com.claritysys.jvm.classfile
Class CfMethod

java.lang.Object
  com.claritysys.jvm.classfile.CfEntry
      com.claritysys.jvm.classfile.CfFieldOrMethod
          com.claritysys.jvm.classfile.CfMethod

All Implemented Interfaces:

AttributeHandler

public class CfMethod
extends CfFieldOrMethod
implements AttributeHandler

A method declared within a ClassFile.

Methods are organized into a linked list within our ClassFile, rather than an array, to allow for efficient dynamic growth.

This class differs greatly from the ClassFile representation, in that the members of the Code attribute are represented here rather than having a separate Code class. From a programmer's perspective, a Method has a sequence of instructions, rather than a Method having a Code attribute which then has instructions.

Constructor Summary

CfMethod(ClassFile classFile)

Method Summary

void	addHandler(ExceptionHandler h)
void	addHandler(int startPc, int endPc, int handlerPc, CpClass catchType)
void	addLine(LineNumber line) Append the given line number to the end of the linked-list of locals for this line number table.
void	addLocal(LocalVariable local) Append the given local to the end of the linked-list of locals for this local variable table.
void	createLocalsFromSignature() Based on the method signature, automatically build a set of matching LocalVariables.
byte[]	getCode()
Attribute	getCodeAttributes()
CodeBuilder	getCodeBuilder() Return a CodeBuilder for constructing the method code attribute.
int[]	getExceptionCps()
int	getHandlerCount()
ExceptionHandler	getHandlers()
ExceptionHandler	getLastHandler()
LineNumber	getLastLine()
LocalVariable	getLastLocal()
int	getLineCount()
LineNumber	getLines()
LocalVariable	getLocal(int index) Return the first found local variable that occupies the given index.
LocalVariable	getLocals()
int	getLocalsCount()
int	getMaxLocals() Max local variable index as per class file specification.
int	getMaxStack()
CfMethod	getNext()
CpRef	getRef() Return a Cp(Method)Ref for invoking this method.
int	getReturnType() Return the return type of this method as one of the JVM.T_XXX constants.
boolean	handleAttribute(java.io.DataInputStream dataIn, java.lang.String name, int length) For methods we must recognize: Code, Exceptions, Synthetic, Deprecated.
void	read(java.io.DataInputStream dataIn) Read the member from the given stream, overwriting any previous values.
void	setCode(byte[] code)
void	setCodeAttributes(Attribute codeAttributes)
void	setExceptionCps(int[] exceptionCps)
void	setExceptions(java.lang.Class[] exceptions)
void	setHandlerCount(int handlerCount)
void	setHandlers(ExceptionHandler handlers)
void	setLastHandler(ExceptionHandler lastHandler)
void	setLastLine(LineNumber lastLine)
void	setLastLocal(LocalVariable lastLocal)
void	setLineCount(int lineCount)
void	setLines(LineNumber lines)
void	setLocals(LocalVariable locals)
void	setLocalsCount(int localsCount)
void	setMaxLocals(int maxLocals)
void	setMaxStack(int maxStack)
void	setNext(CfMethod next)
void	write(java.io.DataOutput dout) Write the field or method to a stream in JVM classfile format.

Methods inherited from class com.claritysys.jvm.classfile.CfFieldOrMethod

getClassFile, getConstantPool, getDescriptorIndex, getName, getNameIndex, getSignature, isSynthetic, setDescriptorIndex, setNameIndex, setSynthetic

Methods inherited from class com.claritysys.jvm.classfile.CfEntry

getAccessFlags, getAttributeCount, getAttributes, isAbstract, isDeprecated, isFinal, isInterface, isNative, isPrivate, isProtected, isPublic, isStatic, isStrict, isSynchronized, isTransient, isVolatile, setAbstract, setAccessFlags, setAttributes, setDeprecated, setFinal, setInterface, setNative, setPrivate, setProtected, setPublic, setStatic, setStrict, setSynchronized, setTransient, setVolatile

Methods inherited from class java.lang.Object

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

Constructor Detail

CfMethod

public CfMethod(ClassFile classFile)

Method Detail

getNext

public CfMethod getNext()

setNext

public void setNext(CfMethod next)

read

public void read(java.io.DataInputStream dataIn)
          throws java.io.IOException,
                 ClassFileFormatException

Description copied from class: CfFieldOrMethod

Read the member from the given stream, overwriting any previous values.

Subclasses must override this method, first invoking this one, and then processing attributes.

  field_info {
          u2 access_flags;
          u2 name_index;
          u2 descriptor_index;
          u2 attributes_count;
          attribute_info attributes[attributes_count];
 }

  method_info {
      u2 access_flags;
            u2 name_index;
            u2 descriptor_index;
            u2 attributes_count;
            attribute_info attributes[attributes_count];
 }
 

Overrides:

read in class CfFieldOrMethod

Throws:

java.io.IOException

ClassFileFormatException

handleAttribute

public boolean handleAttribute(java.io.DataInputStream dataIn,
                               java.lang.String name,
                               int length)
                        throws java.io.IOException,
                               ClassFileFormatException

For methods we must recognize: Code, Exceptions, Synthetic, Deprecated. We also handle the attribute table for any encountered Code attribute, so this also must process: LineNumberTable, LocalVariableTable.

Specified by:

handleAttribute in interface AttributeHandler

Parameters:

dataIn - DataInputStream, positioned to attribute's data.

name - Attribute name from constant pool.

length - Length of info[] in bytes.

Returns:

true if the handler processed it, false if not.

Throws:

java.io.IOException - If an I/O error ocurrs.

ClassFileFormatException - If the attribute was processed but was incorrectly formed.

write

public void write(java.io.DataOutput dout)
           throws java.io.IOException

Description copied from class: CfFieldOrMethod

Write the field or method to a stream in JVM classfile format.

Subclasses must override this and extend the behavior by writing the attribute table.

Overrides:

write in class CfFieldOrMethod

Throws:

java.io.IOException

addLocal

public void addLocal(LocalVariable local)

Append the given local to the end of the linked-list of locals for this local variable table.

Parameters:

local - The localvariable to append.

addLine

public void addLine(LineNumber line)

Append the given line number to the end of the linked-list of locals for this line number table.

Parameters:

line - the line number to add.

getReturnType

public int getReturnType()

Return the return type of this method as one of the JVM.T_XXX constants.

getCodeAttributes

public Attribute getCodeAttributes()

setCodeAttributes

public void setCodeAttributes(Attribute codeAttributes)

addHandler

public void addHandler(ExceptionHandler h)

addHandler

public void addHandler(int startPc,
                       int endPc,
                       int handlerPc,
                       CpClass catchType)

getExceptionCps

public int[] getExceptionCps()

setExceptionCps

public void setExceptionCps(int[] exceptionCps)

setExceptions

public void setExceptions(java.lang.Class[] exceptions)

getMaxStack

public int getMaxStack()

setMaxStack

public void setMaxStack(int maxStack)

getMaxLocals

public int getMaxLocals()

Max local variable index as per class file specification.

This is actually the NEXT available local index, as the maximum index for a double or long local variable is maxLocals - 2, and for any other local is maxLocals - 1.

Returns:

Max locals, eg the next available local variable index.

setMaxLocals

public void setMaxLocals(int maxLocals)

getCode

public byte[] getCode()

setCode

public void setCode(byte[] code)

getHandlerCount

public int getHandlerCount()

setHandlerCount

public void setHandlerCount(int handlerCount)

getHandlers

public ExceptionHandler getHandlers()

setHandlers

public void setHandlers(ExceptionHandler handlers)

getLastHandler

public ExceptionHandler getLastHandler()

setLastHandler

public void setLastHandler(ExceptionHandler lastHandler)

getLocalsCount

public int getLocalsCount()

setLocalsCount

public void setLocalsCount(int localsCount)

getLocals

public LocalVariable getLocals()

setLocals

public void setLocals(LocalVariable locals)

createLocalsFromSignature

public void createLocalsFromSignature()

Based on the method signature, automatically build a set of matching LocalVariables.

It is an error to invoke this if locals already are defined. This method is only for the case when a new method is generated and the user wants to work with LocalVariable objects for generating code.

getLocal

public LocalVariable getLocal(int index)

Return the first found local variable that occupies the given index.

Note that multiple locals can use the same index within different scopes. This method just returns the first one it finds, and not in any particular order. Specifically, it does not guarantee this to be the first declared local of this name.

getLastLocal

public LocalVariable getLastLocal()

setLastLocal

public void setLastLocal(LocalVariable lastLocal)

getLineCount

public int getLineCount()

setLineCount

public void setLineCount(int lineCount)

getLines

public LineNumber getLines()

setLines

public void setLines(LineNumber lines)

getLastLine

public LineNumber getLastLine()

setLastLine

public void setLastLine(LineNumber lastLine)

getRef

public CpRef getRef()

Return a Cp(Method)Ref for invoking this method.

getCodeBuilder

public CodeBuilder getCodeBuilder()

Return a CodeBuilder for constructing the method code attribute.

This is the preferred method, since the ClassFile caches a single CodeBuilder to be re-used.