCLOBJ */
	int argc, Tcl_Obj *CONST objv[]
#endif /* TCLOBJ */
)
{
	GVC_t          *gvc;
	unsigned long	id;
	char            c, buf[16], **argv2;
	int             i, j, length, argc2;
	Agraph_t       *g;
	Agnode_t      **np, *n, *head;
	Agedge_t      **ep, *e;
	Agsym_t        *a;

	if (argc < 2) {
		Tcl_AppendResult(interp, "wrong # args: should be \"",
						 argv[0], " option ?arg arg ...?\"", (char *) NULL);
		return TCL_ERROR;
	}
	if (!(np = (Agnode_t **) tclhandleXlate(nodeTblPtr, argv[0]))) {
		Tcl_AppendResult(interp, " \"", argv[0], "\"", (char *) NULL);
		return TCL_ERROR;
	}
	gvc = (GVC_t *)clientData;
	n = *np;
	g = n->graph;

	c = argv[1][0];
	length = strlen(argv[1]);


	if ((c == 'a') && (strncmp(argv[1], "addedge", length) == 0)) {
		if ((argc < 3) || (! (argc % 2))) {
			Tcl_AppendResult(interp, "wrong # args: should be \"",
				argv[0], " addedge head ?attributename attributevalue? ?...?\"",
				(char *) NULL);
			return TCL_ERROR;
		}
		if (!(np = (Agnode_t **) tclhandleXlate(nodeTblPtr, argv[2]))) {
			if (!(head = agfindnode(g, argv[2]))) {
			        Tcl_AppendResult(interp, "Head node \"", argv[2],
							 "\" not found.", (char *) NULL);
			    return TCL_ERROR;
			}
		} else {
			head = *np;
			if (g->root != head->graph->root) {
			    Tcl_AppendResult(interp, "Nodes ", argv[0], " and ", argv[2],
					" are not in the same graph.", (char *) NULL);
			    return TCL_ERROR;
			}
		}
		e = agedge(g, n, head);
		if (!(ep = (Agedge_t **) tclhandleXlateIndex(edgeTblPtr, e->handle)) || *ep != e) {
			ep = (Agedge_t **) tclhandleAlloc (edgeTblPtr, interp->result, &id);
			*ep = e;
			e->handle = id;
#ifndef TCLOBJ
			Tcl_CreateCommand(interp, interp->result, edgecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
			Tcl_CreateObjCommand(interp, interp->result, edgecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
		} else {
			tclhandleString(edgeTblPtr, interp->result, e->handle);
		}
		setedgeattributes(g->root, e, &argv[3], argc-3);
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 'd') && (strncmp(argv[1], "delete", length) == 0)) {
		deleteEdges(interp, g, n);
		tclhandleFreeIndex(nodeTblPtr, n->handle);
		Tcl_DeleteCommand(interp, argv[0]);
		agdelete(g, n);
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 'f') && (strncmp(argv[1], "findedge", length) == 0)) {
		if (argc < 3) {
			Tcl_AppendResult(interp, "wrong # args: should be \"",
							 argv[0], " findedge headnodename\"",
							 (char *) NULL);
			return TCL_ERROR;
		}
		if (!(head = agfindnode(g, argv[2]))) {
			Tcl_AppendResult(interp, "Head node \"", argv[2],
							 "\" not found.", (char *) NULL);
			return TCL_ERROR;
		}
		if (!(e = agfindedge(g, n, head))) {
			tclhandleString(nodeTblPtr, buf, head->handle);
			Tcl_AppendResult(interp, "Edge \"", argv[0],
							 " - ", buf, "\" not found.",
							 (char *) NULL);
			return TCL_ERROR;
		}
		tclhandleString(edgeTblPtr, buf, e->handle);
		Tcl_AppendElement(interp, buf);
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listattributes", length) == 0)) {
		for (i = 0; i < dtsize(g->univ->nodeattr->dict); i++) {
			a = g->univ->nodeattr->list[i];
			Tcl_AppendElement(interp, a->name);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listedges", length) == 0)) {
		for (e = agfstedge(g, n); e; e = agnxtedge(g, e, n)) {
			tclhandleString(edgeTblPtr, buf, e->handle);
			Tcl_AppendElement(interp, buf);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listinedges", length) == 0)) {
		for (e = agfstin(g, n); e; e = agnxtin(g, e)) {
			tclhandleString(edgeTblPtr, buf, e->handle);
			Tcl_AppendElement(interp, buf);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listoutedges", length) == 0)) {
		for (e = agfstout(g, n); e; e = agnxtout(g, e)) {
			tclhandleString(edgeTblPtr, buf, e->handle);
			Tcl_AppendElement(interp, buf);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryattributes", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->n, argv2[j]))) {
					Tcl_AppendElement(interp, agxget(n, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryattributevalues", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->n, argv2[j]))) {
					Tcl_AppendElement(interp, argv2[j]);
					Tcl_AppendElement(interp, agxget(n, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "setattributes", length) == 0)) {
		g = g->root;
		if (argc == 3) {
			if (Tcl_SplitList(interp, argv[2], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			if ((argc2 == 0) || (argc2 % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
				Tcl_Free((char *)argv2);
				return TCL_ERROR;
			}
			setnodeattributes(g, n, argv2, argc2);
			Tcl_Free((char *)argv2);
		}
		else {
			if ((argc < 4) || (argc % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
				return TCL_ERROR;
			}
			setnodeattributes(g, n, &argv[2], argc-2);
		}
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "showname", length) == 0)) {
		interp->result = n->name;
		return TCL_OK;

	} else {
		Tcl_AppendResult(interp, "bad option \"", argv[1],
			"\": must be one of:",
			"\n\taddedge, listattributes, listedges, listinedges,",
			"\n\tlistoutedges, queryattributes, queryattributevalues,",
			"\n\tsetattributes, showname.",
			(char *) NULL);
		return TCL_ERROR;
	}
}

static void
tcldot_layout(Agraph_t *g, char *engine)
{
	char		buf[256];
	Agsym_t		*a;

	reset_layout(g);        /* in case previously drawn */

	if (engine && strcasecmp(engine, "dot") == 0)
		dot_layout(g);
	else if (engine && strcasecmp(engine, "neato") == 0)
		neato_layout(g);
	else if (engine && strcasecmp(engine, "twopi") == 0)
		twopi_layout(g);
	else if (engine && strcasecmp(engine, "fdp") == 0)
		fdp_layout(g);
	else if (engine && strcasecmp(engine, "circo") == 0)
		circular_layout(g);
/* support old behaviors if engine isn't specified*/
	else if (AG_IS_DIRECTED(g))
		dot_layout(g);
	else
		neato_layout(g);

/* set bb attribute for basic layout.
 * doesn't yet include margins, scaling or page sizes because
 * those depend on the renderer being used. */
	if (GD_drawing(g)->landscape)
		sprintf(buf,"%d %d %d %d",
			ROUND(GD_bb(g).LL.y), ROUND(GD_bb(g).LL.x),
			ROUND(GD_bb(g).UR.y), ROUND(GD_bb(g).UR.x));
	else
		sprintf(buf,"%d %d %d %d",
			ROUND(GD_bb(g).LL.x), ROUND(GD_bb(g).LL.y),
			ROUND(GD_bb(g).UR.x), ROUND(GD_bb(g).UR.y));
	if (!(a = agfindattr(g, "bb"))) {
		a = agraphattr(g, "bb", "");
	}
	agxset(g, a->index, buf);
}

static int
graphcmd(ClientData clientData, Tcl_Interp *interp,
#ifndef TCLOBJ
    int argc, char *argv[]
#else /* TCLOBJ */
	int argc, Tcl_Obj *CONST objv[]
#endif /* TCLOBJ */
)
{

	Agraph_t       *g, **gp, *sg, **sgp;
	Agnode_t      **np, *n, *tail, *head;
	Agedge_t      **ep, *e;
	Agsym_t        *a;
	char            c, buf[256], **argv2;
	int             i, j, length, argc2;
	unsigned long	id;
	GVC_t          *gvc;

	if (argc < 2) {
		Tcl_AppendResult(interp, "wrong # args: should be \"",
			argv[0], " option ?arg arg ...?\"", (char *) NULL);
		return TCL_ERROR;
	}
	if (!(gp = (Agraph_t **) tclhandleXlate(graphTblPtr, argv[0]))) {
		Tcl_AppendResult(interp, " \"", argv[0], "\"", (char *) NULL);
		return TCL_ERROR;
	}

	gvc = (GVC_t *)clientData;
	g = *gp;

	c = argv[1][0];
	length = strlen(argv[1]);

	if ((c == 'a') && (strncmp(argv[1], "addedge", length) == 0)) {
		if ((argc < 4) || (argc % 2)) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
				" addedge tail head ?attributename attributevalue? ?...?\"",
	            (char *) NULL);
			return TCL_ERROR;
		}
		if (!(np = (Agnode_t **) tclhandleXlate(nodeTblPtr, argv[2]))) {
			if (!(tail = agfindnode(g, argv[2]))) {
			        Tcl_AppendResult(interp, "Tail node \"", argv[2],
					 "\" not found.", (char *) NULL);
			    return TCL_ERROR;
			}
		} else {
			tail = *np;
			if (g->root != tail->graph->root) {
			    Tcl_AppendResult(interp, "Node ", argv[2],
					" is not in the graph.", (char *) NULL);
			    return TCL_ERROR;
			}
		}
		if (!(np = (Agnode_t **) tclhandleXlate(nodeTblPtr, argv[3]))) {
			if (!(head = agfindnode(g, argv[3]))) {
			        Tcl_AppendResult(interp, "Head node \"", argv[3],
							 "\" not found.", (char *) NULL);
			    return TCL_ERROR;
			}
		} else {
			head = *np;
			if (g->root != head->graph->root) {
			    Tcl_AppendResult(interp, "Node ", argv[3],
					" is not in the graph.", (char *) NULL);
			    return TCL_ERROR;
			}
		}
		e = agedge(g, tail, head);
		if (!(ep = (Agedge_t **) tclhandleXlateIndex(edgeTblPtr, e->handle)) || *ep != e) {
			ep = (Agedge_t **) tclhandleAlloc (edgeTblPtr, interp->result, &id);
			*ep = e;
			e->handle = id;
#ifndef TCLOBJ
			Tcl_CreateCommand(interp, interp->result, edgecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
			Tcl_CreateObjCommand(interp, interp->result, edgecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
		} else {
			tclhandleString(edgeTblPtr, interp->result, e->handle);
		}
		setedgeattributes(g->root, e, &argv[4], argc-4);
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 'a') && (strncmp(argv[1], "addnode", length) == 0)) {
	    if (argc % 2) {
			/* if odd number of args then argv[2] is name */
			n = agnode(g, argv[2]);
			i = 3;
			if (!(np = (Agnode_t **) tclhandleXlateIndex(nodeTblPtr, n->handle)) || *np != n) {
				np = (Agnode_t **) tclhandleAlloc (nodeTblPtr, interp->result, &id);
				*np = n;
				n->handle = id;
#ifndef TCLOBJ
				Tcl_CreateCommand(interp, interp->result, nodecmd,
					(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
				Tcl_CreateObjCommand(interp, interp->result, nodecmd,
					(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
			} else {
				tclhandleString(nodeTblPtr, interp->result, n->handle);
			}
		} else {
			/* else use handle as name */
			np = (Agnode_t **) tclhandleAlloc (nodeTblPtr, interp->result, &id);
			n = agnode(g, interp->result);
			i = 2;
			*np = n;
			n->handle = id;
#ifndef TCLOBJ
			Tcl_CreateCommand(interp, interp->result, nodecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
			Tcl_CreateObjCommand(interp, interp->result, nodecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
		}
		setnodeattributes(g->root, n, &argv[i], argc-i);
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 'a') && (strncmp(argv[1], "addsubgraph", length) == 0)) {
		if (argc < 2) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
			     "\" addsubgraph ?name? ?attributename attributevalue? ?...?",
				 (char *) NULL);
		}
	    if (argc % 2) {
	        /* if odd number of args then argv[2] is name */
	        sg = agsubg(g, argv[2]);
	        i = 3;
		if (!(sgp = (Agraph_t **) tclhandleXlateIndex(graphTblPtr, sg->handle)) || *sgp != sg) {
			sgp = (Agraph_t **) tclhandleAlloc (graphTblPtr, interp->result, &id);
			*sgp = sg;
			sg->handle = id;
#ifndef TCLOBJ
			Tcl_CreateCommand(interp, interp->result, graphcmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
			Tcl_CreateObjCommand(interp, interp->result, graphcmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
		} else {
			tclhandleString(graphTblPtr, interp->result, sg->handle);
		}
	    } else {
	        /* else use handle as name */
		sgp = (Agraph_t **) tclhandleAlloc (graphTblPtr, interp->result, &id);
	        sg = agsubg(g, interp->result);
	        i = 2;
		*sgp = sg;
		sg->handle = id;
#ifndef TCLOBJ
		Tcl_CreateCommand(interp, interp->result, graphcmd,
			(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
		Tcl_CreateObjCommand(interp, interp->result, graphcmd,
			(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
	    }
		setgraphattributes(sg, &argv[i], argc-i);
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 'c') && (strncmp(argv[1], "countnodes", length) == 0)) {
		sprintf(buf, "%d", agnnodes(g));
		Tcl_AppendResult(interp, buf, (char *) NULL);
		return TCL_OK;

	} else if ((c == 'c') && (strncmp(argv[1], "countedges", length) == 0)) {
		sprintf(buf, "%d", agnedges(g));
		Tcl_AppendResult(interp, buf, (char *) NULL);
		return TCL_OK;

	} else if ((c == 'd') && (strncmp(argv[1], "delete", length) == 0)) {
		reset_layout(g);
		deleteNodes(interp, g);
		deleteGraph(interp, g);
		return TCL_OK;

	} else if ((c == 'f') && (strncmp(argv[1], "findedge", length) == 0)) {
		if (argc < 4) {
			Tcl_AppendResult(interp, "wrong # args: should be \"",
				argv[0], " findedge tailnodename headnodename\"",
				(char *) NULL);
			return TCL_ERROR;
		}
		if (!(tail = agfindnode(g, argv[2]))) {
			Tcl_AppendResult(interp, "Tail node \"", argv[2],
				"\" not found.", (char *) NULL);
			return TCL_ERROR;
		}
		if (!(head = agfindnode(g, argv[3]))) {
			Tcl_AppendResult(interp, "Head node \"", argv[3],
							 "\" not found.", (char *) NULL);
			return TCL_ERROR;
		}
		if (!(e = agfindedge(g, tail, head))) {
			Tcl_AppendResult(interp, "Edge \"", argv[2],
				" - ", argv[3], "\" not found.",
				(char *) NULL);
			return TCL_ERROR;
		}
		tclhandleString(edgeTblPtr, buf, e->handle);
		Tcl_AppendElement(interp, buf);
		return TCL_OK;

	} else if ((c == 'f') && (strncmp(argv[1], "findnode", length) == 0)) {
		if (argc < 3) {
			Tcl_AppendResult(interp, "wrong # args: should be \"",
				argv[0], " findnode nodename\"",
				(char *) NULL);
			return TCL_ERROR;
		}
		if (!(n = agfindnode(g, argv[2]))) {
			Tcl_AppendResult(interp, "Node not found.",
				(char *) NULL);
			return TCL_ERROR;
		}
		tclhandleString(nodeTblPtr, buf, n->handle);
		Tcl_AppendResult(interp, buf, (char *) NULL);
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "layoutedges", length) == 0)) {
		g = g->root;
		if (!GD_drawing(g)) 
			tcldot_layout(g,(argc>2)?argv[2]:(char *) NULL);
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "layoutnodes", length) == 0)) {
		g = g->root;
		if (!GD_drawing(g))
			tcldot_layout(g,(argc>2)?argv[2]:(char *) NULL);
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listattributes", length) == 0)) {
		for (i = 0; i < dtsize(g->univ->globattr->dict); i++) {
			a = g->univ->globattr->list[i];
			Tcl_AppendElement(interp, a->name);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listedgeattributes", length) == 0)) {
		for (i = 0; i < dtsize(g->univ->edgeattr->dict); i++) {
			a = g->univ->edgeattr->list[i];
			Tcl_AppendElement(interp, a->name);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listnodeattributes", length) == 0)) {
		for (i = 0; i < dtsize(g->univ->nodeattr->dict); i++) {
			a = g->univ->nodeattr->list[i];
			Tcl_AppendElement(interp, a->name);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listedges", length) == 0)) {
		for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
			for (e = agfstout(g, n); e; e = agnxtout(g, e)) {
				tclhandleString(edgeTblPtr, buf, e->handle);
				Tcl_AppendElement(interp, buf);
			}
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listnodes", length) == 0)) {
		for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
			tclhandleString(nodeTblPtr, buf, n->handle);
			Tcl_AppendElement(interp, buf);
		}
		return TCL_OK;

	} else if ((c == 'l') && (strncmp(argv[1], "listsubgraphs", length) == 0)) {
		if (g->meta_node) {
			for (e = agfstout(g->meta_node->graph, g->meta_node); e; e = agnxtout(g->meta_node->graph, e)) {
			    sg = agusergraph(e->head);
			    tclhandleString(graphTblPtr, buf, sg->handle);
			    Tcl_AppendElement(interp, buf);
			}
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryattributes", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->root, argv2[j]))) {
					Tcl_AppendElement(interp, agxget(g, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryattributevalues", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->root, argv2[j]))) {
					Tcl_AppendElement(interp, argv2[j]);
					Tcl_AppendElement(interp, agxget(g, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryedgeattributes", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->e, argv2[j]))) {
					Tcl_AppendElement(interp, agxget(g->proto->e, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "queryedgeattributevalues", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->e, argv2[j]))) {
					Tcl_AppendElement(interp, argv2[j]);
					Tcl_AppendElement(interp, agxget(g->proto->e, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "querynodeattributes", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->n, argv2[j]))) {
					Tcl_AppendElement(interp, agxget(g->proto->n, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'q') && (strncmp(argv[1], "querynodeattributevalues", length) == 0)) {
		for (i = 2; i < argc; i++) {
			if (Tcl_SplitList(interp, argv[i], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			for (j = 0; j < argc2; j++) {
				if ((a = agfindattr(g->proto->n, argv2[j]))) {
					Tcl_AppendElement(interp, argv2[j]);
					Tcl_AppendElement(interp, agxget(g->proto->n, a->index));
				} else {
					Tcl_AppendResult(interp, " No attribute named \"",
								 argv2[j], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
			Tcl_Free((char *)argv2);
		}
		return TCL_OK;

	} else if ((c == 'r') && (strncmp(argv[1], "render", length) == 0)) {
		if (argc < 3) {
			tkgendata.canvas = "$c";
		} else {
			tkgendata.canvas = argv[2];
#if 0  /* not implemented */
			if (argc < 4) {
				tkgendata.eval = FALSE;
			} else {
				if ((Tcl_GetBoolean(interp, argv[3], &tkgendata.eval)) != TCL_OK) {
					Tcl_AppendResult(interp, " Invalid boolean: \"",
						 argv[3], "\"", (char *) 0);
					return TCL_ERROR;
				}
			}
#endif
		}
		tkgendata.interp = interp;

		gvrender_output_langname_job(gvc, "TK");
		/* make sure that layout is done */
		gvc->g = g = g->root;
		if (!GD_drawing(g) || argc>3)
			tcldot_layout(g,(argc>3)?argv[3]:(char *) NULL);

		/* render graph TK canvas commands */
		gvc->job->output_lang = lang_select(gvc, gvc->job->output_langname, 0);
		gvc->job->output_file = (FILE *) &tkgendata;
#if ENABLE_CODEGENS
		Output_lang = gvc->job->output_lang;
		Output_file = gvc->job->output_file;
#endif
		gvc->codegen = &TK_CodeGen;
		/* emit graph in sorted order, all nodes then all edges */
		emit_graph(gvc, EMIT_SORTED);
		gvrender_delete_jobs(gvc);
		return TCL_OK;

	} else if ((c == 'r') && (strncmp(argv[1], "rendergd", length) == 0)) {
		if (argc < 3) {
			Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					" rendergd gdhandle ?DOT|NEATO|TWOPI|FDP|CIRCO?\"", (char *) NULL);
			return TCL_ERROR;
		}
		gvrender_output_langname_job(gvc, "memGD");

/* FIXME - nasty hack because memGD is not a language available from command line */
#if 0
		gvc->job->output_lang = lang_select(gvc, gvc->job->output_langname, 0);
#else
		gvc->job->output_lang = memGD;
#endif

		if (! (gvc->job->output_file = (FILE *)tclhandleXlate(GDHandleTable, argv[2]))) {
			Tcl_AppendResult(interp, "GD Image not found.", (char *) NULL);
			return TCL_ERROR;
		}
#if ENABLE_CODEGENS
		Output_lang = gvc->job->output_lang;
		Output_file = gvc->job->output_file;
#endif

		/* make sure that layout is done */
		gvc->g = g = g->root;
		if (!GD_drawing(g) || argc>4)
			tcldot_layout(g,(argc>4)?argv[4]:(char *) NULL);

		/* set a default bitmap output language (to get default margins) */
		dotneato_set_margins(g);
		/* render graph to open GD structure */
		gvc->codegen = &memGD_CodeGen;
		/* emit graph in sorted order, all nodes then all edges */
		emit_graph(gvc, 1);
		gvrender_delete_jobs(gvc);
		Tcl_AppendResult(interp, argv[2], (char *) NULL);
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "setattributes", length) == 0)) {
		if (argc == 3) {
			if (Tcl_SplitList(interp, argv[2], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			if ((argc2 == 0) || (argc2 % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
				Tcl_Free((char *)argv2);
				return TCL_ERROR;
			}
			setgraphattributes(g, argv2, argc2);
			Tcl_Free((char *)argv2);
		}
		else {
			if ((argc < 4) || (argc % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
				return TCL_ERROR;
			}
			setgraphattributes(g, &argv[2], argc-2);
		}
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "setedgeattributes", length) == 0)) {
		if (argc == 3) {
			if (Tcl_SplitList(interp, argv[2], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			if ((argc2 == 0) || (argc2 % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setedgeattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
				Tcl_Free((char *)argv2);
				return TCL_ERROR;
			}
			setedgeattributes(g, g->proto->e, argv2, argc2);
			Tcl_Free((char *)argv2);
		}
		else {
			if ((argc < 4) || (argc % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setedgeattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
			}
			setedgeattributes(g, g->proto->e, &argv[2], argc-2);
		}
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "setnodeattributes", length) == 0)) {
		if (argc == 3) {
			if (Tcl_SplitList(interp, argv[2], &argc2, (CONST84 char***) &argv2) != TCL_OK)
				return TCL_ERROR;
			if ((argc2 == 0) || (argc2 % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setnodeattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
				Tcl_Free((char *)argv2);
				return TCL_ERROR;
			}
			setnodeattributes(g, g->proto->n, argv2, argc2);
			Tcl_Free((char *)argv2);
		}
		else {
			if ((argc < 4) || (argc % 2)) {
				Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
					"\" setnodeattributes attributename attributevalue ?attributename attributevalue? ?...?",
					(char *) NULL);
			}
			setnodeattributes(g, g->proto->n, &argv[2], argc-2);
		}
		reset_layout(g);
		return TCL_OK;

	} else if ((c == 's') && (strncmp(argv[1], "showname", length) == 0)) {
		interp->result = g->name;
		return TCL_OK;

	} else if ((c == 'w') && (strncmp(argv[1], "write", length) == 0)) {
		gvc->g = g = g->root;
		if (argc < 3) {
			Tcl_AppendResult(interp, "wrong # args: should be \"",
				argv[0], " write fileHandle ?language ?DOT|NEATO|TWOPI|FDP|CIRCO??\"", (char *) NULL);
			return TCL_ERROR;
		}
		/* process lang first to create job */
		if (argc < 4) {
			gvrender_output_langname_job(gvc, "dot");
	        } else {
			gvrender_output_langname_job(gvc, argv[3]);
		}
		/* populate new job struct with output language and output file data */
		gvc->job->output_lang = lang_select(gvc, gvc->job->output_langname, 0);
		if (Tcl_GetOpenFile(interp, argv[2], 1, 1, (ClientData *)&(gvc->job->output_file)) != TCL_OK)
			return TCL_ERROR;
#if ENABLE_CODEGENS
		/* old codegens use globals */
		Output_lang = gvc->job->output_lang;
		Output_file = gvc->job->output_file;
#endif
		/* make sure that layout is done  - unless canonical output */
		if ((!GD_drawing(g) || argc>4) && gvc->job->output_lang != CANONICAL_DOT)
			tcldot_layout(g,(argc>4)?argv[4]:(char *) NULL);

                emit_reset(gvc);          /* reset page numbers in postscript */
		dotneato_write_one(gvc);
		gvrender_delete_jobs(gvc);
		return TCL_OK;

	} else {
		Tcl_AppendResult(interp, "bad option \"", argv[1],
			"\": must be one of:",
			"\n\taddedge, addnode, addsubgraph, countedges, countnodes,",
			"\n\tlayout, listattributes, listedgeattributes, listnodeattributes,",
			"\n\tlistedges, listnodes, listsubgraphs, render, rendergd,",
			"\n\tqueryattributes, queryedgeattributes, querynodeattributes,",
			"\n\tqueryattributevalues, queryedgeattributevalues, querynodeattributevalues,",
			"\n\tsetattributes, setedgeattributes, setnodeattributes,",
			"\n\tshowname, write.",
			(char *) NULL);
		return TCL_ERROR;
	}
} /* graphcmd */

static int
dotnew(ClientData clientData, Tcl_Interp *interp,
#ifndef TCLOBJ
	int argc, char *argv[]
#else /* TCLOBJ */
	int argc, Tcl_Obj *CONST objv[]
#endif /* TCLOBJ */
)
{
	GVC_t          *gvc;
	Agraph_t       *g, **gp;
	char            c;
	int             i, length, kind;
	unsigned long	id;

	if ((argc < 2)) {
		Tcl_AppendResult(interp, "wrong # args: should be \"",
			argv[0], " graphtype ?graphname? ?attributename attributevalue? ?...?\"", (char *) NULL);
		return TCL_ERROR;
	}
	gvc = (GVC_t *)clientData;
	c = argv[1][0];
	length = strlen(argv[1]);
	if ((c == 'd') && (strncmp(argv[1], "digraph", length) == 0)) {
		kind = AGDIGRAPH;
	} else if ((c == 'd') && (strncmp(argv[1], "digraphstrict", length) == 0)) {
		kind = AGDIGRAPHSTRICT;
	} else if ((c == 'g') && (strncmp(argv[1], "graph", length) == 0)) {
		kind = AGRAPH;
	} else if ((c == 'g') && (strncmp(argv[1], "graphstrict", length) == 0)) {
		kind = AGRAPHSTRICT;
	} else {
		Tcl_AppendResult(interp, "bad graphtype \"", argv[1],
			"\": must be one of:",
			"\n\tdigraph, digraphstrict, graph, graphstrict.",
			(char *) NULL);
		return TCL_ERROR;
	}
	gp = (Agraph_t **) tclhandleAlloc (graphTblPtr, interp->result, &id);
	if (argc % 2) {
	    /* if odd number of args then argv[2] is name */
	    g = agopen(argv[2], kind);
	    i = 3;
	} else {
	    /* else use handle as name */
	    g = agopen(interp->result, kind);
	    i = 2;
	}
	if (!g) {
		Tcl_AppendResult(interp, "\nFailure to open graph.", (char *) NULL);
		return TCL_ERROR;
	}
	*gp = g;
	g->handle = id;

	/* link graph to context */
	GD_gvc(g) = gvc;
	gvc->g = g;

#ifndef TCLOBJ
	Tcl_CreateCommand(interp, interp->result, graphcmd,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
	Tcl_CreateObjCommand(interp, interp->result, graphcmd,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
	setgraphattributes(g, &argv[i], argc-i);
	/* we use GD_drawing(g) as a flag that layout has been done.
	 * so we make sure that it is initialized to "not done" */
	GD_drawing(g)=NULL;

	return TCL_OK;
}

/*
 * when a graph is read in from a file or string we need to walk
 * it to create the handles and tcl commands for each 
 * graph, subgraph, node, and edge.
 */
static int
tcldot_fixup(Tcl_Interp *interp, GVC_t *gvc) {
	Agraph_t       **gp, *sg, **sgp, *g = gvc->g;
	Agnode_t       *n, **np;
	Agedge_t       *e, **ep;
	char            buf[16];
	unsigned long	id;

	if (g->meta_node) {
		for (n = agfstnode(g->meta_node->graph); n; n = agnxtnode(g->meta_node->graph, n)) {
			sg = agusergraph(n);
			sgp = (Agraph_t **) tclhandleAlloc (graphTblPtr, buf, &id);
			*sgp = sg;
			sg->handle = id;
#ifndef TCLOBJ
			Tcl_CreateCommand(interp, buf, graphcmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
			Tcl_CreateObjCommand(interp, buf, graphcmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
			if (sg == g) strcpy (interp->result, buf);
		}
	} else {
		gp = (Agraph_t **) tclhandleAlloc (graphTblPtr, interp->result, &id);
		*gp = g;
		g->handle = id;
#ifndef TCLOBJ
		Tcl_CreateCommand(interp, interp->result, graphcmd,
			(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
		Tcl_CreateObjCommand(interp, interp->result, graphcmd,
			(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
	}
	for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
	    np = (Agnode_t **) tclhandleAlloc (nodeTblPtr, buf, &id);
		*np = n;
		n->handle = id;
#ifndef TCLOBJ
		Tcl_CreateCommand(interp, buf, nodecmd,
			(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
		Tcl_CreateObjCommand(interp, buf, nodecmd,
			(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
		for (e = agfstout(g, n); e; e = agnxtout(g, e)) {
			ep = (Agedge_t **) tclhandleAlloc (edgeTblPtr, buf, &id);
			*ep = e;
			e->handle = id;
#ifndef TCLOBJ
			Tcl_CreateCommand(interp, buf, edgecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
			Tcl_CreateObjCommand(interp, buf, edgecmd,
				(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */
		}
	}
	return TCL_OK;
}

/*
 * mygets - same api as gets
 *
 * gets one line at a time from a Tcl_Channel and places it in a user buffer
 *    up to a maximum of n characters
 *
 * returns pointer to obtained line in user buffer, or
 * returns NULL when last line read from memory buffer
 *
 * This is probably innefficient because it introduces
 * one more stage of line buffering during reads (at least)
 * but it is needed so that we can take full advantage
 * of the Tcl_Channel mechanism.
 */
static char *mygets (char *ubuf, int n, FILE *channel)
{
	static Tcl_DString	dstr;
	static int		strpos;

	if (!n) { /* a call with n==0 (from aglexinit) resets */
		*ubuf = '\0';
		strpos = 0;
		return NULL;
	}

	/* 
	 * the user buffer might not be big enough to hold the line.
	 */
	if (strpos) {
		if (Tcl_DStringLength(&dstr) > (n + strpos)) {
			/* chunk between first and last */
			strncpy(ubuf,(strpos + Tcl_DStringValue(&dstr)),n-1);
			strpos += (n-1);
			ubuf[n] = '\0';
		}
		else {
			/* last chunk */
			strcpy(ubuf,(strpos + Tcl_DStringValue(&dstr)));
			strpos = 0;
		}
	}
	else {
		Tcl_DStringFree(&dstr);
		Tcl_DStringInit(&dstr);
		if (Tcl_Gets((Tcl_Channel)channel, &dstr) < 0) {
			/* probably EOF, but could be other read errors */
			*ubuf = '\0';
	       		return NULL;
		}
		/* linend char(s) were stripped off by Tcl_Gets,
		 * append a canonical linenend. */
		Tcl_DStringAppend(&dstr,"\n",1);
		if (Tcl_DStringLength(&dstr) > n) {
			/* first chunk */
			strncpy(ubuf,Tcl_DStringValue(&dstr),n-1);
			strpos = n-1;
			ubuf[n] = '\0';
		}
		else {
			/* single chunk */
			strcpy(ubuf,Tcl_DStringValue(&dstr));
		}
	}
	return ubuf;
		
#if 0
	if (!n) { /* a call with n==0 (from aglexinit) resets */
		mempos = (char *)mbuf;  /* cast from FILE* required by API */
	}

	clp = to = ubuf;
	for (i=0; i<n-1; i++) { /* leave room for terminator */
		if (*mempos == '\0') {
			if (i) { /* if mbuf doesn't end in \n, provide one */
				*to++ = '\n';
			}
			else {  /* all done */
				clp = NULL;
				mempos = NULL;
			}
			break; /* last line or end-of-buffer */
		}
		if (*mempos == '\n') {
			*to++ = *mempos++;
			break; /* all done with this line */
		}
		*to++ = *mempos++; /* copy character */
	}
	*to++ = '\0';  /* place terminator in ubuf */
	return clp;
#endif
}

static int
dotread(ClientData clientData, Tcl_Interp *interp,
#ifndef TCLOBJ
    int argc, char *argv[]
#else /* TCLOBJ */
	int argc, Tcl_Obj *CONST objv[]
#endif /* TCLOBJ */
)
{
	GVC_t          *gvc;
	Agraph_t       *g;
	Tcl_Channel	channel;
	int		mode;

	if (argc < 2) {
		Tcl_AppendResult(interp, "wrong # args: should be \"",
			argv[0], " fileHandle\"", (char *) NULL);
		return TCL_ERROR;
	}
	channel  = Tcl_GetChannel(interp, argv[1], &mode);
	if (channel == NULL || ! (mode & TCL_READABLE)) {
		Tcl_AppendResult(interp, "\nChannel \"",
			argv[1], "\"", "is unreadable.", (char *) NULL);
		return TCL_ERROR;
	}
        gvc = (GVC_t *)clientData;
	/*
	 * read a graph from the channel, the channel is left open
	 *   ready to read the first line after the last line of
	 *   a properly parsed graph. If the graph doesn't parse
	 *   during reading then the channel will be left at EOF
	 */
	g = agread_usergets((FILE *)channel, (mygets)); 
	if (!g) {
		Tcl_AppendResult(interp, "\nFailure to read graph \"",
			argv[1], "\"", (char *) NULL);
		if (agerrors()) {
			Tcl_AppendResult(interp, " because of syntax errors.",
				(char *) NULL);
		}
		return TCL_ERROR;
	}
	if (agerrors()) {
		Tcl_AppendResult(interp, "\nSyntax errors in file \"",
			argv[1], " \"", (char *) NULL);
		return TCL_ERROR;
	}
	/* we use GD_drawing(g) as a flag that layout has been done.
	 * so we make sure that it is initialized to "not done" */
	GD_drawing(g)=NULL;

	/* link graph to context */
	GD_gvc(g) = gvc;
	gvc->g = g;

	return (tcldot_fixup(interp, gvc));
}

static int
dotstring(ClientData clientData, Tcl_Interp *interp,
#ifndef TCLOBJ
    int argc, char *argv[]
#else /* TCLOBJ */
	int argc, Tcl_Obj *CONST objv[]
#endif /* TCLOBJ */
)
{
	GVC_t          *gvc;
	Agraph_t       *g;

	if (argc < 2) {
		Tcl_AppendResult(interp, "wrong # args: should be \"",
			argv[0], " string\"", (char *) NULL);
		return TCL_ERROR;
	}
	if (!(g = agmemread(argv[1]))) {
		Tcl_AppendResult(interp, "\nFailure to read string \"",
			argv[1], "\"", (char *) NULL);
		if (agerrors()) {
			Tcl_AppendResult(interp, " because of syntax errors.",
				(char *) NULL);
		}
		return TCL_ERROR;
	}
	if (agerrors()) {
		Tcl_AppendResult(interp, "\nSyntax errors in string \"",
			argv[1], " \"", (char *) NULL);
		return TCL_ERROR;
	}
	/* we use GD_drawing(g) as a flag that layout has been done.
	 * so we make sure that it is initialized to "not done" */
	GD_drawing(g)=NULL;

	/* link graph to context */
        gvc = (GVC_t *)clientData;
	GD_gvc(g) = gvc;
	gvc->g = g;

	return (tcldot_fixup(interp, gvc));
}

#if defined(_BLD_tcldot) && defined(_DLL)
__EXPORT__
#endif
int
Tcldot_Init(Tcl_Interp *interp)
{
	GVC_t  *gvc;
	char *user;

#ifdef USE_TCL_STUBS
        if (Tcl_InitStubs(interp, TCL_VERSION, 0) == NULL) {
            return TCL_ERROR;
        }
#else
        if (Tcl_PkgRequire(interp, "Tcl", TCL_VERSION, 0) == NULL) {
            return TCL_ERROR;
        }
#endif
	if (Tcl_PkgProvide(interp, "Tcldot", VERSION) != TCL_OK) {
	    return TCL_ERROR;
	}

	Gdtclft_Init(interp);

	aginit();
	/* set persistent attributes here */
	agnodeattr(NULL, "label", NODENAME_ESC);

	/* create a GraphViz Context and pass a pointer to it in clientdata */
	user = username();
	gvc = gvNEWcontext(Info, user);

#ifndef TCLOBJ
	Tcl_CreateCommand(interp, "dotnew", dotnew,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
	Tcl_CreateCommand(interp, "dotread", dotread,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
	Tcl_CreateCommand(interp, "dotstring", dotstring,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#else /* TCLOBJ */
	Tcl_CreateObjCommand(interp, "dotnew", dotnew,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
	Tcl_CreateObjCommand(interp, "dotread", dotread,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
	Tcl_CreateObjCommand(interp, "dotstring", dotstring,
		(ClientData) gvc, (Tcl_CmdDeleteProc *) NULL);
#endif /* TCLOBJ */

	graphTblPtr = (void *) tclhandleInit("graph", sizeof(Agraph_t *), 10);
	nodeTblPtr = (void *) tclhandleInit("node", sizeof(Agnode_t *), 100);
	edgeTblPtr = (void *) tclhandleInit("edge", sizeof(Agedge_t *), 100);

	return TCL_OK;
}

int
Tcldot_SafeInit(Tcl_Interp * interp)
{
	return Tcldot_Init(interp);
}