Add a lot of comments. More to come.

src/org/nwapw/abacus/lexing/pattern/PatternChain.java

@@ -1,23 +1,52 @@
 package org.nwapw.abacus.lexing.pattern;
 
+/**
+ * A chain of nodes that can be treated as a single unit.
+ * Used during pattern compilation.
+ * @param <T> the type used to identify which pattern has been matched.
+ */
 public class PatternChain<T> {
 
+    /**
+     * The head node of the chain.
+     */
     public PatternNode<T> head;
+    /**
+     * The tail node of the chain.
+     */
     public PatternNode<T> tail;
 
+    /**
+     * Creates a new chain with the given start and end.
+     * @param head the start of the chain.
+     * @param tail the end of the chain.
+     */
     public PatternChain(PatternNode<T> head, PatternNode<T> tail){
         this.head = head;
         this.tail = tail;
     }
 
+    /**
+     * Creates a chain that starts and ends with the same node.
+     * @param node the node to use.
+     */
     public PatternChain(PatternNode<T> node){
         this(node, node);
     }
 
+    /**
+     * Creates an empty chain.
+     */
     public PatternChain(){
         this(null);
     }
 
+    /**
+     * Appends the other chain to this one. This modifies
+     * the nodes, as well.
+     * If this chain is empty, it is set to the other.
+     * @param other the other chain to append.
+     */
     public void append(PatternChain<T> other){
         if(other.head == null || tail == null) {
             this.head = other.head;
@@ -28,6 +57,12 @@ public class PatternChain<T> {
         }
     }
 
+    /**
+     * Appends a single node to this chain. This modifies
+     * the nodes, as well.
+     * If this chain is empty, it is set to the node.
+     * @param node the node to append to this chain.
+     */
     public void append(PatternNode<T> node){
         if(tail == null){
             head = tail = node;