1 files changed, 84 insertions, 0 deletions
diff --git a/acf2/util.lua b/acf2/util.lua
new file mode 100644
index 0000000..25e885b
--- /dev/null
+++ b/acf2/util.lua
@@ -0,0 +1,84 @@
+--- ACF2 utility functions.
+--
+-- @module acf2.util
+
+--[[
+Copyright (c) 2012-2013 Kaarle Ritvanen
+See LICENSE file for license details
+--]]
+
+
+local M = {}
+
+--- set default value for a key in a table unless it is already set.
+-- @param t the table
+-- @param k the key
+-- @param v the default value
+-- @return the value `t[k]`
+function M.setdefault(t, k, v)
+   if t[k] == nil then t[k] = v end
+   return t[k]
+end
+
+--- merge a table into another.
+-- Copy values for all keys from `src` to `dst` and optionally keep existing
+-- values.
+-- @param dst the destination table
+-- @param src the source table
+-- @param preserve a boolean. If true then will existing entries in `dst` be
+-- kept.
+-- @return the destination table, `dst`
+function M.update(dst, src, preserve)
+   for k, v in pairs(src) do
+      if not preserve or dst[k] == nil then dst[k] = v end
+   end
+   return dst
+end
+
+--- copy default vaules from one table to another.
+-- Copy all entries in `src` to `dst` but keep any already existing values
+-- in `dst`.
+-- @param dst the destination table
+-- @param src the source table containing the default values
+-- @return the destination table, `dst`
+function M.setdefaults(dst, src) return M.update(dst, src, true) end
+
+--- copy a varable.
+-- If `var` is a table, then the table is cloned, otherwise return the value
+-- of `var`.
+-- @param var the variable to copy
+-- @return a clone of `var`
+function M.copy(var)
+   return type(var) == 'table' and M.setdefaults({}, var) or var
+end
+
+--- extend an array.
+-- inserts all elements in `src` into `dst`
+-- @param dst the destination array
+-- @param src the source array
+-- @return the destination array, `dst`
+function M.extend(dst, src)
+   for _, v in ipairs(src) do table.insert(dst, v) end
+   return dst
+end
+
+--- extract the keys of a table as an array.
+-- @param tbl a table
+-- @return an array of keys
+function M.keys(tbl)
+   local res = {}
+   for k, v in pairs(tbl) do table.insert(res, k) end
+   return res
+end
+
+--- map a function over a table.
+-- @param func a function with one argument
+-- @param tbl the table
+-- @return the transformed table
+function M.map(func, tbl)
+   local res = {}
+   for k, v in pairs(tbl) do res[k] = func(v) end
+   return res
+end
+
+return M