Lua Fragment Preprocessor Mockup

local fragments = {}

function load_fragment(location)
    location = location .. ".lua"

    local file = io.open(location, "r")

    if (file) then
        local frag_source = file:read("*all")

        fragments[location] = frag_source
        file:close()

        return frag_source
    end
end

function get_fragment(location)
    if (fragments[location]) then
        return fragments[location]
    else
        return load_fragment(location)
    end
end

function load_source(location)
    location = location .. ".lua"

    local file, err = io.open(location, "r")

    if (file) then
        local source = file:read("*all")

        for statement, fragment_location in source:gmatch("(--@include ([^\n]+))") do
            local fragment = get_fragment(fragment_location) or "--FRAGMENT '" .. fragment_location .. "' NOT FOUND"

            source = source:gsub(statement, fragment)
        end

        return source
    end
end