/**
* Appends a gap at the end of the bytecode sequence.
*
* @param gapLength gap length
*/
public void appendGap(int gapLength) {
byte[] code = bytecode;
int codeLength = code.length;
byte[] newcode = new byte[codeLength + gapLength];
int i;
for (i = 0; i < codeLength; ++i) newcode[i] = code[i];
for (i = codeLength; i < codeLength + gapLength; ++i) newcode[i] = NOP;
codeAttr.setCode(newcode);
bytecode = newcode;
endPos = getCodeLength();
}
/**
* Inserts an inclusive or exclusive gap in front of the instruction at the given index <code>pos
* </code>. 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.
*
* <p>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.
*
* <p>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 <code>GOTO</code> to <code>GOTO_W
* </code>). The index is available from the <code>Gap</code> object returned by this method.
*
* <p>Suppose that the gap is inserted at the position of the next instruction that would be
* returned by <code>next()</code> (not the last instruction returned by the last call to <code>
* next()</code>). The next instruction returned by <code>next()</code> after the gap is inserted
* is still the same instruction. It is not <code>NOP</code> at the first byte of the inserted
* gap.
*
* @param pos the index at which a gap is inserted.
* @param length gap length.
* @param exclusive true if exclusive, otherwise false.
* @return the position and the length of the inserted gap.
* @since 3.11
*/
public Gap insertGapAt(int pos, int length, boolean exclusive) throws BadBytecode {
/** cursorPos indicates the next bytecode whichever exclusive is true or false. */
Gap gap = new Gap();
if (length <= 0) {
gap.position = pos;
gap.length = 0;
return gap;
}
byte[] c;
int length2;
if (bytecode.length + length > Short.MAX_VALUE) {
// currentPos might change after calling insertGapCore0w().
c =
insertGapCore0w(
bytecode, pos, length, exclusive, get().getExceptionTable(), codeAttr, gap);
pos = gap.position;
length2 = length; // == gap.length
} else {
int cur = currentPos;
c = insertGapCore0(bytecode, pos, length, exclusive, get().getExceptionTable(), codeAttr);
// insertGapCore0() never changes pos.
length2 = c.length - bytecode.length;
gap.position = pos;
gap.length = length2;
if (cur >= pos) currentPos = cur + length2;
if (mark > pos || (mark == pos && exclusive)) mark += length2;
}
codeAttr.setCode(c);
bytecode = c;
endPos = getCodeLength();
updateCursors(pos, length2);
return gap;
}
