// 递归遍历
void VisitTree_Recursive(const TreeNode *root, void (*visit_func)(const TreeNode *), int visit_mode = VISIT_PREORDER)
{
if (! root || !visit_func) return;
if (VISIT_PREORDER == visit_mode) visit_func(root);
if (root->left) VisitTree_Recursive(root->left, visit_func, visit_mode);
if (VISIT_INORDER == visit_mode) visit_func(root);
if (root->right) VisitTree_Recursive(root->right, visit_func, visit_mode);
if (VISIT_POSTORDER == visit_mode) visit_func(root);
}
// 非递归遍历实现
void VisitTree_PreOrder(const TreeNode *root, void (*visit_func)(const TreeNode *))
{
// 前序遍历
// 可以利用类似的思路，利用第二个栈，把push次序逆过来，就形成了后序遍历
// 见 VisitTree_PostOrder_v2
if (!root || !visit_func) return;
const TreeNode *cur = NULL;
std::stack<const TreeNode *> st;
st.push(root);
while (!st.empty())
{
cur = st.top();
st.pop();
visit_func(cur);
// 先push右节点
// 这是为了保证左节点在下次循环首先被pop出来处理，
// 同时也被左节点的子节点覆盖在上面，满足处理完左子树，
// 再处理右子树的特点
if (cur->right) st.push(cur->right);
if (cur->left) st.push(cur->left);
}
}
void VisitTree_InOrder(const TreeNode *root, void (*visit_func)(const TreeNode *))
{
// 中序遍历
if (!root || !visit_func) return;
const TreeNode *cur = NULL;
std::stack<const TreeNode *> st;
st.push(root);
while (!st.empty())
{
// 向左走到尽头
while (st.top()->left) st.push(st.top()->left);
// 不断退栈，访问节点，试图找到右出路
do
{
cur = st.top();
st.pop();
visit_func(cur);
// 右结点存在，切换成外循环走左
if (cur->right)
{
st.push(cur->right);
break;
}
} while (!st.empty());
}
}
void list_retraversal(List *L, void (*visit_func)(void *))
{
ListNode *p = L->tail;
while (!IS_NULL(p)) {
visit_func(p->value);
p = p->prev;
}
}
void list_traversal(List *L, void (*visit_func)(void *))
{
ListNode *p = L->head;
while (!IS_NULL(p)) {
visit_func(p->value);
p = p->next;
}
}
void decl_collector::visit(ast* n) {
datatype_util util(m());
m_todo.push_back(n);
while (!m_todo.empty()) {
n = m_todo.back();
m_todo.pop_back();
if (!m_visited.is_marked(n)) {
switch(n->get_kind()) {
case AST_APP: {
app * a = to_app(n);
for (expr* arg : *a) {
m_todo.push_back(arg);
}
m_todo.push_back(a->get_decl());
break;
}
case AST_QUANTIFIER: {
quantifier * q = to_quantifier(n);
unsigned num_decls = q->get_num_decls();
for (unsigned i = 0; i < num_decls; ++i) {
m_todo.push_back(q->get_decl_sort(i));
}
m_todo.push_back(q->get_expr());
for (unsigned i = 0; i < q->get_num_patterns(); ++i) {
m_todo.push_back(q->get_pattern(i));
}
break;
}
case AST_SORT:
visit_sort(to_sort(n));
break;
case AST_FUNC_DECL: {
func_decl * d = to_func_decl(n);
for (sort* srt : *d) {
m_todo.push_back(srt);
}
m_todo.push_back(d->get_range());
visit_func(d);
break;
}
case AST_VAR:
break;
default:
UNREACHABLE();
}
m_visited.mark(n, true);
}
}
}
void decl_collector::visit(ast* n) {
ptr_vector<ast> todo;
todo.push_back(n);
while (!todo.empty()) {
n = todo.back();
todo.pop_back();
if (!m_visited.is_marked(n)) {
m_visited.mark(n, true);
switch(n->get_kind()) {
case AST_APP: {
app * a = to_app(n);
for (unsigned i = 0; i < a->get_num_args(); ++i) {
todo.push_back(a->get_arg(i));
}
todo.push_back(a->get_decl());
break;
}
case AST_QUANTIFIER: {
quantifier * q = to_quantifier(n);
unsigned num_decls = q->get_num_decls();
for (unsigned i = 0; i < num_decls; ++i) {
todo.push_back(q->get_decl_sort(i));
}
todo.push_back(q->get_expr());
for (unsigned i = 0; i < q->get_num_patterns(); ++i) {
todo.push_back(q->get_pattern(i));
}
break;
}
case AST_SORT:
visit_sort(to_sort(n));
break;
case AST_FUNC_DECL: {
func_decl * d = to_func_decl(n);
for (unsigned i = 0; i < d->get_arity(); ++i) {
todo.push_back(d->get_domain(i));
}
todo.push_back(d->get_range());
visit_func(d);
break;
}
case AST_VAR:
break;
default:
UNREACHABLE();
}
}
}
}
void VisitTree_PostOrder(const TreeNode *root, void (*visit_func)(const TreeNode *))
{
// 后序遍历
if (!root || !visit_func) return;
const TreeNode *cur = NULL;
// pre指向上次处理的结点，以便判断从左/右子树处理完成回到当前结点
const TreeNode *pre = NULL;
std::stack<const TreeNode *> st;
st.push(root);
while (!st.empty())
{
// 向左走到尽头
while (st.top()->left) st.push(st.top()->left);
// 不断退栈，判断从右子树返回再访问节点，不满足访问条件，
// 把右结点加入栈，走外循环
do
{
pre = cur;
cur = st.top();
// 右结点不存在或者上次已经处理了右结点，表明当前结点可以退栈和处理了
if (cur->right == NULL || cur->right == pre)
{
st.pop();
visit_func(cur);
continue;
}
// 到了这里，表明右子树存在，并且还没被访问
// push右结点，走外循环逻辑
st.push(cur->right);
break;
} while (!st.empty());
}
}
void VisitTree_PostOrder_v2(const TreeNode *root, void (*visit_func)(const TreeNode *))
{
// 后序遍历 双栈法
// 思路类似前序遍历的非递归法
// 顺序栈访问顺序：根->右->左，对逆序栈，则是左->右->根,
// 正是后序遍历需要的顺序
if (!root || !visit_func) return;
const TreeNode *cur = NULL;
std::stack<const TreeNode *> st;
st.push(root);
std::stack<const TreeNode *> st_back;
while (!st.empty())
{
cur = st.top();
st.pop();
// push倒序栈
st_back.push(cur);
// 后push右，保证右先被处理
if (cur->left) st.push(cur->left);
if (cur->right) st.push(cur->right);
}
while (!st_back.empty())
{
visit_func(st_back.top());
st_back.pop();
}
}