From e865255b203f07bd2a15d0de5145ee80eace1933 Mon Sep 17 00:00:00 2001
From: hzcheng <hzcheng@taosdata.com>
Date: Fri, 20 Mar 2020 15:56:44 +0800
Subject: [PATCH] TD-34

---
 src/util/inc/tlist.h | 12 ++++++++++--
 src/util/src/tlist.c | 23 ++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/src/util/inc/tlist.h b/src/util/inc/tlist.h
index 3f58c35e3b..cc99e183ed 100644
--- a/src/util/inc/tlist.h
+++ b/src/util/inc/tlist.h
@@ -19,6 +19,11 @@
 extern "C" {
 #endif
 
+typedef enum {
+  TD_LIST_FORWARD,
+  TD_LIST_BACKWARD
+} TD_LIST_DIRECTION_T;
+
 typedef struct _list_node {
   struct _list_node *next;
   struct _list_node *prev;
@@ -33,7 +38,8 @@ typedef struct {
 } SList;
 
 typedef struct {
-  SListNode *node;
+  SListNode *         next;
+  TD_LIST_DIRECTION_T direction;
 } SListIter;
 
 #define listHead(l) (l)->head
@@ -52,7 +58,9 @@ SListNode *tdListPopHead(SList *list);
 SListNode *tdListPopTail(SList *list);
 SListNode *tdListPopNode(SList *list, SListNode *node);
 
-void tdListNodeGetData(SList *list, SListNode *node, void *target);
+void       tdListNodeGetData(SList *list, SListNode *node, void *target);
+void       tdListInitIter(SList *list, SListIter *pIter, TD_LIST_DIRECTION_T direction);
+SListNode *tdListNext(SListIter *pIter);
 
 #ifdef __cplusplus
 }
diff --git a/src/util/src/tlist.c b/src/util/src/tlist.c
index 42068a717e..a6cb98df5f 100644
--- a/src/util/src/tlist.c
+++ b/src/util/src/tlist.c
@@ -122,4 +122,25 @@ SListNode *tdListPopNode(SList *list, SListNode *node) {
     return node;
 }
 
-void tdListNodeGetData(SList *list, SListNode *node, void *target) { memcpy(node->data, target, list->eleSize); }
\ No newline at end of file
+void tdListNodeGetData(SList *list, SListNode *node, void *target) { memcpy(node->data, target, list->eleSize); }
+
+void tdListInitIter(SList *list, SListIter *pIter, TD_LIST_DIRECTION_T direction) {
+  pIter->direction = direction;
+  if (direction == TD_LIST_FORWARD) {
+    pIter->next = list->head;
+  } else {
+    pIter->next = list->tail;
+  }
+}
+
+SListNode *tdListNext(SListIter *pIter) {
+  SListNode *node = pIter->next;
+  if (node == NULL) return NULL;
+  if (pIter->direction == TD_LIST_FORWARD) {
+    pIter->next = node->next;
+  } else {
+    pIter->next = node->prev;
+  }
+
+  return node;
+}
\ No newline at end of file
-- 
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