public class CodeWriter extends java.lang.Object implements CodeVisitor
CodeVisitor
that generates Java bytecode instructions.
Each visit method of this class appends the bytecode corresponding to the
visited instruction to a byte vector, in the order these methods are called.Modifier | Constructor and Description |
---|---|
protected |
CodeWriter(ClassWriter cw,
boolean computeMaxs)
Constructs a CodeWriter.
|
Modifier and Type | Method and Description |
---|---|
protected byte[] |
getCode()
Returns the current bytecode of this method.
|
protected int |
getCodeSize()
Returns the current size of the bytecode of this method.
|
protected void |
init(int access,
java.lang.String name,
java.lang.String desc,
java.lang.String[] exceptions)
Initializes this CodeWriter to define the bytecode of the specified method.
|
protected int[] |
resizeInstructions(int[] indexes,
int[] sizes,
int len)
Resizes the designated instructions, while keeping jump offsets and
instruction addresses consistent.
|
void |
visitFieldInsn(int opcode,
java.lang.String owner,
java.lang.String name,
java.lang.String desc)
Visits a field instruction.
|
void |
visitIincInsn(int var,
int increment)
Visits an IINC instruction.
|
void |
visitInsn(int opcode)
Visits a zero operand instruction.
|
void |
visitIntInsn(int opcode,
int operand)
Visits an instruction with a single int operand.
|
void |
visitJumpInsn(int opcode,
Label label)
Visits a jump instruction.
|
void |
visitLabel(Label label)
Visits a label.
|
void |
visitLdcInsn(java.lang.Object cst)
Visits a LDC instruction.
|
void |
visitLineNumber(int line,
Label start)
Visits a line number declaration.
|
void |
visitLocalVariable(java.lang.String name,
java.lang.String desc,
Label start,
Label end,
int index)
Visits a local variable declaration.
|
void |
visitLookupSwitchInsn(Label dflt,
int[] keys,
Label[] labels)
Visits a LOOKUPSWITCH instruction.
|
void |
visitMaxs(int maxStack,
int maxLocals)
Visits the maximum stack size and the maximum number of local variables of
the method.
|
void |
visitMethodInsn(int opcode,
java.lang.String owner,
java.lang.String name,
java.lang.String desc)
Visits a method instruction.
|
void |
visitMultiANewArrayInsn(java.lang.String desc,
int dims)
Visits a MULTIANEWARRAY instruction.
|
void |
visitTableSwitchInsn(int min,
int max,
Label dflt,
Label[] labels)
Visits a TABLESWITCH instruction.
|
void |
visitTryCatchBlock(Label start,
Label end,
Label handler,
java.lang.String type)
Visits a try catch block.
|
void |
visitTypeInsn(int opcode,
java.lang.String desc)
Visits a type instruction.
|
void |
visitVarInsn(int opcode,
int var)
Visits a local variable instruction.
|
protected CodeWriter(ClassWriter cw, boolean computeMaxs)
cw
- the class writer in which the method must be added.computeMaxs
- true if the maximum stack size and number of
local variables must be automatically computed.protected void init(int access, java.lang.String name, java.lang.String desc, java.lang.String[] exceptions)
public void visitInsn(int opcode)
CodeVisitor
visitInsn
in interface CodeVisitor
opcode
- the opcode of the instruction to be visited. This opcode is
either NOP, ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2,
ICONST_3, ICONST_4, ICONST_5, LCONST_0, LCONST_1, FCONST_0, FCONST_1,
FCONST_2, DCONST_0, DCONST_1,
IALOAD, LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD,
IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE,
SASTORE,
POP, POP2, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP,
IADD, LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL,
DMUL, IDIV, LDIV, FDIV, DDIV, IREM, LREM, FREM, DREM, INEG, LNEG,
FNEG, DNEG, ISHL, LSHL, ISHR, LSHR, IUSHR, LUSHR, IAND, LAND, IOR,
LOR, IXOR, LXOR,
I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B, I2C,
I2S,
LCMP, FCMPL, FCMPG, DCMPL, DCMPG,
IRETURN, LRETURN, FRETURN, DRETURN, ARETURN, RETURN,
ARRAYLENGTH,
ATHROW,
MONITORENTER, or MONITOREXIT.public void visitIntInsn(int opcode, int operand)
CodeVisitor
visitIntInsn
in interface CodeVisitor
opcode
- the opcode of the instruction to be visited. This opcode is
either BIPUSH, SIPUSH or NEWARRAY.operand
- the operand of the instruction to be visited.public void visitVarInsn(int opcode, int var)
CodeVisitor
visitVarInsn
in interface CodeVisitor
opcode
- the opcode of the local variable instruction to be visited.
This opcode is either ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE,
LSTORE, FSTORE, DSTORE, ASTORE or RET.var
- the operand of the instruction to be visited. This operand is
the index of a local variable.public void visitTypeInsn(int opcode, java.lang.String desc)
CodeVisitor
visitTypeInsn
in interface CodeVisitor
opcode
- the opcode of the type instruction to be visited. This opcode
is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.desc
- the operand of the instruction to be visited. This operand is
must be a fully qualified class name in internal form, or the type
descriptor of an array type (see Type
).public void visitFieldInsn(int opcode, java.lang.String owner, java.lang.String name, java.lang.String desc)
CodeVisitor
visitFieldInsn
in interface CodeVisitor
opcode
- the opcode of the type instruction to be visited. This opcode
is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.owner
- the internal name of the field's owner class (see getInternalName
).name
- the field's name.desc
- the field's descriptor (see Type
).public void visitMethodInsn(int opcode, java.lang.String owner, java.lang.String name, java.lang.String desc)
CodeVisitor
visitMethodInsn
in interface CodeVisitor
opcode
- the opcode of the type instruction to be visited. This opcode
is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or
INVOKEINTERFACE.owner
- the internal name of the method's owner class (see getInternalName
).name
- the method's name.desc
- the method's descriptor (see Type
).public void visitJumpInsn(int opcode, Label label)
CodeVisitor
visitJumpInsn
in interface CodeVisitor
opcode
- the opcode of the type instruction to be visited. This opcode
is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ, IF_ICMPNE,
IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE,
GOTO, JSR, IFNULL or IFNONNULL.label
- the operand of the instruction to be visited. This operand is
a label that designates the instruction to which the jump instruction
may jump.public void visitLabel(Label label)
CodeVisitor
visitLabel
in interface CodeVisitor
label
- a Label
object.public void visitLdcInsn(java.lang.Object cst)
CodeVisitor
visitLdcInsn
in interface CodeVisitor
cst
- the constant to be loaded on the stack. This parameter must be
a non null Integer
, a Float
, a Long
, a Double
or a String
.public void visitIincInsn(int var, int increment)
CodeVisitor
visitIincInsn
in interface CodeVisitor
var
- index of the local variable to be incremented.increment
- amount to increment the local variable by.public void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels)
CodeVisitor
visitTableSwitchInsn
in interface CodeVisitor
min
- the minimum key value.max
- the maximum key value.dflt
- beginning of the default handler block.labels
- beginnings of the handler blocks. labels[i] is the
beginning of the handler block for the min + i key.public void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)
CodeVisitor
visitLookupSwitchInsn
in interface CodeVisitor
dflt
- beginning of the default handler block.keys
- the values of the keys.labels
- beginnings of the handler blocks. labels[i] is the
beginning of the handler block for the keys[i] key.public void visitMultiANewArrayInsn(java.lang.String desc, int dims)
CodeVisitor
visitMultiANewArrayInsn
in interface CodeVisitor
desc
- an array type descriptor (see Type
).dims
- number of dimensions of the array to allocate.public void visitTryCatchBlock(Label start, Label end, Label handler, java.lang.String type)
CodeVisitor
visitTryCatchBlock
in interface CodeVisitor
start
- beginning of the exception handler's scope (inclusive).end
- end of the exception handler's scope (exclusive).handler
- beginning of the exception handler's code.type
- internal name of the type of exceptions handled by the handler,
or null to catch any exceptions (for "finally" blocks).public void visitMaxs(int maxStack, int maxLocals)
CodeVisitor
visitMaxs
in interface CodeVisitor
maxStack
- maximum stack size of the method.maxLocals
- maximum number of local variables for the method.public void visitLocalVariable(java.lang.String name, java.lang.String desc, Label start, Label end, int index)
CodeVisitor
visitLocalVariable
in interface CodeVisitor
name
- the name of a local variable.desc
- the type descriptor of this local variable.start
- the first instruction corresponding to the scope of this
local variable (inclusive).end
- the last instruction corresponding to the scope of this
local variable (exclusive).index
- the local variable's index.public void visitLineNumber(int line, Label start)
CodeVisitor
visitLineNumber
in interface CodeVisitor
line
- a line number. This number refers to the source file
from which the class was compiled.start
- the first instruction corresponding to this line number.protected int[] resizeInstructions(int[] indexes, int[] sizes, int len)
This method must be called after all the method that is being built has
been visited. In particular, the Label
objects used to
construct the method are no longer valid after this method has been called.
indexes
- current positions of the instructions to be resized. Each
instruction must be designated by the index of its last byte,
plus one (or, in other words, by the index of the first byte of
the next instruction).sizes
- the number of bytes to be added to the above
instructions. More precisely, for each i < len,
sizes[i] bytes will be added at the end of the instruction
designated by indexes[i] or, if sizes[i] is
negative, the last |sizes[i]| bytes of the instruction
will be removed (the instruction size must not become negative
or null). The gaps introduced by this method must be filled in
"manually" in the array returned by the getCode
method.len
- the number of instruction to be resized. Must be smaller than or
equal to indexes.length and sizes.length.protected int getCodeSize()
protected byte[] getCode()
getCodeSize
(exclusive).