Merge pull request #942 from grilledham/locale_builder

Locale builder

utils/locale_builder.lua

@@ -0,0 +1,94 @@
+local type = type
+local tostring = tostring
+local setmetatable = setmetatable
+local getmetatable = getmetatable
+
+--- Helper class for concatenating LocalisedStrings / strings.
+-- strings and LocalisedStrings can be combined in any order.
+-- Multiple calls to add will automatically split the LocalisedStrings into a linked list
+-- when needed to prevent exceeding 20 parameter limit imposed by Factorio.
+-- However, if you pass in LocalisedStrings that exceeds 20 parameters then it will fail.
+--
+-- @usage
+--  LocaleBuilder = require 'utils.locale_builder'
+--
+--  local locale_string = LocaleBuilder({'common.fail_no_target', 'player_name'})
+--      :add({'', '- a literal string'})
+--      :add('- short hand for literal string')
+--      :add(3):add(true) -- also works if convertable to string
+--
+-- Or construct multiple LocalisedStrings in parts and combine them.
+-- local part1 = {'', 'part', ' ', 'one'}
+-- local part2 = LocaleBuilder('part'):add(' '):add('two')
+-- local part3 = LocaleBuilder('part'):add(' '):add('three')
+--
+-- local result = LocaleBuilder(part1):add(part2):add(part3)
+--
+-- If you store the LocalisedStrings in global, when you fetch from global you need to restore
+-- the metatable to be able to use :add calls. To do that use
+-- LocaleBuilder(global.stored_locale_string)
+local Public = {}
+
+local add
+
+local function set_tail(self, tail)
+    local mt = getmetatable(self)
+    mt.tail = tail
+end
+
+local function new(obj)
+    local mt = {add = add, tail = nil}
+    mt.__index = mt
+
+    return setmetatable(obj, mt)
+end
+
+local function localise(item)
+    local t = type(item)
+    if t == 'table' then
+        return item
+    elseif t == 'string' then
+        return {'', item}
+    else
+        return {'', tostring(item)}
+    end
+end
+
+function add(self, item)
+    if not item then
+        item = self
+        self = nil
+    end
+
+    item = localise(item)
+
+    if not self then
+        return new(item)
+    end
+
+    local tail = self.tail
+    if not tail then
+        tail = {'', self}
+        self = new(tail)
+        set_tail(self, tail)
+    end
+
+    local count = #tail
+    if count < 20 then
+        tail[count + 1] = item
+    else
+        local new_tail = {'', item}
+        tail[count + 1] = new_tail
+        set_tail(self, new_tail)
+    end
+
+    return self
+end
+
+Public.add = add
+function Public.__call(_, item)
+    return add(nil, item)
+end
+setmetatable(Public, Public)
+
+return Public