adjust file metatables even in compat53.module mode (#67)

* adjust file metatables even in compat53.module mode

* apply tweaks only to LuaJIT; file:write() only to compat=none

1 files changed, 71 insertions, 0 deletions

diff --git a/compat53/file_mt.lua b/compat53/file_mt.lua
new file mode 100644
index 0000000..6433619
--- /dev/null
+++ b/compat53/file_mt.lua
@@ -0,0 +1,71 @@
+local lua_version = _VERSION:sub(-3)
+
+local M = {}
+
+local unpack = lua_version == "5.1" and unpack or table.unpack
+
+local function addasterisk(fmt)
+   if type(fmt) == "string" and fmt:sub(1, 1) ~= "*" then
+      return "*"..fmt
+   else
+      return fmt
+   end
+end
+
+function M.update_file_meta(file_meta, is_luajit52)
+
+   -- make '*' optional for file:read and file:lines
+
+   local file_lines = file_meta.__index.lines
+   file_meta.__index.lines = function(self, ...)
+      local n = select('#', ...)
+      for i = 1, n do
+         local a = select(i, ...)
+         local b = addasterisk(a)
+         -- as an optimization we only allocate a table for the
+         -- modified format arguments when we have a '*' somewhere
+         if a ~= b then
+            local args = { ... }
+            args[i] = b
+            for j = i+1, n do
+               args[j] = addasterisk(args[j])
+            end
+            return file_lines(self, unpack(args, 1, n))
+         end
+      end
+      return file_lines(self, ...)
+   end
+
+   local file_read = file_meta.__index.read
+   file_meta.__index.read = function(self, ...)
+      local n = select('#', ...)
+      for i = 1, n do
+         local a = select(i, ...)
+         local b = addasterisk(a)
+         -- as an optimization we only allocate a table for the
+         -- modified format arguments when we have a '*' somewhere
+         if a ~= b then
+            local args = { ... }
+            args[i] = b
+            for j = i+1, n do
+               args[j] = addasterisk(args[j])
+            end
+            return file_read(self, unpack(args, 1, n))
+         end
+      end
+      return file_read(self, ...)
+   end
+
+   if not is_luajit52 then
+      local file_write = file_meta.__index.write
+      file_meta.__index.write = function(self, ...)
+         local ret, err = file_write(self, ...)
+         if ret then
+            return self
+         end
+         return ret, err
+      end
+   end
+end
+
+return M