util/filters.lua
author Matthew Wild <mwild1@gmail.com>
Wed, 02 Jun 2010 17:23:57 +0100
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util.filters: Ensure initialize() never initializes an object twice - and return the filter function to the caller
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-- Prosody IM
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-- Copyright (C) 2008-2010 Matthew Wild
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-- Copyright (C) 2008-2010 Waqas Hussain
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-- 
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-- This project is MIT/X11 licensed. Please see the
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-- COPYING file in the source package for more information.
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--
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local t_insert, t_remove = table.insert, table.remove;
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module "filters"
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function initialize(session)
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	if not session.filters then
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		local filters = {};
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		session.filters = filters;
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		function session.filter(type, data)
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			local filter_list = filters[type];
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			if filter_list then
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				for i = 1, #filter_list do
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					data = filter_list[i](data);
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					if data == nil then break; end
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				end
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			end
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			return data;
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		end
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	end
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	return session.filter;
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end
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function add_filter(session, type, callback, priority)
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	if not session.filters then
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		initialize(session);
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	end
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	local filter_list = session.filters[type];
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	if not filter_list then
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		filter_list = {};
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		session.filters[type] = filter_list;
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	end
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	priority = priority or 0;
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	local i = 0;
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	repeat
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		i = i + 1;
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	until not filter_list[i] or filter_list[filter_list[i]] >= priority;
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	t_insert(filter_list, i, callback);
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	filter_list[callback] = priority;
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end
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function remove_filter(session, type, callback)
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	if not session.filters then return; end
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	local filter_list = session.filters[type];
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	if filter_list and filter_list[callback] then
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		for i=1, #filter_list do
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			if filter_list[i] == callback then
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				t_remove(filter_list, i);
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				filter_list[callback] = nil;
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				return true;
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			end
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		end
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	end
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end
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return _M;