RFR of constants API

[Brian Goetz]

I’ve split this work off from JEP 303:
    https://bugs.openjdk.java.net/browse/JDK-8203252 <https://bugs.openjdk.java.net/browse/JDK-8203252>


> On May 15, 2018, at 5:36 PM, Vicente Romero <vicente.romero at oracle.com> wrote:
> 
> note: forwarding to amber-dev, also I forgot adding that this work was done under JEP 303 but will be put back under its own JEP earlier than 303.
> 
> Hi all,
> I've run javadoc [1] for the three following packages: java.lang, 
> java.lang.invoke, and the new java.lang.invoke.constant. The highlights:
> 
> - java.lang.invoke.constant: The ConstantDesc hierarchy, which models 
> "descriptors" for constant values. (Interfaces in the ConstantDesc 
> hierarchy correspond to the various kinds of constant pool entry in JVMS 
> 4.4. Just as the JVM resolves a constant pool entry in order to yield a 
> value, you can ask a ConstantDesc object to resolve itself in order to 
> yield the value "described" by the object.) Also, the factory interface 
> Constable, which an ordinary class can implement in order to map its 
> constant values to descriptors.
> 
> - java.lang.invoke: MethodHandle, MethodType, and VarHandle implement 
> Constable. Also, new types that model type descriptors, field 
> descriptors, and method descriptors from JVMS 4.3. Also, the Intrinsics 
> class with methods to instruct the compiler to generate `ldc` and 
> `invokedynamic` bytecodes.
> 
> - java.lang: Class, String, Integer, etc implement Constable. Also, 
> Class implements j.l.i.FieldTypeDescriptor. Also, String, Integer, etc 
> implement ConstantDesc.
> 
> Also as a reference [2] is the last webrev.
> 
> Thanks,
> Vicente
> 
> 
> [1] 
> http://cr.openjdk.java.net/~vromero/constant.api/javadoc.03/java.base-summary.html <http://cr.openjdk.java.net/~vromero/constant.api/javadoc.03/java.base-summary.html>
> [2] 
> http://cr.openjdk.java.net/~vromero/constant.api/webrev.03/constants.api.patch <http://cr.openjdk.java.net/~vromero/constant.api/webrev.03/constants.api.patch>
> 
> On 04/27/2018 01:31 PM, Vicente Romero wrote:
> > Hi all,
> >
> > Please review the current proposal of the constants API, which are 
> > nominal descriptor types defined in pkg java.lang.invoke.constant. The 
> > code can be found at [1]. This API is being developed in the context 
> > of JEP 303: Intrinsics for the LDC and INVOKEDYNAMIC Instructions [2]
> >
> > Thanks in advance for your comments,
> > Vicente
> >
> > [1] http://cr.openjdk.java.net/~vromero/constant.api/webrev.00 <http://cr.openjdk.java.net/~vromero/constant.api/webrev.00>
> > [2] http://openjdk.java.net/jeps/303 <http://openjdk.java.net/jeps/303>
>