more code

include/util/trbtree.h

@@ -38,8 +38,8 @@ SRBTreeNode *tRBTreeDropByKey(SRBTree *pTree, void *pKey);
 SRBTreeNode *tRBTreeGet(SRBTree *pTree, void *pKey);
 
 // SRBTreeIter =============================================
-#define tRBTreeIterCreate(tree) \
-  (SRBTreeIter) { .pTree = (tree), .pNode = (tree)->minNode }
+#define tRBTreeIterCreate(tree, descend) \
+  (SRBTreeIter) { .des = (descend), .pTree = (tree), .pNode = (descend) ? (tree)->maxNode : (tree)->minNode }
 
 SRBTreeNode *tRBTreeIterNext(SRBTreeIter *pIter);
 
@@ -60,6 +60,7 @@ struct SRBTree {
 };
 
 struct SRBTreeIter {
+  int8_t       des;
   SRBTree     *pTree;
   SRBTreeNode *pNode;
 };

source/util/src/trbtree.c

@@ -253,6 +253,30 @@ SRBTreeNode *tRBTreeIterNext(SRBTreeIter *pIter) {
   SRBTree     *pTree = pIter->pTree;
 
   if (pIter->pNode) {
+    if (pIter->des) {
+      // descend
+      if (pIter->pNode->left) {
+        pIter->pNode = pIter->pNode->left;
+        while (pIter->pNode->right) {
+          pIter->pNode = pIter->pNode->right;
+        }
+      } else {
+        while (true) {
+          if (pIter->pNode->parent) {
+            if (pIter->pNode == pIter->pNode->parent->right) {
+              pIter->pNode = pIter->pNode->parent;
+              break;
+            } else {
+              pIter->pNode = pIter->pNode->parent;
+            }
+          } else {
+            pIter->pNode = NULL;
+            break;
+          }
+        }
+      }
+    } else {
+      // ascend
       if (pIter->pNode->right) {
         pIter->pNode = pIter->pNode->right;
         while (pIter->pNode->left) {
@@ -274,6 +298,7 @@ SRBTreeNode *tRBTreeIterNext(SRBTreeIter *pIter) {
         }
       }
     }
+  }
 
 _exit:
   return pNode;

source/util/test/trbtreeTest.cpp

@@ -25,7 +25,7 @@ TEST(trbtreeTest, rbtree_test1) {
     tRBTreePut(&rt, pNode);
   }
 
-  SRBTreeIter  rti = tRBTreeIterCreate(&rt);
+  SRBTreeIter  rti = tRBTreeIterCreate(&rt, 0);
   SRBTreeNode *pNode = tRBTreeIterNext(&rti);
   int          la = 0;
   while (pNode) {