/* *******************************************************************
 * Copyright (c) 2002 Palo Alto Research Center, Incorporated (PARC).
 * 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: 
 *     PARC     initial implementation 
 * ******************************************************************/

package org.aspectj.weaver;

import java.util.Map;

import org.aspectj.bridge.ISourceLocation;
import org.aspectj.util.PartialOrder;

public abstract class ConcreteTypeMunger implements PartialOrder.PartialComparable {
	protected ResolvedTypeMunger munger;
	protected ResolvedType aspectType;

	public ConcreteTypeMunger(ResolvedTypeMunger munger, ResolvedType aspectType) {
		this.munger = munger;
		this.aspectType = aspectType;
	}

	
Equivalence can be true for an EclipseTypeMunger and a BcelTypeMunger that represent the same transformation (just at
different points in the pipeline).
/**
	 * Equivalence can be true for an EclipseTypeMunger and a BcelTypeMunger that represent the same transformation (just at
	 * different points in the pipeline).
	 */
	public boolean equivalentTo(Object other) {
		if (!(other instanceof ConcreteTypeMunger)) {
			return false;
		}
		ConcreteTypeMunger o = (ConcreteTypeMunger) other;
		ResolvedTypeMunger otherTypeMunger = o.getMunger();
		ResolvedTypeMunger thisTypeMunger = getMunger();
		if (thisTypeMunger instanceof NewConstructorTypeMunger && otherTypeMunger instanceof NewConstructorTypeMunger) {
			return (((NewConstructorTypeMunger) otherTypeMunger).equivalentTo(thisTypeMunger))
					&& ((o.getAspectType() == null) ? (getAspectType() == null) : o.getAspectType().equals(getAspectType()));
		} else {
			return ((otherTypeMunger == null) ? (thisTypeMunger == null) : otherTypeMunger.equals(thisTypeMunger))
					&& ((o.getAspectType() == null) ? (getAspectType() == null) : o.getAspectType().equals(getAspectType()));
		}
	}

	// public abstract boolean munge(LazyClassGen gen);

	
returns null for mungers that are used internally, but were not part of a declared thing in source code.
/**
	 * returns null for mungers that are used internally, but were not part of a declared thing in source code.
	 */
	public ResolvedTypeMunger getMunger() {
		return munger;
	}

	public ResolvedType getAspectType() {
		return aspectType;
	}

	public ResolvedMember getSignature() {
		return munger.getSignature();
	}

	public World getWorld() {
		return aspectType.getWorld();
	}

	public ISourceLocation getSourceLocation() {
		if (munger == null) {
			return null;
		}
		return munger.getSourceLocation(); // XXX
	}

	public boolean matches(ResolvedType onType) {
		if (munger == null) {
			throw new RuntimeException("huh: " + this);
		}
		return munger.matches(onType, aspectType);
	}

	public ResolvedMember getMatchingSyntheticMember(Member member) {
		return munger.getMatchingSyntheticMember(member, aspectType);
	}

	public int compareTo(Object other) {
		ConcreteTypeMunger o = (ConcreteTypeMunger) other;

		ResolvedType otherAspect = o.aspectType;

		if (aspectType.equals(otherAspect)) {
			return getSignature().getStart() < o.getSignature().getStart() ? -1 : +1;
		} else if (aspectType.isAssignableFrom(o.aspectType)) {
			return +1;
		} else if (o.aspectType.isAssignableFrom(aspectType)) {
			return -1;
		} else {
			return 0;
		}
	}

	public int fallbackCompareTo(Object other) {
		// ConcreteTypeMunger o = (ConcreteTypeMunger) other;
		return 0;
	}

	
returns true if the ITD target type used type variables, for example I. When they are specified like this, the ITDs
'share' type variables with the generic type. Usually this method is called because we need to know whether to tailor the
munger for addition to a particular type. For example: 
  interface I {}
  
  aspect X implements I {
    List I.foo { return null; }
  }
 In this case the munger matches X but it matches with the form 
  List foo() { return null; }

/**
	 * returns true if the ITD target type used type variables, for example I<T>. When they are specified like this, the ITDs
	 * 'share' type variables with the generic type. Usually this method is called because we need to know whether to tailor the
	 * munger for addition to a particular type. For example: <code>
	 *   interface I<T> {}
	 *   
	 *   aspect X implements I<String> {
	 *     List<T> I<T>.foo { return null; }
	 *   }
	 * </code> In this case the munger matches X but it matches with the form <code>
	 *   List<String> foo() { return null; }
	 * </code>
	 */
	public boolean isTargetTypeParameterized() {
		if (munger == null) {
			return false;
		}
		return munger.sharesTypeVariablesWithGenericType();
	}

	
For an ITD made on a generic type that shares type variables with that target type, this method will tailor the ITD for a
particular usage of the generic type - either in its raw or parameterized form.
/**
	 * For an ITD made on a generic type that shares type variables with that target type, this method will tailor the ITD for a
	 * particular usage of the generic type - either in its raw or parameterized form.
	 */
	public abstract ConcreteTypeMunger parameterizedFor(ResolvedType targetType);

	public boolean isLateMunger() {
		if (munger == null) {
			return false;
		}
		return munger.isLateMunger();
	}

	public abstract ConcreteTypeMunger parameterizeWith(Map<String, UnresolvedType> parameterizationMap, World world);

	
Some type mungers are created purely to help with the implementation of shadow mungers. For example to support the cflow()
pointcut we create a new cflow field in the aspect, and that is added via a BcelCflowCounterFieldAdder.
During compilation we need to compare sets of type mungers, and if some only come into existence after the 'shadowy' type
things have been processed, we need to ignore them during the comparison.
Returning true from this method indicates the type munger exists to support 'shadowy' stuff - and so can be ignored in some
comparison.
/**
	 * Some type mungers are created purely to help with the implementation of shadow mungers. For example to support the cflow()
	 * pointcut we create a new cflow field in the aspect, and that is added via a BcelCflowCounterFieldAdder.
	 * 
	 * During compilation we need to compare sets of type mungers, and if some only come into existence after the 'shadowy' type
	 * things have been processed, we need to ignore them during the comparison.
	 * 
	 * Returning true from this method indicates the type munger exists to support 'shadowy' stuff - and so can be ignored in some
	 * comparison.
	 */
	public boolean existsToSupportShadowMunging() {
		if (munger != null) {
			return munger.existsToSupportShadowMunging();
		}
		return false;
	}

	public boolean shouldOverwrite() {
		return true;
	}
}