ClassGeneratorUtil utilizes the ASM (www.objectweb.org) bytecode generator by Eric Bruneton in order to generate class "stubs" for BeanShell at runtime.

Stub classes contain all of the fields of a BeanShell scripted class as well as two "callback" references to BeanShell namespaces: one for static methods and one for instance methods. Methods of the class are delegators which invoke corresponding methods on either the static or instance bsh object and then unpack and return the results. The static namespace utilizes a static import to delegate variable access to the class' static fields. The instance namespace utilizes a dynamic import (i.e. mixin) to delegate variable access to the class' instance variables.

Constructors for the class delegate to the static initInstance() method of ClassGeneratorUtil to initialize new instances of the object. initInstance() invokes the instance intializer code (init vars and instance blocks) and then delegates to the corresponding scripted constructor method in the instance namespace. Constructors contain special switch logic which allows the BeanShell to control the calling of alternate constructors (this() or super() references) at runtime.

Specially named superclass delegator methods are also generated in order to allow BeanShell to access overridden methods of the superclass (which reflection does not normally allow).

Nested and Inner Type Summary

Modifier and Type	Class and Description
public static class	ClassGeneratorUtil.ConstructorArgs A ConstructorArgs object holds evaluated arguments for a constructor call as well as the index of a possible alternate selector to invoke.

Field Summary

Modifier and Type	Field and Description
pack-priv static final String	BSHCONSTRUCTORS The bsh static namespace variable that holds the constructor methods
pack-priv static final String	BSHINIT The bsh static namespace variable name of the instance initializer
pack-priv static final String	BSHSTATIC The name of the static field holding the reference to the bsh static This (the callback namespace for static methods)
pack-priv static final String	BSHSUPER The prefix for the name of the super delegate methods.
pack-priv static final String	BSHTHIS The name of the instance field holding the reference to the bsh instance This (the callback namespace for instance methods)
pack-priv Modifiers	classModifiers
pack-priv String	className
pack-priv NameSpace	classStaticNameSpace
pack-priv DelayedEvalBshMethod[]	constructors
pack-priv static final int	DEFAULTCONSTRUCTOR The switch branch number for the default constructor.
pack-priv String	fqClassName fully qualified class name (with package) e.g. foo/bar/Blah
pack-priv Class<T>[]	interfaces
pack-priv boolean	isInterface
pack-priv DelayedEvalBshMethod[]	methods
pack-priv static final String	OBJECT
pack-priv Class<T>	superClass
pack-priv String	superClassName
pack-priv Constructor<T>[]	superConstructors
pack-priv Variable[]	vars

Constructor Summary

Access	Constructor and Description
public	ClassGeneratorUtil(Modifiers classModifiers, String className, String e.g. "com.foo.bar" packageName, Class<T> superClass, Class<T>[] interfaces, Variable[] vars, DelayedEvalBshMethod[] bshmethods, NameSpace classStaticNameSpace, boolean isInterface)

Method Summary

Modifier and Type	Method and Description
pack-priv boolean	classContainsMethod(Class<T> clas, String methodName, String[] paramTypes)
private static String	descriptorToClassName(String s) If a non-array object type, remove the prefix "L" and suffix ";".
pack-priv static void	doSwitchBranch(int index, String targetClassName, String[] paramTypes, bsh.org.objectweb.asm.Label endLabel, bsh.org.objectweb.asm.Label[] labels, int consArgsVar, bsh.org.objectweb.asm.CodeVisitor cv)
public byte[]	generateClass() Generate the class bytecode for this class.
pack-priv void	generateConstructor(int index, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a constructor.
pack-priv void	generateConstructorSwitch(int consIndex, int argsVar, int consArgsVar, bsh.org.objectweb.asm.CodeVisitor cv) Generate a switch with a branch for each possible alternate constructor.
pack-priv static void	generateField(String fieldName, String type, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a field - static or instance.
pack-priv static void	generateMethod(String className, String fqClassName, String methodName, String returnType, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a delegate method - static or instance.
public static void	generateParameterReifierCode(String[] paramTypes, boolean the enclosing methods is static isStatic, final bsh.org.objectweb.asm.CodeVisitor the code visitor to be used to generate the bytecode. cv) Generates the code to reify the arguments of the given method.
pack-priv static void	generatePlainReturnCode(String returnType, bsh.org.objectweb.asm.CodeVisitor cv) Generate return code for a normal bytecode
public static void	generateReturnCode(String returnType, bsh.org.objectweb.asm.CodeVisitor the code visitor to be used to generate the bytecode. cv) Generates the code to unreify the result of the given method.
pack-priv static void	generateSuperDelegateMethod(String superClassName, String methodName, String returnType, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a superclass method delegate accessor method.
pack-priv static int	getASMModifiers(Modifiers modifiers) Translate bsh.Modifiers into ASM modifier bitflags.
private static String	getBaseName(String className)
pack-priv static This	Returns: the class instance This object or null if the object has not been initialized. getClassInstanceThis(Object instance, String className) Get the instance bsh namespace field from the object instance.
pack-priv static This	getClassStaticThis(Class<T> clas, String may be the name of clas itself or a superclass of clas. className) Get the static bsh namespace field from the class.
public static ClassGeneratorUtil.ConstructorArgs	Returns: the ConstructorArgs object containing a constructor selector and evaluated arguments for the alternate constructor getConstructorArgs(String superClassName, This classStaticThis, Object[] the arguments to the constructor. These are necessary in the evaluation of the alt constructor args. e.g. Foo(a) { super(a); } consArgs, int index) Evaluate the arguments (if any) for the constructor specified by the constructor index.
pack-priv static String	getMethodDescriptor(String returnType, String[] paramTypes)
pack-priv static String[]	getTypeDescriptors(Class<T>[] cparams)
public static void	initInstance(Object instance, String className, Object[] args) Initialize an instance of the class.
private static boolean	isPrimitive(String typeDescriptor) Does the type descriptor string describe a primitive type?
public static void	startInterpreterForClass(Class<T> clas) Attempt to load a script named for the class: e.g. Foo.class Foo.bsh.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

BSHCONSTRUCTORS	back to summary
pack-priv static final String BSHCONSTRUCTORS The bsh static namespace variable that holds the constructor methods

BSHINIT	back to summary
pack-priv static final String BSHINIT The bsh static namespace variable name of the instance initializer

BSHSTATIC	back to summary
pack-priv static final String BSHSTATIC The name of the static field holding the reference to the bsh static This (the callback namespace for static methods)

BSHSUPER	back to summary
pack-priv static final String BSHSUPER The prefix for the name of the super delegate methods. e.g. _bshSuperfoo() is equivalent to super.foo()

BSHTHIS	back to summary
pack-priv static final String BSHTHIS The name of the instance field holding the reference to the bsh instance This (the callback namespace for instance methods)

classModifiers	back to summary
pack-priv Modifiers classModifiers

className	back to summary
pack-priv String className

classStaticNameSpace	back to summary
pack-priv NameSpace classStaticNameSpace

constructors	back to summary
pack-priv DelayedEvalBshMethod[] constructors

DEFAULTCONSTRUCTOR	back to summary
pack-priv static final int DEFAULTCONSTRUCTOR The switch branch number for the default constructor. The value -1 will cause the default branch to be taken.

fqClassName	back to summary
pack-priv String fqClassName fully qualified class name (with package) e.g. foo/bar/Blah

interfaces	back to summary
pack-priv Class<T>[] interfaces

isInterface	back to summary
pack-priv boolean isInterface

methods	back to summary
pack-priv DelayedEvalBshMethod[] methods

OBJECT	back to summary
pack-priv static final String OBJECT

superClass	back to summary
pack-priv Class<T> superClass

superClassName	back to summary
pack-priv String superClassName

superConstructors	back to summary
pack-priv Constructor<T>[] superConstructors

vars	back to summary
pack-priv Variable[] vars

Constructor Detail

ClassGeneratorUtil	back to summary
public ClassGeneratorUtil(Modifiers classModifiers, String className, String packageName, Class<T> superClass, Class<T>[] interfaces, Variable[] vars, DelayedEvalBshMethod[] bshmethods, NameSpace classStaticNameSpace, boolean isInterface) Parameters packageName:String e.g. "com.foo.bar"

Method Detail

classContainsMethod	back to summary
pack-priv boolean classContainsMethod(Class<T> clas, String methodName, String[] paramTypes)

descriptorToClassName	back to summary
private static String descriptorToClassName(String s) If a non-array object type, remove the prefix "L" and suffix ";".

doSwitchBranch	back to summary
pack-priv static void doSwitchBranch(int index, String targetClassName, String[] paramTypes, bsh.org.objectweb.asm.Label endLabel, bsh.org.objectweb.asm.Label[] labels, int consArgsVar, bsh.org.objectweb.asm.CodeVisitor cv)

generateClass	back to summary
public byte[] generateClass() Generate the class bytecode for this class.

generateConstructor	back to summary
pack-priv void generateConstructor(int index, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a constructor.

generateConstructorSwitch	back to summary
pack-priv void generateConstructorSwitch(int consIndex, int argsVar, int consArgsVar, bsh.org.objectweb.asm.CodeVisitor cv) Generate a switch with a branch for each possible alternate constructor. This includes all superclass constructors and all constructors of this class. The default branch of this switch is the default superclass constructor. This method also generates the code to call the static ClassGeneratorUtil getConstructorArgs() method which inspects the scripted constructor to find the alternate constructor signature (if any) and evalute the arguments at runtime. The getConstructorArgs() method returns the actual arguments as well as the index of the constructor to call.

generateConstructorSwitch

back to summary

pack-priv void generateConstructorSwitch(int consIndex, int argsVar, int consArgsVar, bsh.org.objectweb.asm.CodeVisitor cv)

Generate a switch with a branch for each possible alternate constructor. This includes all superclass constructors and all constructors of this class. The default branch of this switch is the default superclass constructor.

This method also generates the code to call the static ClassGeneratorUtil getConstructorArgs() method which inspects the scripted constructor to find the alternate constructor signature (if any) and evalute the arguments at runtime. The getConstructorArgs() method returns the actual arguments as well as the index of the constructor to call.

generateField	back to summary
pack-priv static void generateField(String fieldName, String type, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a field - static or instance.

generateMethod	back to summary
pack-priv static void generateMethod(String className, String fqClassName, String methodName, String returnType, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a delegate method - static or instance. The generated code packs the method arguments into an object array (wrapping primitive types in bsh.Primitive), invokes the static or instance namespace invokeMethod() method, and then unwraps / returns the result.

generateMethod

back to summary

pack-priv static void generateMethod(String className, String fqClassName, String methodName, String returnType, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw)

Generate a delegate method - static or instance. The generated code packs the method arguments into an object array (wrapping primitive types in bsh.Primitive), invokes the static or instance namespace invokeMethod() method, and then unwraps / returns the result.

generateParameterReifierCode	back to summary
public static void generateParameterReifierCode(String[] paramTypes, boolean isStatic, final bsh.org.objectweb.asm.CodeVisitor cv) Generates the code to reify the arguments of the given method. For a method "int m (int i, String s)", this code is the bytecode corresponding to the "new Object[] { new bsh.Primitive(i), s }" expression. Parameters isStatic:boolean the enclosing methods is static cv:bsh.org.objectweb.asm.CodeVisitor the code visitor to be used to generate the bytecode. Authors Eric Bruneton, Pat Niemeyer

generateParameterReifierCode

back to summary

public static void generateParameterReifierCode(String[] paramTypes, boolean isStatic, final bsh.org.objectweb.asm.CodeVisitor cv)

Generates the code to reify the arguments of the given method. For a method "int m (int i, String s)", this code is the bytecode corresponding to the "new Object[] { new bsh.Primitive(i), s }" expression.

Parameters

isStatic:boolean: the enclosing methods is static
cv:bsh.org.objectweb.asm.CodeVisitor: the code visitor to be used to generate the bytecode.

Authors

Eric Bruneton, Pat Niemeyer

generatePlainReturnCode	back to summary
pack-priv static void generatePlainReturnCode(String returnType, bsh.org.objectweb.asm.CodeVisitor cv) Generate return code for a normal bytecode

generateReturnCode	back to summary
public static void generateReturnCode(String returnType, bsh.org.objectweb.asm.CodeVisitor cv) Generates the code to unreify the result of the given method. For a method "int m (int i, String s)", this code is the bytecode corresponding to the "((Integer)...).intValue()" expression. Parameters cv:bsh.org.objectweb.asm.CodeVisitor the code visitor to be used to generate the bytecode. Authors Eric Bruneton, Pat Niemeyer

generateReturnCode

back to summary

public static void generateReturnCode(String returnType, bsh.org.objectweb.asm.CodeVisitor cv)

Generates the code to unreify the result of the given method. For a method "int m (int i, String s)", this code is the bytecode corresponding to the "((Integer)...).intValue()" expression.

Parameters

cv:bsh.org.objectweb.asm.CodeVisitor: the code visitor to be used to generate the bytecode.

Authors

Eric Bruneton, Pat Niemeyer

generateSuperDelegateMethod	back to summary
pack-priv static void generateSuperDelegateMethod(String superClassName, String methodName, String returnType, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw) Generate a superclass method delegate accessor method. These methods are specially named methods which allow access to overridden methods of the superclass (which the Java reflection API normally does not allow).

generateSuperDelegateMethod

back to summary

pack-priv static void generateSuperDelegateMethod(String superClassName, String methodName, String returnType, String[] paramTypes, int modifiers, bsh.org.objectweb.asm.ClassWriter cw)

Generate a superclass method delegate accessor method. These methods are specially named methods which allow access to overridden methods of the superclass (which the Java reflection API normally does not allow).

getASMModifiers	back to summary
pack-priv static int getASMModifiers(Modifiers modifiers) Translate bsh.Modifiers into ASM modifier bitflags.

getBaseName	back to summary
private static String getBaseName(String className)

getClassInstanceThis	back to summary
pack-priv static This getClassInstanceThis(Object instance, String className) Get the instance bsh namespace field from the object instance. Returns:This the class instance This object or null if the object has not been initialized.

getClassInstanceThis

back to summary

pack-priv static This getClassInstanceThis(Object instance, String className)

Get the instance bsh namespace field from the object instance.

Returns:This: the class instance This object or null if the object has not been initialized.

getClassStaticThis	back to summary
pack-priv static This getClassStaticThis(Class<T> clas, String className) Get the static bsh namespace field from the class. Parameters className:String may be the name of clas itself or a superclass of clas.

getClassStaticThis

back to summary

pack-priv static This getClassStaticThis(Class<T> clas, String className)

Get the static bsh namespace field from the class.

Parameters

className:String: may be the name of clas itself or a superclass of clas.

getConstructorArgs	back to summary
public static ClassGeneratorUtil.ConstructorArgs getConstructorArgs(String superClassName, This classStaticThis, Object[] consArgs, int index) Evaluate the arguments (if any) for the constructor specified by the constructor index. Return the ConstructorArgs object which contains the actual arguments to the alternate constructor and also the index of that constructor for the constructor switch. Parameters consArgs:Object[] the arguments to the constructor. These are necessary in the evaluation of the alt constructor args. e.g. Foo(a) { super(a); } Returns:ClassGeneratorUtil.ConstructorArgs the ConstructorArgs object containing a constructor selector and evaluated arguments for the alternate constructor

getConstructorArgs

back to summary

public static ClassGeneratorUtil.ConstructorArgs getConstructorArgs(String superClassName, This classStaticThis, Object[] consArgs, int index)

Evaluate the arguments (if any) for the constructor specified by the constructor index. Return the ConstructorArgs object which contains the actual arguments to the alternate constructor and also the index of that constructor for the constructor switch.

Parameters

consArgs:Object[]: the arguments to the constructor. These are necessary in the evaluation of the alt constructor args. e.g. Foo(a) { super(a); }

Returns:ClassGeneratorUtil.ConstructorArgs

the ConstructorArgs object containing a constructor selector and evaluated arguments for the alternate constructor

getMethodDescriptor	back to summary
pack-priv static String getMethodDescriptor(String returnType, String[] paramTypes)

getTypeDescriptors	back to summary
pack-priv static String[] getTypeDescriptors(Class<T>[] cparams)

initInstance	back to summary
public static void initInstance(Object instance, String className, Object[] args) Initialize an instance of the class. This method is called from the generated class constructor to evaluate the instance initializer and scripted constructor in the instance namespace.

isPrimitive	back to summary
private static boolean isPrimitive(String typeDescriptor) Does the type descriptor string describe a primitive type?

startInterpreterForClass	back to summary
public static void startInterpreterForClass(Class<T> clas) Attempt to load a script named for the class: e.g. Foo.class Foo.bsh. The script is expected to (at minimum) initialize the class body. That is, it should contain the scripted class definition. This method relies on the fact that the ClassGenerator generateClass() method will detect that the generated class already exists and initialize it rather than recreating it.

startInterpreterForClass

back to summary

public static void startInterpreterForClass(Class<T> clas)

Attempt to load a script named for the class: e.g. Foo.class Foo.bsh. The script is expected to (at minimum) initialize the class body. That is, it should contain the scripted class definition. This method relies on the fact that the ClassGenerator generateClass() method will detect that the generated class already exists and initialize it rather than recreating it.

bsh back to summary

public Class ClassGeneratorUtil.ConstructorArgs

Class Inheritance

extends Object

java.lang.Object
bsh.ClassGeneratorUtil.ConstructorArgs

A ConstructorArgs object holds evaluated arguments for a constructor call as well as the index of a possible alternate selector to invoke. This object is used by the constructor switch.

See Also: generateConstructor(int , String [] , int , ClassWriter)

Field Summary

Modifier and Type	Field and Description
pack-priv int	arg
pack-priv Object[]	args
public static ClassGeneratorUtil.ConstructorArgs	DEFAULT A ConstructorArgs which calls the default constructor
public int	selector

Constructor Summary

Access	Constructor and Description
pack-priv	ConstructorArgs() The index of the constructor to call.
pack-priv	ConstructorArgs(int selector, Object[] args)

Method Summary

Modifier and Type	Method and Description
public boolean	getBoolean()
public byte	getByte()
public char	getChar()
public double	getDouble()
public float	getFloat()
public int	getInt()
public long	getLong()
public Object	getObject()
public short	getShort()
pack-priv Object	next()

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

arg	back to summary
pack-priv int arg

args	back to summary
pack-priv Object[] args

DEFAULT	back to summary
public static ClassGeneratorUtil.ConstructorArgs DEFAULT A ConstructorArgs which calls the default constructor

selector	back to summary
public int selector

Constructor Detail

ConstructorArgs	back to summary
pack-priv ConstructorArgs() The index of the constructor to call.

ConstructorArgs	back to summary
pack-priv ConstructorArgs(int selector, Object[] args)

Method Detail

getBoolean	back to summary
public boolean getBoolean()

getByte	back to summary
public byte getByte()

getChar	back to summary
public char getChar()

getDouble	back to summary
public double getDouble()

getFloat	back to summary
public float getFloat()

getInt	back to summary
public int getInt()

getLong	back to summary
public long getLong()

getObject	back to summary
public Object getObject()

getShort	back to summary
public short getShort()

next	back to summary
pack-priv Object next()