Rewrite

test/ser.lua

@@ -0,0 +1,143 @@
+--[[
+Copyright (c) 2011,2013 Robin Wellner
+
+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.
+]]
+
+local pairs, ipairs, tostring, type, concat, dump, floor, format = pairs, ipairs, tostring, type, table.concat, string.dump, math.floor, string.format
+
+local function getchr(c)
+	return "\\" .. c:byte()
+end
+
+local function make_safe(text)
+	return ("%q"):format(text):gsub('\n', 'n'):gsub("[\128-\255]", getchr)
+end
+
+local oddvals = {[tostring(1/0)] = '1/0', [tostring(-1/0)] = '-1/0', [tostring(-(0/0))] = '-(0/0)', [tostring(0/0)] = '0/0'}
+local function write(t, memo, rev_memo)
+	local ty = type(t)
+	if ty == 'number' then
+		t = format("%.17g", t)
+		return oddvals[t] or t
+	elseif ty == 'boolean' or ty == 'nil' then
+		return tostring(t)
+	elseif ty == 'string' then
+		return make_safe(t)
+	elseif ty == 'table' or ty == 'function' then
+		if not memo[t] then
+			local index = #rev_memo + 1
+			memo[t] = index
+			rev_memo[index] = t
+		end
+		return '_[' .. memo[t] .. ']'
+	else
+		error("Trying to serialize unsupported type " .. ty)
+	end
+end
+
+local kw = {['and'] = true, ['break'] = true, ['do'] = true, ['else'] = true,
+	['elseif'] = true, ['end'] = true, ['false'] = true, ['for'] = true,
+	['function'] = true, ['goto'] = true, ['if'] = true, ['in'] = true,
+	['local'] = true, ['nil'] = true, ['not'] = true, ['or'] = true,
+	['repeat'] = true, ['return'] = true, ['then'] = true, ['true'] = true,
+	['until'] = true, ['while'] = true}
+local function write_key_value_pair(k, v, memo, rev_memo, name)
+	if type(k) == 'string' and k:match '^[_%a][_%w]*$' and not kw[k] then
+		return (name and name .. '.' or '') .. k ..'=' .. write(v, memo, rev_memo)
+	else
+		return (name or '') .. '[' .. write(k, memo, rev_memo) .. ']=' .. write(v, memo, rev_memo)
+	end
+end
+
+-- fun fact: this function is not perfect
+-- it has a few false positives sometimes
+-- but no false negatives, so that's good
+local function is_cyclic(memo, sub, super)
+	local m = memo[sub]
+	local p = memo[super]
+	return m and p and m < p
+end
+
+local function write_table_ex(t, memo, rev_memo, srefs, name)
+	if type(t) == 'function' then
+		return '_[' .. name .. ']=loadstring' .. make_safe(dump(t))
+	end
+	local m = {}
+	local mi = 1
+	for i = 1, #t do -- don't use ipairs here, we need the gaps
+		local v = t[i]
+		if v == t or is_cyclic(memo, v, t) then
+			srefs[#srefs + 1] = {name, i, v}
+			m[mi] = 'nil'
+			mi = mi + 1
+		else
+			m[mi] = write(v, memo, rev_memo)
+			mi = mi + 1
+		end
+	end
+	for k,v in pairs(t) do
+		if type(k) ~= 'number' or floor(k) ~= k or k < 1 or k > #t then
+			if v == t or k == t or is_cyclic(memo, v, t) or is_cyclic(memo, k, t) then
+				srefs[#srefs + 1] = {name, k, v}
+			else
+				m[mi] = write_key_value_pair(k, v, memo, rev_memo)
+				mi = mi + 1
+			end
+		end
+	end
+	return '_[' .. name .. ']={' .. concat(m, ',') .. '}'
+end
+
+return function(t)
+	local memo = {[t] = 0}
+	local rev_memo = {[0] = t}
+	local srefs = {}
+	local result = {}
+
+	-- phase 1: recursively descend the table structure
+	local n = 0
+	while rev_memo[n] do
+		result[n + 1] = write_table_ex(rev_memo[n], memo, rev_memo, srefs, n)
+		n = n + 1
+	end
+
+	-- phase 2: reverse order
+	for i = 1, n*.5 do
+		local j = n - i + 1
+		result[i], result[j] = result[j], result[i]
+	end
+
+	-- phase 3: add all the tricky cyclic stuff
+	for i, v in ipairs(srefs) do
+		n = n + 1
+		result[n] = write_key_value_pair(v[2], v[3], memo, rev_memo, '_[' .. v[1] .. ']')
+	end
+
+	-- phase 4: add something about returning the main table
+	if result[n]:sub(1, 5) == '_[0]=' then
+		result[n] = 'return ' .. result[n]:sub(6)
+	else
+		result[n + 1] = 'return _[0]'
+	end
+
+	-- phase 5: just concatenate everything
+	result = concat(result, '\n')
+	return n > 1 and 'local _={}\n' .. result or result
+end