1 files changed, 243 insertions, 0 deletions
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/Callback.java b/bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/Callback.java
new file mode 100755
index 0000000000..ce73d17e0e
--- /dev/null
+++ b/bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/Callback.java
@@ -0,0 +1,243 @@
+/*******************************************************************************
+ * Copyright (c) 2000, 2007 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.internal;
+
+
+/**
+ * Instances of this class represent entry points into Java
+ * which can be invoked from operating system level callback
+ * routines.
+ * <p>
+ * IMPORTANT: A callback is only valid when invoked on the
+ * thread which created it. The results are undefined (and
+ * typically bad) when a callback is passed out to the 
+ * operating system (or other code) in such a way that the
+ * callback is called from a different thread.
+ */
+
+public class Callback {
+	
+	Object object;
+	String method, signature;
+	int argCount;
+	int /*long*/ address, errorResult;
+	boolean isStatic, isArrayBased;
+
+	static final String PTR_SIGNATURE = C.PTR_SIZEOF == 4 ? "I" : "J"; //$NON-NLS-1$  //$NON-NLS-2$
+	static final String SIGNATURE_0 = getSignature(0);
+	static final String SIGNATURE_1 = getSignature(1);
+	static final String SIGNATURE_2 = getSignature(2);
+	static final String SIGNATURE_3 = getSignature(3);
+	static final String SIGNATURE_4 = getSignature(4);
+	static final String SIGNATURE_N = "(["+PTR_SIGNATURE+")"+PTR_SIGNATURE; //$NON-NLS-1$  //$NON-NLS-2$
+
+/**
+ * Constructs a new instance of this class given an object
+ * to send the message to, a string naming the method to
+ * invoke and an argument count. Note that, if the object
+ * is an instance of <code>Class</code> it is assumed that
+ * the method is a static method on that class.
+ *
+ * @param object the object to send the message to
+ * @param method the name of the method to invoke
+ * @param argCount the number of arguments that the method takes
+ */
+public Callback (Object object, String method, int argCount) {
+	this (object, method, argCount, false);
+}
+
+/**
+ * Constructs a new instance of this class given an object
+ * to send the message to, a string naming the method to
+ * invoke, an argument count and a flag indicating whether
+ * or not the arguments will be passed in an array. Note 
+ * that, if the object is an instance of <code>Class</code>
+ * it is assumed that the method is a static method on that
+ * class.
+ *
+ * @param object the object to send the message to
+ * @param method the name of the method to invoke
+ * @param argCount the number of arguments that the method takes
+ * @param isArrayBased <code>true</code> if the arguments should be passed in an array and false otherwise
+ */
+public Callback (Object object, String method, int argCount, boolean isArrayBased) {
+	this (object, method, argCount, isArrayBased, 0);
+}
+
+/**
+ * Constructs a new instance of this class given an object
+ * to send the message to, a string naming the method to
+ * invoke, an argument count, a flag indicating whether
+ * or not the arguments will be passed in an array and a value
+ * to return when an exception happens. Note that, if
+ * the object is an instance of <code>Class</code>
+ * it is assumed that the method is a static method on that
+ * class.
+ *
+ * @param object the object to send the message to
+ * @param method the name of the method to invoke
+ * @param argCount the number of arguments that the method takes
+ * @param isArrayBased <code>true</code> if the arguments should be passed in an array and false otherwise
+ * @param errorResult the return value if the java code throws an exception
+ */
+public Callback (Object object, String method, int argCount, boolean isArrayBased, int /*long*/ errorResult) {
+
+	/* Set the callback fields */
+	this.object = object;
+	this.method = method;
+	this.argCount = argCount;
+	this.isStatic = object instanceof Class;
+	this.isArrayBased = isArrayBased;
+	this.errorResult = errorResult;
+	
+	/* Inline the common cases */
+	if (isArrayBased) {
+		signature = SIGNATURE_N;
+	} else {
+		switch (argCount) {
+			case 0: signature = SIGNATURE_0; break; //$NON-NLS-1$
+			case 1: signature = SIGNATURE_1; break; //$NON-NLS-1$
+			case 2: signature = SIGNATURE_2; break; //$NON-NLS-1$
+			case 3: signature = SIGNATURE_3; break; //$NON-NLS-1$
+			case 4: signature = SIGNATURE_4; break; //$NON-NLS-1$
+			default:
+				signature = getSignature(argCount);
+		}
+	}
+	
+	/* Bind the address */
+	address = bind (this, object, method, signature, argCount, isStatic, isArrayBased, errorResult);
+}
+
+/**
+ * Allocates the native level resources associated with the
+ * callback. This method is only invoked from within the
+ * constructor for the argument.
+ *
+ * @param callback the callback to bind
+ * @param object the callback's object
+ * @param method the callback's method
+ * @param signature the callback's method signature
+ * @param argCount the callback's method argument count
+ * @param isStatic whether the callback's method is static
+ * @param isArrayBased whether the callback's method is array based
+ * @param errorResult the callback's error result
+ */
+static native synchronized int /*long*/ bind (Callback callback, Object object, String method, String signature, int argCount, boolean isStatic, boolean isArrayBased, int /*long*/ errorResult);
+
+/**
+ * Releases the native level resources associated with the callback,
+ * and removes all references between the callback and
+ * other objects. This helps to prevent (bad) application code
+ * from accidentally holding onto extraneous garbage.
+ */
+public void dispose () {
+	if (object == null) return;
+	unbind (this);
+	object = method = signature = null;
+	address = 0;
+}
+
+/**
+ * Returns the address of a block of machine code which will
+ * invoke the callback represented by the receiver.
+ *
+ * @return the callback address
+ */
+public int /*long*/ getAddress () {
+	return address;
+}
+
+/**
+ * Returns the SWT platform name.
+ *
+ * @return the platform name of the currently running SWT
+ */
+public static native String getPlatform ();
+
+/**
+ * Returns the number of times the system has been recursively entered
+ * through a callback.
+ * <p>
+ * Note: This should not be called by application code.
+ * </p>
+ * 
+ * @return the entry count
+ * 
+ * @since 2.1
+ */
+public static native int getEntryCount ();
+
+static String getSignature(int argCount) {
+	String signature = "("; //$NON-NLS-1$
+	for (int i = 0; i < argCount; i++) signature += PTR_SIGNATURE;
+	signature += ")" + PTR_SIGNATURE; //$NON-NLS-1$
+	return signature;
+}
+
+/**
+ * Indicates whether or not callbacks which are triggered at the
+ * native level should cause the messages described by the matching
+ * <code>Callback</code> objects to be invoked. This method is used
+ * to safely shut down SWT when it is run within environments
+ * which can generate spurious events.
+ * <p>
+ * Note: This should not be called by application code.
+ * </p>
+ *
+ * @param enable true if callbacks should be invoked
+ */
+public static final native synchronized void setEnabled (boolean enable);
+
+/**
+ * Returns whether or not callbacks which are triggered at the
+ * native level should cause the messages described by the matching
+ * <code>Callback</code> objects to be invoked. This method is used
+ * to safely shut down SWT when it is run within environments
+ * which can generate spurious events.
+ * <p>
+ * Note: This should not be called by application code.
+ * </p>
+ *
+ * @return true if callbacks should not be invoked
+ */
+public static final native synchronized boolean getEnabled ();
+
+/**
+ * This might be called directly from native code in environments
+ * which can generate spurious events. Check before removing it.
+ *
+ * @deprecated
+ *
+ * @param ignore true if callbacks should not be invoked
+ */
+static final void ignoreCallbacks (boolean ignore) {
+	setEnabled (!ignore);
+} 
+
+/**
+ * Immediately wipes out all native level state associated
+ * with <em>all</em> callbacks.
+ * <p>
+ * <b>WARNING:</b> This operation is <em>extremely</em> dangerous,
+ * and should never be performed by application code.
+ * </p>
+ */
+public static final native synchronized void reset ();
+
+/**
+ * Releases the native level resources associated with the callback.
+ *
+ * @see #dispose
+ */
+static final native synchronized void unbind (Callback callback);
+
+}