added headers, comments and TODO

Author: Dingshilun

src/include/parser/alter_statement.h

@@ -20,6 +20,7 @@ namespace parser {
 /**
  * @struct AlterTableStatement
  * @brief Represents "ALTER TABLE add column COLUMN_NAME COLUMN_TYPE"
+ * TODO: add implementation of AlterTableStatement
  */
 class AlterTableStatement : public TableRefStatement {
  public:
@@ -30,10 +31,6 @@ class AlterTableStatement : public TableRefStatement {
         names(new std::vector<char *>) {}
 
   virtual ~AlterTableStatement() {
-    //      if (columns != nullptr) {
-    //        for (auto col : *columns) delete col;
-    //        delete columns;
-    //      }
     if (names != nullptr) {
       for (auto name : *names) delete name;
       delete names;

src/include/parser/rename_function_statement.h

@@ -1,6 +1,14 @@
+//===----------------------------------------------------------------------===//
 //
-// Created by Nevermore on 01/04/2018.
+//                         Peloton
 //
+// rename_function_statement.h
+//
+// Identification: src/include/parser/rename_function_statement.h
+//
+// Copyright (c) 2015-17, Carnegie Mellon University Database Group
+//
+//===----------------------------------------------------------------------===//
 
 #pragma once
 
@@ -9,6 +17,10 @@
 
 namespace peloton {
 namespace parser {
+/** @brief Rename statement
+ *  The statement that used for transform from postgress statement
+ *  to Peloton statement
+ */
 class RenameFuncStatement : public TableRefStatement {
  public:
   enum class ObjectType { INVALID = 0, COLUMN = 1 };

src/include/planner/alter_plan.h

@@ -1,13 +1,24 @@
+//===----------------------------------------------------------------------===//
 //
-// Created by Nevermore on 03/04/2018.
+//                         Peloton
 //
+// alter_plan.h
+//
+// Identification: src/include/parser/alter_plan.h
+//
+// Copyright (c) 2015-17, Carnegie Mellon University Database Group
+//
+//===----------------------------------------------------------------------===//
 
 #pragma once
 #include "planner/abstract_plan.h"
 #include "parser/alter_statement.h"
 namespace peloton {
 
 namespace planner {
+/** @brief The plan used for altering
+ *  TODO: adding support for add/drop column
+ */
 class AlterPlan : public AbstractPlan {
  public:
   AlterPlan() = delete;

src/include/planner/rename_plan.h

@@ -1,12 +1,25 @@
+//===----------------------------------------------------------------------===//
 //
-// Created by Nevermore on 03/04/2018.
+//                         Peloton
 //
+// rename_plan.h
+//
+// Identification: src/include/parser/rename_plan.h
+//
+// Copyright (c) 2015-17, Carnegie Mellon University Database Group
+//
+//===----------------------------------------------------------------------===//
 
 #pragma once
 
 #include "planner/abstract_plan.h"
 #include "parser/rename_function_statement.h"
 
+/** @brief: The Plan used for rename
+ *  The plan contains the necessary information for
+ *  renaming, including old names, new names and
+ *  which object and database
+ */
 namespace peloton {
 namespace planner {
 class RenamePlan : public AbstractPlan {