# DuplicateFrameEliminator.java

    /*******************************************************************************
     * Copyright (c) 2009, 2013 Mountainminds GmbH & Co. KG and Contributors
     * 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:
     *    Marc R. Hoffmann - initial API and implementation
     *
     *******************************************************************************/
    package org.jacoco.core.internal.instr;

    import org.objectweb.asm.Handle;
    import org.objectweb.asm.Label;
    import org.objectweb.asm.MethodVisitor;
    import org.objectweb.asm.Opcodes;

    /**
     * Eliminates consecutive stackmap frame definitions which causes ASM to create
     * invalid class files. This situation occurs when the original class files
     * contains additional stackmap frames at unexpected offsets, which is case for
     * some class files compiled with ECJ.
     */
    class DuplicateFrameEliminator extends MethodVisitor {

    	private boolean instruction;

    	public DuplicateFrameEliminator(final MethodVisitor mv) {
    		super(Opcodes.ASM4, mv);
    		instruction = true;
    	}

    	@Override
    	public void visitFrame(final int type, final int nLocal,
    			final Object[] local, final int nStack, final Object[] stack) {
    		if (instruction) {
    			instruction = false;
    			mv.visitFrame(type, nLocal, local, nStack, stack);
    		}
    	}

    	@Override
    	public void visitInsn(final int opcode) {
    		instruction = true;
    		mv.visitInsn(opcode);
    	}

    	@Override
    	public void visitIntInsn(final int opcode, final int operand) {
    		instruction = true;
    		mv.visitIntInsn(opcode, operand);
    	}

    	@Override
    	public void visitVarInsn(final int opcode, final int var) {
    		instruction = true;
    		mv.visitVarInsn(opcode, var);
    	}

    	@Override
    	public void visitTypeInsn(final int opcode, final String type) {
    		instruction = true;
    		mv.visitTypeInsn(opcode, type);
    	}

    	@Override
    	public void visitFieldInsn(final int opcode, final String owner,
    			final String name, final String desc) {
    		instruction = true;
    		mv.visitFieldInsn(opcode, owner, name, desc);
    	}

    	@Override
    	public void visitMethodInsn(final int opcode, final String owner,
    			final String name, final String desc) {
    		instruction = true;
    		mv.visitMethodInsn(opcode, owner, name, desc);
    	}

    	@Override
    	public void visitInvokeDynamicInsn(final String name, final String desc,
    			final Handle bsm, final Object... bsmArgs) {
    		instruction = true;
    		mv.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);
    	}

    	@Override
    	public void visitJumpInsn(final int opcode, final Label label) {
    		instruction = true;
    		mv.visitJumpInsn(opcode, label);
    	}

    	@Override
    	public void visitLdcInsn(final Object cst) {
    		instruction = true;
    		mv.visitLdcInsn(cst);
    	}

    	@Override
    	public void visitIincInsn(final int var, final int increment) {
    		instruction = true;
    		mv.visitIincInsn(var, increment);
    	}

    	@Override
    	public void visitTableSwitchInsn(final int min, final int max,
    			final Label dflt, final Label... labels) {
    		instruction = true;
    		mv.visitTableSwitchInsn(min, max, dflt, labels);
    	}

    	@Override
    	public void visitLookupSwitchInsn(final Label dflt, final int[] keys,
    			final Label[] labels) {
    		instruction = true;
    		mv.visitLookupSwitchInsn(dflt, keys, labels);
    	}

    	@Override
    	public void visitMultiANewArrayInsn(final String desc, final int dims) {
    		instruction = true;
    		mv.visitMultiANewArrayInsn(desc, dims);
    	}

    }