FormatString = Object.subtype(#FormatString);

FormatString.new(elements) {
    self = super.new();
    self.elements = elements;
    self;
}

FormatString.__eval__(env) {
    local result = "";
    for(elem in self.elements) {
        local elemval = elem.__eval__(env);
        if (elemval.__name__ == #String) {
            result.push(elemval);
        } else {
            elemval.__codeon__(result);
        }
    }
    result;
}

FormatString.__codeon__(str) {
    str.push("f\"");
    for(elem in self.elements) {
        if (elem.__name__ == #String) {
            str.push(elem.escaped());
        } else {
            str.push("$");
            elem.__codeon__(str);
        }
    }
    str.push("\"");
}

nonSpaceEatingId = parseDefinition(
"nonSpaceEatingId = < LETTER ALNUM* >           { $$ = intern(yytext) }
");

nonSpaceEatingBlock = parseDefinition(
"nonSpaceEatingBlock = LBRACE b:mkobj
                     (  e:stmt                  { $$ = b.push(e) }
                     )* \"}\"                   { $$ = b }
");

fStringChar = parseDefinition(
"fStringChar = < (!\"\\\"\" !\"$\" char )+ > { $$ = yytext.unescaped() }
             | \"\\\\$\"                     { $$ = \"$\" }
");

fStringRule = parseDefinition(
"fstring = \"f\\\"\" elements:mkobj
        ( \"$\" i:nonSpaceEatingId              { $$ = elements.push(GetVar.new(name: i)) }
        | \"$\" b:nonSpaceEatingBlock           { $$ = elements.push(Block.new(body: b)) }
        | c:fStringChar                         { $$ = elements.push(c) }
        )* \"\\\"\"                             { $$ = FormatString.new(elements) }
");

// regenerate the expression to be executed
metaGrammar.addRule(nonSpaceEatingBlock.name, nonSpaceEatingBlock.expression);
metaGrammar.addRule(nonSpaceEatingId.name, nonSpaceEatingId.expression);
metaGrammar.addRule(fStringChar.name, fStringChar.expression);
metaGrammar.addRule(fStringRule.name, fStringRule.expression);

metaGrammar.primary.prepend("fstring");

formatInt(integer) {
    if (integer > 1000) {
        return f"${formatInt((integer - integer % 1000) / 1000)},${integer % 1000}";
    }
    return f"$integer";
}
a = 69;
print(f"Reimu has $a power and ${6*7} point items and \$${ formatInt(1 << 32) } money.\n");

n = 100;
print(f"Sum of integers from 1 to $n : ${local sum = 0; for (i in n + 1) sum += i}\n");
print(f"${formatInt.function}\n");

//{
//    print(f"${__env__()}\n");
//}