edu.umd.cs.findbugs.ba.bcp
Class PatternMatcher

java.lang.Object
  edu.umd.cs.findbugs.ba.bcp.PatternMatcher

All Implemented Interfaces:

DFSEdgeTypes

public class PatternMatcher
extends java.lang.Object
implements DFSEdgeTypes

Match a ByteCodePattern against the code of a method, represented by a CFG. Produces some number of ByteCodePatternMatch objects, which indicate how the pattern matched the bytecode instructions in the method.

This code is a hack and should probably be rewritten.

Author:

David Hovemeyer

See Also:

ByteCodePattern

Nested Class Summary

private class

PatternMatcher.State Object representing the current state of the matching algorithm.

Field Summary

private CFG	cfg
private org.apache.bcel.generic.ConstantPoolGen	cpg
private static boolean	DEBUG
private DepthFirstSearch	dfs
private DominatorsAnalysis	domAnalysis
private ByteCodePattern	pattern
private java.util.LinkedList<ByteCodePatternMatch>	resultList
private static boolean	SHOW_WILD
private java.util.IdentityHashMap<BasicBlock,BasicBlock>	visitedBlockMap
private ValueNumberDataflow	vnaDataflow
private java.util.LinkedList<BasicBlock>	workList

Fields inherited from interface edu.umd.cs.findbugs.graph.DFSEdgeTypes

BACK_EDGE, CROSS_EDGE, FORWARD_EDGE, TREE_EDGE, UNKNOWN_EDGE

Constructor Summary

PatternMatcher(ByteCodePattern pattern, ClassContext classContext, org.apache.bcel.classfile.Method method)
Constructor.

Method Summary

private void	attemptMatch(BasicBlock basicBlock, BasicBlock.InstructionIterator instructionIterator) Attempt to begin a match.
java.util.Iterator<ByteCodePatternMatch>	byteCodePatternMatchIterator() Return an Iterator over the ByteCodePatternMatch objects representing successful matches of the ByteCodePattern.
PatternMatcher	execute() Search for examples of the ByteCodePattern.
private void	work(PatternMatcher.State state) Match a sequence of pattern elements, starting at the given one.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEBUG

private static final boolean DEBUG

SHOW_WILD

private static final boolean SHOW_WILD

pattern

private ByteCodePattern pattern

cfg

private CFG cfg

cpg

private org.apache.bcel.generic.ConstantPoolGen cpg

dfs

private DepthFirstSearch dfs

vnaDataflow

private ValueNumberDataflow vnaDataflow

domAnalysis

private DominatorsAnalysis domAnalysis

workList

private java.util.LinkedList<BasicBlock> workList

visitedBlockMap

private java.util.IdentityHashMap<BasicBlock,BasicBlock> visitedBlockMap

resultList

private java.util.LinkedList<ByteCodePatternMatch> resultList

Constructor Detail

PatternMatcher

public PatternMatcher(ByteCodePattern pattern,
                      ClassContext classContext,
                      org.apache.bcel.classfile.Method method)
               throws CFGBuilderException,
                      DataflowAnalysisException

Constructor.

Parameters:

pattern - the ByteCodePattern to look for examples of

classContext - ClassContext for the class to analyze

method - the Method to analyze

Throws:

CFGBuilderException

DataflowAnalysisException

Method Detail

execute

public PatternMatcher execute()
                       throws DataflowAnalysisException

Search for examples of the ByteCodePattern.

Returns:

this object

Throws:

DataflowAnalysisException - if the ValueNumberAnalysis did not produce useful values for the method

byteCodePatternMatchIterator

public java.util.Iterator<ByteCodePatternMatch> byteCodePatternMatchIterator()

Return an Iterator over the ByteCodePatternMatch objects representing successful matches of the ByteCodePattern.

attemptMatch

private void attemptMatch(BasicBlock basicBlock,
                          BasicBlock.InstructionIterator instructionIterator)
                   throws DataflowAnalysisException

Attempt to begin a match.

Parameters:

basicBlock - the basic block

instructionIterator - the instruction iterator positioned just before the first instruction to be matched

Throws:

DataflowAnalysisException

work

private void work(PatternMatcher.State state)
           throws DataflowAnalysisException

Match a sequence of pattern elements, starting at the given one. The InstructionIterator should generally be positioned just before the next instruction to be matched. However, it may be positioned at the end of a basic block, in which case nothing will happen except that we will try to continue the match in the non-backedge successors of the basic block.

Throws:

DataflowAnalysisException