Refactored to use strictly locals

frontend/document/documentregistry.lua

@@ -0,0 +1,35 @@
+--[[
+This is a registry for document providers
+]]--
+local DocumentRegistry = {
+	providers = { }
+}
+
+function DocumentRegistry:addProvider(extension, mimetype, provider)
+	table.insert(self.providers, { extension = extension, mimetype = mimetype, provider = provider })
+end
+
+function DocumentRegistry:getProvider(file)
+	-- TODO: some implementation based on mime types?
+	local extension = string.lower(string.match(file, ".+%.([^.]+)") or "")
+	for _, provider in ipairs(self.providers) do
+		if extension == provider.extension then
+			return provider.provider
+		end
+	end
+end
+
+function DocumentRegistry:openDocument(file)
+    local provider = self:getProvider(file)
+    if provider ~= nil then
+        return provider:new{file = file}
+    end
+end
+
+-- load implementations:
+
+require("document/pdfdocument"):register(DocumentRegistry)
+require("document/djvudocument"):register(DocumentRegistry)
+require("document/credocument"):register(DocumentRegistry)
+
+return DocumentRegistry