why unexpected token: * in when doing operation over two lines

Question

Running the following in a 1.8 console:

def accessories = null
final int prime = 31;
int result = 1;
result = prime
    * result
        + ((accessories == null) ? 0 : accessories
                .hashCode());

I get a compilation error stating:

unexpected token: * at line: 5, column: 13

Yet, when I move "* result" up to the previous line, it compiles and runs cleanly. I've searched to try to find an explanation, but have had no luck thus far. Can someone explain?

def accessories = null
final int prime = 31;
int result = 1;
result = prime * result
        + ((accessories == null) ? 0 : accessories
                .hashCode());

Answer 1

Because Groovy's statements are not delimited by ;, but rather by line break. It can't know the line below is a continuation of the statement on the line above. You can escape the line break:

int i = 10 \
    * 9
assert i == 90

---

Update:

Actually Groovy does identify some statements as from the above line. At least the dot is recognized:

assert [1, 2]
  .join("")
  .padLeft(4, "a") == "aa12"

And a statement with either +, - and ~ (and maybe more) could be methods:

def m = "aa"
  - m // fails with "No signature of method: java.lang.String.negative()"

Answer 2

This is necessary because otherwise the parser for Groovy would have to do a lot more work.

There are lots of places ie:

String s = "tim"
             + "_yates"

Where it would be possible for the parser to work out what you meant, but in all of them, I believe it would involve backtracking (or implementing a two pass parse) which is slow