add testcase & remove unused code

src/main/java/com/alibaba/druid/sql/ast/statement/SQLExprTableSource.java

@@ -54,4 +54,25 @@ public class SQLExprTableSource extends SQLTableSourceImpl {
     public void output(StringBuffer buf) {
         this.expr.output(buf);
     }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((expr == null) ? 0 : expr.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null) return false;
+        if (getClass() != obj.getClass()) return false;
+        SQLExprTableSource other = (SQLExprTableSource) obj;
+        if (expr == null) {
+            if (other.expr != null) return false;
+        } else if (!expr.equals(other.expr)) return false;
+        return true;
+    }
+
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLIndexDefinition.java

@@ -1,21 +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.statement;
-
-
-public class SQLIndexDefinition {
-
-}

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectItem.java

@@ -29,15 +29,15 @@ public class SQLSelectItem extends SQLObjectImpl {
     public SQLSelectItem(){
 
     }
-    
-    public SQLSelectItem(SQLExpr expr) {
+
+    public SQLSelectItem(SQLExpr expr){
         this(expr, null);
     }
 
     public SQLSelectItem(SQLExpr expr, String alias){
         this.expr = expr;
         this.alias = alias;
-        
+
         if (expr != null) {
             expr.setParent(this);
         }
@@ -76,4 +76,29 @@ public class SQLSelectItem extends SQLObjectImpl {
         }
         visitor.endVisit(this);
     }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((alias == null) ? 0 : alias.hashCode());
+        result = prime * result + ((expr == null) ? 0 : expr.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null) return false;
+        if (getClass() != obj.getClass()) return false;
+        SQLSelectItem other = (SQLSelectItem) obj;
+        if (alias == null) {
+            if (other.alias != null) return false;
+        } else if (!alias.equals(other.alias)) return false;
+        if (expr == null) {
+            if (other.expr != null) return false;
+        } else if (!expr.equals(other.expr)) return false;
+        return true;
+    }
+
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectOrderByItem.java

@@ -63,4 +63,31 @@ public class SQLSelectOrderByItem extends SQLObjectImpl {
 
         visitor.endVisit(this);
     }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((collate == null) ? 0 : collate.hashCode());
+        result = prime * result + ((expr == null) ? 0 : expr.hashCode());
+        result = prime * result + ((type == null) ? 0 : type.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null) return false;
+        if (getClass() != obj.getClass()) return false;
+        SQLSelectOrderByItem other = (SQLSelectOrderByItem) obj;
+        if (collate == null) {
+            if (other.collate != null) return false;
+        } else if (!collate.equals(other.collate)) return false;
+        if (expr == null) {
+            if (other.expr != null) return false;
+        } else if (!expr.equals(other.expr)) return false;
+        if (type != other.type) return false;
+        return true;
+    }
+
 }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLTableConstaintImpl.java

@@ -1,32 +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.statement;
-
-import com.alibaba.druid.sql.visitor.SQLASTVisitor;
-
-@SuppressWarnings("serial")
-public class SQLTableConstaintImpl extends SQLConstaintImpl implements SQLTableConstaint {
-
-    public SQLTableConstaintImpl(){
-
-    }
-
-    @Override
-    protected void accept0(SQLASTVisitor visitor) {
-
-    }
-
-}