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/*
 * Copyright (c) 2002 - 2014 IBM Corporation.
 * 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:
 *     IBM Corporation - initial API and implementation
 */

package com.ibm.wala.cfg.exc;

import com.ibm.wala.cfg.exc.inter.InterprocNullPointerAnalysis;
import com.ibm.wala.cfg.exc.intra.ExplodedCFGNullPointerAnalysis;
import com.ibm.wala.cfg.exc.intra.MethodState;
import com.ibm.wala.cfg.exc.intra.ParameterState;
import com.ibm.wala.cfg.exc.intra.SSACFGNullPointerAnalysis;
import com.ibm.wala.ipa.callgraph.CallGraph;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.ISSABasicBlock;
import com.ibm.wala.ssa.SSAInstruction;
import com.ibm.wala.ssa.analysis.IExplodedBasicBlock;
import com.ibm.wala.types.TypeReference;
import com.ibm.wala.util.CancelException;
import com.ibm.wala.util.MonitorUtil.IProgressMonitor;
import com.ibm.wala.util.WalaException;
import com.ibm.wala.util.graph.GraphIntegrity.UnsoundGraphException;

/**
 * Tries to detect impossible (or always appearing) NullPointerExceptions and removes impossible
 * control flow from the CFG.
 *
 * @author Juergen Graf <[email protected]>
 */
public final class NullPointerAnalysis {

  public static final TypeReference[] DEFAULT_IGNORE_EXCEPTIONS = {
    TypeReference.JavaLangOutOfMemoryError,
    TypeReference.JavaLangExceptionInInitializerError,
    TypeReference.JavaLangNegativeArraySizeException
  };

  private NullPointerAnalysis() {
    throw new IllegalStateException("No instances of this class allowed.");
  }

  public static ExceptionPruningAnalysis
      createIntraproceduralExplodedCFGAnalysis(IR ir) {
    return createIntraproceduralExplodedCFGAnalysis(DEFAULT_IGNORE_EXCEPTIONS, ir, null, null);
  }

  public static ExceptionPruningAnalysis
      createIntraproceduralExplodedCFGAnalysis(TypeReference[] ignoredExceptions, IR ir) {
    return createIntraproceduralExplodedCFGAnalysis(ignoredExceptions, ir, null, null);
  }

  public static ExceptionPruningAnalysis
      createIntraproceduralExplodedCFGAnalysis(
          TypeReference[] ignoredExceptions, IR ir, ParameterState paramState, MethodState mState) {
    return new ExplodedCFGNullPointerAnalysis(ignoredExceptions, ir, paramState, mState, false);
  }

  public static ExceptionPruningAnalysis
      createIntraproceduralExplodedCFGAnalysis(
          TypeReference[] ignoredExceptions,
          IR ir,
          ParameterState paramState,
          MethodState mState,
          boolean optHasException) {
    return new ExplodedCFGNullPointerAnalysis(
        ignoredExceptions, ir, paramState, mState, optHasException);
  }

  public static ExceptionPruningAnalysis
      createIntraproceduralSSACFGAnalyis(IR ir) {
    return createIntraproceduralSSACFGAnalyis(DEFAULT_IGNORE_EXCEPTIONS, ir, null, null);
  }

  public static ExceptionPruningAnalysis
      createIntraproceduralSSACFGAnalyis(TypeReference[] ignoredExceptions, IR ir) {
    return createIntraproceduralSSACFGAnalyis(ignoredExceptions, ir, null, null);
  }

  public static ExceptionPruningAnalysis
      createIntraproceduralSSACFGAnalyis(
          TypeReference[] ignoredExceptions, IR ir, ParameterState paramState, MethodState mState) {
    return new SSACFGNullPointerAnalysis(ignoredExceptions, ir, paramState, mState);
  }

  public static InterprocAnalysisResult
      computeInterprocAnalysis(final CallGraph cg, final IProgressMonitor progress)
          throws WalaException, UnsoundGraphException, CancelException {
    return computeInterprocAnalysis(DEFAULT_IGNORE_EXCEPTIONS, cg, null, progress);
  }

  public static InterprocAnalysisResult
      computeInterprocAnalysis(
          final TypeReference[] ignoredExceptions,
          final CallGraph cg,
          final MethodState defaultExceptionMethodState,
          final IProgressMonitor progress)
          throws WalaException, UnsoundGraphException, CancelException {
    return computeInterprocAnalysis(
        ignoredExceptions, cg, defaultExceptionMethodState, progress, false);
  }

  public static InterprocAnalysisResult
      computeInterprocAnalysis(
          final TypeReference[] ignoredExceptions,
          final CallGraph cg,
          final MethodState defaultExceptionMethodState,
          final IProgressMonitor progress,
          boolean optHasExceptions)
          throws WalaException, UnsoundGraphException, CancelException {
    final InterprocNullPointerAnalysis inpa =
        InterprocNullPointerAnalysis.compute(
            ignoredExceptions, cg, defaultExceptionMethodState, progress, optHasExceptions);

    return inpa.getResult();
  }
}