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package ftbsc.lll.tools;
import ftbsc.lll.exception.InstructionMismatchException;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.InsnList;
import java.util.Objects;
/**
* Represents a sequence of instructions contained within two given nodes.
* Extends InsnList, but provides additional flexibility.
*/
public class InsnSequence extends InsnList {
/**
* Public constructor.
* Must be given two non-null, connected nodes.
* @param startNode the starting node of the pattern
* @param endNode the first node of the pattern
*/
public InsnSequence(AbstractInsnNode startNode, AbstractInsnNode endNode) {
Objects.requireNonNull(startNode);
Objects.requireNonNull(endNode);
for(; startNode != endNode && startNode != null; startNode = startNode.getNext())
super.add(startNode);
if (startNode == null)
throw new InstructionMismatchException("Nodes" + getFirst() + " and " + getLast() + " are not connected.");
}
/**
* Extends the existing get function from InsnList to allow for negative indexes.
* @param index the index of the instruction that must be returned
* @return the instruction whose index is given
*/
@Override
public AbstractInsnNode get(int index) {
if(index >= 0)
return super.get(index);
index = Math.abs(index);
if(index > size())
throw new IndexOutOfBoundsException();
return this.toArray()[size() - index];
}
/**
* Replaces a node with another one. Mostly used internally.
* @param oldNode node to replace
* @param newNode new node
*/
public void replaceNode(AbstractInsnNode oldNode, AbstractInsnNode newNode) {
super.insert(oldNode, newNode);
super.remove(oldNode);
}
/**
* Replaces n occurrences of said opcode with the given node.
* @param opcode the opcode to replace
* @param newNode the replacement node
* @param amount how many occurrences to replace, set to 0 to replace all
* @return true if anything was changed, false otherwise
*/
public boolean replace(int opcode, AbstractInsnNode newNode, int amount) {
return replace(opcode, newNode, amount, false);
}
/**
* Replaces n occurrences of said opcode with the given node.
* @param opcode the opcode to replace
* @param newNode the replacement node
* @param reverse whether the search should be done from the end
* @param amount how many occurrences to replace, set to 0 to replace all
* @return true if anything was changed, false otherwise
*/
public boolean replace(int opcode, AbstractInsnNode newNode, int amount, boolean reverse) {
boolean changed = false;
for(AbstractInsnNode cur = this.getFirst();
cur != null && cur.getPrevious() != this.getLast() && cur.getNext() != this.getFirst();
cur = reverse ? cur.getPrevious() : cur.getNext()) {
if(cur.getOpcode() == opcode) {
this.replaceNode(cur, newNode);
changed = true;
amount--; // will go to negative if it was already 0, causing it to go on until for loop finishes
if(amount == 0)
return changed;
}
}
return changed;
}
/**
* Cut a number of nodes from the list.
* @param amount how many nodes to cut
* @param reverse true if should cut from the end, false otherwise
*/
public void cut(int amount, boolean reverse) {
for(int i = 0; i < amount; i++)
this.remove(reverse ? getLast() : getFirst());
}
}
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