org.codelibs.sai.internal.runtime.linker.SaiBeansLinker Maven / Gradle / Ivy
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package org.codelibs.sai.internal.runtime.linker;
import static org.codelibs.sai.internal.lookup.Lookup.MH;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import org.codelibs.sai.api.scripting.ScriptUtils;
import org.codelibs.sai.internal.dynalink.CallSiteDescriptor;
import org.codelibs.sai.internal.dynalink.beans.BeansLinker;
import org.codelibs.sai.internal.dynalink.linker.ConversionComparator.Comparison;
import org.codelibs.sai.internal.dynalink.linker.GuardedInvocation;
import org.codelibs.sai.internal.dynalink.linker.GuardingDynamicLinker;
import org.codelibs.sai.internal.dynalink.linker.LinkRequest;
import org.codelibs.sai.internal.dynalink.linker.LinkerServices;
import org.codelibs.sai.internal.dynalink.linker.MethodHandleTransformer;
import org.codelibs.sai.internal.dynalink.support.DefaultInternalObjectFilter;
import org.codelibs.sai.internal.dynalink.support.Lookup;
import org.codelibs.sai.internal.runtime.ConsString;
import org.codelibs.sai.internal.runtime.Context;
import org.codelibs.sai.internal.runtime.ScriptObject;
import org.codelibs.sai.internal.runtime.options.Options;
/**
* This linker delegates to a {@code BeansLinker} but passes it a special linker services object that has a modified
* {@code compareConversion} method that favors conversion of {@link ConsString} to either {@link String} or
* {@link CharSequence}. It also provides a {@link #createHiddenObjectFilter()} method for use with bootstrap that will
* ensure that we never pass internal engine objects that should not be externally observable (currently ConsString and
* ScriptObject) to Java APIs, but rather that we flatten it into a String. We can't just add this functionality as
* custom converters via {@code GuaardingTypeConverterFactory}, since they are not consulted when
* the target method handle parameter signature is {@code Object}. This linker also makes sure that primitive
* {@link String} operations can be invoked on a {@link ConsString}, and allows invocation of objects implementing
* the {@link FunctionalInterface} attribute.
*/
public class SaiBeansLinker implements GuardingDynamicLinker {
// System property to control whether to wrap ScriptObject->ScriptObjectMirror for
// Object type arguments of Java method calls, field set and array set.
private static final boolean MIRROR_ALWAYS = Options.getBooleanProperty("sai.mirror.always", true);
private static final MethodHandle EXPORT_ARGUMENT;
private static final MethodHandle IMPORT_RESULT;
private static final MethodHandle FILTER_CONSSTRING;
static {
final Lookup lookup = new Lookup(MethodHandles.lookup());
EXPORT_ARGUMENT = lookup.findOwnStatic("exportArgument", Object.class, Object.class);
IMPORT_RESULT = lookup.findOwnStatic("importResult", Object.class, Object.class);
FILTER_CONSSTRING = lookup.findOwnStatic("consStringFilter", Object.class, Object.class);
}
// cache of @FunctionalInterface method of implementor classes
private static final ClassValue FUNCTIONAL_IFACE_METHOD_NAME = new ClassValue() {
@Override
protected String computeValue(final Class type) {
return findFunctionalInterfaceMethodName(type);
}
};
private final BeansLinker beansLinker = new BeansLinker();
@Override
public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {
final Object self = linkRequest.getReceiver();
final CallSiteDescriptor desc = linkRequest.getCallSiteDescriptor();
if (self instanceof ConsString) {
// In order to treat ConsString like a java.lang.String we need a link request with a string receiver.
final Object[] arguments = linkRequest.getArguments();
arguments[0] = "";
final LinkRequest forgedLinkRequest = linkRequest.replaceArguments(desc, arguments);
final GuardedInvocation invocation = getGuardedInvocation(beansLinker, forgedLinkRequest, linkerServices);
// If an invocation is found we add a filter that makes it work for both Strings and ConsStrings.
return invocation == null ? null : invocation.filterArguments(0, FILTER_CONSSTRING);
}
if (self != null && "call".equals(desc.getNameToken(CallSiteDescriptor.OPERATOR))) {
// Support dyn:call on any object that supports some @FunctionalInterface
// annotated interface. This way Java method, constructor references or
// implementations of java.util.function.* interfaces can be called as though
// those are script functions.
final String name = getFunctionalInterfaceMethodName(self.getClass());
if (name != null) {
final MethodType callType = desc.getMethodType();
// drop callee (Undefined ScriptFunction) and change the request to be dyn:callMethod:
final SaiCallSiteDescriptor newDesc =
SaiCallSiteDescriptor.get(desc.getLookup(), "dyn:callMethod:" + name,
desc.getMethodType().dropParameterTypes(1, 2), SaiCallSiteDescriptor.getFlags(desc));
final GuardedInvocation gi =
getGuardedInvocation(beansLinker, linkRequest.replaceArguments(newDesc, linkRequest.getArguments()),
new SaiBeansLinkerServices(linkerServices));
// drop 'thiz' passed from the script.
return gi.replaceMethods(
MH.dropArguments(linkerServices.filterInternalObjects(gi.getInvocation()), 1, callType.parameterType(1)),
gi.getGuard());
}
}
return getGuardedInvocation(beansLinker, linkRequest, linkerServices);
}
/**
* Delegates to the specified linker but injects its linker services wrapper so that it will apply all special
* conversions that this class does.
* @param delegateLinker the linker to which the actual work is delegated to.
* @param linkRequest the delegated link request
* @param linkerServices the original link services that will be augmented with special conversions
* @return the guarded invocation from the delegate, possibly augmented with special conversions
* @throws Exception if the delegate throws an exception
*/
public static GuardedInvocation getGuardedInvocation(final GuardingDynamicLinker delegateLinker, final LinkRequest linkRequest,
final LinkerServices linkerServices) throws Exception {
return delegateLinker.getGuardedInvocation(linkRequest, new SaiBeansLinkerServices(linkerServices));
}
@SuppressWarnings("unused")
private static Object exportArgument(final Object arg) {
return exportArgument(arg, MIRROR_ALWAYS);
}
static Object exportArgument(final Object arg, final boolean mirrorAlways) {
if (arg instanceof ConsString) {
return arg.toString();
} else if (mirrorAlways && arg instanceof ScriptObject) {
return ScriptUtils.wrap((ScriptObject) arg);
} else {
return arg;
}
}
@SuppressWarnings("unused")
private static Object importResult(final Object arg) {
return ScriptUtils.unwrap(arg);
}
@SuppressWarnings("unused")
private static Object consStringFilter(final Object arg) {
return arg instanceof ConsString ? arg.toString() : arg;
}
private static String findFunctionalInterfaceMethodName(final Class clazz) {
if (clazz == null) {
return null;
}
for (final Class iface : clazz.getInterfaces()) {
// check accessibility up-front
if (!Context.isAccessibleClass(iface)) {
continue;
}
// check for @FunctionalInterface
if (iface.isAnnotationPresent(FunctionalInterface.class)) {
// return the first abstract method
for (final Method m : iface.getMethods()) {
if (Modifier.isAbstract(m.getModifiers()) && !isOverridableObjectMethod(m)) {
return m.getName();
}
}
}
}
// did not find here, try super class
return findFunctionalInterfaceMethodName(clazz.getSuperclass());
}
// is this an overridable java.lang.Object method?
private static boolean isOverridableObjectMethod(final Method m) {
switch (m.getName()) {
case "equals":
if (m.getReturnType() == boolean.class) {
final Class[] params = m.getParameterTypes();
return params.length == 1 && params[0] == Object.class;
}
return false;
case "hashCode":
return m.getReturnType() == int.class && m.getParameterCount() == 0;
case "toString":
return m.getReturnType() == String.class && m.getParameterCount() == 0;
}
return false;
}
// Returns @FunctionalInterface annotated interface's single abstract
// method name. If not found, returns null.
static String getFunctionalInterfaceMethodName(final Class clazz) {
return FUNCTIONAL_IFACE_METHOD_NAME.get(clazz);
}
static MethodHandleTransformer createHiddenObjectFilter() {
return new DefaultInternalObjectFilter(EXPORT_ARGUMENT, MIRROR_ALWAYS ? IMPORT_RESULT : null);
}
private static class SaiBeansLinkerServices implements LinkerServices {
private final LinkerServices linkerServices;
SaiBeansLinkerServices(final LinkerServices linkerServices) {
this.linkerServices = linkerServices;
}
@Override
public MethodHandle asType(final MethodHandle handle, final MethodType fromType) {
return linkerServices.asType(handle, fromType);
}
@Override
public MethodHandle asTypeLosslessReturn(final MethodHandle handle, final MethodType fromType) {
return Implementation.asTypeLosslessReturn(this, handle, fromType);
}
@Override
public MethodHandle getTypeConverter(final Class sourceType, final Class targetType) {
return linkerServices.getTypeConverter(sourceType, targetType);
}
@Override
public boolean canConvert(final Class from, final Class to) {
return linkerServices.canConvert(from, to);
}
@Override
public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest) throws Exception {
return linkerServices.getGuardedInvocation(linkRequest);
}
@Override
public Comparison compareConversion(final Class sourceType, final Class targetType1, final Class targetType2) {
if (sourceType == ConsString.class) {
if (String.class == targetType1 || CharSequence.class == targetType1) {
return Comparison.TYPE_1_BETTER;
}
if (String.class == targetType2 || CharSequence.class == targetType2) {
return Comparison.TYPE_2_BETTER;
}
}
return linkerServices.compareConversion(sourceType, targetType1, targetType2);
}
@Override
public MethodHandle filterInternalObjects(final MethodHandle target) {
return linkerServices.filterInternalObjects(target);
}
}
}
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