1 files changed, 250 insertions, 0 deletions
diff --git a/src/main/java/ftbsc/lll/utils/PatternMatcher.java b/src/main/java/ftbsc/lll/utils/PatternMatcher.java
new file mode 100644
index 0000000..9518749
--- /dev/null
+++ b/src/main/java/ftbsc/lll/utils/PatternMatcher.java
@@ -0,0 +1,250 @@
+package ftbsc.lll.utils;
+
+import ftbsc.lll.exceptions.PatternNotFoundException;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Predicate;
+
+/**
+ * Describes a pattern to match on a list of ASM instructions.
+ */
+public class PatternMatcher {
+	/**
+	 * The list of predicates to match.
+	 */
+	private final List<Predicate<AbstractInsnNode>> predicates;
+
+	/**
+	 * Whether pattern search should be done from the end.
+	 */
+	private final boolean reverse;
+
+	/**
+	 * Patterns flagged with this ignore labels.
+	 */
+	private final boolean ignoreLabels;
+
+	/**
+	 * Patterns flagged with this ignore FRAME instructions.
+	 */
+	private final boolean ignoreFrames;
+
+	/**
+	 * Patterns flagged with this ignore LINENUMBER instructions.
+	 */
+	private final boolean ignoreLineNumbers;
+
+	/**
+	 * Private constructor because a PatternMatcher should only ever be initialized
+	 * through the builder.
+	 * @param predicates the list of predicates to match
+	 * @param reverse search direction
+	 * @param ignoreLabels whether LABEL instructions should be ignored
+	 * @param ignoreFrames whether FRAME instructions should be ignored
+	 * @param ignoreLineNumbers whether LINENUMBER instructions should be ignored
+	 */
+	private PatternMatcher(List<Predicate<AbstractInsnNode>> predicates, boolean reverse,
+	                       boolean ignoreLabels, boolean ignoreFrames, boolean ignoreLineNumbers) {
+		this.predicates = predicates;
+		this.reverse = reverse;
+		this.ignoreLabels = ignoreLabels;
+		this.ignoreFrames = ignoreFrames;
+		this.ignoreLineNumbers = ignoreLineNumbers;
+	}
+
+	/**
+	 * @return the Builder object for this {@link PatternMatcher}
+	 */
+	public static Builder builder() {
+		return new Builder();
+	}
+
+	/**
+	 * Tries to match the given pattern on a given {@link MethodNode}.
+	 * @param node the {@link MethodNode} to search
+	 * @return the InsnSequence object representing the matched pattern
+	 */
+	public InsnSequence find(MethodNode node) {
+		return find(reverse ? node.instructions.getLast() : node.instructions.getFirst());
+	}
+
+	/**
+	 * Tries to match the given pattern starting from a given node.
+	 * @param node the node to start the search on
+	 * @return the {@link InsnSequence} object representing the matched pattern
+	 */
+	public InsnSequence find(AbstractInsnNode node) {
+		if(node != null) {
+			AbstractInsnNode first, last;
+			for(AbstractInsnNode cur = node; cur != null; cur = reverse ? cur.getPrevious() : cur.getNext()) {
+				if(predicates.size() == 0) return new InsnSequence(cur); //match whatever
+				first = cur;
+				last = cur;
+				for(int match = 0; last != null && match < predicates.size(); last = reverse ? last.getPrevious() : last.getNext()) {
+					if(match != 0) {
+						if(ignoreLabels && last.getType() == AbstractInsnNode.LABEL) continue;
+						if(ignoreFrames && last.getType() == AbstractInsnNode.FRAME) continue;
+						if(ignoreLineNumbers && last.getType() == AbstractInsnNode.LINE) continue;
+					}
+					if(!predicates.get(match).test(last)) break;
+					if(match == predicates.size() - 1) {
+						if(reverse) return new InsnSequence(last, first); //we are matching backwards
+						else return new InsnSequence(first, last);
+					} else match++;
+				}
+			}
+		}
+		throw new PatternNotFoundException("Failed to find pattern!");
+	}
+
+	/**
+	 * The Builder object for {@link PatternMatcher}.
+	 */
+	public static class Builder {
+
+		/**
+		 * List of predicates the pattern has to match.
+		 */
+		private final List<Predicate<AbstractInsnNode>> predicates = new ArrayList<>();
+
+		/**
+		 * Whether the pattern matching should proceed in reversed order.
+		 */
+		private boolean reverse = false;
+
+		/**
+		 * Patterns flagged with this ignore labels.
+		 */
+		private boolean ignoreLabels = false;
+
+		/**
+		 * Patterns flagged with this ignore FRAME instructions.
+		 */
+		private boolean ignoreFrames = false;
+
+		/**
+		 * Patterns flagged with this ignore LINENUMBER instructions.
+		 */
+		private boolean ignoreLineNumbers = false;
+
+		/**
+		 * Builds the pattern defined so far.
+		 * @return the built {@link PatternMatcher}
+		 */
+		public PatternMatcher build() {
+			return new PatternMatcher(predicates, reverse, ignoreLabels, ignoreFrames, ignoreLineNumbers);
+		}
+
+		/**
+		 * Sets the pattern to match starting from the end.
+		 * @return the builder's state after the operation
+		 */
+		public Builder reverse() {
+			this.reverse = true;
+			return this;
+		}
+
+		/**
+		 * Adds a custom predicate to the list. Also used internally.
+		 * @param predicate the predicate to add
+		 * @return the builder's state after the operation
+		 */
+		public Builder check(Predicate<AbstractInsnNode> predicate) {
+			predicates.add(predicate);
+			return this;
+		}
+
+		/**
+		 * Wildcard, matches any kind of node.
+		 * @return the builder's state after the operation
+		 */
+		public Builder any() {
+			return check(i -> true);
+		}
+
+		/**
+		 * Matches a specific opcode.
+		 * @param opcode opcode to match
+		 * @return the builder's state after the operation
+		 */
+		public Builder opcode(int opcode) {
+			return check(i -> i.getOpcode() == opcode);
+		}
+
+		/**
+		 * Matches a list of opcodes.
+		 * @param opcodes list of opcodes to match
+		 * @return the builder's state after the operation
+		 */
+		public Builder opcodes(int... opcodes) {
+			Builder res = this;
+			for(int o : opcodes)
+				res = opcode(o);
+			return res;
+		}
+
+		/**
+		 * Matches a method invokation of any kind: one of INVOKEVIRTUAL,
+		 * INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
+		 * @return the builder's state after the operation
+		 */
+		public Builder method() {
+			return check(i -> i.getType() == AbstractInsnNode.METHOD_INSN);
+		}
+
+		/**
+		 * Matches a field invokation of any kind: one of GETSTATIC, PUTSTATIC,
+		 * GETFIELD or PUTFIELD.
+		 * @return the builder's state after the operation
+		 */
+		public Builder field() {
+			return check(i -> i.getType() == AbstractInsnNode.FIELD_INSN);
+		}
+
+		/**
+		 * Matches any kind of jump instruction.
+		 * @return the builder's state after the operation
+		 */
+		public Builder jump() {
+			return check(i -> i.getType() == AbstractInsnNode.JUMP_INSN);
+		}
+
+		/**
+		 * Matches any kind of label.
+		 * @return the builder's state after the operation
+		 */
+		public Builder label() {
+			return check(i -> i.getType() == AbstractInsnNode.LABEL);
+		}
+
+		/**
+		 * Tells the pattern matcher to ignore LABEL instructions.
+		 * @return the builder's state after the operation
+		 */
+		public Builder ignoreLabels() {
+			this.ignoreLabels = true;
+			return this;
+		}
+
+		/**
+		 * Tells the pattern matcher to ignore FRAME instructions.
+		 * @return the builder's state after the operation
+		 */
+		public Builder ignoreFrames() {
+			this.ignoreFrames = true;
+			return this;
+		}
+
+		/**
+		 * Tells the pattern matcher to ignore LINENUMBER instructions.
+		 * @return the builder's state after the operation
+		 */
+		public Builder ignoreLineNumbers() {
+			this.ignoreLineNumbers = true;
+			return this;
+		}
+	}
+}