content: /*******************************************************************************
   * Copyright (c) 2009, 2019 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:
   *    Evgeny Mandrikov - initial API and implementation
   *
   *******************************************************************************/
  package org.jacoco.core.internal.analysis.filter;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.objectweb.asm.Opcodes;
  import org.objectweb.asm.tree.AbstractInsnNode;
  import org.objectweb.asm.tree.MethodInsnNode;
  import org.objectweb.asm.tree.MethodNode;
  import org.objectweb.asm.tree.TypeInsnNode;
  import org.objectweb.asm.tree.VarInsnNode;
  
  abstract class AbstractMatcher {
  
  	final Map<String, VarInsnNode> vars = new HashMap<String, VarInsnNode>();
  
  	AbstractInsnNode cursor;
  
  	/**
  	 * Sets {@link #cursor} to first instruction of method if it is
  	 * <code>ALOAD 0</code>, otherwise sets it to <code>null</code>.
  	 */
  	final void firstIsALoad0(final MethodNode methodNode) {
  		cursor = methodNode.instructions.getFirst();
  		skipNonOpcodes();
  		if (cursor.getOpcode() == Opcodes.ALOAD
  				&& ((VarInsnNode) cursor).var == 0) {
  			return;
  		}
  		cursor = null;
  	}
  
  	/**
  	 * Moves {@link #cursor} to next instruction if it is {@link TypeInsnNode}
  	 * with given opcode and operand, otherwise sets it to <code>null</code>.
  	 */
  	final void nextIsType(final int opcode, final String desc) {
  		nextIs(opcode);
  		if (cursor == null) {
  			return;
  		}
  		if (((TypeInsnNode) cursor).desc.equals(desc)) {
  			return;
  		}
  		cursor = null;
  	}
  
  	/**
  	 * Moves {@link #cursor} to next instruction if it is {@link MethodInsnNode}
  	 * with given opcode, owner, name and descriptor, otherwise sets it to
  	 * <code>null</code>.
  	 */
  	final void nextIsInvoke(final int opcode, final String owner,
  			final String name, final String descriptor) {
  		nextIs(opcode);
  		if (cursor == null) {
  			return;
  		}
  		final MethodInsnNode m = (MethodInsnNode) cursor;
  		if (owner.equals(m.owner) && name.equals(m.name)
  				&& descriptor.equals(m.desc)) {
  			return;
  		}
  		cursor = null;
  	}
  
  	final void nextIsVar(final int opcode, final String name) {
  		nextIs(opcode);
  		if (cursor == null) {
  			return;
  		}
  		final VarInsnNode actual = (VarInsnNode) cursor;
  		final VarInsnNode expected = vars.get(name);
  		if (expected == null) {
  			vars.put(name, actual);
  		} else if (expected.var != actual.var) {
  			cursor = null;
  		}
  	}
  
  	/**
  	 * Moves {@link #cursor} to next instruction if it is
  	 * <code>TABLESWITCH</code> or <code>LOOKUPSWITCH</code>, otherwise sets it
  	 * to <code>null</code>.
  	 */
  	final void nextIsSwitch() {
  		next();
  		if (cursor == null) {
  			return;
  		}
  		switch (cursor.getOpcode()) {
  		case Opcodes.TABLESWITCH:
  		case Opcodes.LOOKUPSWITCH:
  			return;
  		default:
  			cursor = null;
  		}
  	}
  
  	/**
  	 * Moves {@link #cursor} to next instruction if it has given opcode,
  	 * otherwise sets it to <code>null</code>.
  	 */
  	final void nextIs(final int opcode) {
  		next();
  		if (cursor == null) {
  			return;
  		}
  		if (cursor.getOpcode() != opcode) {
  			cursor = null;
  		}
  	}
  
  	/**
  	 * Moves {@link #cursor} to next instruction.
  	 */
  	final void next() {
  		if (cursor == null) {
  			return;
  		}
  		cursor = cursor.getNext();
  		skipNonOpcodes();
  	}
  
  	/**
  	 * Moves {@link #cursor} through {@link AbstractInsnNode#FRAME},
  	 * {@link AbstractInsnNode#LABEL}, {@link AbstractInsnNode#LINE}.
  	 */
  	final void skipNonOpcodes() {
  		cursor = skipNonOpcodes(cursor);
  	}
  
  	/**
  	 * Returns first instruction from given and following it that is not
  	 * {@link AbstractInsnNode#FRAME}, {@link AbstractInsnNode#LABEL},
  	 * {@link AbstractInsnNode#LINE}.
  	 */
  	static AbstractInsnNode skipNonOpcodes(AbstractInsnNode cursor) {
  		while (cursor != null && (cursor.getType() == AbstractInsnNode.FRAME
  				|| cursor.getType() == AbstractInsnNode.LABEL
  				|| cursor.getType() == AbstractInsnNode.LINE)) {
  			cursor = cursor.getNext();
  		}
  		return cursor;
  	}
  
  }
  