implement Engine; include "sys.m";	sys: Sys;include "draw.m";include "../spree.m";	spree: Spree;	Attributes, Range, Object, Clique, Member: import spree; clique: ref Clique; init(g: ref Clique, srvmod: Spree): string{	sys = load Sys Sys->PATH;	clique = g;	spree = srvmod;	return nil;} join(nil: ref Member): string{	return nil;} leave(nil: ref Member){} number := 0;currmember: ref Member; obj(ext: int): ref Object{	o := currmember.obj(ext);	if (o == nil)		sys->raise("parse:bad object");	return o;} Eusage: con "bad command usage"; assert(b: int, err: string){	if (b == 0)		sys->raise("parse:" + err);} command(member: ref Member, cmd: string): string{	e := ref Sys->Exception;	if (sys->rescue("parse:*", e) == Sys->EXCEPTION) {		sys->rescued(Sys->ONCE, nil);		currmember = nil;		return e.name[6:];	}	currmember = member;	(nlines, lines) := sys->tokenize(cmd, "\n");	assert(nlines > 0, "unknown command");	(n, toks) := sys->tokenize(hd lines, " ");	assert(n > 0, "unknown command");	case hd toks {	"new" =>			# new parent visibility\nvisibility attr val\nvisibility attr val...		assert(n == 3, Eusage);		setattrs(clique.newobject(obj(int hd tl toks), int hd tl tl toks), tl lines);	"deck" =>		stack := clique.newobject(nil, ~0);		stack.setattr("type", "stack", ~0);		for (i := 0; i < 6; i++) {			o := clique.newobject(stack, ~0);			o.setattr("face", "down", ~0);			o.setattr("number", string number++, 0);		}	"flip" =>		# flip objid start [end]		assert(n == 2 || n == 3 || n == 4, Eusage);		o := obj(int hd tl toks);		if (n > 2) {			start := int hd tl tl toks;			end := start + 1;			if (n == 4)				end = int hd tl tl tl toks;			assert(start >= 0 && start < len o.children &&					end >= start && end >= 0 && end <= len o.children, "index out of range");			for (; start < end; start++)				flip(o.children[start]);		} else			flip(o);			"set" =>			# set objid attr val		assert(n == 4, Eusage);		obj(int hd tl toks).setattr(hd tl tl toks, hd tl tl tl toks, ~0);	"vis" =>			# vis objid flags		assert(n == 3, Eusage);		obj(int hd tl toks).setvisibility(int hd tl tl toks);	"attrvis" =>		# attrvis objid attr flags		assert(n == 4, Eusage);		o := obj(int hd tl toks);		name := hd tl tl toks;		attr := o.attrs.get(name);		assert(attr != nil, "attribute not found");		o.setattrvisibility(name, int hd tl tl tl toks);	"show" =>			# show [memberid]		p: ref Member = nil;		if (n == 2) {			memberid := int hd tl toks;			p = clique.member(memberid);			assert(p != nil, "bad memberid");		}		clique.show(p);	"del" or "delete" =>			# del obj		assert(n == 2, Eusage);		obj(int hd tl toks).delete();	"tx" =>					# tx src from to dest [index]		assert(n == 5 || n == 6, Eusage);		src, dest: ref Object;		r: Range;		(src, toks) = (obj(int hd tl toks), tl tl toks);		(r.start, toks) = (int hd toks, tl toks);		(r.end, toks) = (int hd toks, tl toks);		(dest, toks) = (obj(int hd toks), tl toks);		index := len dest.children;		if (n == 6)			index = int hd toks;		assert(r.start >= 0 && r.start < len src.children &&				r.end >= 0 && r.end <= len src.children && r.end >= r.start,				"bad range");		src.transfer(r, dest, index);	* =>		assert(0, "bad command");	}	currmember = nil;	return nil;}  flip(o: ref Object){	face := o.getattr("face");	if (face == "down") {		face = "up";		o.setattrvisibility("number", ~0);	} else {		face = "down";		o.setattrvisibility("number", 0);	}	o.setattr("face", face, ~0);} setattrs(o: ref Object, lines: list of string): string{	for (; lines != nil; lines = tl lines) {		# attr val [visibility]		(n, toks) := sys->tokenize(hd lines, " ");		if (n != 2 && n != 3)			return "bad attribute line";		vis := 0;		if (n == 3)			vis = int hd tl tl toks;		o.setattr(hd toks, hd tl toks, vis);	}	return nil;}