Examples of javassist.bytecode.CodeIterator.insertGapAt()

javassist.bytecode.CodeIterator.insertGapAt()

Inserts an inclusive or exclusive gap in front of the instruction at the given index 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. @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

/* 377 */       if (pos >= 0) {
/* 378 */         int mref = iterator.u16bitAt(pos + 1);
/* 379 */         String desc = ca.getConstPool().getMethodrefType(mref);
/* 380 */         int num = Descriptor.numOfParameters(desc) + 1;
/* 381 */         if (num > 3) {
/* 382 */           pos = iterator.insertGapAt(pos, num - 3, false).position;
/*     */         }
/* 384 */         iterator.writeByte(87, pos++);
/* 385 */         iterator.writeByte(0, pos);
/* 386 */         iterator.writeByte(0, pos + 1);
/* 387 */         Descriptor.Iterator it = new Descriptor.Iterator(desc);

            int mref = iterator.u16bitAt(pos + 1);
            ConstPool constPool = codeAttribute.getConstPool();
            iterator.write16bit(constPool.addMethodrefInfo(constPool.addClassInfo("java.lang.Object"), "<init>", "()V"), pos + 1);
            String desc = constPool.getMethodrefType(mref);
            int num = Descriptor.numOfParameters(desc) + 1;
            pos = iterator.insertGapAt(pos, num, false).position;
            Descriptor.Iterator i$ = new Descriptor.Iterator(desc);
            for (i$.next(); i$.isParameter(); i$.next()) {
              iterator.writeByte(i$.is2byte() ? Opcode.POP2 : Opcode.POP, pos++);
            }
          }

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