void prompt(void) {
char buf[IDLEN+1];
#if defined(TINY_BUILD)
msgp(M_prompt);
#else
// Run the script named "prompt" if there is one else print "> "
strncpy_P(buf, getmsg(M_promptid), IDLEN); // get the name "prompt" in our cmd buf
if (findscript(buf)) doCommand(buf);
else if (find_user_function(buf)) dofunctioncall(symval);
else msgp(M_prompt); // else print default prompt
#endif
}
//
// Recursive descent parser, old-school style.
//
void getfactor(void) {
numvar thesymval = symval;
byte thesym = sym;
getsym(); // eat the sym we just saved
switch (thesym) {
case s_nval:
vpush(thesymval);
break;
case s_nvar:
if (sym == s_equals) { // assignment, push is after the break;
getsym();
assignVar(thesymval, getnum());
}
else if (sym == s_incr) { // postincrement nvar++
vpush(getVar(thesymval));
assignVar(thesymval, getVar(thesymval) + 1);
getsym();
break;
}
else if (sym == s_decr) { // postdecrement nvar--
vpush(getVar(thesymval));
assignVar(thesymval, getVar(thesymval) - 1);
getsym();
break;
}
vpush(getVar(thesymval)); // both assignment and reference get pushed here
break;
case s_nfunct:
dofunctioncall(thesymval); // get its value onto the stack
break;
// Script-function-returning-value used as a factor
case s_script_eeprom: // macro returning value
callscriptfunction(SCRIPT_EEPROM, findend(thesymval));
break;
case s_script_progmem:
callscriptfunction(SCRIPT_PROGMEM, thesymval);
break;
case s_script_file:
callscriptfunction(SCRIPT_FILE, (numvar) 0); // name implicitly in idbuf!
break;
case s_apin: // analog pin reference like a0
if (sym == s_equals) { // digitalWrite or analogWrite
getsym();
analogWrite(thesymval, getnum());
vpush(expval);
}
else vpush(analogRead(thesymval));
break;
case s_dpin: // digital pin reference like d1
if (sym == s_equals) { // digitalWrite or analogWrite
getsym();
digitalWrite(thesymval, getnum());
vpush(expval);
}
else vpush(digitalRead(thesymval));
break;
case s_incr:
if (sym != s_nvar) expected(M_var);
assignVar(symval, getVar(symval) + 1);
vpush(getVar(symval));
getsym();
break;
case s_decr: // pre decrement
if (sym != s_nvar) expected(M_var);
assignVar(symval, getVar(symval) - 1);
vpush(getVar(symval));
getsym();
break;
case s_arg: // arg(n) - argument value
if (sym != s_lparen) expectedchar(s_lparen);
getsym(); // eat '('
vpush(getarg(getnum()));
if (sym != s_rparen) expectedchar(s_rparen);
getsym(); // eat ')'
break;
case s_lparen: // expression in parens
getexpression();
if (exptype != s_nval) expected(M_number);
if (sym != s_rparen) missing(M_rparen);
vpush(expval);
getsym(); // eat the )
break;
//
// The Family of Unary Operators, which Bind Most Closely to their Factor
//
case s_add: // unary plus (like +3) is kind of a no-op
getfactor(); // scan a factor and leave its result on the stack
break; // done
case s_sub: // unary minus (like -3)
getfactor();
vpush(-vpop()); // similar to above but we adjust the stack value
break;
case s_bitnot:
getfactor();
vpush(~vpop());
break;
case s_logicalnot:
getfactor();
vpush(!vpop());
break;
case s_bitand: // &var gives address-of-var; ¯o gives eeprom address of macro
if (sym == s_nvar) vpush((numvar) &vars[symval]);
else if (sym == s_script_eeprom) vpush(symval);
else expected(M_var);
getsym(); // eat the var reference
break;
case s_mul: // *foo is contents-of-address-foo; *foo=bar is byte poke assignment
/*****
// what is really acceptable for an lvalue here? ;)
// *y = 5 is failing now by assigning 5 to y before the * is dereferenced
// due to calling getfactor
// everything else works :(
*****/
getfactor();
#if 0
if (sym == s_equals) {
getsym(); // eat '='
getexpression();
* (volatile byte *) vpop() = (byte) expval;
vpush((numvar) (byte) expval);
}
else
#endif
vpush((numvar) (* (volatile byte *) vpop()));
break;
default:
unexpected(M_number);
}
}
