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java.lang.Objectjavassist.bytecode.CodeIterator
public class CodeIterator
An iterator for editing a code attribute.
If there are multiple CodeIterator
s referring to the
same Code_attribute
, then inserting a gap by one
CodeIterator
will break the other
CodeIterator
.
This iterator does not provide remove()
.
If a piece of code in a Code_attribute
is unnecessary,
it should be overwritten with NOP
.
CodeAttribute.iterator()
Nested Class Summary | |
---|---|
static class |
CodeIterator.Gap
An inserted gap. |
Field Summary | |
---|---|
protected byte[] |
bytecode
|
protected CodeAttribute |
codeAttr
|
protected int |
currentPos
|
protected int |
endPos
|
protected int |
mark
|
Constructor Summary | |
---|---|
protected |
CodeIterator(CodeAttribute ca)
|
Method Summary | |
---|---|
int |
append(byte[] code)
Appends the given bytecode sequence at the end. |
void |
append(ExceptionTable et,
int offset)
Copies and appends the entries in the given exception table at the end of the exception table in the code attribute edited by this object. |
void |
appendGap(int gapLength)
Appends a gap at the end of the bytecode sequence. |
void |
begin()
Moves to the first instruction. |
int |
byteAt(int index)
Returns the unsigned 8bit value at the given index. |
CodeAttribute |
get()
Returns a Code attribute read with this iterator. |
int |
getCodeLength()
Returns code_length of Code_attribute . |
int |
getMark()
Gets the index of the position of the mark set by setMark . |
boolean |
hasNext()
Returns true if there is more instructions. |
int |
insert(byte[] code)
Inserts the given bytecode sequence before the next instruction that would be returned by next() (not before the instruction returned
by the last call to next() ). |
void |
insert(ExceptionTable et,
int offset)
Copies and inserts the entries in the given exception table at the beginning of the exception table in the code attribute edited by this object. |
void |
insert(int pos,
byte[] code)
Inserts the given bytecode sequence before the instruction at the given index pos . |
int |
insertAt(int pos,
byte[] code)
Inserts the given bytecode sequence before the instruction at the given index pos . |
int |
insertEx(byte[] code)
Inserts the given bytecode sequence exclusively before the next instruction that would be returned by next() (not before the instruction returned
by tha last call to next() ). |
void |
insertEx(int pos,
byte[] code)
Inserts the given bytecode sequence exclusively before the instruction at the given index pos . |
int |
insertExAt(int pos,
byte[] code)
Inserts the given bytecode sequence exclusively before the instruction at the given index pos . |
int |
insertExGap(int length)
Inserts an exclusive gap before the next instruction that would be returned by next() (not before the instruction returned
by the last call to next() ). |
int |
insertExGap(int pos,
int length)
Inserts an exclusive gap in front of the instruction at the given index pos . |
int |
insertGap(int length)
Inserts a gap before the next instruction that would be returned by next() (not before the instruction returned
by the last call to next() ). |
int |
insertGap(int pos,
int length)
Inserts a gap in front of the instruction at the given index pos . |
CodeIterator.Gap |
insertGapAt(int pos,
int length,
boolean exclusive)
Inserts an inclusive or exclusive gap in front of the instruction at the given index pos . |
int |
lookAhead()
Obtains the value that the next call to next() will return. |
void |
move(int index)
Moves to the given index. |
int |
next()
Returns the index of the next instruction (not the operand following the current opcode). |
int |
s16bitAt(int index)
Returns the signed 16bit value at the given index. |
int |
s32bitAt(int index)
Returns the signed 32bit value at the given index. |
void |
setMark(int index)
Sets a mark to the bytecode at the given index. |
int |
skipConstructor()
Moves to the instruction for either super() or this() . |
int |
skipSuperConstructor()
Moves to the instruction for super() . |
int |
skipThisConstructor()
Moves to the instruction for this() . |
int |
u16bitAt(int index)
Returns the unsigned 16bit value at the given index. |
protected void |
updateCursors(int pos,
int length)
Is called when a gap is inserted. |
void |
write(byte[] code,
int index)
Writes a byte array at the index. |
void |
write16bit(int value,
int index)
Writes a 16 bit integer at the index. |
void |
write32bit(int value,
int index)
Writes a 32bit integer at the index. |
void |
writeByte(int value,
int index)
Writes an 8bit value at the given index. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
---|
protected CodeAttribute codeAttr
protected byte[] bytecode
protected int endPos
protected int currentPos
protected int mark
Constructor Detail |
---|
protected CodeIterator(CodeAttribute ca)
Method Detail |
---|
public void begin()
public void move(int index)
The index of the next instruction is set to the given index.
The successive call to next()
returns the index that has been given to move()
.
Note that the index is into the byte array returned by
get().getCode()
.
CodeAttribute.getCode()
public void setMark(int index)
getMark()
public int getMark()
setMark
.
setMark(int)
public CodeAttribute get()
public int getCodeLength()
code_length
of Code_attribute
.
public int byteAt(int index)
public void writeByte(int value, int index)
public int u16bitAt(int index)
public int s16bitAt(int index)
public void write16bit(int value, int index)
public int s32bitAt(int index)
public void write32bit(int value, int index)
public void write(byte[] code, int index)
code
- may be a zero-length array.public boolean hasNext()
public int next() throws BadBytecode
Note that the index is into the byte array returned by
get().getCode()
.
BadBytecode
CodeAttribute.getCode()
,
byteAt(int)
public int lookAhead()
next()
will return.
This method is side-effects free.
Successive calls to lookAhead()
return the
same value until next()
is called.
public int skipConstructor() throws BadBytecode
super()
or this()
.
This method skips all the instructions for computing arguments
to super()
or this()
, which should be
placed at the beginning of a constructor body.
This method returns the index of INVOKESPECIAL instruction
executing super()
or this()
.
A successive call to next()
returns the
index of the next instruction following that INVOKESPECIAL.
This method works only for a constructor.
BadBytecode
public int skipSuperConstructor() throws BadBytecode
super()
.
This method skips all the instructions for computing arguments to
super()
, which should be
placed at the beginning of a constructor body.
This method returns the index of INVOKESPECIAL instruction
executing super()
.
A successive call to next()
returns the
index of the next instruction following that INVOKESPECIAL.
This method works only for a constructor.
this()
is found.
BadBytecode
public int skipThisConstructor() throws BadBytecode
this()
.
This method skips all the instructions for computing arguments to
this()
, which should be
placed at the beginning of a constructor body.
This method returns the index of INVOKESPECIAL instruction
executing this()
.
A successive call to next()
returns the
index of the next instruction following that INVOKESPECIAL.
This method works only for a constructor.
super()
is found.
BadBytecode
public int insert(byte[] code) throws BadBytecode
next()
(not before the instruction returned
by the last call to next()
).
Branch offsets and the exception table are also updated.
If the next instruction is at the beginning of a block statement, then the bytecode is inserted within that block.
An extra gap may be inserted at the end of the inserted
bytecode sequence for adjusting alignment if the code attribute
includes LOOKUPSWITCH
or TABLESWITCH
.
code
- inserted bytecode sequence.
BadBytecode
public void insert(int pos, byte[] code) throws BadBytecode
pos
.
Branch offsets and the exception table are also updated.
If the instruction at the given index is at the beginning of a block statement, then the bytecode is inserted within that block.
An extra gap may be inserted at the end of the inserted
bytecode sequence for adjusting alignment if the code attribute
includes LOOKUPSWITCH
or TABLESWITCH
.
The index at which the byte sequence is actually inserted
might be different from pos since some other bytes might be
inserted at other positions (e.g. to change GOTO
to GOTO_W
).
pos
- the index at which a byte sequence is inserted.code
- inserted bytecode sequence.
BadBytecode
public int insertAt(int pos, byte[] code) throws BadBytecode
pos
.
Branch offsets and the exception table are also updated.
If the instruction at the given index is at the beginning of a block statement, then the bytecode is inserted within that block.
An extra gap may be inserted at the end of the inserted
bytecode sequence for adjusting alignment if the code attribute
includes LOOKUPSWITCH
or TABLESWITCH
.
pos
- the index at which a byte sequence is inserted.code
- inserted bytecode sequence.
BadBytecode
public int insertEx(byte[] code) throws BadBytecode
next()
(not before the instruction returned
by tha last call to next()
).
Branch offsets and the exception table are also updated.
If the next instruction is at the beginning of a block statement, then the bytecode is excluded from that block.
An extra gap may be inserted at the end of the inserted
bytecode sequence for adjusting alignment if the code attribute
includes LOOKUPSWITCH
or TABLESWITCH
.
code
- inserted bytecode sequence.
BadBytecode
public void insertEx(int pos, byte[] code) throws BadBytecode
pos
.
Branch offsets and the exception table are also updated.
If the instruction at the given index is at the beginning of a block statement, then the bytecode is excluded from that block.
An extra gap may be inserted at the end of the inserted
bytecode sequence for adjusting alignment if the code attribute
includes LOOKUPSWITCH
or TABLESWITCH
.
The index at which the byte sequence is actually inserted
might be different from pos since some other bytes might be
inserted at other positions (e.g. to change GOTO
to GOTO_W
).
pos
- the index at which a byte sequence is inserted.code
- inserted bytecode sequence.
BadBytecode
public int insertExAt(int pos, byte[] code) throws BadBytecode
pos
.
Branch offsets and the exception table are also updated.
If the instruction at the given index is at the beginning of a block statement, then the bytecode is excluded from that block.
An extra gap may be inserted at the end of the inserted
bytecode sequence for adjusting alignment if the code attribute
includes LOOKUPSWITCH
or TABLESWITCH
.
pos
- the index at which a byte sequence is inserted.code
- inserted bytecode sequence.
BadBytecode
public int insertGap(int length) throws BadBytecode
next()
(not before the instruction returned
by the last call to next()
).
Branch offsets and the exception table are also updated.
The inserted gap is filled with NOP. The gap length may be
extended to a multiple of 4.
If the next instruction is at the beginning of a block statement, then the gap is inserted within that block.
length
- gap length
BadBytecode
public int insertGap(int pos, int length) throws BadBytecode
pos
.
Branch offsets and the exception table are also updated.
The inserted gap is filled with NOP. The gap length may be
extended to a multiple of 4.
If the instruction at the given index is at the beginning of a block statement, then the gap is inserted within that block.
pos
- the index at which a gap is inserted.length
- gap length.
length
.
BadBytecode
public int insertExGap(int length) throws BadBytecode
next()
(not before the instruction returned
by the last call to next()
).
Branch offsets and the exception table are also updated.
The inserted gap is filled with NOP. The gap length may be
extended to a multiple of 4.
If the next instruction is at the beginning of a block statement, then the gap is excluded from that block.
length
- gap length
BadBytecode
public int insertExGap(int pos, int length) throws BadBytecode
pos
.
Branch offsets and the exception table are also updated.
The inserted gap is filled with NOP. The gap length may be
extended to a multiple of 4.
If the instruction at the given index is at the beginning of a block statement, then the gap is excluded from that block.
pos
- the index at which a gap is inserted.length
- gap length.
length
.
BadBytecode
public CodeIterator.Gap insertGapAt(int pos, int length, boolean exclusive) throws BadBytecode
pos
.
Branch offsets and the exception table in the method body
are also updated. The inserted gap is filled with NOP.
The gap length may be extended to a multiple of 4.
Suppose that the instruction at the given index is at the beginning of a block statement. If the gap is inclusive, then it is included within that block. If the gap is exclusive, then it is excluded from that block.
The index at which the gap is actually inserted
might be different from pos since some other bytes might be
inserted at other positions (e.g. to change GOTO
to GOTO_W
). The index is available from the Gap
object returned by this method.
Suppose that the gap is inserted at the position of
the next instruction that would be returned by
next()
(not the last instruction returned
by the last call to next()
). The next
instruction returned by next()
after the gap is
inserted is still the same instruction. It is not NOP
at the first byte of the inserted gap.
pos
- the index at which a gap is inserted.length
- gap length.exclusive
- true if exclusive, otherwise false.
BadBytecode
protected void updateCursors(int pos, int length)
pos
- the position where a gap is inserted.length
- the length of the gap.public void insert(ExceptionTable et, int offset)
offset
- the value added to the code positions included
in the entries.public int append(byte[] code)
code
- the bytecode appended.
public void appendGap(int gapLength)
gapLength
- gap lengthpublic void append(ExceptionTable et, int offset)
offset
- the value added to the code positions included
in the entries.
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