Class InstructionList

java.lang.Object
org.apache.bcel.generic.InstructionList
All Implemented Interfaces:
Iterable<InstructionHandle>
public class InstructionList extends Object implements Iterable<InstructionHandle>
This class is a container for a list of Instruction objects. Instructions can be appended, inserted, moved, deleted, and so on. Instructions are being wrapped into InstructionHandles objects that are returned upon append/insert operations. They give the user (read only) access to the list structure, such that it can be traversed and manipulated in a controlled way.

A list is finally dumped to a byte code array with getByteCode.

See Also:

  • Constructor Details

    • InstructionList

      public InstructionList()
      Create (empty) instruction list.

    • InstructionList

      public InstructionList(BranchInstruction i)
      Create instruction list containing one instruction.
      Parameters:
      i - initial instruction.

    • InstructionList

      public InstructionList(byte[] code)
      Initialize instruction list from byte array.
      Parameters:
      code - byte array containing the instructions.

    • InstructionList

      public InstructionList(CompoundInstruction c)
      Initialize list with (nonnull) compound instruction. Consumes argument list, that is, it becomes empty.
      Parameters:
      c - compound instruction (list).

    • InstructionList

      public InstructionList(Instruction i)
      Create instruction list containing one instruction.
      Parameters:
      i - initial instruction.

  • Method Details

    • findHandle

      public static InstructionHandle findHandle(InstructionHandle[] ihs, int[] pos, int count, int target)
      Find the target instruction (handle) that corresponds to the given target position (byte code offset).
      Parameters:
      ihs - array of instruction handles, for example il.getInstructionHandles().
      pos - array of positions corresponding to ihs, for example il.getInstructionPositions().
      count - length of arrays.
      target - target position to search for.
      Returns:
      target position's instruction handle if available.

    • addObserver

      public void addObserver(InstructionListObserver o)
      Add observer for this object.
      Parameters:
      o - the observer to add.

    • append

      public BranchHandle append(BranchInstruction i)
      Append a branch instruction to the end of this list.
      Parameters:
      i - branch instruction to append.
      Returns:
      branch instruction handle of the appended instruction.

    • append

      public InstructionHandle append(CompoundInstruction c)
      Append a compound instruction.
      Parameters:
      c - The composite instruction (containing an InstructionList).
      Returns:
      instruction handle of the first appended instruction.

    • append

      public InstructionHandle append(Instruction i)
      Append an instruction to the end of this list.
      Parameters:
      i - instruction to append.
      Returns:
      instruction handle of the appended instruction.

    • append

      public InstructionHandle append(Instruction i, CompoundInstruction c)
      Append a compound instruction, after instruction i.
      Parameters:
      i - Instruction in list.
      c - The composite instruction (containing an InstructionList).
      Returns:
      instruction handle of the first appended instruction.

    • append

      public InstructionHandle append(Instruction i, Instruction j)
      Append a single instruction j after another instruction i, which must be in this list of course!
      Parameters:
      i - Instruction in list.
      j - Instruction to append after i in list.
      Returns:
      instruction handle of the first appended instruction.

    • append

      public InstructionHandle append(Instruction i, InstructionList il)
      Append another list after instruction i contained in this list. Consumes argument list, that is, it becomes empty.
      Parameters:
      i - where to append the instruction list.
      il - Instruction list to append to this one.
      Returns:
      instruction handle pointing to the first appended instruction.

    • append

      public BranchHandle append(InstructionHandle ih, BranchInstruction i)
      Append an instruction after instruction (handle) ih contained in this list.
      Parameters:
      ih - where to append the instruction list.
      i - Instruction to append.
      Returns:
      instruction handle pointing to the first appended instruction.

    • append

      public InstructionHandle append(InstructionHandle ih, CompoundInstruction c)
      Append a compound instruction.
      Parameters:
      ih - where to append the instruction list.
      c - The composite instruction (containing an InstructionList).
      Returns:
      instruction handle of the first appended instruction.

    • append

      public InstructionHandle append(InstructionHandle ih, Instruction i)
      Append an instruction after instruction (handle) ih contained in this list.
      Parameters:
      ih - where to append the instruction list.
      i - Instruction to append.
      Returns:
      instruction handle pointing to the first appended instruction.

    • append

      public InstructionHandle append(InstructionHandle ih, InstructionList il)
      Append another list after instruction (handle) ih contained in this list. Consumes argument list, that is, it becomes empty.
      Parameters:
      ih - where to append the instruction list.
      il - Instruction list to append to this one.
      Returns:
      instruction handle pointing to the first appended instruction.

    • append

      public InstructionHandle append(InstructionList il)
      Append another list to this one. Consumes argument list, that is, it becomes empty.
      Parameters:
      il - list to append to end of this list.
      Returns:
      instruction handle of the first appended instruction.

    • contains

      public boolean contains(Instruction i)
      Checks if the list contains the given instruction.
      Parameters:
      i - the instruction to check.
      Returns:
      true if the list contains the instruction.

    • contains

      public boolean contains(InstructionHandle i)
      Checks if the list contains the given instruction handle.
      Parameters:
      i - the instruction handle to check.
      Returns:
      true if the list contains the instruction handle.

    • copy

      public InstructionList copy()
      Creates a complete deep copy of this list.
      Returns:
      complete, that is, deep copy of this list.

    • delete

      public void delete(Instruction i) throws TargetLostException
      Remove instruction from this list. The corresponding Instruction handles must not be reused!
      Parameters:
      i - instruction to remove.
      Throws:
      TargetLostException - if target is lost.

    • delete

      public void delete(Instruction from, Instruction to) throws TargetLostException
      Remove instructions from instruction 'from' to instruction 'to' contained in this list. The user must ensure that 'from' is an instruction before 'to', or risk havoc. The corresponding Instruction handles must not be reused!
      Parameters:
      from - where to start deleting (inclusive).
      to - where to end deleting (inclusive).
      Throws:
      TargetLostException - if target is lost.

    • delete

      public void delete(InstructionHandle ih) throws TargetLostException
      Remove instruction from this list. The corresponding Instruction handles must not be reused!
      Parameters:
      ih - instruction (handle) to remove.
      Throws:
      TargetLostException - if target is lost.

    • delete

      public void delete(InstructionHandle from, InstructionHandle to) throws TargetLostException
      Remove instructions from instruction 'from' to instruction 'to' contained in this list. The user must ensure that 'from' is an instruction before 'to', or risk havoc. The corresponding Instruction handles must not be reused!
      Parameters:
      from - where to start deleting (inclusive).
      to - where to end deleting (inclusive).
      Throws:
      TargetLostException - if target is lost.

    • dispose

      public void dispose()
      Delete contents of list. Provides better memory utilization, because the system then may reuse the instruction handles. This method is typically called right after MethodGen.getMethod().

    • findHandle

      public InstructionHandle findHandle(int pos)
      Gets instruction handle for instruction at byte code position pos. This only works properly, if the list is freshly initialized from a byte array or setPositions() has been called before this method.
      Parameters:
      pos - byte code position to search for.
      Returns:
      target position's instruction handle if available.

    • getByteCode

      public byte[] getByteCode()
      When everything is finished, use this method to convert the instruction list into an array of bytes.
      Returns:
      the byte code ready to be dumped.

    • getEnd

      public InstructionHandle getEnd()
      Gets the end of list.
      Returns:
      end of list.

    • getInstructionHandles

      public InstructionHandle[] getInstructionHandles()
      Gets array containing all instructions.
      Returns:
      array containing all instructions (handles).

    • getInstructionPositions

      public int[] getInstructionPositions()
      Gets positions (offsets) of all instructions in the list. This relies on that the list has been freshly created from an byte code array, or that setPositions() has been called. Otherwise this may be inaccurate.
      Returns:
      array containing all instruction's offset in byte code.

    • getInstructions

      public Instruction[] getInstructions()
      Gets an array of instructions without target information for branch instructions.
      Returns:
      an array of instructions without target information for branch instructions.

    • getLength

      public int getLength()
      Gets the length of list.
      Returns:
      length of list (Number of instructions, not bytes).

    • getStart

      public InstructionHandle getStart()
      Gets the start of list.
      Returns:
      start of list.

    • insert

      public BranchHandle insert(BranchInstruction i)
      Insert a branch instruction at start of this list.
      Parameters:
      i - branch instruction to insert.
      Returns:
      branch instruction handle of the appended instruction.

    • insert

      public InstructionHandle insert(CompoundInstruction c)
      Insert a compound instruction.
      Parameters:
      c - The composite instruction (containing an InstructionList).
      Returns:
      instruction handle of the first inserted instruction.

    • insert

      public InstructionHandle insert(Instruction i)
      Insert an instruction at start of this list.
      Parameters:
      i - instruction to insert.
      Returns:
      instruction handle of the inserted instruction.

    • insert

      public InstructionHandle insert(Instruction i, CompoundInstruction c)
      Insert a compound instruction before instruction i.
      Parameters:
      i - Instruction in list.
      c - The composite instruction (containing an InstructionList).
      Returns:
      instruction handle of the first inserted instruction.

    • insert

      public InstructionHandle insert(Instruction i, Instruction j)
      Insert a single instruction j before another instruction i, which must be in this list of course!
      Parameters:
      i - Instruction in list.
      j - Instruction to insert before i in list.
      Returns:
      instruction handle of the first inserted instruction.

    • insert

      public InstructionHandle insert(Instruction i, InstructionList il)
      Insert another list before Instruction i contained in this list. Consumes argument list, that is, it becomes empty.
      Parameters:
      i - where to append the instruction list.
      il - Instruction list to insert.
      Returns:
      instruction handle pointing to the first inserted instruction, that is, il.getStart().

    • insert

      public BranchHandle insert(InstructionHandle ih, BranchInstruction i)
      Insert an instruction before instruction (handle) ih contained in this list.
      Parameters:
      ih - where to insert to the instruction list.
      i - Instruction to insert.
      Returns:
      instruction handle of the first inserted instruction.

    • insert

      public InstructionHandle insert(InstructionHandle ih, CompoundInstruction c)
      Insert a compound instruction.
      Parameters:
      ih - where to insert the instruction list.
      c - The composite instruction (containing an InstructionList).
      Returns:
      instruction handle of the first inserted instruction.

    • insert

      public InstructionHandle insert(InstructionHandle ih, Instruction i)
      Insert an instruction before instruction (handle) ih contained in this list.
      Parameters:
      ih - where to insert to the instruction list.
      i - Instruction to insert.
      Returns:
      instruction handle of the first inserted instruction.

    • insert

      public InstructionHandle insert(InstructionHandle ih, InstructionList il)
      Insert another list before Instruction handle ih contained in this list. Consumes argument list, that is, it becomes empty.
      Parameters:
      ih - where to append the instruction list.
      il - Instruction list to insert.
      Returns:
      instruction handle of the first inserted instruction.

    • insert

      public InstructionHandle insert(InstructionList il)
      Insert another list.
      Parameters:
      il - list to insert before start of this list.
      Returns:
      instruction handle of the first inserted instruction.

    • isEmpty

      public boolean isEmpty()
      Tests for empty list.

    • iterator

      public Iterator<InstructionHandle> iterator()
      Specified by:
      iterator in interface Iterable<InstructionHandle>
      Returns:
      iterator that lists all instructions (handles).

    • move

      public void move(InstructionHandle ih, InstructionHandle target)
      Move a single instruction (handle) to a new location.
      Parameters:
      ih - moved instruction.
      target - new location of moved instruction.

    • move

      public void move(InstructionHandle start, InstructionHandle end, InstructionHandle target)
      Take all instructions (handles) from "start" to "end" and append them after the new location "target". Of course, "end" must be after "start" and target must not be located withing this range. If you want to move something to the start of the list use null as value for target.

      Any instruction targeters pointing to handles within the block, keep their targets.

      Parameters:
      start - of moved block.
      end - of moved block.
      target - of moved block.

    • redirectBranches

      public void redirectBranches(InstructionHandle oldTarget, InstructionHandle newTarget)
      Redirect all references from oldTarget to newTarget, that is, update targets of branch instructions.
      Parameters:
      oldTarget - the old target instruction handle.
      newTarget - the new target instruction handle.

    • redirectExceptionHandlers

      public void redirectExceptionHandlers(CodeExceptionGen[] exceptions, InstructionHandle oldTarget, InstructionHandle newTarget)
      Redirect all references of exception handlers from oldTarget to newTarget.
      Parameters:
      exceptions - array of exception handlers.
      oldTarget - the old target instruction handle.
      newTarget - the new target instruction handle.
      See Also:

    • redirectLocalVariables

      public void redirectLocalVariables(LocalVariableGen[] lg, InstructionHandle oldTarget, InstructionHandle newTarget)
      Redirect all references of local variables from oldTarget to newTarget.
      Parameters:
      lg - array of local variables.
      oldTarget - the old target instruction handle.
      newTarget - the new target instruction handle.
      See Also:

    • removeObserver

      public void removeObserver(InstructionListObserver o)
      Remove observer for this object.
      Parameters:
      o - the observer to remove.

    • replaceConstantPool

      public void replaceConstantPool(ConstantPoolGen oldCp, ConstantPoolGen newCp)
      Replace all references to the old constant pool with references to the new constant pool.
      Parameters:
      oldCp - the old constant pool.
      newCp - the new constant pool.

    • setPositions

      public void setPositions()
      Sets positions with no sanity checks.

    • setPositions

      public void setPositions(boolean check)
      Give all instructions their position number (offset in byte stream), that is, make the list ready to be dumped.
      Parameters:
      check - Perform sanity checks, for example if all targeted instructions really belong to this list.

    • size

      public int size()
      Gets the length of list.
      Returns:
      length of list (Number of instructions, not bytes).

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • toString

      public String toString(boolean verbose)
      Gets string containing all instructions in this list.
      Parameters:
      verbose - toggle output format.
      Returns:
      String containing all instructions in this list.

    • update

      public void update()
      Call notify() method on all observers. This method is not called automatically whenever the state has changed, but has to be called by the user after he has finished editing the object.