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@amix
Created January 31, 2015 13:01
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fixedlist implemented in Lua
-- List functions
--
--
LIST_DELIM = "~"
function list_add(key, value)
--- Determine the limit by inspecting if | is in the key
local limit = 200
if string.find(key, '|') then
local key_parts = _tokenize(key, '|')
limit = tonumber(key_parts[1])
key = key_parts[2]
end
local current_value = _get(key) or ''
--- Filter out values so we don't insert duplicates
local search_val = LIST_DELIM .. current_value
local values = _tokenize(value, LIST_DELIM)
local filtered = {}
for i=1, #values do
if not string.match(search_val, LIST_DELIM .. values[i] .. LIST_DELIM) then
table.insert(filtered, values[i])
end
end
--- Check if they are all duplicates
if #filtered == 0 then
return "ok"
end
values = filtered
--- Check if we should apply cleanup
local list_size = char_count(search_val, LIST_DELIM)
list_size = list_size + #values
if list_size > (limit + 100) then
local current_list = _current_list(current_value, nil)
_list_cleanup(key, current_list, limit, #values)
end
--- Append values at the end of the list
_putcat(key, value)
return "ok"
end
function list_remove(key, value)
local current_list = _get(key)
if not current_list then
return "ok"
end
local tokens = _tokenize(value, LIST_DELIM)
for i = 1, #tokens do
current_list = string.gsub(current_list, tokens[i] .. LIST_DELIM, "")
end
_put(key, current_list)
return "ok"
end
--
-- Helpers
--
function _tokenize(text, delims)
local tokens = {}
for token in string.gmatch(text, "[^" .. delims .. "]+") do
if #token > 0 then
table.insert(tokens, token)
end
end
return tokens
end
function _current_list(old_list, tokens)
if old_list then
if tokens then
for i = 1, #tokens do
old_list = string.gsub(old_list, "^" .. tokens[i] .. LIST_DELIM, "")
old_list = string.gsub(old_list, LIST_DELIM .. tokens[i] .. LIST_DELIM, LIST_DELIM)
end
end
return _tokenize(old_list, LIST_DELIM)
else
return {}
end
end
--- Deletes the first entries in the list
--- so there's only `limit` entires left in the list
function _list_cleanup(key, current_list, limit, new_items_size)
local current_size = #current_list + new_items_size
while current_size > limit do
--remove the first item
table.remove(current_list, 1)
current_size = current_size - 1
end
_list_store(key, current_list)
return current_size
end
function _list_store(key, list)
local result = table.concat(list, LIST_DELIM) .. LIST_DELIM
_put(key, result)
end
function char_count(str, char)
if not str then
return 0
end
local count = 0
local byte_char = string.byte(char)
for i = 1, #str do
if string.byte(str, i) == byte_char then
count = count + 1
end
end
return count
end
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