feat: add delete-where in sql parser

`execute_delete_where()` in vm.h is not implemented yet.

btree.h

@@ -421,14 +421,16 @@ cursor_t *leaf_node_find(table_t *table, uint32_t page_num, uint32_t key)
 
 /**
  * Fake deletion of B+Tree
- * Suppose there are `num_cell = 4` cells in `node` (which are [2,5,6,7]), and `key = 2`.
+ * 1) Suppose there are `num_cell = 4` cells in `node` (which are [2,5,6,7]), and `key = 2`.
  * We simply delete the `key` like deletion in a sorted array (move data forward).
- * 
- * After deleting `key = 2`, num_cells = 3 (which are [5,6,7]), and
+ *
+ * 2) After deleting `key = 2`, num_cells = 3 (which are [5,6,7]), and
  * we DO NOT adjust the parent of `node`, and the structure of our B+Tree.
- * 
- * Thus, we call it "fake_delete", since even if the row(cell) is deleted, 
+ *
+ * 3) Thus, we call it "fake_delete", since even if the row(cell) is deleted,
  * it still occupy disk space.
+ *
+ * 4) If the `num_cells` of leaf node is ZERO, then just return and delete nothing.
  **/
 void leaf_node_fake_delete(cursor_t *cursor, uint32_t key_to_delete)
 {

global.h

@@ -1,18 +1,17 @@
 #ifndef GLOBAL_H
 #define GLOBAL_H
 /**
- * 1. 某些头文件的循环引用, 因此引入这一文件作为函数的全局声明, 破除循环 include 
- * 2. 工程上并不是一个好的设计, tinydb 为了方便, 把所有的函数实现都写在了 header file
+ * 1. 某些头文件存在循环引用, 因此引入这一文件作为函数的全局声明, 破除循环 include
+ * 2. 工程上并不是一个好的设计, tinydb 为了方便, 把所有的函数实现都写在了头文件
  **/
 void serialize_row(row_t *source, void *dest);
 void *cursor_value(cursor_t *cursor);
 void print_btree(pager_t *pager, uint32_t page_num, uint32_t indent_level);
 
-#define TODO(filename, line_num)                        \
-    do                                                  \
-    {                                                   \
-        printf("TODO at %s: %d\n", filename, line_num); \
-        assert(0);                                      \
+#define TODO(filename, line_num)                                          \
+    do {                                                                  \
+        printf("\033[31m TODO at %s: %d \033[0m \n", filename, line_num); \
+        assert(0);                                                        \
     } while (0)
 
 // #define CUSTOMED_LEAF_MAX_CELLS ((uint32_t)3)

sql-parser/sqlex.l

@@ -16,6 +16,9 @@
 "rollback" |
 "ROLLBACK" { return ROLLBACK; }
 
+"delete" |
+"DELETE" { return DELETE; }
+
 "create" |
 "CREATE" { return CREATE; }
 

sql-parser/sqlparser.y

@@ -39,7 +39,8 @@ void yyerror(const char *msg) { fprintf(stderr, "[tinydb] SQL Parser: %s\n", msg
 }
 
 // sql keywords
-%token SELECT INSERT FROM TABLE CREATE WHERE VALUES INTO
+%token SELECT INSERT CREATE DELETE
+%token FROM TABLE WHERE VALUES INTO
 %token COMMIT ROLLBACK
 
 // sql operator
@@ -74,10 +75,18 @@ statement:
 |   selectsql {}
 |   createsql {}
 |   insertsql {}
+|   deletesql {}
 |   commitsql {}
 |   rollbacksql {}
 ;
 
+deletesql:
+    DELETE FROM IDNAME WHERE conditions ';'
+    {
+        statement_set(stm_ptr, STATEMENT_DELETE_WHERE, $3, select_list, $5);
+    }
+;
+
 commitsql:
     COMMIT ';'
     {
@@ -112,15 +121,15 @@ selectsql:
     }
 |   SELECT selectitemlist FROM IDNAME ';'
     {
-        statement_set(stm_ptr, STATEMENT_SELECT_FIELDS, $4, select_list, NULL);
+        statement_set(stm_ptr, STATEMENT_SELECT_WHERE, $4, select_list, NULL);
     }
 |   SELECT '*' FROM IDNAME WHERE conditions ';'
     {
-        statement_set(stm_ptr, STATEMENT_SELECT_FIELDS, $4, select_list, $6);
+        statement_set(stm_ptr, STATEMENT_SELECT_WHERE, $4, select_list, $6);
     }
 |   SELECT selectitemlist FROM IDNAME WHERE conditions ';'
     {
-        statement_set(stm_ptr, STATEMENT_SELECT_FIELDS, $4, select_list, $6);
+        statement_set(stm_ptr, STATEMENT_SELECT_WHERE, $4, select_list, $6);
     }
 ;
 

sql-statement/statement.h

@@ -7,9 +7,10 @@ typedef enum
 {
     STATEMENT_INSERT,
     STATEMENT_SELECT,
-    STATEMENT_SELECT_FIELDS,
+    STATEMENT_SELECT_WHERE,
     STATEMENT_UPDATE,
     STATEMENT_DELETE,
+    STATEMENT_DELETE_WHERE,
     STATEMENT_COMMIT,
     STATEMENT_ROLLBACK
 } statement_type_t;

sql-vm/vm.h

@@ -6,12 +6,16 @@
 #define TINYDB_VM_H
 
 /**
- * The parsing result of a SQL statement sentence is stored in statement_t.
+ * The parsing result of a SQL statement is stored in statement_t.
  * These `execute_xxx` functions are equal to the "Vitrual Machine" in sqlite.
  * SQL Statement:
- * - insert id username email
- * - select
- * - update id username email
+ * 1) execute_select, execute_delete are used by the dummy sql parser.
+ *    > select (this will print all the rows)
+ *    > delete [id] (this will delete the row whose id is `[id]` from B+Tree)
+ *
+ * 2) select_where, delete_where are used by the sql parser based on flex-bison.
+ *    > select * from table where id > 10 and id < 30;
+ *    > delete * from table where id > 10 and id < 30;
  **/
 
 execute_result_t execute_insert(statement_t *statement, table_t *table)
@@ -59,7 +63,7 @@ execute_result_t execute_select(statement_t *statement, table_t *table)
     return EXECUTE_SUCCESS;
 }
 
-execute_result_t execute_select_fields(statement_t *statement, table_t *table)
+execute_result_t execute_select_where(statement_t *statement, table_t *table)
 {
     cursor_t *cursor = table_start(table);
     row_t row;
@@ -106,8 +110,6 @@ execute_result_t execute_delete(statement_t *statement, table_t *table)
     cursor_t *cursor = table_exists(table, key_to_delete);
     if (cursor != NULL)
     {
-        // printf("[execute_delete] page num: %u\n", cursor->page_num);
-        // printf("[execute_delete] cell num: %u\n", cursor->cell_num);
         leaf_node_fake_delete(cursor, key_to_delete);
 #ifdef OPEN_TRANSACTION
         row_t temp;
@@ -120,6 +122,13 @@ execute_result_t execute_delete(statement_t *statement, table_t *table)
     return EXECUTE_NO_SUCH_KEY;
 }
 
+execute_result_t execute_delete_where(statement_t *statement, table_t *table)
+{
+    /* There is bugs while scanning B+Tree and deleting at the same time. */
+    TODO(__FILE__, __LINE__);
+    return EXECUTE_UNKNOWN_STATEMENT;
+}
+
 execute_result_t execute_commit(statement_t *statement, table_t *table)
 {
     assert(statement->type == STATEMENT_COMMIT);
@@ -150,12 +159,14 @@ execute_result_t vm_executor(statement_t *statement, table_t *table)
         return execute_insert(statement, table);
     case STATEMENT_SELECT:
         return execute_select(statement, table);
-    case STATEMENT_SELECT_FIELDS:
-        return execute_select_fields(statement, table);
+    case STATEMENT_SELECT_WHERE:
+        return execute_select_where(statement, table);
     case STATEMENT_UPDATE:
         return execute_update(statement, table);
     case STATEMENT_DELETE:
         return execute_delete(statement, table);
+    case STATEMENT_DELETE_WHERE:
+        return execute_delete_where(statement, table);
     case STATEMENT_COMMIT:
         return execute_commit(statement, table);
     case STATEMENT_ROLLBACK: