edu.umd.cs.findbugs.ba.bcp

Class PatternElement

java.lang.Object

edu.umd.cs.findbugs.ba.bcp.PatternElement

Direct Known Subclasses:

Invoke, MatchAny, Opcode, SingleInstruction, Wild

public abstract class PatternElement
extends java.lang.Object

A PatternElement is an element of a ByteCodePattern. It potentially matches some number of bytecode instructions.

Constructor Summary

Constructors

Constructor and Description
PatternElement()

Method Summary

Methods

Modifier and Type	Method and Description
abstract boolean	acceptBranch(Edge edge, org.apache.bcel.generic.InstructionHandle source) Return whether or not it is acceptable to take the given branch.
protected static BindingSet	addOrCheckDefinition(java.lang.String varName, Variable variable, BindingSet bindingSet) Add a variable definition to the given BindingSet, or if there is an existing definition, make sure it is consistent with the new definition.
boolean	allowTrailingEdges() Return whether or not this PatternElement may match trailing edges.
PatternElement	dominatedBy(java.lang.String dominatedBy) Set the label of another pattern element whose first matched instruction must dominate the instruction(s) matched by this element.
java.lang.String	getDominatedBy() Get the label of the pattern element whose first matched instruction must dominate the instruction(s) matched by this element.
java.lang.String	getLabel() Get the label of this PatternElement.
PatternElement	getNext() Get the next PatternElement.
PatternElement	label(java.lang.String label) Set a label for this PatternElement.
static Variable	lookup(java.lang.String varName, BindingSet bindingSet) Look up a variable definition in given BindingSet.
abstract MatchResult	match(org.apache.bcel.generic.InstructionHandle handle, org.apache.bcel.generic.ConstantPoolGen cpg, ValueNumberFrame before, ValueNumberFrame after, BindingSet bindingSet) Return whether or not this element matches the given instruction with the given Bindings in effect.
abstract int	maxOccur() Return the maximum number of instructions this PatternElement must match in the ByteCodePattern.
abstract int	minOccur() Return the minimum number of instructions this PatternElement must match in the ByteCodePattern.
PatternElement	setAllowTrailingEdges(boolean allowTrailingEdges) Set whether or not this PatternElement allows trailing edges to be matched.
void	setIndex(int index) Set the index.
void	setNext(PatternElement patternElement) Set the next PatternElement.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

PatternElement

public PatternElement()

Method Detail

getNext

public PatternElement getNext()

Get the next PatternElement.

setNext

public void setNext(PatternElement patternElement)

Set the next PatternElement.

label

public PatternElement label(java.lang.String label)

Set a label for this PatternElement.

Parameters:

label - the label

Returns:

this object

getLabel

public java.lang.String getLabel()

Get the label of this PatternElement.

Returns:

the label, or null if the PatternElement is not labeled

dominatedBy

public PatternElement dominatedBy(java.lang.String dominatedBy)

Set the label of another pattern element whose first matched instruction must dominate the instruction(s) matched by this element.

getDominatedBy

public java.lang.String getDominatedBy()

Get the label of the pattern element whose first matched instruction must dominate the instruction(s) matched by this element.

setIndex

public void setIndex(int index)

Set the index. This is just for debugging.

setAllowTrailingEdges

public PatternElement setAllowTrailingEdges(boolean allowTrailingEdges)

Set whether or not this PatternElement allows trailing edges to be matched. By default, trailing edges may be matched. When this value is set to false, it ensures that the successor instruction must be in the same basic block.

Parameters:

allowTrailingEdges - true if trailing edges may be matched, false if trailing edges will never be matched

allowTrailingEdges

public boolean allowTrailingEdges()

Return whether or not this PatternElement may match trailing edges.

lookup

public static Variable lookup(java.lang.String varName,
              BindingSet bindingSet)

Look up a variable definition in given BindingSet.

Parameters:

varName - the name of the variable

bindingSet - the BindingSet to look in

Returns:

the Variable, or null if no Variable is bound to the name

match

@CheckForNull
public abstract MatchResult match(org.apache.bcel.generic.InstructionHandle handle,
                             org.apache.bcel.generic.ConstantPoolGen cpg,
                             ValueNumberFrame before,
                             ValueNumberFrame after,
                             BindingSet bindingSet)
                           throws DataflowAnalysisException

Return whether or not this element matches the given instruction with the given Bindings in effect.

Parameters:

handle - the instruction

cpg - the ConstantPoolGen from the method

before - the ValueNumberFrame representing values in the Java stack frame just before the execution of the instruction

after - the ValueNumberFrame representing values in the Java stack frame just after the execution of the instruction

bindingSet - the set of Bindings

Returns:

if the match is successful, returns a MatchResult with the PatternElement and BindingSet; if the match is not successful, returns null

Throws:

DataflowAnalysisException

acceptBranch

public abstract boolean acceptBranch(Edge edge,
                   org.apache.bcel.generic.InstructionHandle source)

Return whether or not it is acceptable to take the given branch.

Parameters:

edge - the Edge representing the branch

source - the source instruction of the branch

Returns:

true if the Edge is acceptable, false if not

minOccur

public abstract int minOccur()

Return the minimum number of instructions this PatternElement must match in the ByteCodePattern.

maxOccur

public abstract int maxOccur()

Return the maximum number of instructions this PatternElement must match in the ByteCodePattern.

addOrCheckDefinition

protected static BindingSet addOrCheckDefinition(java.lang.String varName,
                              Variable variable,
                              BindingSet bindingSet)

Add a variable definition to the given BindingSet, or if there is an existing definition, make sure it is consistent with the new definition.

Parameters:

varName - the name of the variable

variable - the Variable which should be added or checked for consistency

bindingSet - the existing set of bindings

Returns:

the updated BindingSet (if the variable is consistent with the previous bindings), or null if the new variable is inconsistent with the previous bindings

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object