Introduce the abstract mode_lease mechanism to acquire and release slots.

include/ircd/mode_lease.h

@@ -0,0 +1,82 @@
+/*
+ * Copyright (C) 2016 Charybdis Development Team
+ * Copyright (C) 2016 Jason Volk <jason@zemos.net>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice is present in all copies.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+#define HAVE_IRCD_MODE_LEASE_H
+
+#ifdef __cplusplus
+namespace ircd  {
+
+template<class T,
+         mode_table<T> &table>
+class mode_lease
+{
+	using mask_t = typename mode_table<T>::mask_t;
+
+	char c = '\0';
+
+	virtual void release()                       { table[c] = { 0 };                               }
+
+  public:
+	explicit operator const char &() const       { return c;                                       }
+	operator const mask_t &() const              { return static_cast<const mask_t &>(table[c]);   }
+	bool operator!() const                       { return !c;                                      }
+
+	template<class... args> mode_lease(const char &c, args&&...);
+	mode_lease() = default;
+	mode_lease(mode_lease &&) noexcept;
+	mode_lease(const mode_lease &) = delete;
+	~mode_lease() noexcept;
+};
+
+template<class T,
+         mode_table<T> &table>
+template<class... args>
+mode_lease<T, table>::mode_lease(const char &c,
+                                 args&&... a)
+:c(c)
+{
+	if(!!table[c])
+		throw mode_filled("Character [%c] is already leased", c);
+
+	table[c] = { find_slot(table), std::forward<args>(a)... };
+}
+
+template<class T,
+         mode_table<T> &table>
+mode_lease<T, table>::mode_lease(mode_lease &&other)
+noexcept
+:c(other.c)
+{
+	other.c = '\0';
+}
+
+template<class T,
+         mode_table<T> &table>
+mode_lease<T, table>::~mode_lease()
+noexcept
+{
+	if(c)
+		release();
+}
+
+}      // namespace ircd
+#endif // __cplusplus

include/ircd/mode_table.h

@@ -25,6 +25,8 @@
 #ifdef __cplusplus
 namespace ircd  {
 
+IRCD_EXCEPTION(error, mode_filled)
+
 /* The mode_table is a generic template to replace the arrays mapping characters to mode flags
  * (or other structures) like `extern uint umode_table[256]` or `struct chm chmode_table[256]`.
  * Instead an `mode_table<uint>` or `mode_table<chm>` etc can be used.

include/ircd/stdinc.h

@@ -75,6 +75,7 @@ namespace ircd
 #include "s_assert.h"
 #include "match.h"
 #include "mode_table.h"
+#include "mode_lease.h"
 
 #include "cache.h"
 #include "whowas.h"