Type of filter by reflection

[pvojtechovsky]

The type of the Filter does not have to be specified in constructor, but is computed by reflection from the matches parameter type.

This PR is based on #1013, so I have to rebase it after you merge #1013. Just have a look if code like this OK, or we can make it even simpler?

List<CtNewClass<?>> elements = foo.getElements(new AbstractFilter<CtNewClass<?>>() {
	@Override
	public boolean matches(CtNewClass<?> element) {
		return true;
	}
});

[monperrus]

you can go ahead with rebasing!

[pvojtechovsky]

You can already write it using java 8 lambda like this:

List<CtExpression<?>> expressions2 = foo.getElements((CtExpression<?> e)->true);

expressions2.forEach(it->{
	assertTrue(it instanceof CtExpression);
});

but it will not infer type correctly. It will fail with ClassCastException in call of matches. But it is expected and handled as not matches. I guess this ClassCastException has a performance impact...

May be in Java 9 the parameter type of lambda can be get by reflection.

[monperrus]

interesting. could you add tests to check that the inferred filteredType is correct?

[pvojtechovsky]

Can I replace all the calls of new AbstractFilter(CLASS), by new AbstractFilter() in all tests and all spoon code? It would be good test that it works. And it would shorten code again...

Should I will keep new AbstractFilter(CLASS) for compatibility?

[pvojtechovsky]

OK, I will add these tests probably tomorrow in the evening. Good night ;)

[pvojtechovsky]

Tests were added