Combining two repos

luprex/core/cpp/luasnap.hpp

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+////////////////////////////////////////////////////////////
+//
+// LUASNAP
+//
+// A lua interpreter that can be checkpointed (snapshotted).
+// This makes it possible to roll the entire interpreter back
+// to a previously-snapshotted state.
+//
+// To accomplish this, we take advantage of the 'allocf' parameter
+// to lua_newstate.  This lets us hook the lua allocator, which
+// in turn lets us find every block of memory currently in use by
+// lua.  To snapshot, we 'memcpy' every block of memory
+// that lua is using into a buffer.  To rollback, we just 'memcpy'
+// the data back.
+//
+// The current implementation is a proof-of-concept.  It's quite
+// wasteful of memory, roughly doubling the amount of RAM that
+// LUA uses. But it does demonstrate that this method of snapshot
+// and rollback is feasible.
+//
+////////////////////////////////////////////////////////////
+
+#ifndef LUASNAP_HPP
+#define LUASNAP_HPP
+
+#include "luastack.hpp"
+
+class LuaSnapData;
+class LuaSnap {
+private:
+    lua_State *state_;
+    LuaSnapData *data_;
+    
+public:
+    LuaSnap();
+    ~LuaSnap();
+
+    // Get the lua intepreter.
+    //
+    lua_State *state() const { return state_; }
+
+    // Return true if there's a saved snapshot.
+    //
+    bool have_snapshot() const;
+
+    // snapshot the state of the lua interpreter.
+    //
+    // If there is already a snapshot, this panics.
+    //
+    void snapshot();
+
+    // Rollback the lua intepreter to the snapshotted state.
+    //
+    // If there is no snapshot, this panics.
+    //
+    void rollback();
+};
+
+
+#endif // LUASNAP_HPP