classcontext.java

一个查找java程序里bug的程序的源代码,该程序本身也是java写的,对提高java编程水平很有用

/*
 * Bytecode Analysis Framework
 * Copyright (C) 2003,2004 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.ba;

import java.util.*;

import org.apache.bcel.Constants;

import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;

import org.apache.bcel.generic.ClassGen;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.FieldInstruction;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InstructionList;
import org.apache.bcel.generic.INVOKESTATIC;
import org.apache.bcel.generic.MethodGen;

/**
 * A ClassContext caches all of the auxiliary objects used to analyze
 * the methods of a class.  That way, these objects don't need to
 * be created over and over again.
 *
 * @author David Hovemeyer
 */
public class ClassContext implements AnalysisFeatures {
	/**
	 * We only do pruning of infeasible exception edges
	 * if the <code>WORK_HARD</code> analysis feature
	 * is enabled.
	 */
	public static final boolean PRUNE_INFEASIBLE_EXCEPTION_EDGES = WORK_HARD;

	/**
	 * Only try to determine unconditional exception throwers
	 * if we're not trying to conserve space.
	 */
	public static final boolean PRUNE_UNCONDITIONAL_EXCEPTION_THROWER_EDGES =
	        !CONSERVE_SPACE;

	public static final boolean DEBUG = Boolean.getBoolean("classContext.debug");

	private static final int PRUNED_INFEASIBLE_EXCEPTIONS = 1;
	private static final int PRUNED_UNCONDITIONAL_THROWERS = 2;

	private static final boolean TIME_ANALYSES = Boolean.getBoolean("classContext.timeAnalyses");

	private static final boolean DEBUG_CFG = Boolean.getBoolean("classContext.debugCFG");

	/* ----------------------------------------------------------------------
	 * Helper classes
	 * ---------------------------------------------------------------------- */

	private static int depth;

	private static void indent() {
		for (int i = 0; i < depth; ++i) System.out.print("  ");
	}
	
	/**
	 * An AnalysisResult stores the result of requesting an analysis
	 * from an AnalysisFactory.  It can represent a successful outcome
	 * (where the Analysis object can be returned), or an unsuccessful
	 * outcome (where an exception was thrown trying to create the
	 * analysis).  For unsuccessful outcomes, we rethrow the original
	 * exception rather than making another attempt to create the analysis
	 * (since if it fails once, it will never succeed). 
	 */
	private static class AnalysisResult<Analysis> {
		private boolean analysisSetExplicitly;
		private Analysis analysis;
		private AnalysisException analysisException;
		private CFGBuilderException cfgBuilderException;
		private DataflowAnalysisException dataflowAnalysisException;
		
		public Analysis getAnalysis() throws CFGBuilderException, DataflowAnalysisException {
			if (analysisSetExplicitly)
				return analysis;
			if (dataflowAnalysisException != null)
				throw dataflowAnalysisException;
			if (analysisException != null)
				throw analysisException;
			if (cfgBuilderException != null)
				throw cfgBuilderException;
			throw new IllegalStateException();
		}
		
		/**
		 * Record a successful outcome, where the analysis was created.
		 * 
		 * @param analysis the Analysis
		 */
		public void setAnalysis(Analysis analysis) {
			this.analysisSetExplicitly = true;
			this.analysis = analysis;
		}
		
		/**
		 * Record that an AnalysisException occurred while attempting
		 * to create the Analysis.
		 * 
		 * @param analysisException the AnalysisException
		 */
		public void setAnalysisException(AnalysisException analysisException) {
			this.analysisException = analysisException;
		}
		
		/**
		 * Record that a CFGBuilderException occurred while attempting
		 * to create the Analysis.
		 * 
		 * @param cfgBuilderException the CFGBuilderException
		 */
		public void setCFGBuilderException(CFGBuilderException cfgBuilderException) {
			this.cfgBuilderException = cfgBuilderException;
		}
		
		/**
		 * Record that a DataflowAnalysisException occurred while attempting
		 * to create the Analysis.
		 *  
		 * @param dataflowException the DataflowAnalysisException
		 */
		public void setDataflowAnalysisException(DataflowAnalysisException dataflowException) {
			this.dataflowAnalysisException = dataflowException;
		}
	}

	/**
	 * Abstract factory class for creating analysis objects.
	 * Handles caching of analysis results for a method.
	 */
	private abstract class AnalysisFactory <Analysis> {
		private String analysisName;
		private HashMap<Method, ClassContext.AnalysisResult<Analysis>> map =
			new HashMap<Method, ClassContext.AnalysisResult<Analysis>>();

		/**
		 * Constructor.
		 * 
		 * @param analysisName name of the analysis factory: for diagnostics/debugging
		 */
		public AnalysisFactory(String analysisName) {
			this.analysisName = analysisName;
		}

		/**
		 * Get the Analysis for given method.
		 * If Analysis has already been performed, the cached result is
		 * returned.
		 * 
		 * @param method the method to analyze
		 * @return the Analysis object representing the result of analyzing the method
		 * @throws CFGBuilderException       if the CFG can't be constructed for the method
		 * @throws DataflowAnalysisException if dataflow analysis fails on the method
		 */
		public Analysis getAnalysis(Method method) throws CFGBuilderException, DataflowAnalysisException {
			AnalysisResult<Analysis> result = map.get(method);
			if (result == null) {
				if (TIME_ANALYSES) {
					++depth;
					indent();
					System.out.println("CC: Starting " + analysisName + " for " +
					        SignatureConverter.convertMethodSignature(jclass, method) + ":");
				}

				long begin = System.currentTimeMillis();
				
				// Create a new AnalysisResult
				result = new AnalysisResult<Analysis>();

				// Attempt to create the Analysis and store it in the AnalysisResult.
				// If an exception occurs, record it in the AnalysisResult.
				Analysis analysis = null;
				try {
					analysis = analyze(method);
					result.setAnalysis(analysis);
				} catch (CFGBuilderException e) {
					result.setCFGBuilderException(e);
				} catch (DataflowAnalysisException e) {
					if (TIME_ANALYSES) {
						long end = System.currentTimeMillis();
						indent();
						System.out.println("CC: " + analysisName + " killed by exception after " +
						        (end - begin) + " millis");
						e.printStackTrace();
						--depth;
					}
					result.setDataflowAnalysisException(e);
				} catch (AnalysisException e) {
					result.setAnalysisException(e);
				}

				if (TIME_ANALYSES) {
					long end = System.currentTimeMillis();
					indent();
					System.out.println("CC: finished " + analysisName + " in " + (end - begin) + " millis");
					--depth;
				}

				// Cache the outcome of this analysis attempt.
				map.put(method, result);
			}
			
			return result.getAnalysis();
		}

		protected abstract Analysis analyze(Method method)
		        throws CFGBuilderException, DataflowAnalysisException;
	}

	private abstract class NoExceptionAnalysisFactory <AnalysisResult> extends AnalysisFactory<AnalysisResult> {
		public NoExceptionAnalysisFactory(String analysisName) {
			super(analysisName);
		}

		public AnalysisResult getAnalysis(Method method) {
			try {
				return super.getAnalysis(method);
			} catch (DataflowAnalysisException e) {
				throw new IllegalStateException("Should not happen");
			} catch (CFGBuilderException e) {
				throw new IllegalStateException("Should not happen");
			}
		}
	}

	private abstract class NoDataflowAnalysisFactory <AnalysisResult> extends AnalysisFactory<AnalysisResult> {
		public NoDataflowAnalysisFactory(String analysisName) {
			super(analysisName);
		}

		public AnalysisResult getAnalysis(Method method) throws CFGBuilderException {
			try {
				return super.getAnalysis(method);
			} catch (DataflowAnalysisException e) {
				throw new IllegalStateException("Should not happen");
			}
		}
	}

	private static final Set<String> busyCFGSet = new HashSet<String>();

	private class CFGFactory extends AnalysisFactory<CFG> {

		public CFGFactory() {
			super("CFG construction");
		}

		public CFG getAnalysis(Method method) throws CFGBuilderException {
			try {
				return super.getAnalysis(method);
			} catch (DataflowAnalysisException e) {
				throw new IllegalStateException("Should not happen");
			}
		}

		public CFG getRawCFG(Method method) throws CFGBuilderException {
			return getAnalysis(method);
		}

		public CFG getRefinedCFG(Method method) throws CFGBuilderException {
			MethodGen methodGen = getMethodGen(method);

			CFG cfg = getRawCFG(method);

			// HACK:
			// Due to recursive method invocations, we may get a recursive
			// request for the pruned CFG of a method.  In this case,
			// we just return the raw CFG.
			String methodId = methodGen.getClassName() + "." + methodGen.getName() + ":" + methodGen.getSignature();
			if (DEBUG_CFG) {
				indent();
				System.out.println("CC: getting refined CFG for " + methodId);
			}
			if (DEBUG) System.out.println("ClassContext: request to prune " + methodId);
			if (!busyCFGSet.add(methodId))
				return cfg;

			if (PRUNE_INFEASIBLE_EXCEPTION_EDGES && !cfg.isFlagSet(PRUNED_INFEASIBLE_EXCEPTIONS)) {
				try {
					TypeDataflow typeDataflow = getTypeDataflow(method);
					new PruneInfeasibleExceptionEdges(cfg, getMethodGen(method), typeDataflow).execute();
				} catch (DataflowAnalysisException e) {
					// FIXME: should report the error
				} catch (ClassNotFoundException e) {
					getLookupFailureCallback().reportMissingClass(e);
				}
			}
			cfg.setFlags(cfg.getFlags() | PRUNED_INFEASIBLE_EXCEPTIONS);

			if (PRUNE_UNCONDITIONAL_EXCEPTION_THROWER_EDGES && !cfg.isFlagSet(PRUNED_UNCONDITIONAL_THROWERS)) {