added table library

1 files changed, 33 insertions, 0 deletions

diff --git a/table.lua b/table.lua
new file mode 100644
index 0000000..bb34f2f
--- /dev/null
+++ b/table.lua
@@ -0,0 +1,33 @@
+local M = {}
+
+-- shallow copies a table, dst optional.
+M.copy = function(src, dst)
+    dst = dst or {}
+    for k, v in pairs(src) do
+        dst[k] = v
+    end
+    return dst
+end
+
+-- recursively copies a table, dst optional.
+-- might implode for infinitely nested tables.
+M.deepcopy = function(src, dst)
+    dst = dst or {}
+    -- convenience.
+    if type(src) ~= "table" then return src end
+    for k, v in pairs(src) do
+        dst[k] = M.deepcopy(v)
+    end
+    return dst
+end
+
+-- replaces all values of a table with fn(value).
+M.map = function(fn, tbl)
+    local res = M.copy(tbl)
+    for k, v in pairs(tbl) do
+        res[k] = fn(v)
+    end
+    return res
+end
+
+return M