git subrepo clone git@github.com:Rconybea/xo-alloc.git xo-alloc

subrepo:
  subdir:   "xo-alloc"
  merged:   "fc656313"
upstream:
  origin:   "git@github.com:Rconybea/xo-alloc.git"
  branch:   "main"
  commit:   "fc656313"
git-subrepo:
  version:  "0.4.9"
  origin:   "???"
  commit:   "???"

xo-alloc/include/xo/alloc/Stack.hpp

@@ -0,0 +1,49 @@
+/* Stack.hpp
+ *
+ * author: Roland Conybeare, jul 2025
+ */
+
+#pragma once
+
+#include <vector>
+
+namespace xo {
+    namespace gc {
+        /** Simple stack implementation
+         **/
+        template <typename T>
+        class Stack {
+        public:
+            explicit Stack(std::size_t capacity) {
+                this->contents_.reserve(capacity);
+            }
+
+            bool is_empty() const { return contents_.empty(); }
+            std::size_t available() const { return contents_.capacity() - contents_.size(); }
+            void drop() { contents_.resize(contents_.size() - 1); }
+            void push(const T & x) { contents_.push_back(x); }
+            T pop() {
+                T retval = contents_[contents_.size() - 1];
+                this->drop();
+                return retval;
+            }
+            const T & top() const {
+                return this->lookup(0);
+            }
+            const T & lookup(std::size_t i) const {
+                return contents_.at(contents_.size() - 1 - i);
+            }
+            void clear() { contents_.clear(); }
+            void reset_to(std::size_t z) { contents_.resize(z); }
+
+            std::size_t n_elements() const { return contents_.size(); }
+            std::size_t capacity() const { return contents_.capacity(); }
+
+        private:
+            std::vector<T> contents_;
+        };
+
+    } /*namespace gc*/
+} /*namespace xo*/
+
+/* end Stack.hpp */