From 3f82be9bc8588c1dc64b34eb511a372160f74ea8 Mon Sep 17 00:00:00 2001
From: Joseph Walton-Rivers <joseph@walton-rivers.uk>
Date: Sat, 23 Jul 2022 16:18:33 +0100
Subject: [PATCH] fake a slotmap for API purposes
---
include/fggl/ds/placeholder.hpp | 47 +++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/include/fggl/ds/placeholder.hpp b/include/fggl/ds/placeholder.hpp
index e1cdfdc..ab9d9f7 100644
--- a/include/fggl/ds/placeholder.hpp
+++ b/include/fggl/ds/placeholder.hpp
@@ -21,8 +21,55 @@
#ifndef FGGL_DS_PLACEHOLDER_HPP
#define FGGL_DS_PLACEHOLDER_HPP
+#include <map>
+#include <cassert>
+
namespace fggl::ds {
+ template<typename T, std::size_t N>
+ class FakeSlotMap {
+ public:
+ using WeakRef = std::size_t;
+ constexpr static WeakRef BAD_INDEX = 0;
+
+ bool valid(WeakRef idx) const {
+ return m_data.find(idx) != m_data.end();
+ }
+
+ WeakRef allocate() {
+ if ( N <= m_data.size() ) {
+ assert(0 && "Fake slot map emulated out of space");
+ return BAD_INDEX;
+ }
+
+ auto myIdx = m_nextIdx++;
+ m_data[myIdx] = T();
+ }
+
+ void free(WeakRef idx) {
+ m_data.erase(idx);
+ }
+
+ T& get(WeakRef idx) const {
+ assert( valid(idx) );
+ return m_data[idx];
+ }
+
+ T* tryGet(WeakRef idx) const {
+ if( valid(idx) ) {
+ return &m_data[idx];
+ }
+ return nullptr;
+ }
+
+ private:
+ std::map<WeakRef, T> m_data;
+ std::size_t m_nextIdx = 1;
+ };
+
+ template<typename T, std::size_t N>
+ using SlotMap = FakeSlotMap<T, N>;
+
} // namespace fggl::ds
#endif //FGGL_DS_PLACEHOLDER_HPP
--
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