implement Format;include "sys.m";	sys: Sys;include "bufio.m";	bufio: Bufio;	Iobuf: import bufio;include "sexprs.m";	sexprs: Sexprs;	Sexp: import sexprs;include "format.m"; # possible addition?# se2spec(se: list of ref Sexp): (array of Fmtspec, string) init(){	sys = load Sys Sys->PATH;	sexprs = load Sexprs Sexprs->PATH;	sexprs->init();	bufio = load Bufio Bufio->PATH;} spec2se(spec: array of Fmtspec): list of ref Sexp{	l: list of ref Sexp;	for(i := len spec - 1; i >= 0; i--){		if((sp := spec[i]).fields != nil)			l = ref Sexp.List(ref Sexp.String(sp.name, nil) :: spec2se(sp.fields)) :: l;		else if(sp.name != nil)			l = ref Sexp.String(sp.name, nil) :: l;	}	return l;} spec2fmt(specs: array of Fmtspec): array of Fmt{	if(specs == nil)		return nil;	f := array[len specs] of Fmt;	for(i := 0; i < len specs; i++){		if(specs[i].name == nil)			f[i].kind = -1;		else			f[i] = (i, spec2fmt(specs[i].fields));	}	return f;}  se2fmt(spec: array of Fmtspec, se: ref Sexp): (array of Fmt, string){	if(!se.islist())		return (nil, "format must be a list");	return ses2fmt(spec, se.els());} ses2fmt(spec: array of Fmtspec, els: list of ref Sexp): (array of Fmt, string){	a := array[len els] of Fmt;	for(i := 0; els != nil; els = tl els){		name := (hd els).op();		for(j := 0; j < len spec; j++)			if(spec[j].name == name)				break;		if(j == len spec)			return (nil, sys->sprint("format name %#q not found", name));		sp := spec[j];		if((hd els).islist() == 0)			a[i++] = Fmt(j, spec2fmt(sp.fields));		else if(sp.fields == nil)			return (nil, sys->sprint("unexpected list %#q", name));		else{			(f, err) := ses2fmt(sp.fields, (hd els).args());			if(f == nil)				return (nil, err);			a[i++] = Fmt(j, f);		}	}	return (a, nil);} rec2val(spec: array of Fmtspec, se: ref Sexprs->Sexp): (array of Fmtval, string){	if(se.islist() == 0)		return (nil, "expected list of fields; got "+se.text());	els := se.els();	if(len els > len spec)		return (nil, sys->sprint("too many fields found, expected %d, got %s", len spec, se.text()));	a := array[len spec] of Fmtval;	err: string;	for(i := 0; i < len spec; i++){		f := spec[i];		if(f.name == nil)			continue;		if(els == nil)			return (nil, sys->sprint("too few fields found, expected %d, got %s", len spec, se.text()));		el := hd els;		if(f.fields == nil)			a[i].val = el;		else{			if(el.islist() == 0)				return (nil, "expected list of elements; got "+el.text());			vl := el.els();			a[i].recs = recs := array[len vl] of array of Fmtval;			for(j := 0; vl != nil; vl = tl vl){				(recs[j++], err) = rec2val(spec[i].fields, hd vl);				if(err != nil)					return (nil, err);			}		}		els = tl els;	}	return (a, nil);} Fmtval.text(v: self Fmtval): string{	return v.val.astext();}			 Fmtfile.new(spec: array of Fmtspec): Fmtfile{	return (spec, (ref Sexp.List(spec2se(spec))).pack());} Fmtfile.open(f: self Fmtfile, name: string): ref Bufio->Iobuf{	fd := sys->open(name, Sys->ORDWR);	if(fd == nil){		sys->werrstr(sys->sprint("open failed: %r"));		return nil;	}	if(sys->write(fd, f.descr, len f.descr) == -1){		sys->werrstr(sys->sprint("format write failed: %r"));		return nil;	}	sys->seek(fd, big 0, Sys->SEEKSTART);	return bufio->fopen(fd, Sys->OREAD);} Fmtfile.read(f: self Fmtfile, iob: ref Iobuf): (array of Fmtval, string){	(se, err) := Sexp.read(iob);	if(se == nil)		return (nil, err);	return rec2val(f.spec, se);}