org.aspectj/runtime/src/main/java/org/aspectj/runtime/reflect/JoinPointImpl.java

/* *******************************************************************
 * Copyright (c) 1999-2001 Xerox Corporation,
 *               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 v 2.0
 * which accompanies this distribution and is available at
 * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
 *
 * Contributors:
 *     Xerox/PARC     initial implementation
 * ******************************************************************/

package org.aspectj.runtime.reflect;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.reflect.SourceLocation;
import org.aspectj.runtime.internal.AroundClosure;

import java.util.ArrayList;
import java.util.List;

class JoinPointImpl implements ProceedingJoinPoint {
	static class StaticPartImpl implements StaticPart {
		String kind;
		Signature signature;
		SourceLocation sourceLocation;
		private final int id;

		public StaticPartImpl(int id, String kind, Signature signature, SourceLocation sourceLocation) {
			this.kind = kind;
			this.signature = signature;
			this.sourceLocation = sourceLocation;
			this.id = id;
		}

		public int getId() {
			return id;
		}

		public String getKind() {
			return kind;
		}

		public Signature getSignature() {
			return signature;
		}

		public SourceLocation getSourceLocation() {
			return sourceLocation;
		}

		String toString(StringMaker sm) {
			return sm.makeKindName(getKind()) + "(" + ((SignatureImpl) getSignature()).toString(sm) + ")";
		}

		public final String toString() {
			return toString(StringMaker.middleStringMaker);
		}

		public final String toShortString() {
			return toString(StringMaker.shortStringMaker);
		}

		public final String toLongString() {
			return toString(StringMaker.longStringMaker);
		}
	}

	static class EnclosingStaticPartImpl extends StaticPartImpl implements EnclosingStaticPart {
		public EnclosingStaticPartImpl(int count, String kind, Signature signature, SourceLocation sourceLocation) {
			super(count, kind, signature, sourceLocation);
		}
	}

	Object _this;
	Object target;
	Object[] args;
	StaticPart staticPart;

	public JoinPointImpl(StaticPart staticPart, Object _this, Object target, Object[] args) {
		this.staticPart = staticPart;
		this._this = _this;
		this.target = target;
		this.args = args;
	}

	public Object getThis() {
		return _this;
	}

	public Object getTarget() {
		return target;
	}

	public Object[] getArgs() {
		if (args == null)
			args = new Object[0];
		Object[] argsCopy = new Object[args.length];
		System.arraycopy(args, 0, argsCopy, 0, args.length);
		return argsCopy;
	}

	public StaticPart getStaticPart() {
		return staticPart;
	}

	public String getKind() {
		return staticPart.getKind();
	}

	public Signature getSignature() {
		return staticPart.getSignature();
	}

	public SourceLocation getSourceLocation() {
		return staticPart.getSourceLocation();
	}

	public final String toString() {
		return staticPart.toString();
	}

	public final String toShortString() {
		return staticPart.toShortString();
	}

	public final String toLongString() {
		return staticPart.toLongString();
	}

	// To proceed we need a closure to proceed on. Generated code
	// will either be using arc or arcs but not both. arcs being non-null
	// indicates it is in use (even if an empty stack)
	private AroundClosure arc = null;
	private List<AroundClosure> arcs = null;
	private final ThreadLocal<Integer> arcIndex = ThreadLocal.withInitial(() -> arcs == null ? -1 : arcs.size() - 1);

	public void set$AroundClosure(AroundClosure arc) {
		this.arc = arc;
	}

	public void stack$AroundClosure(AroundClosure arc) {
		// If input parameter arc is null this is the 'unlink' call from AroundClosure
		if (arcs == null)
			arcs = new ArrayList<>();
		if (arc == null) {
			int newIndex = arcIndex.get() - 1;
			if (newIndex > -1)
				arcIndex.set(newIndex);
			else
				arcIndex.remove();
		}
		else {
			this.arcs.add(arc);
			arcIndex.set(arcs.size() - 1);
		}
	}

	public Object proceed() throws Throwable {
		// when called from a before advice, but be a no-op
		if (arcs == null) {
			return arc == null ? null : arc.run(arc.getState());
		} else {
			final AroundClosure ac = arcs.get(arcIndex.get());
			return ac.run(ac.getState());
		}
	}

	public Object proceed(Object[] adviceBindings) throws Throwable {
		// when called from a before advice, but be a no-op
		AroundClosure ac = arcs == null ? arc : arcs.get(arcIndex.get());

		if (ac == null)
			return null;

		// Based on the bit flags in the AroundClosure we can determine what to
		// expect in the adviceBindings array. We may or may not be expecting
		// the first value to be a new this or a new target... (see pr126167)
		int flags = ac.getFlags();
		boolean unset = (flags & 0x100000) != 0;
		boolean thisTargetTheSame = (flags & 0x010000) != 0;
		boolean hasThis = (flags & 0x001000) != 0;
		boolean bindsThis = (flags & 0x000100) != 0;
		boolean hasTarget = (flags & 0x000010) != 0;
		boolean bindsTarget = (flags & 0x000001) != 0;

		// state is always consistent with caller?,callee?,formals...,jp
		Object[] state = ac.getState();

		// these next two numbers can differ because some join points have a this and
		// target that are the same (eg. call) - and yet you can bind this and target
		// separately.

		// In the state array, [0] may be this, [1] may be target

		int firstArgumentIndexIntoAdviceBindings = 0;
		int firstArgumentIndexIntoState = 0;
		firstArgumentIndexIntoState += (hasThis ? 1 : 0);
		firstArgumentIndexIntoState += (hasTarget && !thisTargetTheSame ? 1 : 0);
		if (hasThis) {
			if (bindsThis) {
				// replace [0] (this)
				firstArgumentIndexIntoAdviceBindings = 1;
				state[0] = adviceBindings[0];
			} else {
				// leave state[0] alone, its OK
			}
		}
		if (hasTarget) {
			if (bindsTarget) {
				if (thisTargetTheSame) {
					// this and target are the same so replace state[0]
					firstArgumentIndexIntoAdviceBindings = 1 + (bindsThis ? 1 : 0);
					state[0] = adviceBindings[(bindsThis ? 1 : 0)];
				} else {
					// need to replace the target, and it is different to this, whether
					// that means replacing state[0] or state[1] depends on whether
					// the join point has a this

					// This previous variant doesn't seem to cope with only binding target at a joinpoint which has both this and
					// target. It forces you to supply this even if you didn't bind it.
					/*
					firstArgumentIndexIntoAdviceBindings = (hasThis ? 1 : 0) + 1;
					state[hasThis ? 1 : 0] = adviceBindings[hasThis ? 1 : 0];
					*/

					int targetPositionInAdviceBindings = (hasThis && bindsThis) ? 1 : 0;
					firstArgumentIndexIntoAdviceBindings = ((hasThis&&bindsThis)?1:0)+((hasTarget&&bindsTarget&&!thisTargetTheSame)?1:0);
					state[hasThis ? 1 : 0] = adviceBindings[targetPositionInAdviceBindings];
				}
			} else {
				// leave state[0]/state[1] alone, they are OK
			}
		}

		// copy the rest across
		for (int i = firstArgumentIndexIntoAdviceBindings; i < adviceBindings.length; i++) {
			state[firstArgumentIndexIntoState + (i - firstArgumentIndexIntoAdviceBindings)] = adviceBindings[i];
		}

		// old code that did this, didnt allow this/target overriding
		/*
		for (int i = state.length - 2; i >= 0; i--) {
			int formalIndex = (adviceBindings.length - 1) - (state.length - 2) + i;
			if (formalIndex >= 0 && formalIndex < adviceBindings.length) {
				state[i] = adviceBindings[formalIndex];
			}
		}
		*/
		return ac.run(state);
	}

}