[glacier] Move LinkedList to glacier.

lib/glacier/container/linked_list.h

@@ -0,0 +1,78 @@
+#pragma once
+
+#include <stdint.h>
+
+namespace glcr {
+
+template <typename T>
+class LinkedList {
+ public:
+  LinkedList() {}
+
+  LinkedList(const LinkedList&) = delete;
+
+  bool empty() const { return size_ == 0; }
+  uint64_t size() const { return size_; }
+
+  void PushBack(const T& item) {
+    size_++;
+    ListItem* new_item = new ListItem{
+        .item = item,
+        .next = nullptr,
+    };
+    if (front_ == nullptr) {
+      front_ = new_item;
+      return;
+    }
+    ListItem* litem = front_;
+    while (litem->next != nullptr) {
+      litem = litem->next;
+    }
+    litem->next = new_item;
+  }
+
+  T PopFront() {
+    size_--;
+
+    ListItem* old_front = front_;
+    front_ = front_->next;
+    T ret = old_front->item;
+    delete old_front;
+    return ret;
+  }
+
+  T PeekFront() const { return front_->item; }
+
+  struct ListItem {
+    T item;
+    ListItem* next;
+  };
+  class Iterator {
+   public:
+    Iterator(ListItem* item) : item_(item) {}
+
+    Iterator next() { return {item_->next}; }
+    Iterator& operator++() {
+      item_ = item_->next;
+      return *this;
+    }
+
+    T& operator*() { return item_->item; }
+    T* operator->() { return &item_->item; }
+    bool operator==(const Iterator& other) { return item_ == other.item_; }
+    bool operator!=(const Iterator& other) { return item_ != other.item_; }
+
+   private:
+    ListItem* item_;
+  };
+
+  Iterator begin() { return {front_}; }
+  Iterator end() { return {nullptr}; }
+
+ private:
+  uint64_t size_ = 0;
+
+  ListItem* front_ = nullptr;
+};
+
+}  // namespace glcr