static value_t fl_top_level_value(value_t *args, u_int32_t nargs)
{
argcount("top-level-value", nargs, 1);
symbol_t *sym = tosymbol(args[0], "top-level-value");
if (sym->binding == UNBOUND)
fl_raise(fl_list2(UnboundError, args[0]));
return sym->binding;
}
static value_t fl_f_raise(value_t *args, u_int32_t nargs)
{
argcount("raise", nargs, 1);
fl_raise(args[0]);
}
// label is the backreference we'd like to fix up with this read
static value_t do_read_sexpr(value_t label)
{
value_t v, sym, oldtokval, *head;
value_t *pv;
u_int32_t t;
char c;
t = peek();
take();
switch (t) {
case TOK_CLOSE:
lerror(ParseError, "read: unexpected ')'");
case TOK_CLOSEB:
lerror(ParseError, "read: unexpected ']'");
case TOK_DOT:
lerror(ParseError, "read: unexpected '.'");
case TOK_SYM:
case TOK_NUM:
return tokval;
case TOK_COMMA:
head = , goto listwith;
case TOK_COMMAAT:
head = &COMMAAT; goto listwith;
case TOK_COMMADOT:
head = &COMMADOT; goto listwith;
case TOK_BQ:
head = &BACKQUOTE; goto listwith;
case TOK_QUOTE:
head = "E;
listwith:
v = cons_reserve(2);
car_(v) = *head;
cdr_(v) = tagptr(((cons_t*)ptr(v))+1, TAG_CONS);
car_(cdr_(v)) = cdr_(cdr_(v)) = NIL;
PUSH(v);
if (label != UNBOUND)
ptrhash_put(&readstate->backrefs, (void*)label, (void*)v);
v = do_read_sexpr(UNBOUND);
car_(cdr_(Stack[SP-1])) = v;
return POP();
case TOK_SHARPQUOTE:
// femtoLisp doesn't need symbol-function, so #' does nothing
return do_read_sexpr(label);
case TOK_OPEN:
PUSH(NIL);
read_list(&Stack[SP-1], label);
return POP();
case TOK_SHARPSYM:
sym = tokval;
if (sym == tsym || sym == Tsym)
return FL_T;
else if (sym == fsym || sym == Fsym)
return FL_F;
// constructor notation
c = nextchar();
if (c != '(') {
take();
lerrorf(ParseError, "read: expected argument list for %s",
symbol_name(tokval));
}
PUSH(NIL);
read_list(&Stack[SP-1], UNBOUND);
if (sym == vu8sym) {
sym = arraysym;
Stack[SP-1] = fl_cons(uint8sym, Stack[SP-1]);
}
else if (sym == fnsym) {
sym = FUNCTION;
}
v = symbol_value(sym);
if (v == UNBOUND)
fl_raise(fl_list2(UnboundError, sym));
return fl_apply(v, POP());
case TOK_OPENB:
return read_vector(label, TOK_CLOSEB);
case TOK_SHARPOPEN:
return read_vector(label, TOK_CLOSE);
case TOK_SHARPDOT:
// eval-when-read
// evaluated expressions can refer to existing backreferences, but they
// cannot see pending labels. in other words:
// (... #2=#.#0# ... ) OK
// (... #2=#.(#2#) ... ) DO NOT WANT
sym = do_read_sexpr(UNBOUND);
if (issymbol(sym)) {
v = symbol_value(sym);
if (v == UNBOUND)
fl_raise(fl_list2(UnboundError, sym));
return v;
}
return fl_toplevel_eval(sym);
case TOK_LABEL:
// create backreference label
if (ptrhash_has(&readstate->backrefs, (void*)tokval))
lerrorf(ParseError, "read: label %ld redefined", numval(tokval));
oldtokval = tokval;
v = do_read_sexpr(tokval);
ptrhash_put(&readstate->backrefs, (void*)oldtokval, (void*)v);
return v;
case TOK_BACKREF:
// look up backreference
v = (value_t)ptrhash_get(&readstate->backrefs, (void*)tokval);
if (v == (value_t)HT_NOTFOUND)
lerrorf(ParseError, "read: undefined label %ld", numval(tokval));
return v;
case TOK_GENSYM:
pv = (value_t*)ptrhash_bp(&readstate->gensyms, (void*)tokval);
if (*pv == (value_t)HT_NOTFOUND)
*pv = fl_gensym(NULL, 0);
return *pv;
case TOK_DOUBLEQUOTE:
return read_string();
}
return FL_UNSPECIFIED;
}
