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Handle multiple interface lambdas, stubs to handle bridging, marker interfaces
This commit is contained in:
Mike Hearn
Andras Slemmer
parent
8ff5f2a26a
commit
52d1ca9799
@ -33,9 +33,17 @@ import avian.Assembler;
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import avian.ConstantPool.PoolEntry;
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import avian.SystemClassLoader;
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// To understand what this is all about, please read:
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//
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// http://cr.openjdk.java.net/~briangoetz/lambda/lambda-translation.html
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public class LambdaMetafactory {
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private static int nextNumber = 0;
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public static final int FLAG_SERIALIZABLE = 1;
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public static final int FLAG_MARKERS = 2;
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public static final int FLAG_BRIDGES = 4;
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private static Class resolveReturnInterface(MethodType type) {
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int index = 1;
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byte[] s = type.spec;
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@ -212,13 +220,15 @@ public class LambdaMetafactory {
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new MethodHandle(implementationClass,
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implementationName,
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implementationSpec,
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implementationKind));
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implementationKind),
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emptyInterfaceList);
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}
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private static byte[] makeLambda(String invokedName,
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MethodType invokedType,
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MethodType methodType,
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MethodHandle methodImplementation)
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MethodHandle methodImplementation,
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Class[] interfaces)
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{
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String className;
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{ int number;
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@ -230,8 +240,12 @@ public class LambdaMetafactory {
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List<PoolEntry> pool = new ArrayList();
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int interfaceIndex = ConstantPool.addClass
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(pool, invokedType.returnType().getName().replace('.', '/'));
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int[] interfaceIndexes = new int[interfaces.length + 1];
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interfaceIndexes[0] = ConstantPool.addClass(pool, invokedType.returnType().getName().replace('.', '/'));
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for (int i = 0; i < interfaces.length; i++) {
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String name = interfaces[i].getName().replace('.', '/');
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interfaceIndexes[i + 1] = ConstantPool.addClass(pool, name);
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}
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List<FieldData> fieldTable = new ArrayList();
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@ -280,7 +294,7 @@ public class LambdaMetafactory {
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ByteArrayOutputStream out = new ByteArrayOutputStream();
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try {
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Assembler.writeClass
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(out, pool, nameIndex, superIndex, new int[] { interfaceIndex },
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(out, pool, nameIndex, superIndex, interfaceIndexes,
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fieldTable.toArray(new FieldData[fieldTable.size()]),
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methodTable.toArray(new MethodData[methodTable.size()]));
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} catch (IOException e) {
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@ -292,6 +306,24 @@ public class LambdaMetafactory {
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return out.toByteArray();
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}
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private static CallSite makeCallSite(MethodType invokedType, byte[] classData) throws AssertionError {
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try {
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return new CallSite
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(new MethodHandle
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(MethodHandle.REF_invokeStatic, invokedType.loader, Classes.toVMMethod
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(avian.SystemClassLoader.getClass
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(avian.Classes.defineVMClass
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(invokedType.loader, classData, 0, classData.length))
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.getMethod("make", invokedType.parameterArray()))));
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} catch (NoSuchMethodException e) {
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AssertionError error = new AssertionError();
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error.initCause(e);
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throw error;
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}
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}
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private static final Class[] emptyInterfaceList = new Class[] {};
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public static CallSite metafactory(MethodHandles.Lookup caller,
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String invokedName,
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MethodType invokedType,
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@ -300,30 +332,79 @@ public class LambdaMetafactory {
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MethodType instantiatedMethodType)
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throws LambdaConversionException
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{
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byte[] classData = makeLambda(invokedName, invokedType, methodType, methodImplementation);
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try {
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return new CallSite
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(new MethodHandle
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(MethodHandle.REF_invokeStatic, invokedType.loader, Classes.toVMMethod
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(avian.SystemClassLoader.getClass
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(avian.Classes.defineVMClass
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(invokedType.loader, classData, 0, classData.length))
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.getMethod("make", invokedType.parameterArray()))));
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} catch (NoSuchMethodException e) {
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AssertionError error = new AssertionError();
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error.initCause(e);
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throw error;
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}
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byte[] classData = makeLambda(invokedName, invokedType, methodType, methodImplementation, emptyInterfaceList);
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return makeCallSite(invokedType, classData);
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}
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public static CallSite altMetafactory(MethodHandles.Lookup caller,
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String invokedName,
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MethodType invokedType,
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Object... args)
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throws LambdaConversionException
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{
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// todo: handle flags
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return metafactory(caller, invokedName, invokedType, (MethodType) args[0], (MethodHandle) args[1], (MethodType) args[2]);
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Object... args) throws LambdaConversionException {
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// Behaves as if the prototype is like this:
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//
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// CallSite altMetafactory(
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// MethodHandles.Lookup caller,
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// String invokedName,
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// MethodType invokedType,
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// MethodType methodType,
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// MethodHandle methodImplementation,
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// MethodType instantiatedMethodType,
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// int flags,
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// int markerInterfaceCount, // IF flags has MARKERS set
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// Class... markerInterfaces, // IF flags has MARKERS set
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// int bridgeCount, // IF flags has BRIDGES set
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// MethodType... bridges // IF flags has BRIDGES set
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// )
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MethodType methodType = (MethodType) args[0];
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MethodHandle methodImplementation = (MethodHandle) args[1];
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int flags = (Integer) args[3];
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boolean serializable = (flags & FLAG_SERIALIZABLE) != 0;
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// Marker interfaces are added to a lambda when they're written like this:
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//
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// Runnable r = (Runnable & Serializable) () -> foo()
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//
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// The intersection type in the cast here indicates to the compiler what interfaces
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// the generated lambda class should implement. Because a lambda has (by definition)
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// one method only, it is meaningless for these interfaces to contain anything, thus
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// they are only allowed to be empty marker interfaces. In practice the Serializable
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// interface is handled specially and the use of markers is extremely rare. Adding
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// support would be easy though.
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if ((flags & FLAG_MARKERS) != 0)
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throw new UnsupportedOperationException("Marker interfaces on lambdas are not supported on Avian yet. Sorry.");
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// In some cases there is a mismatch between what the JVM type system supports and
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// what the Java language supports. In other cases the type of a lambda expression
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// may not perfectly match the functional interface which represents it. Consider the
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// following case:
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//
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// interface I { void foo(Integer i, String s1, Strings s2) }
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// class Foo { static void m(Number i, Object... rest) {} }
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//
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// I lambda = Foo::m
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//
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// This is allowed by the Java language, even though the interface representing the
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// lambda specifies three specific arguments and the method implementing the lambda
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// uses varargs and a different type signature. Behind the scenes the compiler generates
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// a "bridge" method that does the adaptation.
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//
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// You can learn more here: http://www.oracle.com/technetwork/java/jvmls2013heid-2013922.pdf
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// and here: http://cr.openjdk.java.net/~briangoetz/lambda/lambda-translation.html
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if ((flags & FLAG_BRIDGES) != 0) {
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int bridgeCount = (Integer) args[4];
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if (bridgeCount > 0)
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throw new UnsupportedOperationException("A lambda that requires bridge methods was used, this is not yet supported by Avian. Sorry.");
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}
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// TODO: This is not necessary if the function type interface is already inheriting
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// from Serializable.
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Class[] interfaces = new Class[serializable ? 1 : 0];
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if (serializable)
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interfaces[0] = java.io.Serializable.class;
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byte[] classData = makeLambda(invokedName, invokedType, methodType, methodImplementation, interfaces);
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return makeCallSite(invokedType, classData);
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}
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}
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