de.fub.bytecode.generic
Class Instruction

java.lang.Object
  |
  +--de.fub.bytecode.generic.Instruction

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable

Direct Known Subclasses:

ACONST_NULL, ArithmeticInstruction, ArrayInstruction, ARRAYLENGTH, ATHROW, BIPUSH, BranchInstruction, BREAKPOINT, ConversionInstruction, CPInstruction, DCMPG, DCMPL, DCONST, FCMPG, FCMPL, FCONST, ICONST, IMPDEP1, IMPDEP2, LCMP, LCONST, LocalVariableInstruction, MONITORENTER, MONITOREXIT, NEWARRAY, NOP, RET, ReturnInstruction, SIPUSH, StackInstruction

public abstract class Instruction

extends java.lang.Object

implements java.lang.Cloneable, java.io.Serializable

Abstract super class for all Java byte codes.

Version:

$Id: Instruction.java,v 1.13 2001/10/11 11:59:27 dahm Exp $

Author:

M. Dahm

See Also:

Serialized Form

Field Summary

protected short	length
protected short	opcode

Constructor Summary

Instruction(short opcode, short length)

Method Summary

abstract void	accept(Visitor v) Call corresponding visitor method(s).
int	consumeStack() Deprecated. Use consumeStack(cp) instead which always gives correct results
int	consumeStack(ConstantPoolGen cpg) This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.
Instruction	copy() Use with caution, since `BranchInstruction's have a `target' reference which is not copied correctly (only basic types are).
void	dump(java.io.DataOutputStream out) Dump instruction as byte code to stream out.
int	getLength()
short	getOpcode()
short	getTag() Deprecated. in favor of getOpcode()
protected void	initFromFile(ByteSequence bytes, boolean wide) Read needed data (e.g.
int	produceStack() Deprecated. Use produceStack(cp) instead which always gives correct results
int	produceStack(ConstantPoolGen cpg) This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.
static Instruction	readInstruction(ByteSequence bytes) Read an instruction from (byte code) input stream and return the appropiate object.
java.lang.String	toString()
java.lang.String	toString(boolean verbose) Long output format: <name of opcode> "["<opcode number>"]" "("<length of instruction>")"
java.lang.String	toString(ConstantPool cp)

Methods inherited from class java.lang.Object

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

Field Detail

length

protected short length

opcode

protected short opcode

Constructor Detail

Instruction

public Instruction(short opcode,
                   short length)

Method Detail

dump

public void dump(java.io.DataOutputStream out)
          throws java.io.IOException

Dump instruction as byte code to stream out.

Parameters:

out - Output stream

toString

public java.lang.String toString(boolean verbose)

Long output format: <name of opcode> "["<opcode number>"]" "("<length of instruction>")"

Parameters:

verbose - long/short format switch

Returns:

mnemonic for instruction

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

mnemonic for instruction in verbose format

toString

public java.lang.String toString(ConstantPool cp)

Returns:

mnemonic for instruction with sumbolic references resolved

copy

public Instruction copy()

Use with caution, since `BranchInstruction's have a `target' reference which is not copied correctly (only basic types are). This also applies for `Select' instructions with their multiple branch targets.

Returns:

(shallow) copy of an instruction

See Also:

BranchInstruction

initFromFile

protected void initFromFile(ByteSequence bytes,
                            boolean wide)
                     throws java.io.IOException

Read needed data (e.g. index) from file.

Parameters:

bytes - byte sequence to read from

wide - "wide" instruction flag

readInstruction

public static final Instruction readInstruction(ByteSequence bytes)
                                         throws java.io.IOException

Read an instruction from (byte code) input stream and return the appropiate object.

Parameters:

file - file to read from

Returns:

instruction object being read

consumeStack

public int consumeStack()

Deprecated. Use consumeStack(cp) instead which always gives correct results

Returns:

Number of words consumed from stack by this instruction, or Constants.UNPREDICTABLE, if this can not be computed statically

produceStack

public int produceStack()

Deprecated. Use produceStack(cp) instead which always gives correct results

Returns:

Number of words produced onto stack by this instruction, or Constants.UNPREDICTABLE, if this can not be computed statically

consumeStack

public int consumeStack(ConstantPoolGen cpg)

This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.

Returns:

Number of words consumed from stack by this instruction

produceStack

public int produceStack(ConstantPoolGen cpg)

This method also gives right results for instructions whose effect on the stack depends on the constant pool entry they reference.

Returns:

Number of words produced onto stack by this instruction

getTag

public short getTag()

Deprecated. in favor of getOpcode()

Returns:

opcode number

getOpcode

public short getOpcode()

Returns:

this instructions opcode

getLength

public int getLength()

Returns:

length (in bytes) of instruction

accept

public abstract void accept(Visitor v)

Call corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call methods according to the class hierarchy in descending order, i.e., the most specific visitXXX() call comes last.

Parameters:

v - Visitor object