Copyright (c) 2000, 2009 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.core.util;

import org.eclipse.jdt.core.util.ClassFormatException;
import org.eclipse.jdt.core.util.IConstantPool;
import org.eclipse.jdt.core.util.IStackMapFrame;
import org.eclipse.jdt.core.util.IVerificationTypeInfo;

Default implementation of IStackMapFrame
/**
 * Default implementation of IStackMapFrame
 */
public class StackMapFrame extends ClassFileStruct implements IStackMapFrame {
	private static final IVerificationTypeInfo[] EMPTY_LOCALS_OR_STACK_ITEMS = new IVerificationTypeInfo[0];

	private int readOffset;
	private int frameType;
	private int numberOfLocals;
	private int numberOfStackItems;
	private IVerificationTypeInfo[] locals;
	private IVerificationTypeInfo[] stackItems;
	private int offsetDelta;

	
Constructor for StackMapFrame.
Params:
classFileBytes – 
constantPool – 
offset – 
Throws:
ClassFormatException – /**
	 * Constructor for StackMapFrame.
	 *
	 * @param classFileBytes
	 * @param constantPool
	 * @param offset
	 * @throws ClassFormatException
	 */
	public StackMapFrame(
			byte[] classFileBytes,
			IConstantPool constantPool,
			int offset) throws ClassFormatException {

		final int type = u1At(classFileBytes, 0, offset);
		this.frameType = type;
		switch(type) {
			case 247 : // SAME_LOCALS_1_STACK_ITEM_EXTENDED
				this.offsetDelta = u2At(classFileBytes, 1, offset);
				this.numberOfStackItems = 1;
				this.stackItems = new VerificationInfo[1];
				this.readOffset = 3;
				VerificationInfo info = new VerificationInfo(classFileBytes, constantPool, offset + this.readOffset);
				this.stackItems[0] = info;
				this.readOffset += info.sizeInBytes();
				this.locals = EMPTY_LOCALS_OR_STACK_ITEMS;
				this.numberOfLocals = 0;
				break;
			case 248 :
			case 249 :
			case 250:
				// CHOP
				this.offsetDelta = u2At(classFileBytes, 1, offset);
				this.numberOfStackItems = 0;
				this.stackItems = EMPTY_LOCALS_OR_STACK_ITEMS;
				this.readOffset = 3;
				this.locals = EMPTY_LOCALS_OR_STACK_ITEMS;
				this.numberOfLocals = 0;
				break;
			case 251 :
				// SAME_FRAME_EXTENDED
				this.offsetDelta = u2At(classFileBytes, 1, offset);
				this.numberOfStackItems = 0;
				this.stackItems = EMPTY_LOCALS_OR_STACK_ITEMS;
				this.readOffset = 3;
				this.locals = EMPTY_LOCALS_OR_STACK_ITEMS;
				this.numberOfLocals = 0;
				break;
			case 252 :
			case 253 :
			case 254 :
				// APPEND
				this.offsetDelta = u2At(classFileBytes, 1, offset);
				this.numberOfStackItems = 0;
				this.stackItems = EMPTY_LOCALS_OR_STACK_ITEMS;
				this.readOffset = 3;
				int diffLocals = type - 251;
				this.numberOfLocals = diffLocals;
				this.locals = new IVerificationTypeInfo[diffLocals];
				for (int i = 0; i < diffLocals; i++) {
					VerificationInfo verificationInfo = new VerificationInfo(classFileBytes, constantPool, offset + this.readOffset);
					this.locals[i] = verificationInfo;
					this.readOffset += verificationInfo.sizeInBytes();
				}
				break;
			case 255 :
				// FULL_FRAME
				this.offsetDelta = u2At(classFileBytes, 1, offset);
				int tempLocals = u2At(classFileBytes, 3, offset);
				this.numberOfLocals = tempLocals;
				this.readOffset = 5;
				if (tempLocals != 0) {
					this.locals = new IVerificationTypeInfo[tempLocals];
					for (int i = 0; i < tempLocals; i++) {
						VerificationInfo verificationInfo = new VerificationInfo(classFileBytes, constantPool, offset + this.readOffset);
						this.locals[i] = verificationInfo;
						this.readOffset += verificationInfo.sizeInBytes();
					}
				} else {
					this.locals = EMPTY_LOCALS_OR_STACK_ITEMS;
				}
				int tempStackItems = u2At(classFileBytes, this.readOffset, offset);
				this.readOffset += 2;
				this.numberOfStackItems = tempStackItems;
				if (tempStackItems != 0) {
					this.stackItems = new IVerificationTypeInfo[tempStackItems];
					for (int i = 0; i < tempStackItems; i++) {
						VerificationInfo verificationInfo = new VerificationInfo(classFileBytes, constantPool, offset + this.readOffset);
						this.stackItems[i] = verificationInfo;
						this.readOffset += verificationInfo.sizeInBytes();
					}
				} else {
					this.stackItems = EMPTY_LOCALS_OR_STACK_ITEMS;
				}
				break;
			default:
				if (type <= 63) {
					// SAME_FRAME
					this.offsetDelta = type;
					this.numberOfStackItems = 0;
					this.stackItems = EMPTY_LOCALS_OR_STACK_ITEMS;
					this.locals = EMPTY_LOCALS_OR_STACK_ITEMS;
					this.numberOfLocals = 0;
					this.readOffset = 1;
				} else if (type <= 127) {
					// SAME_LOCALS_1_STACK_ITEM
					this.offsetDelta = type - 64;
					this.numberOfStackItems = 1;
					this.stackItems = new VerificationInfo[1];
					this.readOffset = 1;
					info = new VerificationInfo(classFileBytes, constantPool, offset + this.readOffset);
					this.stackItems[0] = info;
					this.readOffset += info.sizeInBytes();
					this.locals = EMPTY_LOCALS_OR_STACK_ITEMS;
					this.numberOfLocals = 0;
				}
		}
	}
	int sizeInBytes() {
		return this.readOffset;
	}
	@Override
	public int getFrameType() {
		return this.frameType;
	}
	@Override
	public IVerificationTypeInfo[] getLocals() {
		return this.locals;
	}
	@Override
	public int getNumberOfLocals() {
		return this.numberOfLocals;
	}
	@Override
	public int getNumberOfStackItems() {
		return this.numberOfStackItems;
	}
	@Override
	public int getOffsetDelta() {
		return this.offsetDelta;
	}
	@Override
	public IVerificationTypeInfo[] getStackItems() {
		return this.stackItems;
	}
}