From bc35e185e7b261a2302ecfcba9cf8942d87513b6 Mon Sep 17 00:00:00 2001
From: King_DuckZ <king_duckz@gmx.com>
Date: Thu, 18 Feb 2016 19:07:37 +0100
Subject: [PATCH] Import safe_ptr from Kakoune project

---
 include/kakoune/ref_ptr.hh  | 125 ++++++++++++++++++++++++++++++++++++
 include/kakoune/safe_ptr.hh |  95 +++++++++++++++++++++++++++
 2 files changed, 220 insertions(+)
 create mode 100644 include/kakoune/ref_ptr.hh
 create mode 100644 include/kakoune/safe_ptr.hh

diff --git a/include/kakoune/ref_ptr.hh b/include/kakoune/ref_ptr.hh
new file mode 100644
index 0000000..a061cff
--- /dev/null
+++ b/include/kakoune/ref_ptr.hh
@@ -0,0 +1,125 @@
+#ifndef ref_ptr_hh_INCLUDED
+#define ref_ptr_hh_INCLUDED
+
+#include <utility>
+
+namespace Kakoune
+{
+
+struct WorstMatch { [[gnu::always_inline]] WorstMatch(...) {} };
+
+[[gnu::always_inline]]
+inline void ref_ptr_moved(WorstMatch, void*, void*) noexcept {}
+
+template<typename T, typename TForOverload = T>
+struct RefPtr
+{
+    RefPtr() = default;
+    explicit RefPtr(T* ptr) : m_ptr(ptr) { acquire(); }
+    ~RefPtr() { release(); }
+    RefPtr(const RefPtr& other) : m_ptr(other.m_ptr) { acquire(); }
+    RefPtr(RefPtr&& other)
+        noexcept(noexcept(std::declval<RefPtr>().moved(nullptr)))
+        : m_ptr(other.m_ptr) { other.m_ptr = nullptr; moved(&other); }
+
+    RefPtr& operator=(const RefPtr& other)
+    {
+        if (other.m_ptr != m_ptr)
+        {
+            release();
+            m_ptr = other.m_ptr;
+            acquire();
+        }
+        return *this;
+    }
+
+    RefPtr& operator=(RefPtr&& other)
+    {
+        release();
+        m_ptr = other.m_ptr;
+        other.m_ptr = nullptr;
+        moved(&other);
+        return *this;
+    }
+
+    RefPtr& operator=(T* ptr)
+    {
+        if (ptr != m_ptr)
+        {
+            release();
+            m_ptr = ptr;
+            acquire();
+        }
+        return *this;
+    }
+
+    [[gnu::always_inline]]
+    T* operator->() const { return m_ptr; }
+    [[gnu::always_inline]]
+    T& operator*() const { return *m_ptr; }
+
+    [[gnu::always_inline]]
+    T* get() const { return m_ptr; }
+
+    [[gnu::always_inline]]
+    explicit operator bool() const { return m_ptr; }
+
+    void reset(T* ptr = nullptr)
+    {
+        if (ptr == m_ptr)
+            return;
+        release();
+        m_ptr = ptr;
+        acquire();
+    }
+
+    friend bool operator==(const RefPtr& lhs, const RefPtr& rhs) { return lhs.m_ptr == rhs.m_ptr; }
+    friend bool operator!=(const RefPtr& lhs, const RefPtr& rhs) { return lhs.m_ptr != rhs.m_ptr; }
+
+private:
+    T* m_ptr = nullptr;
+
+    [[gnu::always_inline]]
+    void acquire()
+    {
+        if (m_ptr)
+            inc_ref_count(static_cast<TForOverload*>(m_ptr), this);
+    }
+
+    [[gnu::always_inline]]
+    void release()
+    {
+        if (m_ptr)
+            dec_ref_count(static_cast<TForOverload*>(m_ptr), this);
+        m_ptr = nullptr;
+    }
+
+    [[gnu::always_inline]]
+    void moved(void* from)
+        noexcept(noexcept(ref_ptr_moved(static_cast<TForOverload*>(nullptr), nullptr, nullptr)))
+    {
+        if (m_ptr)
+            ref_ptr_moved(static_cast<TForOverload*>(m_ptr), from, this);
+    }
+};
+
+struct RefCountable
+{
+    int refcount = 0;
+    virtual ~RefCountable() = default;
+
+    friend void inc_ref_count(RefCountable* r, void*)
+    {
+        ++r->refcount;
+    }
+
+    friend void dec_ref_count(RefCountable* r, void*)
+    {
+        if (--r->refcount == 0)
+            delete r;
+    }
+};
+
+}
+
+#endif // ref_ptr_hh_INCLUDED
diff --git a/include/kakoune/safe_ptr.hh b/include/kakoune/safe_ptr.hh
new file mode 100644
index 0000000..12a9b4a
--- /dev/null
+++ b/include/kakoune/safe_ptr.hh
@@ -0,0 +1,95 @@
+#ifndef safe_ptr_hh_INCLUDED
+#define safe_ptr_hh_INCLUDED
+
+// #define SAFE_PTR_TRACK_CALLSTACKS
+
+#include "assert.hh"
+#include "ref_ptr.hh"
+#include "backtrace.hh"
+
+#include <type_traits>
+#include <utility>
+
+#ifdef SAFE_PTR_TRACK_CALLSTACKS
+#include "vector.hh"
+#include <algorithm>
+#endif
+
+namespace Kakoune
+{
+
+// *** SafePtr: objects that assert nobody references them when they die ***
+
+class SafeCountable
+{
+public:
+#ifdef KAK_DEBUG
+    SafeCountable() : m_count(0) {}
+    ~SafeCountable()
+    {
+        kak_assert(m_count == 0);
+        #ifdef SAFE_PTR_TRACK_CALLSTACKS
+        kak_assert(m_callstacks.empty());
+        #endif
+    }
+
+    friend void inc_ref_count(const SafeCountable* sc, void* ptr)
+    {
+        ++sc->m_count;
+        #ifdef SAFE_PTR_TRACK_CALLSTACKS
+        sc->m_callstacks.emplace_back(ptr);
+        #endif
+    }
+
+    friend void dec_ref_count(const SafeCountable* sc, void* ptr)
+    {
+        --sc->m_count;
+        kak_assert(sc->m_count >= 0);
+        #ifdef SAFE_PTR_TRACK_CALLSTACKS
+        auto it = std::find_if(sc->m_callstacks.begin(), sc->m_callstacks.end(),
+                               [=](const Callstack& cs) { return cs.ptr == ptr; });
+        kak_assert(it != sc->m_callstacks.end());
+        sc->m_callstacks.erase(it);
+        #endif
+    }
+
+    friend void ref_ptr_moved(const SafeCountable* sc, void* from, void* to)
+    {
+        #ifdef SAFE_PTR_TRACK_CALLSTACKS
+        auto it = std::find_if(sc->m_callstacks.begin(), sc->m_callstacks.end(),
+                               [=](const Callstack& cs) { return cs.ptr == from; });
+        kak_assert(it != sc->m_callstacks.end());
+        it->ptr = to;
+        #endif
+    }
+
+private:
+    #ifdef SAFE_PTR_TRACK_CALLSTACKS
+    struct Callstack
+    {
+        Callstack(void* p) : ptr(p) {}
+        void* ptr;
+        Backtrace bt;
+    };
+
+    mutable Vector<Callstack> m_callstacks;
+    #endif
+    mutable int m_count;
+#else
+    [[gnu::always_inline]]
+    friend void inc_ref_count(const SafeCountable* sc, void* ptr) {}
+
+    [[gnu::always_inline]]
+    friend void dec_ref_count(const SafeCountable* sc, void* ptr) {}
+#endif
+};
+
+template<typename T, typename U>
+using PropagateConst = typename std::conditional<std::is_const<T>::value, const U, U>::type;
+
+template<typename T>
+using SafePtr = RefPtr<T, PropagateConst<T, SafeCountable>>;
+
+}
+
+#endif // safe_ptr_hh_INCLUDED