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

  • Constructor Details

    • PatternElement

      public PatternElement()

  • Method Details

    • getNext

      public PatternElement getNext()
      Get the next PatternElement.

    • setNext

      public void setNext(PatternElement patternElement)
      Set the next PatternElement.

    • label

      public PatternElement label(String label)
      Set a label for this PatternElement.
      Parameters:
      label - the label
      Returns:
      this object

    • getLabel

      public String getLabel()
      Get the label of this PatternElement.
      Returns:
      the label, or null if the PatternElement is not labeled

    • dominatedBy

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

    • getDominatedBy

      public 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(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(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 String toString()
      Overrides:
      toString in class Object