Lua require relative path fix

require.lua

local realRequire = require;

local function get_source_dir()

    local up = debug.getinfo(3).source:gsub("\\", "/");
    if up:sub(1, 1) ~= '@' then
        return realRequire(name);
    end
    up = up:sub(2)

    local sep_index = find_sep(up);
    if sep_index ~= 0 then
        return up:sub(1, sep_index)
    end

    return
end

local function find_sep(s)
    local sep_index = 0;
    local _s = 1
    while _s do
        _s = s:find("/", _s)
        if _s then
            sep_index = _s;
            _s = _s + 1
        else
            break
        end
    end

    return sep_index
end

local function relative_require(name)
    -- fix relative path
    if name:sub(1, 1) == '.' then
        local _name = name:gsub("\\", "/");
        local rela_path = _name:match("^[./]+")
        local short_name = _name:sub(#rela_path + 1)

        local source_dir = get_source_dir()

        local old_ppath = package.path;
        if source_dir then
            local pdir = (source_dir .. "/" .. rela_path .. "/"):gsub("//", "/")

            package.path = pdir .. "?.lua;" .. pdir .. "?/init.lua;" .. package.path
        end
        local ret = realRequire(short_name)
        package.path = old_ppath;
        return ret;
    else
        return realRequire(name)
    end
end

function require(name)
    if not name or #name == 0 then
        return realRequire(name)
    end

    return relative_require(name)
end