Initial import from SVN

scripts/lua/modules/persistence.lua

@@ -0,0 +1,209 @@
+-- Internal persistence library
+
+--[[ Provides ]]
+-- persistence.store(path, ...): Stores arbitrary items to the file at the given path
+-- persistence.load(path): Loads files that were previously stored with store and returns them
+
+--[[ Limitations ]]
+-- Does not export userdata, threads or most function values
+-- Function export is not portable
+
+--[[ License: MIT (see bottom) ]]
+
+-- Private methods
+local write, writeIndent, writers, refCount;
+
+persistence =
+{
+	store = function (path, ...)
+		local file, e;
+		if type(path) == "string" then
+			-- Path, open a file
+			file, e = io.open(path, "w");
+			if not file then
+				return error(e);
+			end
+		else
+			-- Just treat it as file
+			file = path;
+		end
+		local n = select("#", ...);
+		-- Count references
+		local objRefCount = {}; -- Stores reference that will be exported
+		for i = 1, n do
+			refCount(objRefCount, (select(i,...)));
+		end;
+		-- Export Objects with more than one ref and assign name
+		-- First, create empty tables for each
+		local objRefNames = {};
+		local objRefIdx = 0;
+		file:write("-- Persistent Data\n");
+		file:write("local multiRefObjects = {\n");
+		for obj, count in pairs(objRefCount) do
+			if count > 1 then
+				objRefIdx = objRefIdx + 1;
+				objRefNames[obj] = objRefIdx;
+				file:write("{};"); -- table objRefIdx
+			end;
+		end;
+		file:write("\n} -- multiRefObjects\n");
+		-- Then fill them (this requires all empty multiRefObjects to exist)
+		for obj, idx in pairs(objRefNames) do
+			for k, v in pairs(obj) do
+				file:write("multiRefObjects["..idx.."][");
+				write(file, k, 0, objRefNames);
+				file:write("] = ");
+				write(file, v, 0, objRefNames);
+				file:write(";\n");
+			end;
+		end;
+		-- Create the remaining objects
+		for i = 1, n do
+			file:write("local ".."obj"..i.." = ");
+			write(file, (select(i,...)), 0, objRefNames);
+			file:write("\n");
+		end
+		-- Return them
+		if n > 0 then
+			file:write("return obj1");
+			for i = 2, n do
+				file:write(" ,obj"..i);
+			end;
+			file:write("\n");
+		else
+			file:write("return\n");
+		end;
+		file:close();
+	end;
+
+	load = function (path)
+		local f, e = loadfile(path);
+		if f then
+			return f();
+		else
+			return nil, e;
+		end;
+	end;
+}
+
+-- Private methods
+
+-- write thing (dispatcher)
+write = function (file, item, level, objRefNames)
+	writers[type(item)](file, item, level, objRefNames);
+end;
+
+-- write indent
+writeIndent = function (file, level)
+	for i = 1, level do
+		file:write("\t");
+	end;
+end;
+
+-- recursively count references
+refCount = function (objRefCount, item)
+	-- only count reference types (tables)
+	if type(item) == "table" then
+		-- Increase ref count
+		if objRefCount[item] then
+			objRefCount[item] = objRefCount[item] + 1;
+		else
+			objRefCount[item] = 1;
+			-- If first encounter, traverse
+			for k, v in pairs(item) do
+				refCount(objRefCount, k);
+				refCount(objRefCount, v);
+			end;
+		end;
+	end;
+end;
+
+-- Format items for the purpose of restoring
+writers = {
+	["nil"] = function (file, item)
+			file:write("nil");
+		end;
+	["number"] = function (file, item)
+			file:write(tostring(item));
+		end;
+	["string"] = function (file, item)
+			file:write(string.format("%q", item));
+		end;
+	["boolean"] = function (file, item)
+			if item then
+				file:write("true");
+			else
+				file:write("false");
+			end
+		end;
+	["table"] = function (file, item, level, objRefNames)
+			local refIdx = objRefNames[item];
+			if refIdx then
+				-- Table with multiple references
+				file:write("multiRefObjects["..refIdx.."]");
+			else
+				-- Single use table
+				file:write("{\n");
+				for k, v in pairs(item) do
+					writeIndent(file, level+1);
+					file:write("[");
+					write(file, k, level+1, objRefNames);
+					file:write("] = ");
+					write(file, v, level+1, objRefNames);
+					file:write(";\n");
+				end
+				writeIndent(file, level);
+				file:write("}");
+			end;
+		end;
+	["function"] = function (file, item)
+			-- Does only work for "normal" functions, not those
+			-- with upvalues or c functions
+			local dInfo = debug.getinfo(item, "uS");
+			if dInfo.nups > 0 then
+				file:write("nil --[[functions with upvalue not supported]]");
+			elseif dInfo.what ~= "Lua" then
+				file:write("nil --[[non-lua function not supported]]");
+			else
+				local r, s = pcall(string.dump,item);
+				if r then
+					file:write(string.format("loadstring(%q)", s));
+				else
+					file:write("nil --[[function could not be dumped]]");
+				end
+			end
+		end;
+	["thread"] = function (file, item)
+			file:write("nil --[[thread]]\n");
+		end;
+	["userdata"] = function (file, item)
+			file:write("nil --[[userdata]]\n");
+		end;
+}
+
+return persistence
+
+--[[
+ Copyright (c) 2010 Gerhard Roethlin
+
+ Permission is hereby granted, free of charge, to any person
+ obtaining a copy of this software and associated documentation
+ files (the "Software"), to deal in the Software without
+ restriction, including without limitation the rights to use,
+ copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the
+ Software is furnished to do so, subject to the following
+ conditions:
+
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ OTHER DEALINGS IN THE SOFTWARE.
+]]