import (
	"gop/scanner"
	"gop/token"
	"os"
)

func calc(expr string) string {
	var vals []float64
	s := scanner.new(expr, nil, 0)
	for {
		pos, tok, lit := s.scan()
		switch tok {
		case token.INT, token.FLOAT:
			vals <- lit.float!
		case token.ADD, token.SUB, token.MUL, token.QUO:
			x := len(vals) - 1
			switch tok {
			case token.ADD:
				vals[x-1] += vals[x]
			case token.SUB:
				vals[x-1] -= vals[x]
			case token.MUL:
				vals[x-1] *= vals[x]
			case token.QUO:
				vals[x-1] /= vals[x]
			}
			vals = vals[:x]
		case token.EOF, token.SEMICOLON:
			return vals[0].string
		default:
			return "${pos}: invalid token ${tok}"
		}
	}
}

print "> "
for line <- os.Stdin {
	print "${calc(line)}\n> "
}