ref: 09cf3c0ae6c0fed01e32a149f4668b7a7d52944b
dir: /appl/lib/ubfa.b/
implement UBFa;
#
# UBF(A) data encoding interpreter
#
include "sys.m";
sys: Sys;
include "bufio.m";
bufio: Bufio;
Iobuf: import bufio;
include "ubfa.m";
Syntax: exception(string);
Badwrite: exception;
dict: array of list of string;
dictlock: chan of int;
init(m: Bufio)
{
sys = load Sys Sys->PATH;
bufio = m;
dict = array[74] of list of string;
dictlock = chan[1] of int;
}
uvatom(s: string): ref UValue.Atom
{
return ref UValue.Atom(uniq(s));
}
uvint(i: int): ref UValue.Int
{
return ref UValue.Int(i);
}
uvbig(i: big): ref UValue.Int
{
return ref UValue.Int(int i);
}
uvbinary(a: array of byte): ref UValue.Binary
{
return ref UValue.Binary(a);
}
uvstring(s: string): ref UValue.String
{
return ref UValue.String(s);
}
uvtuple(a: array of ref UValue): ref UValue.Tuple
{
return ref UValue.Tuple(a);
}
uvlist(l: list of ref UValue): ref UValue.List
{
return ref UValue.List(l);
}
uvtag(s: string, o: ref UValue): ref UValue.Tag
{
return ref UValue.Tag(uniq(s), o);
}
# needed only to avoid O(n) len s.s
Stack: adt {
s: list of ref UValue;
n: int;
new: fn(): ref Stack;
pop: fn(s: self ref Stack): ref UValue raises(Syntax);
push: fn(s: self ref Stack, o: ref UValue);
};
Stack.new(): ref Stack
{
return ref Stack(nil, 0);
}
Stack.pop(s: self ref Stack): ref UValue raises(Syntax)
{
if(--s.n < 0 || s.s == nil)
raise Syntax("parse stack underflow");
v := hd s.s;
s.s = tl s.s;
return v;
}
Stack.push(s: self ref Stack, o: ref UValue)
{
s.s = o :: s.s;
s.n++;
}
Parse: adt {
input: ref Iobuf;
stack: ref Stack;
reg: array of ref UValue;
getb: fn(nil: self ref Parse): int raises(Syntax);
unget: fn(nil: self ref Parse);
};
Parse.getb(p: self ref Parse): int raises(Syntax)
{
c := p.input.getb();
if(c < 0){
if(c == Bufio->EOF)
raise Syntax("unexpected end-of-file");
raise Syntax(sys->sprint("read error: %r"));
}
return c;
}
Parse.unget(p: self ref Parse)
{
p.input.ungetb();
}
uniq(s: string): string
{
if(s == nil)
return "";
dictlock <-= 1;
h := 0;
for(i:=0; i<len s; i++){
h = (h<<4) + s[i];
if((g := h & int 16rF0000000) != 0)
h ^= ((g>>24) & 16rFF) | g;
}
h = (h & Sys->Maxint)%len dict;
for(l := dict[h]; l != nil; l = tl l)
if(hd l == s){
s = hd l; # share space
break;
}
if(l == nil)
dict[h] = s :: dict[h];
<-dictlock;
return s;
}
writeubf(out: ref Iobuf, obj: ref UValue): int
{
{
# write it out, put final '$'
if(out != nil)
writeobj(out, obj);
putc(out, '$');
return 0;
}exception{
Badwrite =>
return -1;
}
}
readubf(input: ref Iobuf): (ref UValue, string)
{
{
return (getobj(ref Parse(input, Stack.new(), array[256] of ref UValue)), nil);
}exception e{
Syntax =>
return (nil, sys->sprint("ubf error: offset %bd: %s", input.offset(), e));
}
}
UValue.isatom(o: self ref UValue): int
{
return tagof o == tagof UValue.Atom;
}
UValue.isstring(o: self ref UValue): int
{
return tagof o == tagof UValue.String;
}
UValue.isint(o: self ref UValue): int
{
return tagof o == tagof UValue.Int;
}
UValue.islist(o: self ref UValue): int
{
return tagof o == tagof UValue.List;
}
UValue.istuple(o: self ref UValue): int
{
return tagof o == tagof UValue.Tuple;
}
UValue.isbinary(o: self ref UValue): int
{
return tagof o == tagof UValue.Binary;
}
UValue.istag(o: self ref UValue): int
{
return tagof o == tagof UValue.Tag;
}
UValue.isop(o: self ref UValue, op: string, arity: int): int
{
pick r := o {
Tuple =>
if(len r.a > 0 && (arity <= 0 || len r.a == arity))
pick s := r.a[0] {
Atom =>
return s.name == op;
String =>
return s.s == op;
}
}
return 0;
}
UValue.op(o: self ref UValue, arity: int): string
{
pick r := o {
Tuple =>
if(len r.a > 0 && (arity <= 0 || len r.a == arity))
pick s := r.a[0] {
Atom =>
return s.name;
String =>
return s.s;
}
}
return nil;
}
UValue.args(o: self ref UValue, arity: int): array of ref UValue
{
pick r := o {
Tuple =>
if(len r.a > 0 && (arity <= 0 || len r.a == arity))
return r.a[1:];
}
return nil;
}
UValue.els(o: self ref UValue): list of ref UValue
{
pick r := o {
List =>
return r.l;
}
return nil;
}
UValue.val(o: self ref UValue): int
{
pick r := o {
Int =>
return r.value;
}
return 0;
}
UValue.objtag(o: self ref UValue): string
{
pick r := o {
Tag =>
return r.name;
}
return nil;
}
UValue.obj(o: self ref UValue): ref UValue
{
pick r := o {
Tag =>
return r.o;
}
return o;
}
UValue.binary(o: self ref UValue): array of byte
{
pick r := o {
Atom =>
return array of byte r.name;
String =>
return array of byte r.s;
Binary =>
return r.a;
}
return nil;
}
UValue.text(o: self ref UValue): string
{
pick r := o {
Atom =>
return r.name;
String =>
return r.s;
Int =>
return string r.value;
Tuple =>
s := "{";
for(i := 0; i < len r.a; i++)
s += " "+r.a[i].text();
return s+"}";
List =>
s := "[";
for(l := r.l; l != nil; l = tl l)
s += " "+(hd l).text();
return s+"]";
Binary =>
s := "<<";
for(i := 0; i < len r.a; i++)
s += sys->sprint(" %.2ux", int r.a[i]);
return s+">>";
Tag =>
return "{'$TYPE', "+r.name+", "+r.o.text()+"}";
* =>
return "unknown";
}
}
UValue.eq(o: self ref UValue, v: ref UValue): int
{
if(v == nil)
return 0;
if(o == v)
return 1;
pick r := o {
Atom =>
pick s := v {
Atom =>
return r.name == s.name;
}
return 0;
String =>
pick s := v {
String =>
return r.s == s.s;
}
return 0;
Int =>
pick s := v {
Int =>
return r.value == s.value;
}
return 0;
Tuple =>
pick s := v {
Tuple =>
if(len r.a != len s.a)
return 0;
for(i := 0; i < len r.a; i++)
if(!r.a[i].eq(s.a[i]))
return 0;
return 1;
}
return 0;
List =>
pick s := v {
List =>
l1 := r.l;
l2 := s.l;
while(l1 != nil && l2 != nil){
if(!(hd l1).eq(hd l2))
return 0;
l1 = tl l1;
l2 = tl l2;
}
return l1 == l2;
}
return 0;
Binary =>
pick s := v {
Binary =>
if(len r.a != len s.a)
return 0;
for(i := 0; i < len r.a; i++)
if(r.a[i] != s.a[i])
return 0;
return 1;
}
return 0;
Tag =>
pick s := v {
Tag =>
return r.name == s.name && r.o.eq(s.o);
}
return 0;
* =>
raise "ubf: bad object"; # can't happen
}
}
S: con byte 1;
special := array[256] of {
'\n' or '\r' or '\t' or ' ' or ',' => S,
'}' => S, '$' => S, '>' => S, '#' => S, '&' => S,
'"' => S, '\'' => S, '{' => S, '~' => S, '-' => S,
'0' to '9' => S, '%' => S, '`' => S, * => byte 0
};
getobj(p: ref Parse): ref UValue raises(Syntax)
{
{
for(;;){
case p.getb() {
'\n' or '\r' or '\t' or ' ' or ',' =>
; # white space
'%' =>
while((c := p.getb()) != '%'){
if(c == '\\'){ # do comments really use \?
c = p.getb();
if(c != '\\' && c != '%')
raise Syntax("invalid escape in comment");
}
}
'}' =>
a := array[p.stack.n] of ref UValue;
for(i := len a; --i >= 0;)
a[i] = p.stack.pop();
return ref UValue.Tuple(a);
'$' =>
if(p.stack.n != 1)
raise Syntax("unbalanced stack: size "+string p.stack.n);
return p.stack.pop();
'>' =>
r := p.getb();
if(special[r] == S)
raise Syntax("invalid register name");
p.reg[r] = p.stack.pop();
'`' =>
t := uniq(readdelimitedstring(p, '`'));
p.stack.push(ref UValue.Tag(t, p.stack.pop()));
* =>
p.unget();
p.stack.push(readobj(p));
}
}
}exception{
Syntax =>
raise;
}
}
readobj(p: ref Parse): ref UValue raises(Syntax)
{
{
case c := p.getb() {
'#' =>
return ref UValue.List(nil);
'&' =>
a := p.stack.pop();
b := p.stack.pop();
pick r := b {
List =>
return ref UValue.List(a :: r.l); # not changed in place: might be shared register value
* =>
raise Syntax("can't make cons with cdr "+b.text());
}
'"' =>
return ref UValue.String(readdelimitedstring(p, c));
'\'' =>
return ref UValue.Atom(uniq(readdelimitedstring(p, c)));
'{' =>
obj := getobj(ref Parse(p.input, Stack.new(), p.reg));
if(!obj.istuple())
raise Syntax("expected tuple: obj");
return obj;
'~' =>
o := p.stack.pop();
if(!o.isint())
raise Syntax("expected Int before ~");
n := o.val();
if(n < 0)
raise Syntax("negative length for binary");
a := array[n] of byte;
n = p.input.read(a, len a);
if(n != len a){
if(n != Bufio->ERROR)
sys->werrstr("short read");
raise Syntax(sys->sprint("cannot read binary data: %r"));
}
if(p.getb() != '~')
raise Syntax("missing closing ~");
return ref UValue.Binary(a);
'-' or '0' to '9' =>
p.unget();
return ref UValue.Int(int readinteger(p));
* =>
if(p.reg[c] != nil)
return p.reg[c];
p.unget(); # point to error
raise Syntax(sys->sprint("invalid start character/undefined register #%.2ux",c));
}
}exception{
Syntax =>
raise;
}
}
readdelimitedstring(p: ref Parse, delim: int): string raises(Syntax)
{
{
s := "";
while((c := p.input.getc()) != delim){ # note: we'll use UTF-8
if(c < 0){
if(c == Bufio->ERROR)
raise Syntax(sys->sprint("read error: %r"));
raise Syntax("unexpected end of file");
}
if(c == '\\'){
c = p.getb();
if(c != '\\' && c != delim)
raise Syntax("invalid escape");
}
s[len s] = c;
}
return s;
}exception{
Syntax =>
raise;
}
}
readinteger(p: ref Parse): big raises(Syntax)
{
sign := 1;
c := p.getb();
if(c == '-'){
sign = -1;
c = p.getb();
if(!(c >= '0' && c <= '9'))
raise Syntax("expected integer literal");
}
for(n := big 0; c >= '0' && c <= '9'; c = p.getb()){
n = n*big 10 + big((c-'0')*sign);
if(n > big Sys->Maxint || n < big(-Sys->Maxint-1))
raise Syntax("integer overflow");
}
p.unget();
return n;
}
writeobj(out: ref Iobuf, o: ref UValue) raises(Badwrite)
{
{
pick r := o {
Atom =>
writedelimitedstring(out, r.name, '\'');
String =>
writedelimitedstring(out, r.s, '"');
Int =>
puts(out, string r.value);
Tuple => # { el * }
putc(out, '{');
for(i := 0; i < len r.a; i++){
if(i != 0)
putc(out, ' ');
writeobj(out, r.a[i]);
}
putc(out, '}');
List => # # eN & eN-1 & ... & e0 &
putc(out, '#');
# put them out in reverse order, each followed by '&'
rl: list of ref UValue;
for(l := r.l; l != nil; l = tl l)
rl = hd l :: rl;
for(; rl != nil; rl = tl rl){
writeobj(out, hd rl);
putc(out, '&');
}
Binary => # Int ~data~
puts(out, string len r.a);
putc(out, '~');
if(out.write(r.a, len r.a) != len r.a)
raise Badwrite;
putc(out, '~');
Tag => # obj `tag`
writeobj(out, r.o);
writedelimitedstring(out, r.name, '`');
* =>
raise "ubf: unknown object"; # can't happen
}
}exception{
Badwrite =>
raise;
}
}
writedelimitedstring(out: ref Iobuf, s: string, d: int) raises(Badwrite)
{
{
putc(out, d);
for(i := 0; i < len s; i++){
c := s[i];
if(c == d || c == '\\')
putc(out, '\\');
putc(out, c);
}
putc(out, d);
}exception{
Badwrite =>
raise;
}
}
puts(out: ref Iobuf, s: string) raises(Badwrite)
{
if(out.puts(s) == Bufio->ERROR)
raise Badwrite;
}
putc(out: ref Iobuf, c: int) raises(Badwrite)
{
if(out.putc(c) == Bufio->ERROR)
raise Badwrite;
}