fix: finish StructFmt refactor in Unvirt

Unvirt/Utils.hpp

@@ -0,0 +1,54 @@
+#pragma once
+#include <yycc/macro/class_copy_move.hpp>
+
+namespace Unvirt::Utils {
+
+	class PageBreaker {
+	public:
+		/**
+		 * @brief 
+		 * @param[in] count 
+		 * @param[in] count_per_page 
+		 * @exception std::logic_error if the count per page is zero.
+		 */
+		PageBreaker(size_t count, size_t count_per_page);
+		~PageBreaker();
+		YYCC_DEFAULT_COPY_MOVE(PageBreaker)
+
+	public:
+		/**
+		 * @brief 
+		 * @param[in] page The page index (zero-based)
+		 * @return 
+		 * @remarks Page zero is always valid because we at least have one page.
+		 */
+		bool IsValidPage(size_t page) const;
+		/**
+		 * @brief 
+		 * @return The max page index (zero-based, inclusive)
+		 * @remarks Zero count will produce at least one page.
+		 */
+		size_t GetMaxPage() const;
+		/**
+		 * @brief 
+		 * @param[in] page The page index (zero-based)
+		 * @return The start index of this page (inclusive). 
+		 * Is is usually used as the init statement `size_t i = pb.GetPageBeginIndex()` in "for" statement.
+		 * @exception std::runtime_error if page index is out of range.
+		 */
+		size_t GetPageBeginIndex(size_t page) const;
+		/**
+		 * @brief 
+		 * @param[in] page The page index (zero-based)
+		 * @return The end index of this page (exclusive). 
+		 * Is is usually used as the stop statement `i < pb.GetPageEndIndex()` in "for" statement.
+		 * @exception std::runtime_error if page index is out of range.
+		 */
+		size_t GetPageEndIndex(size_t page) const;
+
+	private:
+		size_t count;
+		size_t count_per_page;
+	};
+
+}