Coroutine-based serializer

serialize.lua

--[[
Copyright &copy; 2015 Charles "ChickenNuggers" Heywood <vandor2012@gmail.com>

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 function serialize_value(value, indent, seen, co)
    local t = type(value)
    if t == "string" then
        return string.format("%q", value)
    elseif t == "number" or t == "boolean" or t == "nil" then
        return tostring(value)
    elseif t == "table" then
        if seen[value] then
            error("Recursive table, found " .. tostring(value) .. " repeated")
        else
            seen[value] = true
        end
        if not next(value) then
            -- Simple, return {}
            co("{}")
        else
            seen_now = {}
            -- Not so simple
            co("{")
            for i=1, #value do
                seen_now[i] = true
                co("\n" .. indent .. serialize_value(value[i], indent .. "\t", seen, co) .. ",")
            end
                -- For some reason, won't match numbers past a non-nil
                -- :: TODO ::
            for i, v in ipairs(value) do
                if not seen_now[i] then
                    seen_now[i] = true
                    co("\n" .. indent .. "[" .. tostring(i) .. "] = " .. serialize_value(value[i], indent .. "\t", seen, co) .. ",")
                end
            end
            -- Now, force [] around non-[A-Za-z_][0-9A-Za-z_]* names
            for k, v in pairs(value) do
                if not seen_now[k] then
                    seen_now[k] = true
                    if not tonumber(k) and k:match("^[A-Za-z_][0-9A-Za-z_]*$") then
                        co("\n" .. indent .. k .. " = " .. serialize_value(value[k], indent .. "\t", seen, co) .. ",")
                    elseif tonumber(k) then
                        co("\n" .. indent .. "[" .. k .. "] = " .. serialize_value(value[k], indent .. "\t", seen, co) .. ",")
                    else
                        co("\n" .. indent .. "[" .. string.format("%q", k) .. "] = " .. serialize_value(value[k], indent .. "\t", seen, co) .. ",")
                    end
                end
            end
            co("\n" .. indent:sub(2) .. "}")
        end
    else
        return tostring(value)
    end
    -- finished with no issues
    return co(true)
end

local function serialize(tbl, callback, is_coroutinable, ...)
    local clbk
    if not is_coroutinable then
        clbk = coroutine.wrap(function()
            while true do
                callback(coroutine.yield())
            end
        end)
    else
        clbk = coroutine.wrap(callback)
    end
    clbk(...) -- for cases such as passing files
    -- return in case coroutine yields false
    return serialize_value(tbl, "\t", {}, clbk)
end

local function stringify()
    -- coroutine to create string from a table
    local retvals = {}
    -- don't need to actually create a new string each time
    -- just call table.concat() at the end
    while true do
        local cur_val = coroutine.yield()
        if cur_val == true then
            break
        end
        table.insert(retvals, cur_val)
    end
    -- table.concat() returned values
    coroutine.yield(table.concat(retvals))
end

local function simple(tbl)
    return serialize(tbl, stringify, true)
end

local function tofile(file, close)
    while true do
        local cur_val = coroutine.yield()
        if cur_val == true then
            break
        end
        file:write(cur_val)
    end
    if close then
        file:close()
    end
end

return {
    stringify = stringify;
    serialize = serialize;
    simple    = simple;
    file      = tofile;
}