bsh

Class ClassGeneratorUtil

java.lang.Object

bsh.ClassGeneratorUtil

All Implemented Interfaces:

Opcodes

public class ClassGeneratorUtil
extends java.lang.Object
implements Opcodes

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).

Author:

Pat Niemeyer

Field Summary

Fields inherited from interface bsh.org.objectweb.asm.Opcodes

AALOAD, AASTORE, ACC_ABSTRACT, ACC_ANNOTATION, ACC_BRIDGE, ACC_DEPRECATED, ACC_ENUM, ACC_FINAL, ACC_INTERFACE, ACC_MANDATED, ACC_MODULE, ACC_NATIVE, ACC_OPEN, ACC_PRIVATE, ACC_PROTECTED, ACC_PUBLIC, ACC_RECORD, ACC_STATIC, ACC_STATIC_PHASE, ACC_STRICT, ACC_SUPER, ACC_SYNCHRONIZED, ACC_SYNTHETIC, ACC_TRANSIENT, ACC_TRANSITIVE, ACC_VARARGS, ACC_VOLATILE, ACONST_NULL, ALOAD, ANEWARRAY, ARETURN, ARRAYLENGTH, ASM10_EXPERIMENTAL, ASM4, ASM5, ASM6, ASM7, ASM8, ASM9, ASTORE, ATHROW, BALOAD, BASTORE, BIPUSH, CALOAD, CASTORE, CHECKCAST, D2F, D2I, D2L, DADD, DALOAD, DASTORE, DCMPG, DCMPL, DCONST_0, DCONST_1, DDIV, DLOAD, DMUL, DNEG, DOUBLE, DREM, DRETURN, DSTORE, DSUB, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, F_APPEND, F_CHOP, F_FULL, F_NEW, F_SAME, F_SAME1, F2D, F2I, F2L, FADD, FALOAD, FASTORE, FCMPG, FCMPL, FCONST_0, FCONST_1, FCONST_2, FDIV, FLOAD, FLOAT, FMUL, FNEG, FREM, FRETURN, FSTORE, FSUB, GETFIELD, GETSTATIC, GOTO, H_GETFIELD, H_GETSTATIC, H_INVOKEINTERFACE, H_INVOKESPECIAL, H_INVOKESTATIC, H_INVOKEVIRTUAL, H_NEWINVOKESPECIAL, H_PUTFIELD, H_PUTSTATIC, I2B, I2C, I2D, I2F, I2L, I2S, IADD, IALOAD, IAND, IASTORE, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, ICONST_M1, IDIV, IF_ACMPEQ, IF_ACMPNE, IF_ICMPEQ, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ICMPLT, IF_ICMPNE, IFEQ, IFGE, IFGT, IFLE, IFLT, IFNE, IFNONNULL, IFNULL, IINC, ILOAD, IMUL, INEG, INSTANCEOF, INTEGER, INVOKEDYNAMIC, INVOKEINTERFACE, INVOKESPECIAL, INVOKESTATIC, INVOKEVIRTUAL, IOR, IREM, IRETURN, ISHL, ISHR, ISTORE, ISUB, IUSHR, IXOR, JSR, L2D, L2F, L2I, LADD, LALOAD, LAND, LASTORE, LCMP, LCONST_0, LCONST_1, LDC, LDIV, LLOAD, LMUL, LNEG, LONG, LOOKUPSWITCH, LOR, LREM, LRETURN, LSHL, LSHR, LSTORE, LSUB, LUSHR, LXOR, MONITORENTER, MONITOREXIT, MULTIANEWARRAY, NEW, NEWARRAY, NOP, NULL, POP, POP2, PUTFIELD, PUTSTATIC, RET, RETURN, SALOAD, SASTORE, SIPUSH, SOURCE_DEPRECATED, SOURCE_MASK, SWAP, T_BOOLEAN, T_BYTE, T_CHAR, T_DOUBLE, T_FLOAT, T_INT, T_LONG, T_SHORT, TABLESWITCH, TOP, UNINITIALIZED_THIS, V_PREVIEW, V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V10, V11, V12, V13, V14, V15, V16, V17, V18, V19, V20, V21, V22, V23, V24, V25, V26, V27, V9

Constructor Summary

Constructors

Constructor and Description
ClassGeneratorUtil(Modifiers classModifiers, java.lang.String className, java.lang.String packageName, java.lang.Class<?> superClass, java.lang.Class<?>[] interfaces, Variable[] vars, DelayedEvalBshMethod[] bshmethods, NameSpace classStaticNameSpace, bsh.ClassGenerator.Type type)

Method Summary

Modifier and Type	Method and Description
byte[]	generateClass() Generate the class bytecode for this class.
void	initStaticNameSpace(NameSpace classStaticNameSpace, bsh.BSHBlock instanceInitBlock) This method provides a hook for the class generator implementation to store additional information in the class's bsh static namespace.
static void	startInterpreterForClass(java.lang.Class<?> genClass) Attempt to load a script named for the class: e.g.

Methods inherited from class java.lang.Object

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

Constructor Detail

ClassGeneratorUtil

public ClassGeneratorUtil(Modifiers classModifiers,
                          java.lang.String className,
                          java.lang.String packageName,
                          java.lang.Class<?> superClass,
                          java.lang.Class<?>[] interfaces,
                          Variable[] vars,
                          DelayedEvalBshMethod[] bshmethods,
                          NameSpace classStaticNameSpace,
                          bsh.ClassGenerator.Type type)

Parameters:

packageName - e.g. "com.foo.bar"

Method Detail

initStaticNameSpace

public void initStaticNameSpace(NameSpace classStaticNameSpace,
                                bsh.BSHBlock instanceInitBlock)

This method provides a hook for the class generator implementation to store additional information in the class's bsh static namespace. Currently this is used to store an array of consructors corresponding to the constructor switch in the generated class. This method must be called to initialize the static space even if we are using a previously generated class.

generateClass

public byte[] generateClass()

Generate the class bytecode for this class.

startInterpreterForClass

public static void startInterpreterForClass(java.lang.Class<?> genClass)

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. The only interact that this method has with the process is to initially cache the correct class in the class manager for the interpreter to insure that it is found and associated with the scripted body.