Add a lot of comments. More to come.

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

@@ -4,26 +4,58 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
 
+/**
+ * A base class for a pattern node. Provides all functions
+ * necessary for matching, and is constructed by a Pattern instance
+ * from a string.
+ * @param <T> the type that's used to tell which pattern this node belongs to.
+ */
 public class PatternNode<T> {
 
+    /**
+     * The set of states to which the lexer should continue
+     * should this node be correctly matched.
+     */
     protected HashSet<PatternNode<T>> outputStates;
 
+    /**
+     * Creates a new pattern node.
+     */
     public PatternNode(){
         outputStates = new HashSet<>();
     }
 
+    /**
+     * Determines whether the current input character can
+     * be matched by this node.
+     * @param other the character being matched.
+     * @return true if the character can be matched, false otherwise.
+     */
     public boolean matches(char other){
         return false;
     }
 
+    /**
+     * If this node can be used as part of a range, returns that value.
+     * @return a NULL terminator if this character cannot be converted
+     * into a range bound, or the appropriate range bound if it can.
+     */
     public char range(){
         return '\0';
     }
 
+    /**
+     * Adds this node in a collection of other nodes.
+     * @param into the collection to add into.
+     */
     public void addInto(Collection<PatternNode<T>> into){
         into.add(this);
     }
 
+    /**
+     * Adds the node's children into a collection of other nodes.
+     * @param into the collection to add into.
+     */
     public void addOutputsInto(Collection<PatternNode<T>> into){
         outputStates.forEach(e -> e.addInto(into));
     }