From efe2e4a83be67e31effc93649660270b2d589371 Mon Sep 17 00:00:00 2001
From: Xu Shaohua <shaohua@biofan.org>
Date: Sun, 3 Dec 2023 09:04:49 +0800
Subject: [PATCH] ds: Traverse btree

---
 ds/4.tree/CMakeLists.txt       |  9 +++++-
 ds/4.tree/binary_tree.h        |  7 +++++
 ds/4.tree/binary_tree_test.c   | 16 ++++++++++
 ds/4.tree/linked_binary_tree.c | 57 +++++++++++++++++++++++++++++++++-
 4 files changed, 87 insertions(+), 2 deletions(-)
 create mode 100644 ds/4.tree/binary_tree_test.c

diff --git a/ds/4.tree/CMakeLists.txt b/ds/4.tree/CMakeLists.txt
index 665882e6..658cb7d5 100644
--- a/ds/4.tree/CMakeLists.txt
+++ b/ds/4.tree/CMakeLists.txt
@@ -2,4 +2,11 @@
 add_library(linked-binary-tree-static STATIC
     linked_binary_tree.c
     binary_tree.h
-    )
\ No newline at end of file
+    )
+
+add_executable(binary-tree-test
+    binary_tree_test.c
+)
+target_link_libraries(binary-tree-test
+    linked-binary-tree-static
+)
diff --git a/ds/4.tree/binary_tree.h b/ds/4.tree/binary_tree.h
index eaa9d7e1..dcc1a8b3 100644
--- a/ds/4.tree/binary_tree.h
+++ b/ds/4.tree/binary_tree.h
@@ -45,6 +45,12 @@ extern size_t binary_tree_size(binary_tree_t* tree);
  */
 extern bool binary_tree_is_empty(binary_tree_t* tree);
 
+enum tree_traverse_mode {
+  kTraverseInOrder = 0,
+  kTraversePreOrder,
+  kTraversePostOrder,
+};
+
 /**
  * Calls |apply| function for each node in binary tree.
  *
@@ -53,6 +59,7 @@ extern bool binary_tree_is_empty(binary_tree_t* tree);
  * @param user_data
  */
 extern void binary_tree_traverse(binary_tree_t* tree,
+                                 tree_traverse_mode mode,
                                  void (*apply)(void* value, void* user_data),
                                  void* user_data);
 
diff --git a/ds/4.tree/binary_tree_test.c b/ds/4.tree/binary_tree_test.c
new file mode 100644
index 00000000..dc72b138
--- /dev/null
+++ b/ds/4.tree/binary_tree_test.c
@@ -0,0 +1,16 @@
+// Copyright (c) 2023 Xu Shaohua <shaohua@biofan.org>. All rights reserved.
+// Use of this source is governed by General Public License that can be
+// found in the LICENSE file.
+
+#include <stdio.h>
+
+#include "binary_tree.h"
+
+int main(void) {
+  binary_tree_t* tree = binary_tree_new();
+
+  binary_tree_free(tree);
+  tree = NULL;
+
+  return 0;
+}
diff --git a/ds/4.tree/linked_binary_tree.c b/ds/4.tree/linked_binary_tree.c
index cf7f3701..af3eb8ea 100644
--- a/ds/4.tree/linked_binary_tree.c
+++ b/ds/4.tree/linked_binary_tree.c
@@ -45,4 +45,59 @@ size_t binary_tree_size(binary_tree_t* tree) {
 bool binary_tree_is_empty(binary_tree_t* tree) {
   assert(tree != NULL);
   return tree->size > 0;
-}
\ No newline at end of file
+}
+
+static void tree_node_traverse_in_order(tree_node_t* node,
+                                       void (*apply)(void* value, void* user_data),
+                                       void* user_data) {
+  if (node != NULL) {
+    tree_node_traverse_in_order(node->left, apply, user_data);
+    apply(node->value, user_data);
+    tree_node_traverse_in_order(node->right, apply, user_data);
+  }
+}
+
+static void tree_node_traverse_pre_order(tree_node_t* node,
+                                       void (*apply)(void* value, void* user_data),
+                                       void* user_data) {
+  if (node != NULL) {
+    apply(node->value, user_data);
+    tree_node_traverse_pre_order(node->left, apply, user_data);
+    tree_node_traverse_pre_order(node->right, apply, user_data);
+  }
+}
+
+static void tree_node_traverse_post_order(tree_node_t* node,
+                                       void (*apply)(void* value, void* user_data),
+                                       void* user_data) {
+  if (node != NULL) {
+    tree_node_traverse_post_order(node->left, apply, user_data);
+    tree_node_traverse_post_order(node->right, apply, user_data);
+    apply(node->value, user_data);
+  }
+}
+
+void binary_tree_traverse(binary_tree_t* tree,
+                          tree_traverse_mode mode,
+                          void (*apply)(void* value, void* user_data),
+                          void* user_data) {
+  assert(tree != NULL);
+  switch (mode) {
+    case kTraverseInOrder: {
+      tree_node_traverse_in_order(tree->root, apply, user_data);
+      break;
+    }
+    case kTraversePreOrder: {
+      tree_node_traverse_pre_order(tree->root, apply, user_data);
+      break;
+    }
+    case kTraversePostOrder: {
+      tree_node_traverse_post_order(tree->root, apply, user_data);
+      break;
+    }
+    default: {
+      fprintf(stderr, "Invalid traverse mode\n");
+      assert(0);
+    }
+  }
+}