add testcase & remove unused code

src/main/java/com/alibaba/druid/sql/ast/expr/SQLBinaryOpExpr.java

@@ -24,9 +24,9 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 public class SQLBinaryOpExpr extends SQLExprImpl implements Serializable {
 
     private static final long serialVersionUID = 1L;
-    private SQLExpr            left;
-    private SQLExpr            right;
-    private SQLBinaryOperator  operator;
+    private SQLExpr           left;
+    private SQLExpr           right;
+    private SQLBinaryOperator operator;
 
     public SQLBinaryOpExpr(){
 
@@ -76,14 +76,6 @@ public class SQLBinaryOpExpr extends SQLExprImpl implements Serializable {
         this.operator = operator;
     }
 
-    public void output(StringBuffer buf) {
-        this.left.output(buf);
-        buf.append(" ");
-        buf.append(this.operator.name);
-        buf.append(" ");
-        this.right.output(buf);
-    }
-
     protected void accept0(SQLASTVisitor visitor) {
         if (visitor.visit(this)) {
             acceptChild(visitor, this.left);

src/main/java/com/alibaba/druid/sql/ast/expr/SQLCastExpr.java

@@ -50,14 +50,6 @@ public class SQLCastExpr extends SQLExprImpl {
         this.dataType = dataType;
     }
 
-    public void output(StringBuffer buf) {
-        buf.append("CAST(");
-        this.expr.output(buf);
-        buf.append(" AS ");
-        this.dataType.output(buf);
-        buf.append(")");
-    }
-
     protected void accept0(SQLASTVisitor visitor) {
         if (visitor.visit(this)) {
             acceptChild(visitor, this.expr);

src/main/java/com/alibaba/druid/sql/ast/expr/SQLDateLiteralValue.java

@@ -1,56 +0,0 @@
-/*
- * Copyright 1999-2011 Alibaba Group Holding Ltd.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package com.alibaba.druid.sql.ast.expr;
-
-public class SQLDateLiteralValue {
-
-    private int years;
-    private int months;
-    private int days;
-
-    public int getYears() {
-        return years;
-    }
-
-    public void setYears(int years) {
-        this.years = years;
-    }
-
-    public int getMonths() {
-        return months;
-    }
-
-    public void setMonths(int months) {
-        this.months = months;
-    }
-
-    public int getDays() {
-        return days;
-    }
-
-    public void setDays(int days) {
-        this.days = days;
-    }
-
-    public void output(StringBuffer buf) {
-        buf.append(years);
-        buf.append("-");
-        buf.append(months);
-        buf.append("-");
-        buf.append(days);
-    }
-
-}