double declaration(bool is_const)
//Handle 'name = expression'
//Declare a variable called "name" with initial value "expresion"
{
Token t = ts.get();
if (t.kind != name)
error("name expected in declaration");
string var_name = t.name;
Token t2 = ts.get();
if (t2.kind != '=')
error("= missing in declaration of ",var_name);
double d = expression();
switch (is_const) {
case true:
symtable.declare(var_name, d, true);
break;
default:
if (symtable.is_declared(var_name))
symtable.set(var_name, d);
else
symtable.declare(var_name, d, false);
}
return d;
}
double primary()
{
Token t = ts.get();
switch (t.kind) {
case '(':
{
double d = expression();
t = ts.get();
if (t.kind != ')') error("expected ')'");
return d;
}
case '{':
{
double d = expression();
t = ts.get();
if (t.kind != '}') error("expected '}'");
return d;
}
case number:
return t.value;
case '-':
return - primary();
case '+':
return primary();
case name:
{
Token next = ts.get();
if (next.kind == '=') {
double d = expression();
sym_table.set(t.name,d);
return d;
}
else {
ts.putback(next);
return sym_table.get(t.name);
}
}
default:
error("primary expected");
}
}
