edu.wisc.cs.java
Class LookupSwitch

java.lang.Object
  |
  +--edu.wisc.cs.java.Bytecode
        |
        +--edu.wisc.cs.java.Switch
              |
              +--edu.wisc.cs.java.LookupSwitch

public class LookupSwitch

extends Switch

This class represents the LookupSwitch instruction. This instruction is used to implement switch statements with sparse case coverage. This instruction is less efficient to execute than the TableSwitch, but it can be more space efficient to represent the table. See the Java Virtual Machine specification for more details.

Field Summary

protected int[]	match_values An array of integer values to match the parameter to.
protected int	n_pairs The number of pairs in the jump table.

Fields inherited from class edu.wisc.cs.java.Switch

default_offset, pad, targets

Fields inherited from class edu.wisc.cs.java.Bytecode

opcode, params, wide

Constructor Summary

LookupSwitch(java.io.DataInputStream in, int pad, int pc)
Constructs a LookupSwitch instruction by reading the table of the appropriate type from the given source.

Method Summary

int	getParamBytes() Returns the number of bytes required to represent the parameters for this bytecode.
void	writeTo(java.io.DataOutputStream out, java.util.HashMap labels, int pc) Writes a lookupswitch instruction to a stream in the specified format.

Methods inherited from class edu.wisc.cs.java.Switch

adjustPad, getDefault, getNBytes, getNTargets, getPad, getTarget

Methods inherited from class edu.wisc.cs.java.Bytecode

getConstantIndex, getOpcode, isWide, toString, writeTo

Methods inherited from class java.lang.Object

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

Field Detail

n_pairs

protected int n_pairs

The number of pairs in the jump table.

match_values

protected int[] match_values

An array of integer values to match the parameter to.

Constructor Detail

LookupSwitch

public LookupSwitch(java.io.DataInputStream in,
                    int pad,
                    int pc)
             throws java.io.IOException

Constructs a LookupSwitch instruction by reading the table of the appropriate type from the given source. Note that it is assumed that any padding bytes have already been read or skipped over in the stream.

Parameters:

in - the stream from which to read the jump table.

Throws:

java.io.IOException - if there is a problem reading from the stream.

Method Detail

getParamBytes

public int getParamBytes()

Returns the number of bytes required to represent the parameters for this bytecode. Note that for this instruction, this does not include bytes for the padding between the opcode and the start of the default offset.

Overrides:

getParamBytes in class Switch

Returns:

the number of bytes required to store this jump table.

writeTo

public void writeTo(java.io.DataOutputStream out,
                    java.util.HashMap labels,
                    int pc)
             throws java.io.IOException

Writes a lookupswitch instruction to a stream in the specified format. The pad is already expected to have been adjusted to the proper value given the pc.

Overrides:

writeTo in class Switch

Parameters:

out - a stream to which to write the data for this instruction.

labels - a map comtaining the labels in the method and their pc's.

pc - the program counter for this instruction.

Throws:

java.io.IOException - if there is a problem writing to the stream.