From b9e07c61f309bceef47b073b4c008016afa7793e Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Mon, 11 May 2020 19:35:03 +1000
Subject: [PATCH] AP_Common: added TSIndex.h

---
 libraries/AP_Common/TSIndex.h | 113 ++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 libraries/AP_Common/TSIndex.h

diff --git a/libraries/AP_Common/TSIndex.h b/libraries/AP_Common/TSIndex.h
new file mode 100644
index 0000000000..09b7a0ca8c
--- /dev/null
+++ b/libraries/AP_Common/TSIndex.h
@@ -0,0 +1,113 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define DECLARE_TYPESAFE_INDEX(NAME, TYPE) typedef typesafe_index<TYPE, class TAG_##NAME> NAME
+
+/// This template allows for indexing with compile time check and generating
+/// error for using one index variable for another array that is to be indexed
+/// with different variable.
+/// base_type specifies
+///
+/// @param  base_type      Base integral type
+///
+/// @param tag             Tag Name to prevent copy from one type to other
+///
+template <class base_type, class tag> class typesafe_index
+{
+public:
+    explicit typesafe_index(base_type i = base_type()) : p(i) {}
+
+    void operator=(const base_type& val)
+    {
+        p = val;
+    }
+
+    constexpr base_type get_int() const
+    {
+        return p;
+    }
+
+    typesafe_index operator++()
+    {
+        return typesafe_index(++p);
+    }
+
+    typesafe_index operator++(int)
+    {
+        return typesafe_index(p++);
+    }
+
+    bool operator<(const base_type& val) const
+    {
+        return (p<val);
+    }
+
+    bool operator<=(const base_type& val) const
+    {
+        return (p<=val);
+    }
+
+    bool operator>=(const base_type& val) const
+    {
+        return (p>=val);
+    }
+
+
+    bool operator>(const base_type& val) const
+    {
+        return (p>val);
+    }
+
+    bool operator!=(const base_type& val) const
+    {
+        return (p!=val);
+    }
+
+    bool operator==(const base_type& val) const
+    {
+        return (p==val);
+    }
+
+    explicit constexpr operator base_type() const
+    {
+        return p;
+    }
+
+    typesafe_index operator+(const base_type& val) const
+    {
+        return typesafe_index(p+val);
+    }
+private:
+    base_type p;
+};
+
+/// This template associates the the base_type array with accessor_type(index).
+/// So the elements can be accessed using [] only using accessor_type index
+/// _priv_instance is kept public for use in Parameter declaration.
+///
+template <class base_type, uint32_t num_instances, typename accessor_type> class RestrictIDTypeArray
+{
+public:
+    base_type _priv_instance[num_instances];
+    base_type& operator[](const accessor_type& index)
+    {
+        return _priv_instance[index.get_int()];
+    }
+
+    constexpr const base_type& operator[](const accessor_type& index) const
+    {
+        return _priv_instance[index.get_int()];
+    }
+};
\ No newline at end of file