org.mozilla.javascript.VMBridge Maven / Gradle / Ivy
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
// API class
package org.mozilla.javascript;
import java.lang.reflect.Method;
import java.lang.reflect.Member;
import java.util.Iterator;
public abstract class VMBridge
{
static final VMBridge instance = makeInstance();
private static VMBridge makeInstance()
{
String[] classNames = {
"org.mozilla.javascript.VMBridge_custom",
"org.mozilla.javascript.jdk15.VMBridge_jdk15",
"org.mozilla.javascript.jdk13.VMBridge_jdk13",
"org.mozilla.javascript.jdk11.VMBridge_jdk11",
};
for (int i = 0; i != classNames.length; ++i) {
String className = classNames[i];
Class cl = Kit.classOrNull(className);
if (cl != null) {
VMBridge bridge = (VMBridge)Kit.newInstanceOrNull(cl);
if (bridge != null) {
return bridge;
}
}
}
throw new IllegalStateException("Failed to create VMBridge instance");
}
/**
* Return a helper object to optimize {@link Context} access.
*
* The runtime will pass the resulting helper object to the subsequent
* calls to {@link #getContext(Object contextHelper)} and
* {@link #setContext(Object contextHelper, Context cx)} methods.
* In this way the implementation can use the helper to cache
* information about current thread to make {@link Context} access faster.
*/
protected abstract Object getThreadContextHelper();
/**
* Get {@link Context} instance associated with the current thread
* or null if none.
*
* @param contextHelper The result of {@link #getThreadContextHelper()}
* called from the current thread.
*/
protected abstract Context getContext(Object contextHelper);
/**
* Associate {@link Context} instance with the current thread or remove
* the current association if cx is null.
*
* @param contextHelper The result of {@link #getThreadContextHelper()}
* called from the current thread.
*/
protected abstract void setContext(Object contextHelper, Context cx);
/**
* Return the ClassLoader instance associated with the current thread.
*/
protected abstract ClassLoader getCurrentThreadClassLoader();
/**
* In many JVMSs, public methods in private
* classes are not accessible by default (Sun Bug #4071593).
* VMBridge instance should try to workaround that via, for example,
* calling method.setAccessible(true) when it is available.
* The implementation is responsible to catch all possible exceptions
* like SecurityException if the workaround is not available.
*
* @return true if it was possible to make method accessible
* or false otherwise.
*/
protected abstract boolean tryToMakeAccessible(Object accessibleObject);
/**
* Create helper object to create later proxies implementing the specified
* interfaces later. Under JDK 1.3 the implementation can look like:
*
* return java.lang.reflect.Proxy.getProxyClass(..., interfaces).
* getConstructor(new Class[] {
* java.lang.reflect.InvocationHandler.class });
*
*
* @param interfaces Array with one or more interface class objects.
*/
protected Object getInterfaceProxyHelper(ContextFactory cf,
Class[] interfaces)
{
throw Context.reportRuntimeError(
"VMBridge.getInterfaceProxyHelper is not supported");
}
/**
* Create proxy object for {@link InterfaceAdapter}. The proxy should call
* {@link InterfaceAdapter#invoke(ContextFactory, Object, Scriptable,
* Method, Object[])}
* as implementation of interface methods associated with
* proxyHelper. {@link Method}
*
* @param proxyHelper The result of the previous call to
* {@link #getInterfaceProxyHelper(ContextFactory, Class[])}.
*/
protected Object newInterfaceProxy(Object proxyHelper,
ContextFactory cf,
InterfaceAdapter adapter,
Object target,
Scriptable topScope)
{
throw Context.reportRuntimeError(
"VMBridge.newInterfaceProxy is not supported");
}
/**
* Returns whether or not a given member (method or constructor)
* has variable arguments.
* Variable argument methods have only been supported in Java since
* JDK 1.5.
*/
protected abstract boolean isVarArgs(Member member);
/**
* If "obj" is a java.util.Iterator or a java.lang.Iterable, return a
* wrapping as a JavaScript Iterator. Otherwise, return null.
* This method is in VMBridge since Iterable is a JDK 1.5 addition.
*/
public Iterator getJavaIterator(Context cx, Scriptable scope, Object obj) {
if (obj instanceof Wrapper) {
Object unwrapped = ((Wrapper) obj).unwrap();
Iterator iterator = null;
if (unwrapped instanceof Iterator)
iterator = (Iterator) unwrapped;
return iterator;
}
return null;
}
}