1 files changed, 138 insertions, 0 deletions
diff --git a/src/main/java/ftbsc/lll/utils/InsnSequence.java b/src/main/java/ftbsc/lll/utils/InsnSequence.java
new file mode 100644
index 0000000..4734505
--- /dev/null
+++ b/src/main/java/ftbsc/lll/utils/InsnSequence.java
@@ -0,0 +1,138 @@
+package ftbsc.lll.utils;
+
+import ftbsc.lll.exceptions.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 {@link InsnList}, but provides additional flexibility and features.
+ */
+public class InsnSequence extends InsnList {
+	/**
+	 * Public constructor.
+	 * This creates an empty sequence.
+	 */
+	public InsnSequence() {
+		super();
+	}
+
+	/**
+	 * Public constructor for list with single item.
+	 * Must be given a single non-null node.
+	 * @param node the node in question
+	 */
+	public InsnSequence(AbstractInsnNode node) {
+		super();
+		this.add(node);
+	}
+
+	/**
+	 * 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 != null; startNode = startNode.getNext()) {
+			this.add(startNode);
+			if(startNode == endNode) break;
+		}
+		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 super.get(size() - index);
+	}
+
+	/**
+	 * Adds an array of nodes to the list.
+	 * @param nodes the nodes to add
+	 */
+	public void add(AbstractInsnNode... nodes) {
+		for(AbstractInsnNode node : nodes)
+			this.add(node);
+	}
+
+	/**
+	 * Wraps InsnList's add() to throw an exception
+	 * when given null values.
+	 * @param node to add
+	 */
+	@Override
+	public void add(AbstractInsnNode node) {
+		Objects.requireNonNull(node);
+		super.add(node);
+	}
+
+	/**
+	 * 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());
+	}
+}