From 26b7723f192ad147479b9d79b1c722fc601fdb6c Mon Sep 17 00:00:00 2001
From: rexy712 <rexy712@protonmail.com>
Date: Fri, 15 Jul 2022 16:36:54 -0700
Subject: [PATCH] Make buffer actually constexpr-able

---
 include/rexy/buffer.hpp |  4 ++++
 include/rexy/buffer.tpp | 25 +++++++++++++++----------
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/include/rexy/buffer.hpp b/include/rexy/buffer.hpp
index 2368155..3c6a87e 100644
--- a/include/rexy/buffer.hpp
+++ b/include/rexy/buffer.hpp
@@ -24,6 +24,8 @@
 #include <cstddef> //size_t, ptrdiff_t
 #include <iterator> //reverse_iterator
 
+#include "storage_for.hpp"
+
 #include "compat/standard.hpp"
 
 namespace rexy{
@@ -92,6 +94,8 @@ namespace rexy{
 		constexpr const_reverse_iterator crbegin(void)const;
 		constexpr const_reverse_iterator crend(void)const;
 
+		REXY_CPP20_CONSTEXPR void clear(void);
+
 		REXY_CPP20_CONSTEXPR void append(const_pointer p, size_type len);
 	};
 
diff --git a/include/rexy/buffer.tpp b/include/rexy/buffer.tpp
index e335a6e..6014205 100644
--- a/include/rexy/buffer.tpp
+++ b/include/rexy/buffer.tpp
@@ -21,6 +21,7 @@
 
 #include <utility> //exchange, swap
 #include <algorithm> //max
+#include <memory> //construct_at
 
 namespace rexy{
 
@@ -33,7 +34,7 @@ namespace rexy{
 		m_size(length)
 	{
 		for(size_type i = 0;i < length;++i){
-			new (m_data + i) T(data[i]);
+			std::construct_at(m_data + i, data[i]);
 		}
 	}
 	template<class T, class Allocator>
@@ -48,7 +49,7 @@ namespace rexy{
 
 		count = 0;
 		for(auto it = start;it != last;++it){
-			new (m_data + count) T(*it);
+			std::construct_at(m_data + count, *it);
 			++count;
 		}
 		m_size = count;
@@ -65,7 +66,7 @@ namespace rexy{
 		m_size(b.m_size)
 	{
 		for(size_type i = 0;i < b.m_size;++i){
-			new (m_data + i) T(b.m_data[i]);
+			std::construct_at(m_data + i, b.m_data[i]);
 		}
 	}
 	template<class T, class Allocator>
@@ -76,7 +77,7 @@ namespace rexy{
 	template<class T, class Allocator>
 	REXY_CPP20_CONSTEXPR buffer<T,Allocator>::~buffer(void)noexcept(is_nothrow_allocator_v<Allocator>){
 		for(size_type i = 0;i < m_size;++i){
-			m_data[i].~T();
+			std::destroy_at(m_data + i);
 		}
 		this->deallocate(m_data, m_cap * sizeof(value_type));
 	}
@@ -106,7 +107,7 @@ namespace rexy{
 		if(new_cap > m_cap){
 			buffer tmp(new_cap);
 			for(size_type i = 0;i < m_size;++i){
-				new (tmp.m_data + i) T(std::move(m_data[i]));
+				std::construct_at(tmp.m_data + i, std::move(m_data[i]));
 			}
 			std::swap(tmp.m_data, m_data);
 		}
@@ -202,12 +203,16 @@ namespace rexy{
 	template<class T, class Allocator>
 	REXY_CPP20_CONSTEXPR void buffer<T,Allocator>::append(const_pointer p, size_type len){
 		if(len + m_size > m_cap){
-			resize(std::max(m_cap * 2, len + m_size));
+			buffer b(std::max(m_cap * 2, len + m_size));
+			b.append(m_data, m_size);
+			b.append(p, len);
+			*this = std::move(b);
+		}else{
+			for(size_type i = 0;i < len;++i){
+				std::construct_at(m_data + (m_size + i), p[i]);
+			}
+			m_size += len;
 		}
-		for(size_type i = 0;i < len;++i){
-			new (m_data + (m_size + i)) T(p[i]);
-		}
-		m_size += len;
 	}
 
 }