// errorf returns an error token and terminates the scan by passing
// back a nil pointer that will be the next state, terminating l.nextItem.
func (l *lexer) errorf(format string, args ...interface{}) LexFn {
l.tokens <- token.NewToken(token.ILLEGAL, l.start, fmt.Sprintf(format, args...))
return nil
}
/*func (i token.TokenType) String() string {
s := tokenName[i]
if s == "" {
return fmt.Sprintf("token%d", int(i))
}
return s
}*/
type lexTest struct {
name string
input string
tokens []token.Token
}
var (
tEOF = token.NewToken(token.EOF, 0, "")
tLParen = token.NewToken(token.LPAREN, 0, "(")
tRParen = token.NewToken(token.RPAREN, 0, ")")
)
var lexTests = []lexTest{
{"empty", "", []token.Token{tEOF}},
{"number", "2", []token.Token{
token.NewToken(token.INT, 0, "2"),
token.NewToken(token.EOF, 0, ""),
}},
{"add", "2 + 2", []token.Token{
token.NewToken(token.INT, 0, "2"),
token.NewToken(token.ADD, 0, "+"),
token.NewToken(token.INT, 0, "2"),
tEOF,
// emit passes an item back to the client.
func (l *lexer) emit(t token.TokenType) {
l.tokens <- token.NewToken(t, l.start, l.input[l.start:l.pos])
l.start = l.pos
}