public class PrecedenceTest
- extends Object
Provides static helper methods to indicate if parenthesization is
If your sub-expression has strictly higher precedence than you,
then no brackets are required: 2 + (4 * 5) = 2 + 4 * 5 is
unambiguous, because * has precedence 800 and + has precedence 700.
If your subexpression has lower precedence than you, then
brackets are required; otherwise you will bind to your
grandchild instead of the subexpression. 2 * (4 + 5) without
brackets would mean (2 * 4) + 5.
For a binary operation, if your left sub-expression has the same
precedence as you, no brackets are needed, since binary operations
are all left-associative. If your right sub-expression has the
same precedence than you, then brackets are needed to reproduce the
parse tree (otherwise, parsing will give e.g. (2 + 4) + 5 instead
of the 2 + (4 + 5) that you had to start with.) This is OK for
integer addition and subtraction, but not OK for floating point
multiplication. To be safe, let's put the brackets on.
For the high-precedence operations, I've assigned precedences of
950 to field reads and invoke expressions (.), as well as array reads ().
I've assigned 850 to cast, newarray and newinvoke.
The Dava DCmp?Expr precedences look fishy to me; I've assigned DLengthExpr
a precedence of 950, because it looks like it should parse like a field
read to me.
Basically, the only time I can see that brackets should be required
seems to occur when a cast or a newarray occurs as a subexpression of
an invoke or field read; hence 850 and 950. -PL
|Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public static boolean needsBrackets(ValueBox subExprBox,
public static boolean needsBracketsRight(ValueBox subExprBox,