Instruction (bcel-5.3 API)

java.lang.Object
- org.apache.bcel.generic.Instruction

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

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 386056 2006-03-15 11:31:56Z tcurdt $

Author:

M. Dahm

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

protected short length

protected short opcode

Fields
Modifier and Type	Field	Description
`protected short`	`length`
`protected short`	`opcode`

Constructor Summary

Constructors
Constructor Description

Instruction(short opcode, short length)

Constructors
Constructor	Description
`Instruction(short opcode, short length)`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract void`	`accept(Visitor v)`	Call corresponding visitor method(s).
`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.
`boolean`	`equals(java.lang.Object that)`	Check for equality, delegated to comparator
`static InstructionComparator`	`getComparator()`	Get Comparator object used in the equals() method to determine equality of instructions.
`int`	`getLength()`
`java.lang.String`	`getName()`
`short`	`getOpcode()`
`protected void`	`initFromFile(ByteSequence bytes, boolean wide)`	Read needed data (e.g.
`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.
`static void`	`setComparator(InstructionComparator c)`	Set comparator to be used for equals().
`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, 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
    
    Throws:
    
    java.io.IOException
  - getName
```
public java.lang.String getName()
```
    Returns:
    
    name of instruction, i.e., opcode name
  - 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
    
    Throws:
    
    java.io.IOException
  - 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:
    
    bytes - input stream bytes
    
    Returns:
    
    instruction object being read
    
    Throws:
    
    java.io.IOException
  - 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, or Constants.UNPREDICTABLE, if this can not be computed statically
  - 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, or Constants.UNPREDICTABLE, if this can not be computed statically
  - 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
  - getComparator
```
public static InstructionComparator getComparator()
```
    Get Comparator object used in the equals() method to determine equality of instructions.
    
    Returns:
    
    currently used comparator for equals()
  - setComparator
```
public static void setComparator(InstructionComparator c)
```
    Set comparator to be used for equals().
  - equals
```
public boolean equals(java.lang.Object that)
```
    Check for equality, delegated to comparator
    
    Overrides:
    
    equals in class java.lang.Object
    
    Returns:
    
    true if that is an Instruction and has the same opcode

Class Instruction

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

length

opcode

Constructor Detail

Instruction

Method Detail

dump

getName

toString

toString

toString

copy

initFromFile

readInstruction

consumeStack

produceStack

getOpcode

getLength

accept

getComparator

setComparator

equals