Add sanitization to TreeBuilder.

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

@@ -235,4 +235,16 @@ public class Pattern<T> {
     public PatternNode<T> getHead() {
         return head;
     }
+
+    public static String sanitize(String from){
+        Pattern<Integer> pattern = new Pattern<>("", 0);
+        from = from.replace(".", "\\.");
+        from = from.replace("|", "\\|");
+        from = from.replace("(", "\\(");
+        from = from.replace(")", "\\)");
+        for(Character key : pattern.operations.keySet()){
+            from = from.replace("" + key, "\\" + key);
+        }
+        return from;
+    }
 }

src/org/nwapw/abacus/tree/TreeBuilder.java

@@ -3,6 +3,7 @@ package org.nwapw.abacus.tree;
 import org.nwapw.abacus.function.OperatorAssociativity;
 import org.nwapw.abacus.lexing.Lexer;
 import org.nwapw.abacus.lexing.pattern.Match;
+import org.nwapw.abacus.lexing.pattern.Pattern;
 
 import java.util.*;
 
@@ -48,7 +49,7 @@ public class TreeBuilder {
      * @param function the function to register.
      */
     public void registerFunction(String function){
-        lexer.register(function, TokenType.FUNCTION);
+        lexer.register(Pattern.sanitize(function), TokenType.FUNCTION);
     }
 
     /**
@@ -58,7 +59,7 @@ public class TreeBuilder {
      * @param associativity the associativity of the operator.
      */
     public void registerOperator(String operator, int precedence, OperatorAssociativity associativity){
-        lexer.register(operator, TokenType.OP);
+        lexer.register(Pattern.sanitize(operator), TokenType.OP);
         precedenceMap.put(operator, precedence);
         associativityMap.put(operator, associativity);
     }