/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2003-2007 University of Maryland
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package edu.umd.cs.findbugs.classfile.engine.bcel;

import org.apache.bcel.generic.MethodGen;

import edu.umd.cs.findbugs.ba.CFG;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.MethodUnprofitableException;
import edu.umd.cs.findbugs.ba.deref.UnconditionalValueDerefAnalysis;
import edu.umd.cs.findbugs.ba.deref.UnconditionalValueDerefDataflow;
import edu.umd.cs.findbugs.ba.npe.IsNullValueDataflow;
import edu.umd.cs.findbugs.ba.type.TypeDataflow;
import edu.umd.cs.findbugs.ba.vna.ValueNumberDataflow;
import edu.umd.cs.findbugs.classfile.CheckedAnalysisException;
import edu.umd.cs.findbugs.classfile.IAnalysisCache;
import edu.umd.cs.findbugs.classfile.MethodDescriptor;

/**
 * Analysis engine to produce UnconditionalValueDerefDataflow objects
 * for analyzed methods.
 * 
 * @author David Hovemeyer
 */
public class UnconditionalValueDerefDataflowFactory extends AnalysisFactory<UnconditionalValueDerefDataflow> {
	/**
	 * Constructor.
	 */
	public UnconditionalValueDerefDataflowFactory() {
		super("unconditional value dereference analysis", UnconditionalValueDerefDataflow.class);
	}

	/* (non-Javadoc)
	 * @see edu.umd.cs.findbugs.classfile.IAnalysisEngine#analyze(edu.umd.cs.findbugs.classfile.IAnalysisCache, java.lang.Object)
	 */
	public UnconditionalValueDerefDataflow analyze(IAnalysisCache analysisCache, MethodDescriptor descriptor) throws CheckedAnalysisException {
		MethodGen methodGen =getMethodGen(analysisCache, descriptor);
		if (methodGen == null) {
			throw new MethodUnprofitableException(descriptor);
		}

		CFG cfg = getCFG(analysisCache, descriptor);

		ValueNumberDataflow vnd = getValueNumberDataflow(analysisCache, descriptor);

		UnconditionalValueDerefAnalysis analysis = new UnconditionalValueDerefAnalysis(
				getReverseDepthFirstSearch(analysisCache, descriptor),
				getDepthFirstSearch(analysisCache, descriptor),
				cfg,
				getMethod(analysisCache, descriptor),
				methodGen,
				vnd,
				getAssertionMethods(analysisCache, descriptor.getClassDescriptor())
		);

		IsNullValueDataflow inv = getIsNullValueDataflow(analysisCache, descriptor);
		// XXX: hack to clear derefs on not-null branches
		analysis.clearDerefsOnNonNullBranches(inv);

		TypeDataflow typeDataflow = getTypeDataflow(analysisCache, descriptor);
		// XXX: type analysis is needed to resolve method calls for
		// checking whether call targets unconditionally dereference parameters
		analysis.setTypeDataflow(typeDataflow);

		UnconditionalValueDerefDataflow dataflow =
			new UnconditionalValueDerefDataflow(cfg, analysis);
		dataflow.execute();
		if (ClassContext.DUMP_DATAFLOW_ANALYSIS) {
			dataflow.dumpDataflow(analysis);
		}
		if (UnconditionalValueDerefAnalysis.DEBUG) {
			ClassContext.dumpDataflowInformation(getMethod(analysisCache, descriptor), cfg, vnd, inv, dataflow, typeDataflow);
		}

		return dataflow;
	}
}
