variant.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.ole.win32;

import org.eclipse.swt.*;
import org.eclipse.swt.internal.ole.win32.*;
import org.eclipse.swt.internal.win32.*;
/**
 *
 * A Variant is a generic OLE mechanism for passing data of different types via a common interface.
 *
 * <p>It is used within the OleAutomation object for getting a property, setting a property or invoking
 * a method on an OLE Control or OLE Document.
 *
 */
public final class Variant
{
	// A variant always takes up 16 bytes, no matter what you 
	// store in it. Objects, strings, and arrays are not physically 
	// stored in the Variant; in these cases, four bytes of the 
	// Variant are used to hold either an object reference, or a 
	// pointer to the string or array. The actual data are stored elsewhere.
	public static final int sizeof = 16;
	private short type; // OLE.VT_* type
	
	private boolean booleanData;
	private float   floatData;
	private int     intData;
	private short   shortData;
	private String  stringData;
	private int     byRefPtr;
	private IDispatch dispatchData;
	private IUnknown unknownData;

/**
 * Create an empty Variant object with type VT_EMPTY.
 * 
 * @since 2.0
 */	
public Variant(){
	type = COM.VT_EMPTY;
}
/**
 * Create a Variant object which represents a Java float as a VT_R4.
 *
 * @param val the Java float value that this Variant represents
 *
 */
public Variant(float val) {
	type = COM.VT_R4;
	floatData = val;
	
}
/**
 * Create a Variant object which represents a Java int as a VT_I4.
 *
 * @param val the Java int value that this Variant represents
 *
 */
 public Variant(int val) {
	type = COM.VT_I4;
	intData = val;
}
/**
 * Create a Variant object which contains a reference to the data being transferred.
 *
 * <p>When creating a VT_BYREF Variant, you must give the full Variant type 
 * including VT_BYREF such as
 * 
 * <pre><code>short byRefType = OLE.VT_BSTR | OLE.VT_BYREF</code></pre>.
 *
 * @param ptr a pointer to the data being transferred.
 * @param byRefType the type of the data being transferred such as OLE.VT_BSTR | OLE.VT_BYREF
 *
 */
public Variant(int ptr, short byRefType) {
	type = byRefType;
	byRefPtr = ptr;
}
/**
 * Create a Variant object which represents an IDispatch interface as a VT_Dispatch.
 *
 * @param automation the OleAutomation object that this Variant represents
 * 
 */
public Variant(OleAutomation automation) {
	type = COM.VT_DISPATCH;
	dispatchData = new IDispatch(automation.getAddress());
}
/**
 * Create a Variant object which represents an IDispatch interface as a VT_Dispatch.
 * <p>The caller is expected to have appropriately invoked unknown.AddRef() before creating 
 * this Variant.
 * 
 * @since 2.0
 * 
 * @param idispatch the IDispatch object that this Variant represents
 * 
 */
public Variant(IDispatch idispatch) {
	type = COM.VT_DISPATCH;
	dispatchData = idispatch;
}
/**
 * Create a Variant object which represents an IUnknown interface as a VT_UNKNOWN.
 *
 * <p>The caller is expected to have appropriately invoked unknown.AddRef() before creating 
 * this Variant.
 *
 * @param unknown the IUnknown object that this Variant represents
 *
 */
public Variant(IUnknown unknown) {
	type = COM.VT_UNKNOWN;
	unknownData = unknown;
}
/**
 * Create a Variant object which represents a Java String as a VT_BSTR.
 *
 * @param string the Java String value that this Variant represents
 *
 */
public Variant(String string) {
	type = COM.VT_BSTR;
	stringData = string;
}
/**
 * Create a Variant object which represents a Java short as a VT_I2.
 *
 * @param val the Java short value that this Variant represents
 *
 */
public Variant(short val) {
	type = COM.VT_I2;
	shortData = val;
}
/**
 * Create a Variant object which represents a Java boolean as a VT_BOOL.
 *
 * @param val the Java boolean value that this Variant represents
 *
 */
public Variant(boolean val) {
	type = COM.VT_BOOL;
	booleanData = val;
}

/**
 * Calling dispose will release resources associated with this Variant.
 * If the resource is an IDispatch or IUnknown interface, Release will be called.
 * If the resource is a ByRef pointer, nothing is released.
 * 
 * @since 2.1
 */
public void dispose() {
	if ((type & COM.VT_BYREF) == COM.VT_BYREF) {
		return;
	}
		
	switch (type) {
		case COM.VT_EMPTY :
		case COM.VT_BOOL :
		case COM.VT_R4 :
		case COM.VT_I4 :
		case COM.VT_I2 :
		case COM.VT_BSTR :
			break;
		case COM.VT_DISPATCH :
			dispatchData.Release();
			break;
		case COM.VT_UNKNOWN :
			unknownData.Release();
			break;
	}
	
}
/**
 * Returns the OleAutomation object represented by this Variant.
 *
 * <p>If this Variant does not contain an OleAutomation object, an attempt is made to
 * coerce the Variant type into an OleAutomation object.  If this fails, an error is
 * thrown.  Note that OleAutomation objects must be disposed when no longer
 * needed.
 *
 * @return the OleAutomation object represented by this Variant
 *
 * @exception SWTError
 *		ERROR_CANNOT_CHANGE_VARIANT_TYPE when type of Variant can not be coerced into an OleAutomation object
 */
public OleAutomation getAutomation() {
	if (type == COM.VT_EMPTY) {
		OLE.error(OLE.ERROR_CANNOT_CHANGE_VARIANT_TYPE, -1);
	}
	if (type == COM.VT_DISPATCH) {
		return new OleAutomation(dispatchData);
	}
	// try to coerce the value to the desired type
	int oldPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, sizeof);
	int newPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, sizeof);
	try {
		getData(oldPtr);
		int result = COM.VariantChangeType(newPtr, oldPtr, (short) 0, COM.VT_DISPATCH);
		if (result != COM.S_OK)
			OLE.error(OLE.ERROR_CANNOT_CHANGE_VARIANT_TYPE, result);
		Variant autoVar = new Variant();
		autoVar.setData(newPtr);
		return autoVar.getAutomation();
	} finally {
		COM.VariantClear(oldPtr);
		OS.GlobalFree(oldPtr);
		COM.VariantClear(newPtr); // Note: This must absolutely be done AFTER the 
		                          // OleAutomation object is created as Variant Clear 
		                          // will result in a Release being performed on the 
		                          // Dispatch object
		OS.GlobalFree(newPtr);
	}
}
/**
 * Returns the IDispatch object represented by this Variant.
 *
 * <p>If this Variant does not contain an IDispatch object, an attempt is made to
 * coerce the Variant type into an IDIspatch object.  If this fails, an error is
 * thrown.
 *
 * @since 2.0
 * 
 * @return the IDispatch object represented by this Variant
 *
 * @exception SWTError
 *		ERROR_CANNOT_CHANGE_VARIANT_TYPE when type of Variant can not be coerced into an IDispatch object
 */
public IDispatch getDispatch() {
	if (type == COM.VT_EMPTY) {
		OLE.error(OLE.ERROR_CANNOT_CHANGE_VARIANT_TYPE, -1);
	}
	if (type == COM.VT_DISPATCH) {
		return dispatchData;
	}
	// try to coerce the value to the desired type
	int oldPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, sizeof);
	int newPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, sizeof);
	try {
		getData(oldPtr);
		int result = COM.VariantChangeType(newPtr, oldPtr, (short) 0, COM.VT_DISPATCH);
		if (result != COM.S_OK)
			OLE.error(OLE.ERROR_CANNOT_CHANGE_VARIANT_TYPE, result);
		Variant autoVar = new Variant();
		autoVar.setData(newPtr);
		return autoVar.getDispatch();
	} finally {
		COM.VariantClear(oldPtr);
		OS.GlobalFree(oldPtr);
		COM.VariantClear(newPtr); // Note: This must absolutely be done AFTER the 
		                          // OleAutomation object is created as Variant Clear 
		                          // will result in a Release being performed on the 
		                          // Dispatch object
		OS.GlobalFree(newPtr);
	}
}
/**
 * Returns the Java boolean represented by this Variant.
 *
 * <p>If this Variant does not contain a Java boolean, an attempt is made to
 * coerce the Variant type into a Java boolean.  If this fails, an error is thrown.
 *
 * @return the Java boolean represented by this Variant
 *
 * @exception SWTError
 * <ul><li>ERROR_CANNOT_CHANGE_VARIANT_TYPE when type of Variant can not be coerced into a boolean</ul>
 *
 */
public boolean getBoolean() {
	if (type == COM.VT_EMPTY) {
		OLE.error(OLE.ERROR_CANNOT_CHANGE_VARIANT_TYPE, -1);
	}
	if (type == COM.VT_BOOL) {
		return booleanData;
	}

	// try to coerce the value to the desired type
	int oldPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, sizeof);
	int newPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, sizeof);
	try {
		getData(oldPtr);
		int result = COM.VariantChangeType(newPtr, oldPtr, (short) 0, COM.VT_BOOL);
		if (result != COM.S_OK)
			OLE.error(OLE.ERROR_CANNOT_CHANGE_VARIANT_TYPE, result);
		Variant boolVar = new Variant();
		boolVar.setData(newPtr);
		return boolVar.getBoolean();
	} finally {
		COM.VariantClear(oldPtr);
		OS.GlobalFree(oldPtr);
		COM.VariantClear(newPtr);
		OS.GlobalFree(newPtr);
	}
}
/**
 * Returns a pointer to the referenced data represented by this Variant.
 *
 * <p>If this Variant does not contain a reference to data, zero is returned.
 *
 * @return a pointer to the referenced data represented by this Variant or 0
 *
 */
public int getByRef() {
	if (type == COM.VT_EMPTY) {
		OLE.error(OLE.ERROR_CANNOT_CHANGE_VARIANT_TYPE, -1);
	}
	if ((type & COM.VT_BYREF)== COM.VT_BYREF) {
		return byRefPtr;
	}
		
	return 0;
}
void getData(int pData){
	if (pData == 0) OLE.error(OLE.ERROR_OUT_OF_MEMORY);
	
	COM.VariantInit(pData);

	if ((type & COM.VT_BYREF) == COM.VT_BYREF) {
		COM.MoveMemory(pData, new short[] {type}, 2);
		COM.MoveMemory(pData + 8, new int[]{byRefPtr}, 4);
		return;
	}

	switch (type) {
		case COM.VT_EMPTY :
			break;
		case COM.VT_BOOL :
			COM.MoveMemory(pData, new short[] {type}, 2);
			COM.MoveMemory(pData + 8, new int[]{(booleanData) ? COM.VARIANT_TRUE : COM.VARIANT_FALSE}, 2);
			break;
		case COM.VT_R4 :
			COM.MoveMemory(pData, new short[] {type}, 2);
			COM.MoveMemory(pData + 8, new float[]{floatData}, 4);
			break;
		case COM.VT_I4 :
			COM.MoveMemory(pData, new short[] {type}, 2);
			COM.MoveMemory(pData + 8, new int[]{intData}, 4);
			break;
		case COM.VT_DISPATCH :
			dispatchData.AddRef();
			COM.MoveMemory(pData, new short[] {type}, 2);
			COM.MoveMemory(pData + 8, new int[]{dispatchData.getAddress()}, 4);
			break;
		case COM.VT_UNKNOWN :
			unknownData.AddRef();
			COM.MoveMemory(pData, new short[] {type}, 2);
			COM.MoveMemory(pData + 8, new int[]{unknownData.getAddress()}, 4);
			break;
		case COM.VT_I2 :
			COM.MoveMemory(pData, new short[] {type}, 2);
			COM.MoveMemory(pData + 8, new short[]{shortData}, 2);
			break;
		case COM.VT_BSTR :
			COM.MoveMemory(pData, new short[] {type}, 2);
			char[] data = (stringData+"\0").toCharArray();
			int ptr = COM.SysAllocString(data);
			COM.MoveMemory(pData + 8, new int[] {ptr}, 4);
			break;
	
		default :
			OLE.error(SWT.ERROR_NOT_IMPLEMENTED);
	}