Help detecting interface declarations using Sun Compiler Tree API
Hi,
I have an instance of com.sun.source.tree.ModifiersTree when parsing a Java source-code file. Invoking toString() on the ModifiersTree clearly shows the "interface" modifier yet when I try using the public getModifiers() method it does not return this modifier. The actual Modifier.java source code contains the following lines:
// See JLS2 sections 8.1.1, 8.3.1, 8.4.3, 8.8.3, and 9.1.1.
// java.lang.reflect.Modifier includes INTERFACE, but that's a VMism.
As far as I can tell, there is no way to detect whether a class declaration is an interface using the public API methods, and parsing toString() isn't really an option. Any ideas?
Thank you,
Gili
[703 byte] By [
cowwoca] at [2007-11-27 7:37:51]
# 1
> Hi,
>
> I have an instance of
> com.sun.source.tree.ModifiersTree when parsing a Java
> source-code file. Invoking toString() on the
> ModifiersTree clearly shows the "interface" modifier
> yet when I try using the public getModifiers() method
> it does not return this modifier. The actual
> Modifier.java source code contains the following
> lines:
You can't have an instance of an interface.
The toString() works because you are using the Class (java.lang.Class) not an instance.
>
> As far as I can tell, there is no way to detect
> whether a class declaration is an interface using the
> public API methods, and parsing toString() isn't
> really an option. Any ideas?
The following works exactly as I would expect it to and seems to demonstrate that the interface attribute is in use.
int m = Appendable.class.getModifiers();
System.out.println("getModifiers()=" + m);
System.out.println("interface=" + (m & java.lang.reflect.Modifier.INTERFACE));
# 2
You seem to misunderstand. When you use the Tree API you get the following method to implement:
public Void visitModifiers(ModifiersTree node, Void passback);
there is no way for me to use Class.getModifiers() in this context. I tried invoking node.getClass().getModifiers() and it didn't work. Aside from that I don't know what else you could have meant.
I peeked into the source-code of /j2se/src/share/classes/com/sun/tools/javac/tree/Pretty.java in the jdk7 repository and it looks like they cheat by invoking:
public void visitClassDef(JCClassDecl tree)
{
[...]
if ((tree.mods.flags & INTERFACE) != 0) {
print("interface " + tree.name);
}
When you could against the public API you don't have an instance of JCClassDecl (at least not portably) and you definitely can't access tree.mods.flags directly. I wish I could ask the authors of the Tree API somehow but I'm not sure how to reach them.
Gili
# 4
> You seem to misunderstand.
Yes.
> The problem seems to be that class
> Flags.asModifierSet() as seen at
> https://jdk-jrl-sources.dev.java.net/source/browse/jdk
> -jrl-sources/jdk7/trunk/j2se/src/share/classes/com/sun
> /tools/javac/code/Flags.java?rev=85&view=markup never
> returns INTERFACE as a possible flag. Could this be a
> bug in their code or am I missing something?
You can create a bug for it.
In terms of what you are doing you can create your own modification of the code that correctly implements what you need.
