add preprocess to ast

src/main/java/parser/ast/AST.java

@@ -1,5 +1,7 @@
 package parser.ast;
 
+import parser.grammar.Grammar;
+
 import java.util.Objects;
 
 public class AST {
@@ -18,6 +20,11 @@ public class AST {
         return this.root.size();
     }
 
+    public void preprocess(Grammar grammar) {
+        ASTCompacter.clean(this, grammar);
+        ExpressionBalancer.balance(this);
+    }
+
     @Override
     public boolean equals(Object obj) {
         if (obj instanceof AST) {